Keep It High When Feeling
The Drain

Published: December 2011

I'm new to sailing and a new owner of a 1983 Hunter 22 that has three thru-hulls — one for the knot-meter transducer, one for the galley sink, one aft for the cockpit drain. It also has deck drains and an anchor-locker drain above the waterline. I want to install a bilge pump but don't know where to route the discharge. Should I tee into the galley drain that's close to the bilge pump well, or to one of the above-waterline drains? If I need a new thru-hull, where should it be?



Don Casey: Bilge-pump discharge openings are ALWAYS located above the waterline, and need to be far enough above so that they can never be submerged, either by heeling, or by the stern wave when the boat is moving fast. A discharge line can pass water into the boat just as easily as it passes it out. If, for example, you tee into the sink drain above the waterline, and that connection dips below the waterline when the boat's heeled, water will flow straight into the bilge, flooding the boat. This is equally true of a dedicated thru-hull discharge located just a short distance above the waterline. Even if you route the discharge hose in a high loop before it connects to the outlet, should the pump run while the outlet is submerged, when the pump stops, the full line will set up a siphon and water will again flood into the boat.

Adding a check valve into the discharge line is a bad idea. It not only reduces the capacity of the pump, but the valve can catch debris, blocking the discharge. It will also soon gather enough debris to prevent the valve from sealing, defeating the purpose. The best place for a bilge-pump discharge is high on the transom, just below the deck joint. A thru-hull located here is unlikely to become submerged in normal sailing. If this location is impractical due to the location of the pump, or the design of the boat, then a just-below-the-rail location on either side of the hull can work, assuming that you do not regularly bury the rail when sailing.

How Dark Is Dark?

I live in Fort Lauderdale and have a 1982 34-foot Silverton convertible. I want to tint the front three windows to reduce the heat in the cabin. A company that does window tinting on cars and boats recommended a 35-percent tint film. Does this exceed the standards for tinting marine windows? What do you recommend?



John Adey: The American Boat and Yacht Council (ABYC) has a technical standard for glass on boats. When it comes to tinting, we discuss areas in the "operator's range of visibility" that extends from 90 degrees to port, and 112.5 degrees to starboard, from the helm station(s). In this area, the light transmission must be not less than 70 percent (30-percent tint). In other areas of the boat, you can exceed that amount. So your 35-percent tint is OK, as long as it's not in the operator's range of visibility; there, you'd use a maximum 30-percent tint.

Is Bad Company Destroying My Zincs?

It seems that my zinc anodes need replacement rather quickly for no apparent reason. I recently moved to a new slip and I'm surrounded by sailboats. Could that have anything to do with the corrosion of my zincs?



Don Casey: Yes, but not necessarily because they're sailboats, although that could be a factor. For safety reasons, to keep an AC leak from going to ground in the water, the DC ground on most boats is connected to the AC ground. Anytime two or more boats connect to the same shore power circuit, they share an AC ground connection. That essentially connects the underwater metal on your boat to the underwater metal of the boats around you that are sharing that AC circuit. If your underwater metal is different from the boats around you, then you have the components of a big battery — dissimilar metals submerged in an electrolyte, in this case seawater. If your underwater metal is less noble — an aluminum outdrive, for example — while the neighboring boats have bronze or stainless-steel underwater fittings (as sailboats tend to do), the aluminum suffers corrosion.

DC leakage from nearby boats might also be seeking ground through your shore-power connection, greatly accelerating the corrosion potential. The short-term solution is to unplug your boat. If you have some compelling reason to leave it plugged in, then install a galvanic isolator into the green AC grounding wire, right at the inlet fitting

Belt and Suspenders Approach

I'd like to add another level of safety to my Ranger 2250SS, by installing a fuel fume-monitoring system. I'd like one that has at least two pickup points in the boat.



John Adey: ABYC offers some great advice; I'll sum up the important things for a boat owner here:

  • Make sure it's tested and certified by a third party to UL standard 1110, Marine Combustible Gas Indicators.
  • The unit shall NOT be wired to cut off the engine. You want to make that choice, not a device. Shutting down your engine could cause an entirely different problem!
  • Sensors have to be as low in the bilge as possible without the chance of being submerged. For an inboard engine, at least one has to be lower than the starter motor.
  • If your bilge has compartments, install a sensor in each compartment that has a fuel component (hose or tank).
  • A visible warning (LED, for example) must be installed at the helm station and an audible alarm must be able to be heard from the helm.

Those are the key points you should know when purchasing and installing these items. When it comes to UL, the unit does not have to be "UL Listed," just tested by an independent, third-party lab, not by the manufacturer themselves. You may also find a manufacturer that states they comply to ABYC standard A-14 "Gasoline & Propane Detection Systems," which requires the UL testing.

