Mailboat Letters

Published: October 2013


Excellent article. Heard about ESD but never understood it. Is there a way to test the water for current before swimming? Are we at risk when anchored and running a generator?

Thanks for this valuable information.


Editor: Unfortunately, there is no reliable way to test the water for stray current. The electrical fields that are generated can be very small and localized. The exact strength, size, and shape depend upon the amount of current, size of the underwater metal fittings, water temperature, and a host of other factors. You'd have to test the entire area where anyone might go while swimming. Even then, cycling loads further complicate things because you could test and find no current and then a compressor could kick on and the same area would now be dangerous. That's why we recommend so strongly simply not swimming within 100 yards of an electrified dock. That will not help if someone falls into the water accidentally, which is why it is still important to follow all the electrical codes and standards for boats and docks to minimize the chance of current leakage into the water.

On the generator question, unless you are sharing power with another boat (by passing the output cable to another boat to charge its batteries), the source of the electricity is on your boat, so any stray current trying to return to the source will NOT travel through the water.

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Our community marina in the Providence community outside Annapolis is located on Mill Creek.

I would submit that the salinity level in the Providence Marina is at least equal to and probably lower than out in the Chesapeake Bay off Annapolis, particularly after storm runoff. How high must the salinity level be to be protected from ESD from alternating current leakage?


Editor: There is no absolute answer to this question because there are too many variables. The problem arises at the point when it is easier for a dangerous amount of current in the water to pass through the human body than through the surrounding water. But that exact point depends on many things besides salinity including water temperature, the body composition of the victim, and the amount of current leaking into the water. Even if we knew the answers to these questions, the salinity in a given place varies greatly depending upon rainfall and tidal fluctuations, so an area that might be "safe" one day may not be the next. This is another reason why we recommend to marinas and owners of shared docks like condo associations that they prohibit swimming completely within 100 yards of the docks.

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Photo of a Hioki 3280-20 Clamp On HiTester

Hioki 3280-20 Clamp On HiTester

Our boat club members at Minisceongo Yacht Club in Stony Point, NewYork were engaged with your Seaworthy article on electrical leakage. We are going to check our boats in our marina for AC leakage. You article displayed a clamp meter. Can you tell me the brand and model?


Editor: David Rifkin of Quality Marine Services, who has tested hundreds of docks, recommends the Hioki 3280-20 Clamp On HiTester, which has a multimeter function as well. It retails for about $150.

Pre-Loved Sailboats

Your Seaworthy article titled "Inspecting Older Sailboats" in the July issue was dead-nuts on. As a surveyor with a lot of experience in surveying older boats, the only thing I felt was missing was a suggestion that owners periodically un-step their masts for inspections. Asking longtime boat owners, "When was the last time you unstepped your rig and completely examined it?" usually elicits a blank look. Many times, I will be told that the 30-year-old boat has never had the mast unstepped. That's when I ask my next question: "So, when was the last time a rigger went aloft?" I am often told that it was when the owner lost a mainsail halyard (or jib halyard, or something else) and had a rigger go aloft to retrieve it. When asked whether the rigger inspected the rig while aloft, the answer is usually, "No."

In regard to going aloft for inspections: Wisdom has also taught me to be reluctant in putting my life in the hands of someone I may have only just met, especially going up a rig that is suspect enough to warrant a rigging inspection. I have no fear of height or depth — only a healthy fear of impact.

I have done a considerable amount of rigging work, and I am reasonably knowledgeable about it. During an inspection aloft, important details can be missed. Rig inspections from aloft are beyond the scope of a normal survey. For a proper inspection and/or survey, the rig should be unstepped and removed from the vessel for close and detailed inspection.

Just saying.


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We bought a 1981 Endeavour 37 in Florida when I was still working in Arizona, so I went by the professional survey. I had looked the boat over but not as carefully as I might have because there was another offer on it. After I took delivery, we discovered some very important things that the professional surveyor missed! The steering mechanism was rotted, the fuel tank leaked, and the generator that "powered up" did not even exist! So it is important not only to thoroughly know and inspect your boat, but also to check the credentials of any surveyor you use.


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I recently bought an old Morgan 24, which had spent many years either on land or on a private lift — out of the water. The glass hull is in fine condition, but the interior plywood "ribs" and structure have suffered from dry rot. The "supports" are generally hollow, as much of the wood has turned to dust. I did have a survey on this boat, but these areas were apparently overlooked. As a longtime tinkerer and boat rebuilder, I am making the repairs; but this effort was not something I planned to have to tackle.


Editor: Your chances of getting a quality surveyor that can find such "hidden" problems increase greatly when you hire one who belongs to one of the recognized professional marine survey societies (NAMS and SAMS). Additionally, try to find a surveyor who has experience in the model of boat you're looking at and, for a sailboat, consider hiring someone who specializes in rig surveys. For more on picking a surveyor, see


I'm in the process of purchasing electronic equipment that requires an MMSI (Maritime Mobile Service Identity). I filed with BoatUS and received my number but, according to the July Seaworthy, my number is no good outside the U.S. I plan to go to Mexico and/or Canada in the future. Do I now have to get a different MMSI number from the FCC and remove and send my equipment back to the manufacturer for reprogramming?


Editor: As the website explains (, BoatUS is only authorized to issue MMSIs for national waters. We have recently changed the site to make this absolutely clear. If you intend to go to Canada and Mexico, you will need to get an FCC Ship Station License and they will issue you an MMSI which you would then program into the radio. Your owner's manual will tell you how many attempts you have to program the number. If your radio gives you two attempts to program, you should be able to put the new number in without contacting the manufacturer. If it only allows you to program the unit once, call your manufacturer. They may be able to provide you with a reset code so you can reprogram the MMSI number without sending it back to the manufacturer. Your FCC-issued MMSI will work in U.S. waters.

Trailerable Boat Theft Prevention

Regarding the article, "From Locks to Lockdown," that appeared in the July Seaworthy magazine, one simple way to prevent trailer theft is to paint your trailer a bright color. This has been suggested before by BoatUS. I have a yellow and an orange trailer for my two boats. At my boat ramp where sometimes 60 trailers are parked, my trailers are the only ones that aren't galvanized gray.


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The best place for your hitch when not in use is in your trunk. In fact, it should be a law that all hitches should never be left on the tow vehicle. I was the last car in a three-car pileup one day when taking my wife to her doctor. The hitch had been left on the SUV in front of me. The ball left a hole in the radiator and pushed the engine back. We were lucky we did not get hurt. Yes, it destroyed our car.

I tow my boat, and it's very simple to remove the hitch. Keep it in your vehicle trunk where it will not get stolen — and where it won't hurt anyone.



Addendum: The first paragraph of the "ESD Explained" article in the July Seaworthy described the death of Noah Winstead in Cherokee Lake near Knoxville, Tennessee over the 4th of July weekend last year. Noah's good friend, 11-year-old Nate Parker Lynam, was also incapacitated by ESD in that same incident. Nate was pulled from the water and resuscitated but died early the following evening. We thank Noah's mother for helping us set the record straight and reminding us of the terrible tragedy of two young boys' deaths.


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