I was recently reading an article (http://slowboat.com/2018/07/trusting-your-sources/) on Slow Boat regarding trusting your sources that highlighted the author’s experience in navigating into a small anchorage in Southeast Alaska. The article is a good read and the topic of knowing the source for your navigation data is an important one that I will definitely address in a future post. However, this post is more about an issue that they pose in their article and which I’ve seen plenty of confusion on it the past.
As the title may suggest, that is the scale of the chart they are using. Scale is a very important, though often misunderstood aspect of any nautical chart. I attempted to post a reply to their article discussion regarding, but it never appeared (probably through my inept use of their comment system, that required me to create a login and wasn’t the most intuitive). In their article they state the following:
The charts are…just wrong. As we mentioned before, the NOAA raster chart is the source for both Garmin and Navionics, and the errors in the NOAA chart show up in both. The east entrance is actually a disaster – super shallow due to reefs and eelgrass growing up to the surface. The west entrance, on the other hand, has a nice wide-enough channel in a straight line with a depth of over 9 feet at zero tide.
They are referring to the charted small bay below, which I would agree is not the best depiction of the actual bay, which is pictured underneath the chartlet. However, the NOAA chart is not wrong, it is simply the wrong scale to be used for navigating into this harbor. The chart symbols for ledge happen to be larger than the width of the opening at the scale of the chart and as such they intersect. This chart was never intended to be used for safe navigation into the back of Vixen Harbor. A chart suitable for navigating such a small bay would need to be a much larger scale and, given the extremely light traffic that will be using this cove, it is extremely unlikely that NOAA would invest in creating a chart for this area at a 1:5,000 scale.
The scale of their chart is something that most recreational boaters very rarely take into consideration. It’s very easy to forget that the chart data has a scale when you’re using electronic chart plotters; indeed many professional mariners fall into this trap as well. Just because you can zoom into 1:500 scale, doesn’t mean the chart data will support it. More than likely, that data was collected at a scale of 1:10,000 and the chart was compiled at 1:40,000. A rock symbol on a chart is about 4mm (1/8-in) when printed; that means that at a scale of 1:40,000 that’s equivalent to 160-m (525-ft)…that’s twice the length of the ship I sailed on. Even at 1:10,000 that’s a rock that’s 40-m (130-ft). That’s a point feature that could actually be 1-m in reality; one rock symbol could encompass several rocks.
In fact, if you consult the source data for the chart, the surveys of Vixen Harbor do indeed depict the area similar to how the describe it in the article. Both the smooth sheet sounding plot from Survey H09287 (completed in 1972) and the Bathy Attributed Grid (BAG) from Survey H11824 (completed in 2009) show a relatively deep channel with ledge on either side. However, when you down-sample that date and compile the chart at a smaller scale, this detail gets lost.
These surveys are available for download to the general public from NOAA’s National Geophysical Data Center (NGDC) website (click on the image above to be linked to the respective survey information page), as are all NOAA surveys. If you are planning on anchoring in small bays and have no local knowledge of them, I would encourage you to download the surveys of the area to get a more detailed picture of the bathymetry. They NGDC website provides a fairly easy to use graphical user interface, which allows you to select a point of interest and pull up links directly to the downloadable data for those areas:
Additionally, this article is critical of some cruising guide information, but notes that some other cruising guides provided better information that accurately described the entrance channel. They mention the US Coast Pilot, which is an official NOAA publication, only in passing as it is sited in these other cruising guides, but do not provide the full passage from the Coast Pilot. In the Coast Pilot you will find the following regarding Vixen Harbor:
Vixen Harbor 0.8 mile east of Union Point, is about 0.4 mile long, with an even sand and mud bottom and an average depth of 4½ fathoms. The entrance channel, about 100 yards wide, has depths of only 2 fathoms. In entering, proceed carefully to the north of and close to the small islands in the entrance. Temporary anchorage for larger craft may be had in 16 fathoms, sand and gravel, 0.4 mile north of the small island in the entrance.
The Coast Pilot is intended as a supplement to the nautical chart, which provides information on areas that is not easily depicted on the chart. The Coast Pilot can be dry and general in its descriptions, but utilizing the chart without consulting the Coast Pilot is only getting part of the picture. In this case, they take issue with the stated width and minimum depth in the passage of the Coast Pilot, but both values given were fairly close to those observed. The Coast Pilot does correctly indicate that the channel to enter the bay is to the north of the islands.
I’m really not trying to beat up the people that wrote this article, but their thought process of “the chart is wrong” is indicative of the perception of a lot of mariners. I am hoping that this post will help you understand how the data on the charts is compiled, its limitations, and how you might get a more complete picture of an area. This is not to say that there aren’t errors on NOAA charts; I have found plenty. If you find one, NOAA would love to know about it. You can submit a chart discrepancy report via the “Report an Error” tab on the NOAA customer service website (https://www.nauticalcharts.noaa.gov/customer-service/assist/), but before you do, make sure that you have checked the source information thoroughly and provide as much supporting information as possible.
Until next time, here’s wishing you fair winds and following seas.
With the recent tsunami in Indonesia that occurred on 23-Dec-2018 I’ve seen a lot of speculation on the state of the tsunami warning system and how it works. I thought I might address some of this on my blog as I spent about 4 years working at NOAA’s Pacific Marine Environmental Laboratory (PMEL) in the Engineering Division that designed the tsunami buoys and am intimately familiar with how they operate. I worked with many of the scientists and engineers that developed the first deep ocean moorings, which is a feet unto itself, and pioneered the tsunameter (they invented the word).
