Mailport February 1, 1998 Issue

Mailport 02/01/98

Scanning Sonar
Regarding the article, “Field Testing the New Breed of Scanning Sonars” in the September 1997 issue, I agree that it is very helpful to “see underwater,” but for starters, I would settle for just knowing how deep it is.

A forward-looking sounder operable from the helm has been working on our boat since 1987. We depend on it! In fact, because it draws so little current we leave it on all the time! Our nine-year-old Humminbird LCR 3004 with 200 kHz transducer uses a 12° beam. It determines the actual depth ahead of the boat in just the same way it does the actual depth straight down. The only difference being that in our homegrown set-up the depth figure indicated by the forward-looking transducer must be divided by two.

In the ICW or a narrow channel or canal the helmsman can pan the bow from side to side to search for the deepest part as one would do with a flashlight in a dark alley.

Both depth and fish alarms are operative. Nothing is visible outside the hull.

Full 360° scanning sonar coverage doesn’t seem high priority and there is always the problem of how to display 3-dimensions of information on a 2-dimensional screen.

Shellman Brown
Hyde Park, New York

Cheap Anchor Light Control
In the past I have read in Practical Sailor and elsewhere of photoelectric controls for anchor lights that would automatically turn them on at dusk and off at dawn. The ones I have read of seemed inordinately expensive. I have often wondered if there was a mass-produced device that would serve.

I now have found the economical solution to automatic control of the anchor light. It cost $7.99 at a local hardware store. It is the Intermatic Malibu ML812PR Remote Photo Control. It is sold as a photoelectric control for 12 volt AC yard lights. These lights and accessories for them are very widely available. The control works perfectly well on 12 volt DC. It will work with the polarity either way, but I expect that most sailors would install it, as I did, so that the positive side of the circuit is the one that is switched. The design is such that it could be mounted through the cabin side. I didn’t want yet another hole to try to keep sealed, so I just stuck it to the corner of a cabin window with a glob of silicone.

Frank Wilson
via e-mail

Head Odor Cures
I think I have found the final answer to what I call “the smelly marine head.” I’ve disconnected the saltwater supply line from the ocean and reconnected it to a supply tank. The polypropylene supply tank is filled with freshwater and some of that nice blue liquid tank deodorant. I did this about a year ago.

The results: That all-too-familiar odor is gone (I think stagnant saltwater was the majority of the problem). The build-up of minerals and corrosion on moving parts is drastically reduced. A through-hull has been eliminated.

The downside is that the tank takes up space and adds weight. But everything on a boat seems to be a trade-off. In my case, it’s a motion-sickness-prone wife with an acute sense of smell. The tank has been worth every cubic foot and every pound.

Steve Peterman
Los Angeles, California

We, too, learned firsthand the benefits of keeping seawater out of the toilet when we installed a SeaLand VacuFlush toilet on our previous test boat, a C&C 33. SeaLand’s president, Ed McKeirnan, told us that a lot of bad odor comes from all the tiny critters dying in your bowl. He was right. The VacuFlush, incidentally, only uses a pint or so of freshwater per flush. Another bit of advice is to use rigid PVC instead of hose for low spots where waste can accumulate, heat up and cause odors. The third trick—an in-line deodorant and disinfectant dispenser— is described below.

After reading your various articles on dealing with what I call the “stinky head syndrome,” I finally decided to attack mine. Step one involved installing the Tank-Ette in-line head treatment system. The first thing I discovered—thanks to the blue dye—was several leaks. Step two was to repair these leaks.

One particularly nasty leak was on top of the pump mechanism of my Raritan head, where the shaft comes out of the pump casing. I tried replacing the seal, but it leaked even worse. In consulting with Raritan, I discovered that they had redesigned the seal. I bought the new style seal and pump casing (less than $50), and voila! no more leak. I would strongly recommend this upgrade to anyone with the older style head (1992 or earlier). I must also commend Raritan’s technical assistance line.

With these two moves (Tank-Ette and leak repairs), I now have what I consider to be an odor-free head.

Wes Hardman
Ladysmith, British Columbia

In the March 1, 1996 issue, we tested three in-line dispensers, the Earth Safe (West Marine, 800/538-0775), Mar-Flush (the maker of which we could not reach due to a disconnected phone line) and the Tank-Ette (800/563-5947). All three work, but only the Tank-Ette has a winterizing valve.

Another Hard-to-Remove Fiberglass ‘Restorer’
Regarding your article on fiberglass restoration products (October 1, 1997), I own a 1978 Islander. Three years ago I applied TSRW to both the hull and deck (excluding non-skid). The product had a remarkable effect on all surfaces, much better than what I was able to achieve with various wax products. The following year I applied an additional coat or two as suggested by the manufacturer. Again, a good result was achieved.

