Mailboat Letters

More Marine Corrosion

Thanks to Ed Sherman ("Marine Corrosion 101," July 2015) for an informative article. I have a question that has me puzzled. I have two large zincs on the shaft of my 36-foot sailboat. Normally they are a bit more than half consumed at the end of a four-month season. Last year they were totally consumed. What could be causing this? My boat is on a dock in saltwater, at my yard, near a few other boats in adjacent slips. My galvanic isolator is in working order and there have been no changes in my onboard equipment or wiring.


Ed Sherman responds: The importance of considering environmental conditions that may vary from year to year cannot be over-emphasized. Boat usage also plays into this; anode consumption will increase as boat usage does. All of these things need to be considered as part of the equation before deciding if there is a problem or not.


I was gazing in horror at the corroded sterndrive photo in "Marine Corrosion 101" in the July 2015 issue, and then also noted that the boat is setting on cinder blocks! More horror. ...


Editor: You're right, every year we see boats damaged because someone used cinder blocks as support. The damage ranges from cracked hulls to boats falling off of cinder blocks. The American Boat & Yacht Council has blocking standards — and, in this case, it's obvious these weren't followed!


I was reading your article about navigation, and it reminded me of another problem I have come across here on the Chesapeake Bay. I am seeing more and more of these red and green bow "strip" LED lights. While they are very bright and easy for other boaters to see, they do not have the required arc of visibility. It's hard to tell the boat's position because it's possible to see both red and green lights when the boat is not coming directly at you.


Dan Rutherford responds: I too am concerned about navigation lighting configuration. This is not limited to the new LED lights. I have seen, all too often, lights improperly mounted so as to not show the correct arc (arc of the horizon 112.5 degrees from right ahead to 22.5 degrees abaft the beam on its respective side). The newer LED navigation lights have many positive attributes. They are indeed bright, they use far less power, and the LED is far less susceptible to failure. But I have not run across the LED "strip" lights yet.

So, like any good investigator, I googled them. I have not personally seen them mounted, but from this photo, they do NOT appear to meet the US Coast Guard standard. Looking at the configuration, I would think that you would need quite a large shield to protect the forward end of the light from exceeding the arc of visibility aft.


The Coast Guard needs to review, modernize, and update the requirements regarding navigation lights on all vessels and barges. In my opinion the current regulations are archaic. A single red/green/white light is barely visible under the best of conditions. The lighting requirements on barges according to the regulations is ridiculous. When was the last time lighting requirements were updated?  There are more boats on our waters and more boats operating at night.


Dan Rutherford: I hear you loud and clear. To be honest, though, most of the accidents I have investigated had more to do with the improper display of and/or the misuse of navigation lights as promulgated by the USCG under the current COLREGS. That said, I agree with you on the barge issue, especially when at anchor. There are just not enough lights to be visible from all approach angles. Often, barges are piled high with cargo or work equipment — cranes, pipes, etc., — so the "all-round" light is just not visible. Also, they are frequently solar-powered or battery-powered lights that are dim at best.

It is a difficult task to revise the COLREGS because they are an international standard to which we are but one party. I am fairly certain that if you put one hundred people in the room, you would have one hundred different takes on what changes, if any, should be made. That said, the Coast Guard does provide a way for you to give them input on the existing COLREGS.

In the official publication, COMDTINST M16672.2D, there is a "Record of Changes" page. It is left blank so that the owner of the book can write in any changes as developed. There is the following notation in the front: "Notices of changes to the Navigation Rules and Regulations are published in the Federal Register, Local Notice to Mariners, Weekly Notice to Mariners and Commandant Notice. Comments should be addressed to Commandant (G-MOV-3)." That is the place to let the USCG know your opinion.

I hope this information is helpful. In the meantime, keep a constant vigil and a sharp lookout.

Isolating The Problem

In regards to the article about shore-power isolation transformers, how would this work for electricity on a pier?  Would you still need GFCI on pier wiring?


Editor: As far as the boat goes, an isolation transformer on the boat precludes the need for an ELCI (equipment leakage circuit interrupter) on the shorepower inlet of the boat as long as the transformer is installed within 10 feet of the shorepower inlet on the boat. Because the transformer is the source of the boat's shore power, any leakage will return to it and won't flow through the water toward shore, endangering swimmers. However, a GFCI is still needed on alternating current (AC) outlets inside the boat. That said, you'd be wise to protect anyone dockside with a GFCI at the shorepower pedestal.


I don't agree with the following statement: "An isolation transformer takes your marina's often wild and unpredictable shorepower and converts it to pure clean power." A power transformer will attenuate some of the higher frequency components of noise but by no means will it "clean it." As an example: If presented with a noisy, distorted waveform input, the output will also be a noisy distorted waveform. Equipment requiring a "pure sine wave" will still malfunction.


Overhead Awareness

Minimum Power Line Clearance Distance
Source: OSHA
<50 kV   10 feet
<200 kV   15 feet
<350 kV   20 feet
<500 kV   25 feet
<750 kV   35 feet
<1000 kV   45 feet

Good article on overhead wires ("Power Line Hazards", July 2015). The noise from the mast close to the high-power wires noted in the article is called the "spark gap" effect. That is, you may get a "jump" from the line to your boat's mast if the distance is small enough. Thus, to be sure you'll be safe passing under overhead wires (either in the boat out on the water or with the boat on a trailer), you need to know the voltage of the lines by contacting the authority that manages them.


More Than Just The Manifold

The July 2015 Alert on manifold life was excellent. However, it failed to mention one of the most critical components of all engine plumbing — the watertight joints between components — particularly in saltwater. Failure of the manifold gasket by corrosion, incorrect type, or installation can often be the cause of manifold failure. My costly experience came after only two years with a factory-rebuilt marine 350 V8 engine that used a non-stainless overhead gasket — a serious no-no. When the major US company who did the rebuild was confronted, after many emails, (including sending one gasket to prove my case), their comment was, "…on occasion our suppliers don't supply stainless gaskets." Cost to me: $3,000. Rebuilt engine buyers — beware!


Seaworthy PDFs

I usually download and save a PDF copy of Seaworthy. How can I download and save this issue? I don't see a link to download as PDF — was that option removed? Please provide a method to download a copy so I can save it locally.


Editor: You can download a PDF from the Seaworthy email by clicking on the front cover in the upper right-hand corner of the email or by going to the Seaworthy homepage and clicking on the link to "Archives" and then "PDF Version" in the left navigation pane. Issues from July 2011 through the current issue are available for download there.End of story marker

— Published: October 2015

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