The only true tsunami warning systems in place are based on technologies developed at PMEL); specifically the DART (Deep-ocean Assessment and Reporting of Tsunamis) buoys. The technology was spearheaded by Dr. Eddie Bernard, the current Director of PMEL, who began the project in the late 1970s. The system isn’t really a “warning system” that detects the tsunami and sets off an alarm; although the buoys can do that, that isn’t really their intended purpose. Instead they act as a large sensor network that supplies data to models for more accurate forecasting.
In 2004 when the Indian Ocean Tsunami occurred there were only 6 DART buoys deployed in the Pacific; within 4-years the buoy network had expanded to 39 DART buoys and now includes buoys in the Pacific, Indian, and Atlantic Oceans. As you can see from the plot, buoys are now owned and operated by 8 different countries, but all are the same patented DART buoy developed at PMEL.
The earthquake would be first detected and registered by USGS and that information will be relayed to a Tsunami Warning Center (TWC). You can view near real-time information about detected earthquakes at the USGS website (Latest Earthquakes). That information will be entered into the models, which will indicate whether a tsunami could be generated and how it will likely propagate from the source. While that gives you a decent idea of whether a tsunami was generated and when it will arrive at various places on the other side of the ocean, it does not provide enough information to forecast the size of the tsunami or how many waves or how long an event it will be.
This is where the DART buoys come into the picture as they can provide additional data to be fed into the models and refine the forecast of the tsunami. I won’t go into detail on how the buoys work here, but I will likely put together a post on that topic later. Suffice to say that they can detect a tsunami of just a few centimeters in a depth of water of over 5,000-m. The tsunami models ingest the wave height data from not only the DART buoys, but also shore water level stations (e.g. tide gauges), which refine the predictions for the wave height and event duration. With that the TWC can make better informed decisions on issuing evacuation notices or not.
The above plot of DART buoys is pulled from the NOAA National Data Buoy Center (NDBC) website, where all the buoy data is available in near real-time (NDBC DART® Program). The International Oceanographic Commission (IOC) provides a worldwide plot of water level stations with real-time data on their website (SEA LEVEL STATION MONITORING FACILITY).
Sadly, with the recent Indonesian tsunami there was no warning prior to the wave coming ashore and that means that many are looking for someone to blame. I’ve seen a lot of speculation on the age of the tsunami buoy network, vandalism of the buoys, and the inability to detect small waves (2-m in this case), but none of these factors is to blame and many are just blatantly incorrect.
The fact is that this was a locally generated tsunami, which is regrettably very hard to detect and provide early warning for with tsunameters (e.g. DART buoys). A DART buoy would need to detect the tsunami, go into event mode, and transmit that data via satellite to the Tsunami Warning Center, who would then be able to issue a warning, but that warning would take time to disseminate and for an evacuation to begin. The volcanic event that likely generated this tsunami took place about 20-miles off the coast, with a tsunami being capable of traveling up to 500-mph, that’s about 2.5-minutes of warning if you detected the tsunami immediately.
The DART buoy array can detect tsunami wave heights on the order of centimeters, but this wave did not pass one on its way to the shoreline, as you can see in the close up NDBC buoy plot below. These buoys are meant for deep ocean deployment and for advanced warning/forecasting for distantly generated tsunamis. They are not intended, nor would they be effective, as near shore warning systems.
These sorts of local events are very difficult to detect and provide any advanced warning for, unless they are accompanied by a seismic event, which in essence is the early warning (i.e. you feel the earthquake and know to move to higher ground). In the case of a tsunami generated by a submarine landslide, there would be no warning. I don’t have all the facts/details, but regrettably, I don’t think there is an early warning system that could have prevented this.
Ultimately, providing the most accurate forecasting for tsunamis in a quick manner is what the system does, and that will save lives. Not only by telling authorities when to evacuate, but also by preventing unnecessary evacuations. You don’t want to be the little boy who cried wolf. With every unnecessary evacuation, people become less and less likely to heed future warnings.
It’s that time of year again; time to break out the eggnog, light a fire in the fire place, and snuggle up to watch everyone’s favorite Christmas movie, Die Hard. It’s also that time of year that you can mail it in and write a blog about Christmas gift ideas, which is fortuitous for me since I have a 5-mo old at home and am in the middle of a cross country move.
So, if you’ve waited until now to start looking for a gift for that special boat obsessed person in your life or you’re just looking for ideas to put on your wish list to Santa, this is the post for you. Much of these came from advice given to me on essential gear to purchase prior to reporting aboard my first ship or things I’ve found useful over the years. Without further ado, here’s the top five (we’ll see if this does better than my seminal six list).
1. Binoculars. A pair of good quality binoculars goes with me on almost every boating journey. After spending a few years standing a bridge watch, scrutinizing every navigation marker and passing vessel with my binoculars has become second nature. Having used Fujinon on the bridge, I purchased a more consumer grade version (Fujinon Marinier WPC-XL) for myself, which I’ve been happy with, but there are a plethora of consumer grade binoculars out there. The important thing in choosing binoculars for the marine environment is the optics, which should be 7 x 50. The objective diameter (50) means they have good performance in low light conditions, producing a sharp, bright image, and the 7 time magnification is ideal as they are easy to hold steady on a moving platform, like a boat. Also, I wear glasses and the generous eye relief of these binoculars allows me to use them without difficulty while wearing my glasses.
2. Float Coat/Collar. One of the first things I was issued when I boarded the ship was a float coat, which came in handy in the Alaska. I was first issued a Mustang float coat that was complete with a beaver tail (a neoprene flap that you could secure from front to back between your legs to help hold in the warmth if you went into the drink), but that’s probably a little extreme for your average recreational boater. If you’re operating in a colder climate though, a nice water activated float coat is a nice addition to any mariner’s wardrobe. On my second sea tour I sat behind a desk more than I was out on a boat and I got a Stormy Seas float coat that was a standard jacket with a built in automatic inflating PFD; I can not find one for sale, but here is a similar jacket from Float Tech. If you’re in a warmer climate, a horse collar automatic inflating life vest might be a more useful option, like this one from Mustang.
