Ask The Experts

Solutions from the BoatUS Tech Team

Photo of a windlass

Windlass Woes

I bought a used windlass with no label to tell me who made it. The unit appears to be heavy-duty with a 12-volt motor. I'm going to use 1/0 wire for a 30-foot run to the battery bank. Do I need to install a control box? What other considerations are there?

John Adey: This is a tough question to answer without knowing the rating of the windlass you're going to install. For instance, following ABYC standards, a Maxwell 900-pound unit is rated at 36 amps at 60 feet (we use round-trip numbers) following a 10-percent voltage drop rule (which may be acceptable for this unit) and would take a #4AWG conductor. A three-percent drop (probably better performance) would be a 0AWG. You're on the right track, wire wise, if the unit falls around this 36-amp example. You'll also need to rate the fuse for the amp draw of the unit. Not knowing how much it draws gives you a distinct disadvantage. You may oversize it and not protect the motor, or undersize it and have it trip under load. Finding a picture of a similar unit online and searching for the manufacturer's specs would be advisable.

Controller wise, you need to consider a two-directional, solenoid-type switch for up and down use. Most installations have a foot switch up by the bow, and a toggle back by the helm. These will work in conjunction with the solenoid you'll install. The solenoid reverses the positive and negative and runs the motor backwards in most cases, and is rated based on the amp draw. My final advice is research this unit to find out what you have and look up some specs. Even conducting a garage "bench test" for amperage may not help because I doubt you'll get a full load simulated.

Half Gassed

I own a 32-foot powerboat with twin V8 gas engines. Is it OK to shut down one engine and motor on one for a few hours, and then switch to the other for about the same amount of time?

Tom Neale: Some motors have transmissions that can be damaged by the prop turning for long periods without the engine on. Check with the transmission manufacturer. If you have such a transmission you'd have to lock that prop in place. This is often quite difficult and could be even dangerous. I don't like to let transmissions freewheel with the engine off, even if the manufacturer says it's OK. Further, I doubt it would cut the cost in half. The drag from the running gear not being used is significant, even if you can allow that unused prop to freewheel. The unused prop will pull your boat off course, causing you to have to compensate in steering, probably running with your rudders a bit cocked, also adversely impacting fuel efficiency. I'd just run both of them much slower. With a little experimentation you may find your rig's "sweet spot" where you get fuel economy, and safe comfortable running.

What's That Smell?

There's a strong odor coming from under the floor inside the cabin of my Carver Mariner. I don't see standing water in the bilge. I've heard that if shower water stays in the tank and isn't all pumped out, it could cause a smell. Should I add something down the drain?

Tom Neale: Don't pour a product down the drain unless you know that you don't have a leaking drain hose. A shower sump should be accessible. Inspect yours and pour a bilge-cleaning product directly into that sump. This smell could also come from your holding tank (a prime source) or from your head hoses, particularly if they're old, and have built-up deposits. You can add Raritan CP as a deodorizer for heads and holding tanks, and Raritan CH to clean the inside walls of hoses and head systems. Or StarBrite sells various bilge cleaners and deodorizers for the same purpose.

Dueling Depth Finders

Illustration of a depth sounder and fishfinder transducer©2012 Mirto Art Studio

I sail an older fiberglass sloop, and use a Uniden depth finder with in-hull transducer. I'm considering installing a Garmin chartplotter with fishfinder capabilities. If I install the new Garmin dual-frequency in-hull transducer next to the Uniden transducer, do I risk electronic interference between the two?

Don Casey: Yes, and that applies even if the transducers are not next to each other. If you run both depth sounders at the same time, and they're operating at the same frequency, there's the possibility of interference. Even if your Uniden is transmitting on 200kHz and you set the Garmin for 50kHz, it may not solve the problem. As I understand it, even though the display is limited to the selected frequency, the transducer is still transmitting on both frequencies. Interference does not always occur, but if it happens, you may be able to filter some or all of it out by reducing the gain. Otherwise, the only sure solution is to turn off one of the units. Locating the transducers adjacent to each other is certain to increase the likelihood of interference.

Home Remedy

I'm trying to remove the painted registration numbers from my fiberglass hull and replace them with graphic decals from BoatUS I've heard to use acetone, lacquer thinner, or 1,000-grit sandpaper. What do you suggest to remove them correctly?

John Adey: An old trick that works is standard oven cleaner. Cold formula works best. Take all of the appropriate precautions. I've used it on a variety of boats (old and new) and never had an issue. If that doesn't work for some reason, any good automotive-paint remover should do it without harming the gelcoat, although it's always a good idea to test a spot to see if it gets "gooey" from the chemical. If you end up with "raised" spots under the now removed paint, 1,000-grit wet-sand paper (by hand, no machine!) can flatten them out. Follow that with rubbing compound, then polishing compound, and finally wax (after the new numbers are applied).

Reversed Polarity Needs An Immediate Fix!

I smelled something burning, checked the electrical panel, and the "reversed polarity" warning light was illuminated. I disconnected the shorepower cord; both the male and female plugs were black. I got a new cord and when I plugged that one in, the light illuminated yet again. I disconnected the cord and ran the generator. All the electrical systems on the boat worked fine, with no reverse polarity light. I'm guessing it's the boats receptacle that's shorted? Can I get a new receptacle to replace the old one?

John Adey: The problem could indeed be in the shorepower inlet. They're readily available and on a difficulty scale of one to10 are about a five to install. Before you do this, however, I'd also hook your boat up to another shore-power pedestal. It may be that some electrical work was done on the dock or some damage was caused that allowed the neutral and hot to be reversed, thus the reverse polarity light. As you stated, this can also happen in the inlet itself or somewhere along the wire run between the inlet and the back of the panel. Before doing anything, with the cord disconnected, check the inlet and wire run thoroughly, and replace anything that looks suspect. The cable could have chafed on a sharp object or fallen across a hot exhaust. If you smell burning then there should be signs of damage. These are the type of issues that can cause in-water shock issues and can potentially kill swimmers. If the problem isn't immediately apparent upon your inspection, I suggest finding an ABYC-certified electrical technician and have the problem fixed.