Finding The Right Needle In The Haystack

I'm going offshore and a friend is loaning me his EPIRB. How do I get it registered properly so that if we have to use it they'll look for my boat, and not his?



Tom Neale: Register at You'll need the beacon's identification number (found on the beacon) and your friend's log-in name and password, depending on how he's set up his account. Once on the site for the beacon, you'll find a comments section (scroll down the page to find it), and there you can enter details about your trip. Include your boat's name, description, your name, number of POB, when and where you're going, and indicate that you're borrowing the beacon. Give any other relevant info such as health issues, etc. Your friend should already have emergency contact names and numbers on the site; you'll need to alert these people or change the names and numbers for the trip.

This assumes your friend has already registered the EPIRB and given the proper info. If he hasn't, he (or you as his authorized agent) will have to go to that site and register it, at which time you can give the needed information.

When the trip is over, go back to the site and update the info. If you have questions, there's a phone number for help on the site. I've found them to be very helpful. I'd call them, anyway, to be sure you've covered all the bases, as it's a loaner. Be sure the beacon's battery is good and test it carefully according to its instructions (with which you should become very familiar), before you go.

Hot And Not

We have a hot-water heater that works sometimes, but not at others. There's power at the circuit breaker, but no hot water. Is there a relay or switch between the board and the heater, or should I be changing elements?



Tom Neale: I've never seen a relay switch between the circuit breaker and hot-water heater, but you could have one. Carefully tracing the electric line will give you that answer. Before replacing the element, carefully trace the wiring first, to be sure you don't have a faulty connection somewhere. Also look for burned or overheated insulation, indicating a fault inside.

It's possible that you could have a bad element. These are easy to change and you can get another one inexpensively from a home-supply store. Be sure the water is cool in the tank, all power is off, and the tank is drained. It's good to drain the tank periodically, anyway. Some tanks, such as Raritan's, have zinc anodes. Failure to replace the anodes (or to have them as part of the tank) can result in problems such as leaks and premature failure of heating elements.

You also may have a problem with your thermostat. If you have no continuity between AC-supply thermostat terminals and AC-out thermostat terminals, when the water is cold, you probably have a bad thermostat. Replacing a thermostat should not be difficult or expensive if you have the skills and are familiar with the issues.

Don't do any of this unless you depower the entire boat, including any inverter power. Working on water heaters and with electricity, especially on boats, can be very dangerous.

Trust Your Detector!

I have a Sea Ray 320 Sundancer with a Firebox-Xintex CMD-3M model carbon-monoxide detector hooked up to the battery system. The other day it went off and I didn't have the engines or the generator running. I brought a home unit to the boat and it also went off, so the boat detector must be functioning. I ventilated the boat with all the window hatches open and still can't get the detector to go off. Can humidity or other causes besides CO gas cause a "false positive?"



John Adey: The second detector was a brilliant choice! Often the problem is another boat in your area. A boat tied up to the same bulkhead three boats down from you running its generator, for instance, could cause a buildup of CO. I recall a similar problem during a test where a refrigerated tractor-trailer truck's generator across the marina parking lot set off our equipment!

These detectors are built and tested to a very rigid UL standard. There are provisions for false positives, contaminants, shock, vibration, etc. There is a specific marine portion of the standard to which your Fireboy unit was built. The short answer is that I have not experienced false positives in marine units used on boats.

You didn't mention if the unit was tripping after shutdown of the engines. Had you run them for a while, shut them down, and then gotten the alarm? Check all your exhaust connections; rubber hoses must be double-clamped and should be free of cracks and remain flexible. Eliminate any possibility of your boat causing the problem. Had you been using a propane stove? Regardless, this is a good annual checkup.

Next, I'd look around your boat and see if another boat's generator is running. Take the 9V household detector with you and see if it goes off. Portable generators have particularly dirty exhausts with high CO content, so look for those as well. Take this very seriously. If it is not your boat, talk to the marina (if that is where the boat is) and let them know what the problem is. Never assume a false-alarm condition on these units. They are reliable and tested at extremes by UL. 


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.

John Adey

John Adey
The VP/Technical Director for 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.

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.

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.

Lenny Rudow

Lenny Rudow
One of the most experienced technical writers in the marine business, and an accomplished fisherman, Lenny has a thorough understanding of modern marine electronics on both technical and end-user's levels. He's written five books, and won 18 Boating Writers awards and two awards for excellence from the Outdoor Writers Association. For several years running, he's also been selected as a judge for the NMMA Innovation Awards.

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