3. Marlin Spike/Knife. One thing every good sailor carries is a knife and for years I carried a locking blade Gerber on the ship, but if you’re going to carry a knife, you might as well carry something with a little more functionality. I purchased a Davis Instruments Rigging Knife, which includes a marlin spike for working with lines and a shackle key, to keep in my boating tool kit. However, if you’re looking at a nicer gift knife, you might consider a Myerchin or a Victorinox.
4. Dry Bag. When you’re getting into and out of launches every day for 8-hours of survey work, you want to bring a few things with you and for that purpose Dry Bags were very popular. It was especially helpful when doing open boat work; a Dry Bag would keep your stuff dry and, in the event is was accidentally dropped during the transfer, it would float. This one from Marchway provides the security of a dry bag while also giving you the functionality of a backpack.
5. PPIRB. Nothing says I love you like and emergency signaling device. As smaller version of the EPIRB, or Emergency Position Indicating Radio Beacon, the PPIRB (Personal EPIRB) is idea for recreational boaters and can also be used for emergency signaling during other outdoor activities like hiking. A PPIRB operates under the same principles as an EPIRB, broadcasting a signal on 406-MHz that is received by the COSPAS-SARSAT system. The COSPAS-SARSAT system can triangulate your position with in 3-mi in about 45-min, depending on what satellites are visible, but most EPIRBs are now GPS equipped and will transmit their position instantly, which provides a more precise position (within 100-m) within 3-min. Many will also still transmit a distress homing signal on 121.5-MHz, but you should avoid any that rely on the 121.5-MHz system exclusively as this is an outdated system and is no longer required to be monitored. I have been considering purchasing this PPIRB from ARC, which has GPS and a 121.5-MHz homing signal, and have it on my personal wish list. Just be sure to register your PPIRB so that any distress signals can be verified and rescue can be expedited.
Wishing you and your family have a Happy Christmas and a Merry New Year. Until next time, here's wishing you fair winds and following seas!
Who’s there? Hopefully not another boat, but the risk of collision and allision are always present. If you plan to operate in constricted waters, areas of high traffic, and/or reduced visibility (night time or fog), you’d be well advised in investing in a good Radar…and knowing how to use it.
Radar is now common vernacular, but it used to be an acronym for RAdio Detection And Ranging when it was developed in the 1940s. The radar emits a pulse of high frequency radio waves in a narrow beam that propagates out from the transceiver until it reflects back off some object (another vessel, shoreline, a buoy, etc.). The reflected pulse is then received by the transceiver and, by calculating travel time for the pulse, a range to the detected object can be determined. In order to do this in all direction the radar antenna (transceiver) rotates. Typically it will transmit for a few thousandths of a second and then listen for reflections for up to several seconds (this depends on what range scale you have the radar set to). This data is processed and displayed in a planar form with your vessel at the center of the screen. By observing this, an operator can track nearby vessels, where they are, how quickly they're traveling, and where they're heading.
As an aside, the wives tale about carrots being good for your night vision is a result of the advent of radar, or so I was told. During WWII British fighter planes were equipped with radar and were able to devastate German bombing raids at night. In order to cover up the fact that they were using radar to find and destroy the German aircraft, they attributed their success at night to feeding their pilots a diet of carrots to improve their eyesight in the dark.
In the olden days, you would plot vessels on scope face plotters, but that has gone by the wayside with the advent of ARPA. You can still manually track vessels by transfer plotting and it’s a fun exercise (if you like vector math and/or torturing Ensigns that don’t like vector mat). You can transfer data to a piece of paper (a transfer plotting sheet, like the one below). By plotting the initial position of a detected vessel and then a second position, say 6-minutes later to make the math easier, you can calculate his course, his speed, his relative motion in relation to you, and your CPA (Closest Point of Approach; e.i. how close you’re going to get to each other). With a bit more calculating, you can figure how you can change your course to get the CPA that you want.
Of course, this is all cumbersome and can take a great deal of your attention that should be directed towards navigating your vessel. That’s why ARPA is so great. An ARPA equipped radar will allow you to acquire and track targets and will automatically calculate all that information for you. You acquire a target, give it a few minutes to get good vectors, and it will display that target’s distance, bearing, speed, course, CPA, time to CPA, and a variety of other information. It will also automatically alert you if a tracked target is going to be within a lower bound for CPA, like anything with a CPA of less than 1-nm. By going into trial maneuver you can also see what effect changing your course or speed will have. Watching a radar screen is a bit like playing a video game—except that the spots on the screen represent real vessels.
AIS provides another great tool for identifying other vessels, and this data can be overlaid on most newer radars or chartplotters. The Automatic Identification System is essentially a civilianized version of the military’s friend-or-foe systems. If your vessel is equipped with AIS it takes your vessel data, including name, vessel type, length, beam, crew size, destination, position, course, speed, and a host of other pertinent information and broadcasts it via VHF. Another vessel equipped with AIS can receive this information. As someone that was sailing during the introduction of AIS, let me say that it is a huge leap forward. I can now know exactly who I am trying to raise on the VHF and use their vessel name instead of having to call “the vessel 2-nm south of Point No-Point on course 260 at a speed of 12-kts.” If you want to get an idea of what AIS data is like, there are several online viewers that are receiving AIS data in near real time and posting it on the internet; the one I use fairly often is linked below:
MarineTraffic: Global Ship Tracking Intelligence
There are three options when it comes to AIS; an AIS Class A transceiver, an AIS Class B transceiver, or an AIS receiver. There are differences in the way Class A and B transmit their messages, but that might be getting a little too technical. AIS Class A is the system on commercial vessels that are governed by SOLAS (Safety Of Life At Sea), it must have an integrated display, transmit at 12.5-W, interface capability with multiple systems, and offer several other features and functions. A Class B transmits at 2-W and has no requirements for an integrated display or interfacing with other systems. An AIS receiver is just that, a receive only unit that will not transmit any of your information; so you will receive and be able to display the information of other vessels, but they will not get your information, which means they aren’t as likely to see you.
