Ask The Experts

Solutions from the BoatUS Tech Team

Nuts and bolts illustrationIllustration: Bill Roche

Mystery Boat Screws

When I removed the drain plug at the transom, the whole unit came out. The screws deteriorated away, the stubs look like stainless. The body of the drain is bronze. What kind of screws should I use to reinstall? The boat is in saltwater all summer.

Tom Neale: Stainless shouldn't be affected in this way by bronze. Stainless, absent certain circumstances, is more noble than bronze and I've seen many bronze fittings held on with stainless screws without problem. The following is a culmination of my thoughts and those of Don Casey and John Adey. Of course we can't really know for sure without testing.

It may be that the transom core is wet, and crevice corrosion attacked some inferior-grade stainless. (I've seen what crevice corrosion can do to stainless screws and you'd be amazed. Your description is consistent with this.) A wet core in your transom would be an ideal place for this to occur because of the lack of oxygen. Or perhaps the screws weren't really stainless.

Try using silicon bronze screws and embedding with 3M 4200 or similar product. Don't use brass. Otherwise, buy some 316 screws from a reliable source and bed well. I've used both bronze and, in other cases, stainless (quality 316) with bronze thru-hulls and haven't had the problem you're experiencing, but I bed them well and haven't put them into wet coring. Be sure to check your transom coring. If it's wet, you're going to need to deal with this immediately.

To Tin Or Not To Tin

I have a 25-foot Wellcraft with windlass. I have approximately 300 feet of half-inch anchor line with 16 feet of chain. On a typical day, I usually pay out about half. The line is twisting and hanging up in the windlass. I can go below deck and pull on the line while my first mate hits the switch and it works fine, but if there's no tension from below, it hangs up. Is the solution new line or paying it all out and untwisting it? Or does the line have a memory now and will never be good for anything but to be cut up for docklines?

John Adey: I understand your position and it makes sense. But ABYC was established to be a bare-minimum safety standard — a floor, not a ceiling. Tinned wire is one of those items that's never made it into the standard because committee members (the electrical committee has more than 50 volunteer members from all over the industry) see this as a quality issue, not a life-safety issue. There are other examples of items not in the standard for similar reasons. For example, we don't have standards on "scantlings" or hull thickness and structural layout. This is not a significant cause of accidents or deaths so there's been no reason to create a standard on it.

Solar Battery Maintenance

We'll be storing our sailboat for months at a time and are planning a solar-panel system to keep our batteries topped off. Is there a formula to use to determine how many watts we need to keep our house bank and starter battery charged? We have one group 31 AGM start battery and five group 31 deep cycle AGMs — roughly 630 amp hours total.

Don Casey: I'm assuming you're talking about storage in a sunny place, perhaps in the Caribbean for hurricane season. Given adequate sunlight, the formula is that the output amps of your solar panel or array should be around 0.3 percent of the amp-hour capacity of the bank you're maintaining. That works out to around 2 amps for six group 31 batteries. To get the wattage of the panel, multiply output amps times output volts, typically around 16 or 17 volts (in 90-degree weather) for a 36-cell panel. So a 35-watt panel should be sufficient to keep your batteries topped up.

Of course, there are variables, beginning with lack of sunshine. Shade and shadows reduce output. If you leave anything running — a bilge pump, for example — you need sufficient extra capacity. You wouldn't be wrong to go with a 50-watt panel. You can go up to around 1 percent of amp-hour capacity before you require a regulator to prevent damage to the batteries. That works out to about 100 watts, but unless you're in a sun-challenged environment, you'll just be spending twice as much for no benefit.

Dissolving Calcium Deposits (or Y & Ca)

I've read that muriatic acid will dissolve calcium deposits in holding tank hoses, but I'm concerned about the acid going into the holding tank. The calcium is about an eighth-of-an-inch thick and is creating a clog where the hose enters the Y-valve. Should we pump out the holding tank immediately after the treatment? I'm hesitant to send the acid overboard as I don't want to weaken any of the overboard fittings.

Don Casey: The acid will dissolve the calcium and won't harm bowl, hoses, or synthetic components. Acid can attack metal, but even that's unlikely for the concentration you should be using to clean hose interiors. Try white vinegar first. This is a mild acid, cheap by the gallon, and you can leave it in the lines with impunity. The idea is to immerse the calcium in the acid, so opening a hose at one end and elevating the other end to create a container is the surest way to maximize the effect. Alternatively, pump a fresh cup or two of vinegar from the bowl into the line every 5 or 10 minutes over a period of a couple of hours. If this is going into your holding tank, you'll need to pump out the tank after treatment. Acid will have little effect, positive or negative, on the tank except perhaps to kill bacteria.

Muriatic acid is a more powerful option. You need around a 10-percent solution, so if the acid you buy is listed as, say, 30-percent acid, you need to make up a weaker mixture by adding one part muriatic acid to two parts water. Always add the acid to the water, never water to acid, and be cautious of the fumes that strong concentrations release. This concentration of muriatic acid is way more dangerous for you than for your plumbing. Muriatic acid will be more active than vinegar, so give your lines just one or two treatments, limiting the idle time to a few minutes. It will not harm a plastic holding tank, but if yours is metal (a bad idea for lots of other reasons), do not pump muriatic acid into it. The acid would not harm your seacocks or thru-hull fittings, as it is often used in swimming pools to adjust pH levels. Nevertheless, overboard discharge is illegal, so either send the acid into your tank or do this job when your boat is out of the water. Flush plenty of fresh water through after treatment to carry away any remaining acid. You can dissolve a box of baking soda in a bucket of water and pump that through to make sure of neutralizing the interior of the plumbing.

The Name Game

My boat is titled and registered in Texas and not documented with the USCG. I find myself spending more time on the Gulf than on area lakes. How can I transfer the title to get it documented, or is there a way to name the boat without being documented? I do have an MMSI number that is registered with my boat and personal information.

Beth Leonard: Unless you use your boat for commercial fishing or coastwise trade, you're not required to document your vessel. For recreational boats — including boats used for recreational charter fishing — your state registration and the name on the state registration work just fine for search and rescue, and for communicating with the Coast Guard in U.S. waters. You could go ahead and document your boat if you want, but there would be no advantage unless you try to check into a foreign country. For operating in U.S. waters, in most states you would still need to maintain the state registration, and would be charged a fee to get the documentation in addition to that.

In the UK and some other countries, a boat is only officially named if it's documented, and names can only be used once. But in the U.S., there's no such prohibition. Your state registration and your MMSI number act as your official identification instead of the boat name. If you pushed the distress button on your radio, it would broadcast the MMSI number, and the Coast Guard would use that to identify you. 

— Published: December 2014

Meet the Experts

Photo of Beth Leonard

Beth Leonard
BoatUS Magazine's 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.

Photo of Tom Neale

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

Photo of Don Casey

Don Casey
One of the most consulted experts on boat care and upgrades for 30 years. He and his wife cruise 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, John has 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.


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