Venting the tank
Two 3/4" ID vent hoses run forward to the bow. If you've ever read Peggie Hall's pamphlet, Marine Sanitation: Fact vs. Folklore, then you'll understand that you need a flow of air in and out of the tank. This means big vent hoses, short straight runs, and a scheme that moves the air through the tank. In this installation, the vent hoses are not as short and direct as I'd like. And they're only 3/4" because that's what worked with the tank and through-hull vents. But it's adequate.
The hoses are held level with clamps I fabricated out of a scrap of 3/4" polyethelyne board. It's important to eliminate low spots where moisture might accumulate and block the airflow.
The key to the airflow through the tank is mounting a vent on each side
of the bow. In the same manner that air flowing along the sail creates a
high-pressure zone on one side and a low-pressure zone on the other, so it
is with the airflow down the hull. As long as the airflow is not exactly
symmetrical, the same effect will be seen. Since the pressure will be
greater on one side relative to the other virtually all of the time,
air will flow through from that side to the other.
I've been asked about the through-hull vents I used.
Mine are Perko gas tank vents, mostly because there was already one such on the port bow from the previous owner's installation of a Mansfield TDX treatment system. I suspect ordinary mushroom through-hulls might work as well.
I pointed the scoop aft and slightly down to avoid taking on water which could block the airflow in the hose.
-- George Dinwiddie, Calypso, #543
Special thanks to Mike Lehman of Gilleleje, #505, and Jim Mennucci of Quest, #433, who blazed the trail with the Kracor tank.
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Offshore Sailing
by Bill Seifert with Daniel Spurr
We went to a Windjammers lecture to hear Bill Seifert and I was impressed enough to buy
the book on the spot. I've heard a lot of people talk about ways to improve a boat, but
I've never heard one person suggest so many good ideas that I hadn't considered. Part
of the charm is the specificity of the suggestions. Everyone says you should secure your
floorboards, hatchboards and batteries. Bill shows good suggestions on how to do so.
The suggestions are very practical for the do-it-yourselfer, too. Many show how to
make or adapt inexpensive solutions. Tip #12 on closing the deck blower vents is one
that will pay off for me without ever going offshore. I'll implement that one to
stop the wintertime storms from finding their way belowdecks.
Besides modifications, the book also includes advice for operating offshore, cooking,
boat selection, dealing with bureaucracy, and more.
Bill Seifert has worked at Tartan, TPI, and Alden Yachts. He's a veteran of many
Marion-Bermuda races and now runs his own yacht management company. His tips are
born of experience--not of book-learning--and it shows. He obviously knows his
stuff.
(Note: commissions earned from this link help defray the costs of this website)
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