On a recreational vessel, I would opt for the AIS Class B, which you should be able to find for under $1000. A good ARPA equipped radar will likely run you considerably more; I haven’t priced one recently, but I’d bet on $10k. However, the best equipment in the world won’t help unless you know how to use it; so I think the first order of business would be to look at options for training courses.
If you plan to operate at night or in reduced visibility you should have radar with ARPA (Automatic Radar Plotting Aid) functionality. Many radars now have the ability to integrate AIS (Automatic Identification System) and chart data on their displays, which is a very helpful piece of technology. The most important thing is that you know how to use your Radar. There should be classes for radar and ARPA offered in your area and if you’ve never used either, it’s well worth the investment to get the training. I would suggest going through a training course prior to purchasing a radar/ARPA, then go into a reputable marine dealer and play with the floor models to see which one you find easiest to use and equipped with all the features you want.
Until next time, here's wishing you fair winds and following seas.
A while back I saw a relatively clever riddle going around that went something like this:
You are in a rowboat in a swimming pool with a 500-lb brick in the boat with you; if you throw the brick out of the boat and into the pool, does the water level in the pool go up, go down, or stay the same?
The answer to this riddle is, rather paradoxically, that the water level goes down. Upon first consideration this doesn’t seem right. You might first think that the brick in the pool will displace water and thus the water level should rise, but then you might remember that the brick was already displacing water in the boat (a boat displaces enough water to equal its total weight and keep it afloat) and think that the water level would stay the same. Neither of these is correct and here’s why.
The brick is more dense than water, hence it sinks in the pool, but what does that really mean? That means that the same volume of water would weigh less than the same volume of brick. Thus, when you are floating the brick at the surface in the boat it displaces an equivalent weight of water, which is a greater volume than the brick itself. I’ll dive deeper into the math (pun totally intended), if anyone cares to read on.
In the illustration above (I have mad Paint skillz) you see that the boat on the left must displace an equivalent volume of water to float its weight and the weight of the brick. On the right the brick is displacing a volume of water equal to its volume and the boat is now only displacing a volume of water equivalent to its own weight.
So, on the left the volume of water that the boat and the brick are displacing can be calculated by adding the weight of the boat and the weight of the brick and dividing the result by the density of water (about 62-lbs per cubic foot). If we say that the boat weighs 120-lbs (for no particular reason) and the brick weighs 500-lbs, then the result is 620/62 or about 10-cubic feet of water being displaced.
On the right, to find the volume of water displaced we would divide the weight of the boat by the density of water, but the volume being displaced by the brick would be its actual volume, which is calculated by dividing its weight by the density of bricks (say 120-lbs per cubic foot). You then add these two volumes together to get the total displacement, and that results in 120/62 + 500/120, or 1.9 + 4.2, or 6.1-cubic feet.
Obviously, 6.1 is less than 10, so the volume of water being displaced is smaller when the brick is sunk. As less water is displaced, the water level in the pool will fall.
Just thought that was an interesting little tidbit. Until next time, here’s wishing you fair winds and following seas.
Well, I promised this blog post all the way back in 2017 when I posted about Marine VHF, but am just now getting around to writing it. It’s time to revisit radios and discuss one of the most useful features most users don’t know anything about, Digital Selective Calling (DSC).
Modern-day marine VHF radios offer not only basic transmit and receive capabilities. Permanently mounted marine VHF radios on seagoing vessels are required to have Digital Selective Calling (DSC) and new VHF radios, even recreational models, are now required to include DSC features. DSC allows mariners to instantly send an automatically formatted distress alert to the Coast Guard or other rescue authority anywhere in the world. DSC also allows mariners to initiate or receive distress, urgency, safety, and routine radiotelephone calls to or from any similarly equipped vessel or shore station, without requiring either party to be near a radio loudspeaker. I like to think of DSC like text messaging on your cell phone; you can send short text messages between VHFs, including requests for voice communication with a specified channel indicated. DSC transmits this data over VHF Channel 70.
If you have a VHF radio, you likely have DSC included on your radio, but you have to make sure everything is set up in order for it to function correctly. Firstly, it is important that you register with the USCG to get a Maritime Mobile Service Identity (MMSI) Number and properly enter it into your DSC equipped radio. Registering is relatively. When I registered Serenity, I used SeaTow, which has a free registration system on their website, but there are a host of other options, like the US Power Squadron, BoatUS (there is a fee unless you are a member), and a few of others. Generally, you will need to provide pertinent information regarding the vessel (e.g. LOA, color, HIN, Name, Home Port, etc.) and contact information for the owner of the vessel. This information gets entered into the USCG database and they assign it an MMSI number, which is then provided to you and is forever associated with that vessel.
Once you receive the MMSI number, you can program it into your VHF, which is usually a very straight forward process that is outlined in your owner’s manual. This number acts as your address for DSC and will be transmitted with every DSC message you send. This is also how you would send a message to a specific vessel, but more on that later. Before we get into the more fun aspects of DSC, we should probably make sure that the distress function is working. Having the MMSI issued and programed into the VHF is a good start; now, if you pushed the distress button, instead of a blank message, it would transmit your MMSI number, which would tell the USCG the name of your vessel, associated information, and the contact information for the owner. However, there’s other information that might be nice to include…like where you are.
