Mailport November 1, 2000 Issue

Mailport 11/00

Knife Tests
I was interested to see your comments on the Myerchin Navigator knife tested in the June issue, as that is the knife I chose for my primary on-board knife.I noted a few items I’d like to disagree with:

First, the Myerchin can be opened with one hand, although it’s not especially easy. A well-oiled (or well-used) knife can be opened fairly well by inserting the thumb into the shackle slot, and also leveraging it out with the middle finger. This works quite well for me, and I never need to use both hands.

Second, it is definitely NOT a requirement to close the locked blade by opening the marlinspike, although that works as well. The blade (and marlinspike) can be unlocked by placing forward pressure on the lanyard attachment without touching the marlinspike at all. It’s worth noting that this is the ONLY way to close both blades if you have them open simultaneously, and I suspect this was the designer’s intent. Closing the knife in this manner requires you to place the lanyard attachment against your leg (or thereabouts), where the knife can be easily closed by use of the index finger. Interestingly, this method also pretty much ensures that other fingers do not come between the blade and body while closing the knife.

Third, the “chart light” you mention is also bright enough to move through a darkened boat without disturbing anyone, a nice feature at night on a smaller boat with limited battery power like my Hunter 25.5. While I won’t presume to question the overall scores and results of your bench test, as I have no experience with the majority of knives you tested, I do believe the inexperience of your tester(s) with this particular knife resulted in a flawed review.

Bob Myers
Tampa, Florida


Thank you for including my cobalt lockback in your article on sailor’s knives. I would like to offer a couple of suggestions for future knife tests.

In consideration of long-distance sailors, I feel that a long-term corrosion resistance category should be added to the test criteria. Sea water can degrade or destroy the cutting edge of most iron-based knife materials, including stainless cutlery steel, so it is a very relevant issue. A four-month saltwater kayak test was conducted by Shomer-Tec. The Boye Dendritic Cobalt knife showed virtually zero corrosion, even internally, while other “stainless” test knives were literally “eaten up” by the salty environment.

I would also like to see a category that measures “edge holding” or cutting stamina. Cutting a rope once or twice is one thing, but prolonged cutting, such as one may have to do when a prop is entangled in a fishing net, is a real safety issue. Cutting rope for 15 minutes or more would be a good test to see if a knife would really cut it in an emergency. In a test published last year in Blade magazine, a Boye Dendritic Cobalt folder made 57 clean cuts of 1/2" sisal rope, and was still able to shave arm hair. This unique blade metallurgy will keep cutting, even on tough fibers like nylon and poly.

The article refers to the Boye shallow scallop serrations as less aggressive in cutting, but this geometry has advantages that were not mentioned. They hold up during long-term cutting and cut clean; they do not make a bird’s nest of stretched and partially cut fibers when they start to get dull. They sharpen with just a swipe or two on a flat whetstone. And even with the serrations the blade can still serve fairly well in other kinds of functions, such as whittling or food preparation.

Please note that our current contact address is Boye Knives, PO Box 1238, Dolan Springs, AZ 86441; 800/853-1617.

David Boye
Boye Knives
Dolan Springs, Arizona


Marelon Seacocks
I am writing this at the prompting of a friend who thought I should share a simple solution to a possibly substantial problem.

In the spring of 1998 I replaced all the original bronze through-hulls and gate valves on my 1970 Cal 40 with flange mount Marelon ball valves. Using Marelon was a stretch for me because the idea of “plastic” valves in the bottom makes me really nervous. Good experiences of some careful friends and Practical Sailor’s high marks gave me confidence to go with them.

Come winter I decided to store the boat in the water. I winterized the engine and freshwater systems, closing the related inlets and drains as I went and all with no problems…until I got to the head intake.

The head intake shares a 3/4" flange-mounted Marelon seacock and flush through-hull with the anchor chain washdown pump. I was going to close the seacock, pull the hose off the head intake and run anti-freeze through the washdown pump. Then I’d run some through the head itself. As I turned the valve handle it came off in my hand. I thought I’d hear water rushing in but the valve stayed watertight. Now, however, I couldn’t close the seacock OR winterize the washdown pump.

West Marine cheerfully replaced the valve, but I figured I’d have to haul the boat or get a diver (brrrr) to change it. The only 3/4" Marelon valves they had were not flange mounts but as I looked at the valve I realized the valve body unscrews from the mounting body (flange type or pipe mount). All I had to do was unscrew the damaged valve from the flange mount and screw on the new one. That way I’d never disturb the through-hull or the flange mount or the sealant. But how to stop the rush of water?