Parts From The Past

I bought a 1988 Wellcraft St. Tropez, and need top rollers for the Plexiglas entry door. Can you help me locate replacements?

Tom Neale: I don't know where the company got the rollers they used in 1988. But many people have questions similar to yours because older boats were often built by companies that are no longer in business or, even if they're still in business, don't have records that would give an answer. But you often don't need to spend extra time and money trying to get the exact original parts for something like this. Drawer rollers, door latches, hinges, cabinet latches, and other interior hardware can often be found at Home Depot or Lowes. Buy high-quality parts made from materials that won't be harmed by the marine environment. But you can usually solve this type of problem, too. Remove one of whatever it is from your boat, and take it in for comparison. Frequently the customer-service people will be very interested in helping you to find something that will work for a boat. You might also want to consult one of the many relevant catalogues such as, for example, McMaster Carr, which has a list of sources for odd rollers, tracks, bearings, and so on.

Fumed Fillers

Don, I read about colloidal silica in your Sailboat Maintenance Manual. I've also seen something called fumed silica being sold as a similar product. I've looked online and haven't been able to find any decisive information as to the specific differences of these. Can you expound upon and compare these for us? Which one provides more strength in the laminate repair, or does one or the other bond better with certain resins or fibers?

Don Casey: I'm no chemist, but my understanding is that all silica additives labeled colloidal silica are actually fumed silica. They become colloidal when mixed into a liquid, usually epoxy in the case of boat use. I've heard some boat workers claim that fumed silica has better anti-sag properties, but I'm confident that any differences in the handling of the silica has to do with the surface treatment a specific product has been given, not some supposed difference between fumed and colloidal. I've never seen any definitive data that quantifies a strength difference between, for example, West 406, Cab-o-sil, or a bulk generic fumed silica intended for epoxy thickening, so I consider them all essentially the same.

As for strength, fumed silica is almost certainly up to any demands you're likely to place on it. It's notable that the two additives rated highest in strength and density by West System, for use with their epoxy, are 406 Colloidal Silica and 403 High-Density Filler. The 406 is pure fumed silica, and the 403 is a mixture of fumed silica and a second component (calcium metasilicate). Epoxy thickened with fumed silica also handles and machines nicely. The one caution I'd offer is that fumed silica absorbs resin like a sponge, potentially depriving the surface you're applying the mixture to of sufficient resin for a solid bond. You generally need to first wet out the surface being repaired with plain resin so that the resin will get a chance to penetrate the wood or laminate. After this initial application of resin starts to gel, apply your colloidal-silica-thickened resin. The two resin applications will bond together on a molecular level, delivering maximum adhesive strength.

Standardized Breakers?

House wire has standard amp breakers for the size wire to protect. On a 12-volt system is there a size fuse, per size wire?

Don Casey: The short answer is no. Wire used for 12-volt DC connections does, of course, have a current limit, but except for high-draw appliances like windlasses and inverters, the current-carrying capacity of the wire is likely to significantly exceed the expected draw. Unlike with AC power, voltage drop is usually the guiding concern with DC wiring. That forces the use of "oversize" wiring, at least from a current-carrying perspective. As a result, fuses and breakers are sized based on the expected load on the circuit, not the capacity of the wire. There's no downside to this. The lower threshold still protects the wire, and the smaller breaker trips (or fuse blows) when the draw exceeds what is expected for this circuit, a condition that normally signals a problem. 

Published: August/September 2012

Meet the Experts

Photo of Don Casey

Don Casey
He's been one of the most consulted experts on boat care and upgrades for 30 years, and a panelist on our "Ask The Experts" website for a decade. He and his wife cruise aboard their 30-footer part of the year in the eastern Caribbean. His books include Don Casey's Complete Illustrated Sailboat Maintenance Manual, and the recently updated This Old Boat, the bible for do-it-yourself boaters.

Photo of John Adey

John Adey
The president of the American Boat & Yacht Council (ABYC), John grew up boating. He's been in the industry since 1990, with experience from a yacht brokerage and boatyard to owning a marine supply store. He and his family sail their classic 1976 Irwin ketch, a boat he completely restored. John is a trusted source for technical information for industry professionals.

Photo of Tom Neale

Tom Neale
He's maintained, lived aboard, and cruised long distance on boats with his wife and family for most of his adult life. He can take apart and fix almost every system aboard a boat, has written two books, filmed a two-set DVD on East Coast cruising, written for top marine magazines, and has won seven first-place awards from Boating Writers International and many awards for his technical writing.

Photo of Bob Adriance

Bob Adriance
The editor of Seaworthy, the damage avoidance newsletter of BoatUS Marine Insurance, Bob has written hundreds of articles on safety, loss prevention and causes of boating accidents. His 2006 book, Seaworthy, Essential Lessons of Things Gone Wrong, is based on 20 years of real claims files. He's owned Folkboats to J-Boats and currently sails a 36-foot sloop.

Photo of Beth Leonard

Beth Leonard
BoatUS Magazine's new technical editor, Beth Leonard, grew up powerboating, waterskiing, and fishing on Lake Ontario. Since 1992, she and her husband have completed two circumnavigations on two sailboats, doing all maintenance themselves. They also installed the systems on their 47-foot aluminum sloop. Beth has written The Voyager's Handbook, the how-to bible for offshore sailors, and hundreds of technical articles.


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