Your VHF can automatically include this information if it is connected to a GPS receiver. Many newer VHFs will actually have a GPS receiver built into the unit and will automatically include location information in your DCS messages, that means your set up is pretty much done, but if you have a unit without an integrated GPS you have a little wiring to do. The data standard for most electronics is NMEA 0813 or the newer standard of NMEA 2000; you just have to read the owner’s manuals for your particular GPS receiver and VHF. It will likely be a two wire connection between the VHF and GPS, but while you're at it, you might want to connect the NMEA out from the VHF to the Chartplotter as well. If the GPS receiver is on, this will automatically provide your position, with a timestamp, to any distress message you send and, with the DSC talking to the Plotter, it will allow positions in DSC Distress messages to be displayed on your Chartplotter automatically. For that reason, it is a good idea to make a habit of turning on your GPS receiver or Chartplotter whenever either VHF radio is on, in order to provide this data stream; if the VHF is not receiving this data, you will probably be getting an alarm every few minutes anyway.
So, now we have our MMSI number and GPS data in our VHF, which means your DSC messages will now include who you are, where you are, and when the message was sent. We’re ready to start sending some messages. Every VHF will likely have a slightly different interface, so I’m not going to get into the gritty details of operations, but stay at a relatively high level overview on given operations.
Distress Messages. Sending a Distress Message is probably the most important feature of DSC. While it is advisable to transmit the most detailed distress message possible, I think it’s unlikely that you’ll want to try to enter the nature of the distress, number of people on board, etc. when it’s all hitting the fan. When you’re in the thick of it, you’ll probably be happy to just send a quick message with vessel information a position. That’s pretty simple with your DSC equipped VHF, now that it’s set up:
General Messages. Now we get to the fun part, sending messages to your friends. One of the drawbacks to VHF communication is that it’s a party line and you never know who might be listening in on your conversation. Let me tell you that standing watches on the bridge of a ship at anchor, I would listen excitedly to any interesting conversations. Someone would call someone else on VHF channel 16 or 13, both of which we monitored at all times, and then suggest a new channel to continue their conversation on. Without fail, I would change over to that channel as well, just to see what they were saying (note that the definition of interesting changes when you’re stuck on the bridge for 4-hours without much in the way of entertainment).
This becomes problematic when you want to discuss something that you don’t necessarily want everyone listening in to, like where the prime beaching spot you just found is, or the location of your super-secret fishing hole. With DSC, you now have an option that won’t advertise your conversation to everyone that might be listening in on Channel 16.
If you know the MMSI number of the station you want to communicate with, you can send a DSC message directly to them and no one else. You also have the option of creating a group of several MMSI numbers and sending messages to only that group, or sending to All Stations for a general information broadcast. These all have their uses, but I think for the average user being able to send to one station is probably the most useful feature.
The survey launches on Rainier used to make use of this function fairly often. When 2 or 3 launches were working in close proximity to one another, they would often want to raft up together for lunch. It gave them a chance to BS with the other launch crews, trade lunch items, and generally relax. However, it didn’t wasn’t a practice they wanted to advertise to the FOO (Field Operations Officer) or CO (Commanding Officer). The FOO had two radios in his office and was always listening to the channels the launches were required to monitor, so it was tough to sneak one past him (it was me), but the more radio savvy on the crew began using DSC to clandestinely contact the other launches and arrange a meet-up for lunch.
When you initiate a DSC message, you will be able to input the MMSI number of the station you wish to reach, or select it from a stored list. You then should be prompted to enter the VHF voice channel you want to begin voice communications on, if you want to talk, but you could also enter a purely text based message (e.g. “Meet for lunch at Camp Coogan Bay?”). A station receiving a DSC call can respond via a text based message, or they can Acknowledge the call and their radio will automatically tune to the specified VHF voice channel. The sending unit will automatically shift to the specified VHF voice channel once it receives the Acknowledgement and the two stations may begin conversing over that VHF voice channel and no one else is any the wiser.
If anyone is looking to give it a try, you can always send the Serenity a message; if I’m aboard I’ll be sure to reply…maybe even meet up for lunch. Our MMSI number is 338154427. Until next time, here’s wishing you fair winds and following seas.
Finally, the long awaited continuation of the Boating Necessities Post, as we delve into my small boat tool box. I often joke that my toolbox only needs three tools in it: WD40 (if it doesn’t move and should), duck tape (if it moves and shouldn’t), and a big engineer's hammer (if it’s broken, beat it until it starts working or needs to be replaced completely). Unfortunately, I couldn’t fit a big enough hammer in this toolbox, so I had to go the more traditional tool route.
Again, the tools you will be able to carry will be dictated by the amount of space you have on your boat, but my 14-ft Lone Star Malibu is likely as small a boat as you’re going to find with a dedicated tool box. On the houseboat I have virtually unlimited space/weight restrictions and as a result I went overboard (pun totally intended) on my tool kit; I dedicated an entire closet to tools.
Obviously, I had to scale it back to the barest of necessities on Boaty. It would be nice to have all the tools in the world, but with limited space and weight, I had to put a considerable amount of thought into what tools I might actually need when the stuff hit the fan and I had to do some repair work on the boat. I limited myself to the smallest, and cheapest, Harbor Freight plastic toolbox; the $6 (I think I had a coupon for $4) 12-in toolbox with removable upper tray.
That’s another thing about this toolbox, it’s going to be cheap in addition to being small. I can’t fathom (again pun totally intended…I guess just assume that all puns are totally intended) putting high quality tools in a toolbox that I will hopefully never need to use. Okay, I can’t fathom spending the money for something like Snap-on for my regular tools either, but I do generally buy good quality tools and may have a fine German instrument (some Knipex pliers or a Wera wrench when I find a deal) mixed into my toolbox here and there. That will not be the case with this kit; I’m going cheap, so there will be a lot of Harbor Freight and other bargain tools…as long as they're functional enough to get the job done.