I remembered the concept of a collision mat. If your boat gets holed, drop a sail over the side (hold on to it!) and position it over the hole. The water pressure holds it in and slows the water flow until something more solid can be put in place. I decided to try the idea by using a small blue plastic tarp. With a friend, I tied some thin line to the tarp’s corners, dropped it over the area where the through-hull is and pulled it tight. I went inside and pumped the head until the tarp was sucked up against the through-hull. At the same time, my friend on the dock pushed on the tarp with a deck brush held under the boat as far as possible.

Once the head had pulled the tarp against the hull and wouldn’t pump anymore I loosened the hose clamp at the seacock and spun the top of the valve off. With the water pressure against the tarp only about a cup of water came in until I screwed on the new valve body and turned it off. Then it was a simple matter to remove the hose nipple from the bad valve and reinstall it all on the good one and finish winterizing.

Kevin Tisdall
via e-mail


In our experience, the handles of small Marelon seacocks (by Forespar) can sometimes fail. We have not seen this problem with seacocks larger than 1". What we think happens is that because all plastic is slightly hydroscopic, the ball swells slightly and becomes hard to turn in its seat. In small seacocks, the arm that connects the handle to the ball isn’t strong enough to withstand the torque of the handle turning, and snaps.


Corroded Fasteners
This is the sort of note that editors love to get.

Just after I read a recent issue (we are cruising in the southern Caribbean and get mail infrequently) I was staring at the badly corroded traveler on my Hans Christian 38 and getting it ready to transport to a nearby machine shop for disassembly and cleanup. So I tried the Corrosion Block-tapping recipe you published and by golly after three days of soaking and tapping the immovable stainless machine screws came out! That machinist father-in-law of yours is a wise fellow indeed.

I saved enough money to pay for my last year’s subscription, maybe even more but the joy of solving problems yourself is worth more than money, as you well know. The corrosion problem will require constant vigilance even though I am applying Tef-Gel to each screw because the screws go through an aluminum track into a bronze traveler base, a veritable battery when sea water splashes over it. But now I know how to deal with it effectively.

Jerome Zukosky
S/V Herman Melville
Chaguaramas, Trinidad


Correction
The August 1 article on life raft materials stated that “All PU and PVC rafts are vacuum-packed…” This is not true. Most PU and PVC rafts are vacuum-packed, but not all.


Bilge Pump Wire
On the subject of tinned vs. non-tinned wires on marine bilge pumps, I’ve reviewed why we build our pumps without tinned wire. I found that West Marine (aka Mayfair/Johnson) manufactures their pumps with tinned wires and I have several Mayfair/Johnson samples under their own label with tinned wires. As for Rule, I have looked at numerous samples (old and new) up to 2000 GPH and can find none with tinned wires. I have a Whale sample that does have tinned wires.

Instead of tinning the wires, both Rule and Attwood use “caulk.” This caulk is silicone powder applied to each of the individual wires prior to wrapping and insulating. The caulk fills the voids between the strands. With the voids filled, water cannot wick up to the motor housing should the end of the wire be improperly connected and submerged in water. This is a design we arrived at years ago and have used successfully on hundreds of thousands of delivered pumps. All evidence I have indicates Rule does the same.

We believe caulked but non-tinned wires is an appropriate design choice for marine bilge pumps. Tinning is an anti-corrosion feature which is not really required on properly insulated and terminated wires (waterproof connectors well above the water line). And, it is not recommended by ABYC. There is no exposed wiring in a proper installation and tinning provides no additional benefit. Caulking the wires provides somewhat of a hedge against drawing moisture into the motor housing but, again, it is somewhat moot in a proper installation. We do think the caulk has at least some value and we will continue to produce our pumps with this feature.

Bill Mulligan, Senior Design Engineer
Attwood Corp.
Lowell, Michigan


Mr. Mulligan’s comments were solicited in response to statements made in our June test of electric bilge pumps that non-tinned wire is less desirable than tinned wire. We formed this opinion based on experience with non-tinned wire failing more quickly than tinned wire. Also, in the September 1999 issue we discussed the silicone powder used in Attwood pumps. Spokespersons for several wire companies, including EIS, which makes Attwood’s wire, said the purpose of the silicone powder is to make the wire easier to strip, and has little if nothing to do with corrosion resistance.

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