Now for the downsides: On the hull the surface scuffs and discolors where the fenders contact the hull. Dirt and grime eventually penetrate the product requiring removal, particularly on the deck. Also, uneven wear on the deck requires total removal in order to achieve a uniform surface when recoating.

Based on my experience, I plan to continue to use this or a similar product on the hull, but not on the deck. I found it necessary to use MEK (methyl ethyl ketone) to remove the accumulated coats. The stripper product packaged with TSRW would not budge it. It took a real effort to get this stuff off.

Dennis King
Redmond, Washington

Check This Check Valve
In reference to your article, “Bilge Pumps: Keeping Her Dry” (October 1, 1997), there is one option that was not mentioned. It is possible to use an electric check valve that is normally in the closed position. This check valve can be wired in with the bilge pump to come on only when the pump is turned on.

When the bilge pump is turned on, the check valve solenoid opens the check valve completely, causing very little if any resistance to the flowing water. Depending on the type and size of electric check valve used, the electrical draw can be very small.

When the bilge pump is turned off, the check valve returns to its normally closed position, not allowing any water to move past the valve.

If there is any danger that water can flow or back siphon through an outlet, note that a check valve should never be installed without a ball valve installed between the outlet and the check valve.

Larry Meese
Lawton, Oklahoma

For those who didn’t read the October 1 article, the purpose of check valves in the bilge pump discharge hose is to hold prime in the intake line of a suction bilge pump, to prevent back-siphoning, and to keep water from draining out of the hose and back into the bilge once the pump has been turned off. The problem with most check valves is that they can trap debris and may cause back pressure.

Double Lowers
Double lower shrouds are probably more important on trailerables where a hinged mast can lead to a big headache for cockpit crew when a forestay gives up, and easily avoided (like the fabled hatchet hanging over the doorway) by forward lowers. Yet, with the exception of the Rhodes 22 and few others, double lowers are not to be found on today’s trailerables.

So, while Stainton’s rule for single lower shrouds is “Never ever sail under jib alone,” sailing with a 175% genoa is repertoire #101 for Rhodes 22 owners.

Stan Spitzer
General Boats
Edenton, North Carolina

Spitzer refers above to reader David Stainton’s admonition not to sail under jib alone, a letter appearing in the July 1, 1997 issue. Stainton, a marine surveyor from Cranberry Island, Maine, said he has surveyed at least three boats which had lost their spars while sailing with just the headsail. In each case, he said, the boat had single lower shrouds.

Cheap Laptops
Regarding your article on “marine” laptops in the November 1 issue, why do these laptops need an inverter to work? Since all the IC’s on a computer run at 5 volts, why should one have to go to 110 volts to feed the machine?

On Pampero IV, I have a secondhand GRiD 286 (with a 20-megabyte hard disk) which, though rated at 16 volts (in addition to 110V and 240V), works perfectly with 12 volts fed directly to a pin at the back of the machine. It draws just 1 amp, so is quite economical of electricity.

A 286 may sound antediluvian, but it receives weatherfaxes with “PC HF Facsimile Version 4.0” (another oldie unsullied by “bloatware” Windows) and could work packet radio and receive Navtex. The hard disc capacity is quite adequate for the uses to which I’d want to put it. Why go for unnecessary bells and whistles?

I don’t know if it answers any mil specs, but the case is magnesium and I was told it used to be a favorite of government officials.

J. Somerhausen
Douglaston, New York

If one had several thousand dollars for a computer navigation system, there is a lot of software and hardware to spend it on. But some people might find the prices in Practical Sailor for this equipment not very practical! I found a 486/50 laptop at work that was deemed obsolete, downloaded some shareware (and subsequently paid $30 for it), scanned the charts I already owned, and hooked the computer power inlet port directly to the 12-volt battery (no inverter). Granted, a free computer is exceptional, but a so-called obsolete 486 can be had for a small amount of money. Anyway, the system works very well.

The software is Navigate from Paul Mouland ( It can be downloaded from

If nothing else, perhaps someone might want to try computer navigation before spending a lot of money. They may find that Navigate is all that is needed.

Fitzhugh Miller
Pensacola, Florida

We asked Rick Viggiano of Pro-Tech Marine, maker of the Pro-Box computers mentioned in the November 1 issue, why he uses a low RFI inverter instead of wiring the computer direct to the ship’s 12-volt battery system. He gave us three reasons: an inverter and surge strip protect the computer from voltage spikes, such as might occur during an engine start; without a noise filter, direct DC current can cause interference problems; and related equipment such as printers, disc drives and other peripherals often require AC anyway.

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