Let’s start with the small storage boxes built into the lid. These proved to be the perfect spot for electrical connectors and small parts. I’ve stocked them full of varying sizes of crimp connectors (butt connectors, eyes, spades, etc.), replacement fuses, and wire nuts. Hopefully, everything I would need to do a minor wiring repair to limp back to the dock.
In the top tray I’ve got a few more consumable items and parts, like a small assortment of hose clamps, some JB Weld, spare spark plugs, and a couple new utility knife blades (note I need to buy a new tube of 5200 adhesive/sealant that would also be included there). I also keep a battery terminal cleaning tool and a small roll of SAE wrenches in the upper tray. Fact is, most modern boats and cars are metric, so you'll likely want a metric set, but on a 1968 Evinrude, you’re not going to need any of that European crap, just good old fashioned fractional SAE wrenches will do the trick. In this case I am using an old set that was passed down to me from my grandfather; a Lakeside (Montgomery-Wards house brand, similar to Craftsman for Sears) open end wrench set.
Now we’re getting into the bulk of the tools. More often than not, when I’ve had trouble on the water the nature has been electrical. As a result, I have the extensive collection of connections/fuses above, and I need the associated tools. I’ve included the cheapest Harbor Freight multimeter, which they used to offer as a free coupon, but can be had for about $6; again, I’m not putting a Fluke in this kit and while this Harbor Freight multimeter isn’t the most reliable or well built, I have diagnosed many a problem with them. I also have an old set of wire strippers/cutters/crimpers (not my favorite, but they will definitely work), a length of 12-ga wire, and some electrical tape.
There are a few other consumables that can come it very handy. These include a collection of zip ties, some Teflon tape, and a roll of duck tape (this is duck tape, please stop correcting me to “duct tape” spellcheck; it was developed during WWII to seal ammo cans and shed water as if off a duck's back, it is completely inappropriate to use on duct work as the adhesive dries out and it leaks; use aluminum foil tape instead). You will notice that the duck tape is conspicuously missing from the above picture, that’s because I made an exception for that as it didn’t fit into this small toolbox and had to be carried separately; it can be seen in the photo in the previous post.
The only thing left is to round out the rest of my hand tools. I’ve got a Harbor Freight pliers set, hex key (Allen wrench) sets, utility knife, razor blade scraper, and wire brush. I’ve also put in my old Stanley screwdriver set, which isn’t great quality, but beats the free Harbor Freight sets. One exception I might make is for a more expensive tool is if I can get greater functionality in a smaller package and I’m considering throwing in a multi-bit screwdriver like the MegaPro maritime screwdriver shown below, but sometimes there's no substitute for a real screwdriver and I like the MegaPro I have too much to relegate it to the seldom used boat tool kit...I think Harbor freight might have a free coupon for a 6-in-1 screwdriver now.
Obviously there are several tools that I would like to include, or you might want to add to your kit, but storage space is at a premium when you only have 14-ft of boat. I'd love to include a full socket kit, or even just a ratchet and the necessary sockets for the boat; a spark plug socket sure would be handy, but I can get to my spark plugs with the open end wrench if I have to. Box end or combination wrenches would also be nice, but take up more space and the open ends should be fine. You might need to include a prop wrench, but it's not necessary for my little 33-HP Ski-twin. All of these can be had for very reasonable prices if you look around, even a name brand sets like Crescent or Channellock can be found for between $50-$75 on Amazon. A couple other items that I would have included if I had the space are a mini hacksaw and a soft wood plug set, but I don’t think those are essential and I was plumb out of room. If I add anything, it's going to be a few spare parts, like a propeller, but I haven't yet found those for the right price on eBay.
All in all, it's a pretty compact little set that should get me out of a jamb...if I can figure out what's wrong. If you've got any suggestions for additional tools, I'd love to hear them in the comments; I'm always up for buying new tools. Until next time, here’s wishing you fair winds and following seas.
Vexillology is fascinating (e.g. flags are cool), but what flags should you display on your boat, how do you display them, are there actually rules? In answer, of course there are rules, but very few people know them or follow them. Are the flags in the photo below displayed correctly?
Even though a majority of people would say that the above display was incorrect because the National Ensign isn’t being flown from the highest point, that is actually the correct display for a flagpole with a gaff. It is commonly believed that the US Flag should always be the highest flag of any display. To that point, the Navy's own directive on flag display, section 206 of NTP 13(B), states, “No other flags and pennants shall be placed above or, if on the same level, to the right of the national flag.” However, naval flag traditions date to the days of sail, and with regard to ships, the restriction seems to apply only to flags on the same staff or hoist. On a sailing ship, the ensign was flown from the gaff of the spanker on the aft mast. The other flags and pennants were flown from the mastheads.
This tradition is carried forward to the practice of flying the ensign from a gaff on the aft most mast. Thus, on a flag staff with a gaff, the highest point of honor is the gaff, and thus that is exactly where you should fly the National Ensign.
I got a crash course in flag etiquette when I became that Navigation Officer on the NOAA Ship Rainier just before a large change of command ceremony and the oncoming CO was a stickler for doing things by the book…the only issue was I didn’t know which book.
After weeks of research and consulting all the regulations and directives I could find on the subject, I determined that there wasn’t one all-encompassing document prescribing the proper display of flags for a NOAA ship. There were plenty of NOAA and Department of Commerce regulations (NOA 201-6 and DAO 201-6) and there was a very comprehensive, though sometimes confusing, Navy document (NTP 13(B)), but none of these was a definitive reference for the ship. Ultimately, I was able to combine information from these sources and that fount of nautical knowledge, Chapman Piloting & Seamanship, into a concise guide for the ship.
So, where should you fly the national ensign on your boat, what about courtesy flags of other countries, do you need a burgee or a jack, what about novelty flags, if you fly the Jolly Rodger can you be detained as a pirate? What flags you can, should, or must display will be dependent on where you are, but things are much easier for a recreational vessel than a federal government vessel.
For the most part, the answer is not many people care and you’re likely fine flying whatever flag you want wherever you choose to fly it, but be careful if you’re sailing internationally as some countries take this stuff pretty seriously and you might be subject to fines or worse.
In U.S. territorial waters there are no laws prohibiting the flying of any flags, so feel free to fly that Jolly Rodger or martini glass flag, but don’t be surprised if you might garner a little extra attention from the authorities in the form of safety inspections. There also aren’t any laws requiring any flags be flown. Entering foreign waters will subject you to their laws, which may prohibit the display of some flags and may also have other requirements for display of flags (e.g. you might be required to hoist a courtesy flag). If visiting a foreign port, it’s advisable to check regulations ahead of time and probably forgo the novelty flags. Regardless of where you’re sailing, if you do decide to fly the flags there is a proper way to do it and I figure you might as well do it right.
Rainier has two masts; the aft mast is the mainmast and the forward mast is the foremast. The horizontal structures extending athwart-ships from the masts are the yards. The angled spars extending aft of the masts are called gaffs. The vertical spar at the bow is the jack staff, and the spar at the stern is the flagstaff. You’re vessel will likely have a much simpler arrangement.
As an active commissioned federal vessel, the ship will fly a commissioning pennant from the top of the main mast at all times, expect under special circumstances when a personal flag (like the flag of a Vice Admiral) is flown in its place. The ship also always flies the NOAA service flag from the foremast gaff. As a recreational boater, these are flags you clearly don’t have to worry about.
While underway, the national ensign is flown from the gaff on the mainmast, which is flown day and night per regulations for providing for the identification of the nationality of the vessel. While at anchor or alongside in port, the ship would fly the national ensign from the flag staff at the stern and the union jack at the jack staff. The national ensign and jack are flown from 0800 to sunset. If the two flags are not hoisted simultaneously, the ensign is hoisted before the jack and lowered after. The ensign should be hoisted briskly and smartly, and lowered ceremoniously. The hoisting and striking of these flags is known as Morning Colors and Evening Colors respectively.
This can be translated relatively directly to flying of flags on a recreational sailboat, though you would likely only have one mast. On a recreational motor vessel, you would likely be flying the national ensign from the stern of your vessel both underway and at anchor. I also very rarely see the union jack flown from a recreational vessel, but burgees (pennants denoting a manufacturer or club membership) flying from the bow of vessel. Also, the ensign often flown by recreational vessels is the US Yacht Ensign, which is red and white stripes of our national flag, but with a fouled anchor in a circle of thirteen stars in the canton. Use of the Yacht Ensign was restricted to registered yachts over a certain tonnage, but that ended in 1980 and now it can be used by any US pleasure vessel.
Daily flag etiquette for our ship wasn’t an issue, but I was tasked with ensuring that the ship was in PROPER full dress. Fully dressing a ship involves stringing a “rainbow” of signal flags from bow to stern, flying the national ensign from all mastheads, and flying larger holiday flags from the traditional locations. This is done on holidays, like Independence Day, and is also a common sight among recreational vessels. Our previous CO was more relaxed about…well pretty much everything, and we had been flying the alphabet for full dress, but that obviously wasn’t correct.
I first consulted the US Navy’s directives on the topic, but there was an issue in that we didn’t carry the full Navy flag bag, which meant matching their guidelines for the “rainbow” of signal flags was impossible…so where can you find an authoritative source on how to fully dress a ship using just the standard flag bag? Chapman Piloting & Seamanship of course.
Turns out there is an appropriate order in which to display the signal flags in a pleasing fashion, such that they cannot be confused for a proper signal or convey anything offensive. The customary merchant and yacht sequence for a rainbow of signal flags is:
A, B, 2, U, J, 1, K, E, 3, G, H, 6, I, V, 5, F, L, 4, D, M, 7, P, O, 3rd Sub, R, N, 1st Sub, S, T, 0 (Zero), C, X, 9, W, Q, 8, Z, Y, 2nd Sub.
Another ship in the fleet got into some hot water when someone noticed that their rainbow of signal flags actually spelled out “F*** NOAA”; supposedly arranged by a disgruntled employee that had long since departed the ship before his malfeasance was discovered.
In case you’re thinking no one pays attention, during my nearly 2-years as Navigation Officer on the Rainier I fielded a handful of inquiries regarding our flags. This included a very gruff VHF call from someone I can only assume was an old Navy signalman asking why we were fly a signal indicating “very deep depression approaching and SOS had been cancelled.” I happily informed him that per the regulations for transiting the Lake Union Ship Canal, we were flying our radio call sign, W-T-E-F; he didn’t respond back.
Until next time, here’s wishing you fair winds and following seas.
Recently, one of the owners on the Serenity suggested adding a hot-tub on the upper deck; I was glad when the rest of the membership voted it down for a variety of reasons (maintenance, upkeep, structural concerns, etc.), but one of the primary reasons for my opposing this proposal was that of stability. The stability of your vessel is something that recreational boaters very rarely take into consideration, but when you’re dealing with a larger vessel like our houseboat and a modification that will place thousands of pounds of water high up on that vessel, it’s something that must be factored in.
In the commercial or government world any modifications to a vessel (even small vessels) would go through extensive engineering review and, if they were major enough to result in changes to the stability characteristics of the vessel, would require inclining the ship to determine the new stability values. Every ship is inclined when built to determine its stability characteristics, which essentially requires shifting large weights from one side of the ship to the other and measuring how far the ship heels over, which allows the determination of the metacentric height. The photo below of the NOAA Ship Delaware II is not exactly how an inclining experiment should go.
The metacentric height (GM) is defined as the distance between the center of gravity (G) and the metacenter (M). The greater metacentric height, the greater the stability of the vessel. While you might think that just maximizing the metacentric height would be the best option, that results in what is referred to as a stiff ship and should be avoided.
The term stiff ship refers to a ship that has excessive stability. The characteristics of a stiff ship would be a very short rolling period, which means the ship would return to upright after being heeled over very quickly and result in a very snappy and uncomfortable ride.
The center of gravity is essentially the center of mass, and can be shifted by moving loads to different locations on the vessel (e.g. placing more weight lower in the hull will lower the center of gravity, and placing more weight up high will raise the center of gravity). The metacenter is a fixed point through which the buoyant force acts. Put another way, as the vessel heels over, the center of buoyancy shifts; if you drew a vertical line through the center of buoyancy at various states of heel, they would all intersect at the metacenter. The distance between the vertical line and the center of gravity is referred to as the righting arm (GZ) and results in a righting moment that pushes the vessel back to upright.
As I stated above, having too much stability results in a very large righting moment and a “stiff ship.” Not only will this vessel be uncomfortable, but the quick, snappy righting can cause cargo to shift, throw loose gear/people about, and can cause structural damage.
The opposite of a stiff ship is called a tender ship, which has a very small metacentric height and, as a result, a very small righting moment. A tender ship has a very long roll period, which means that the vessel will return to upright very slowly and has insufficient stability. A “tender ship” will resist rolling less, will roll more steeply, and will tend to remain heeled over for a longer period with a higher likelihood of capsizing.
Neither a stiff nor a tender ship is desirable, but you want to be in a happy middle ground. Calculating the stability is not a trivial matter. Marine architects and engineers will have calculated values for the construction of any vessel, but these must be verified to complete the final modeling of the stability of the vessel and that is where the inclining experiment comes in. Once that test is done, the values are verified and placed in the ship’s stability book (now probably a computer program), which the master and chief engineer will consult every time they load the ship to determine the vessel’s stability prior to leaving port.
Any major modifications, like adding a large mass up high, would have to be factored in and, if a permanent modification, would require a new inclining experiment to update the stability book.
Recreational vessels generally won’t come with a stability book, but should be safe for all normal loading conditions within the limitations of their USCG capacity certification. However, if you start doing things well outside what might be considered normal loading, like adding a hot-tub, you better start thinking about stability.
I doubt I could have tracked down any stability information for Serenity and, even if I could, I’d still want to do an inclining experiment. And this doesn’t even start to take into account the free surface effect of the water, which would further reduce the vessel’s stability.
The free surface effect essentially refers to the tendency of a liquid in a partially filled tank to slosh to one side when the vessel rolls; that moving mass will increase the roll, which then increases the sloshing, which increases the roll in a positive feedback loop that can result in the loss of stability and capsizing of a vessel. As a result, most tanks on vessels have baffles that prevent fluids from freely communicating from one side of a large tank to the other and mitigate the free surface effect. This phenomenon has been the culprit for many vessel sinkings; particularly on ROROs (Roll-on/Roll-off cargo vessels), which have large open decks that allows water, once on board, to flow freely from one side to the other. The USCG investigation into the recent sinking of the El Faro, a RORO, determined that the free surface effect was the mechanism that ultimately sank the ship.
Needless to say, I was very pleased when our owners decided not to pursue putting a hot-tub on Serenity…besides, who would clean it? Until next time, here’s wishing you fair winds and following seas.
Have you ever wondered how hydrographers create accurate depictions of the coastline on their nautical charts? In modern surveys we utilized photogrammetry (aerial photographs) of the coastline or, more recently, LIDAR (Light Detection and Ranging) to produce shoreline on nautical charts, but how did the sailors making those nautical charts from the 1600s to the early 1900s do it?
In the earliest days of exploration charts were often made by estimation. Using the ship’s log, which would include important observations and the ship’s navigation information, one could approximate the shape of the coastline for the purposes of creating a nautical chart. This was inexact at best and resulted in some crude approximations of the actual coastline, as can be seen below in a chart from the 16th century.
As you move into the 17th century, there were some purposeful hydrographic surveys that were conducted to chart coastline accurately. The British Navy began a detailed survey of their coast in the 1680s and produced some very accurate shorelines. The image below is of Delaware Bay and was produced in 1630s, which is pretty accurate compared to a contemporary chart of the same area.
So how did they do it? The answer is Plane Table Mapping. Plane table mapping utilizes a table affixed to the top of a tripod on which to plot positions and a telescopic alidade to get bearings to the features you’re trying to position.
The image above is from the NOAA archives and shows a US Coast and Geodetic Survey team utilizing a plane table to chart the coastline in Alaska. At its most basic, plane table mapping is simply triangulation. From a known location, you can shoot the angle/bearing to a prominent feature, then you can either measure the distance to that feature or you can shoot another angle to that feature from another known location. Either way (with a line of position and a range or two lines of position), you fix that feature in relation to known locations. By fixing several points along the shoreline, you can then generate the overall shape of that shoreline. The simple example below shows the mapping of a courtyard by taking bearings from two known points a set distance apart (the baseline).
There is a great article on the history of the plane table at the link below:
Plane Table Mapping
I think it’s really quite fascinating, but maybe that’s just me. Until next time, here’s wishing you fair winds and following seas.
Brent Pounds has over a decade of experience in the maritime industry and has been involved in recreations boating since he was a child. See the About section for more detailed information.