Year 5, Captain’s Ramblings 1: Thru-Hulls
Date: Wednesday, November 4, 2009
The saying goes “a boat is a hole in the water into which you pour money.” But the systems on a boat require that there are a number of holes in the boat through which water can pass. The critical issue with a boat is how to keep the water on the outside, or at least keep it directed to the appropriate function on the inside before it is pumped overboard again.
There are several reasons to bring salt water into a boat: to flush the toilet, to provide water for the desalination system to make fresh water, to cool the engine, to provide cooling water for a heat pump air conditioner, and to wash dishes before rinsing in fresh water to conserve the fresh water you may have. Some boats may have more than these, but, except for washing dishes, these are the functions that Windbird uses salt water for (though we haven’t used the air conditioner since leaving Boston).
There are other reasons to have holes in your boat below the waterline: to drain the toilet when you flush and to drain the sinks in the galley and the head(s). Windbird has three sinks to drain and two toilets.
If you add all this up you will find that Windbird could have as many as ten holes below the water line! We actually had eight before the valve bringing water to the forward head broke on Monday. Reducing the number from ten to eight was accomplished by feeding the aft head, the water maker, and the air conditioner from one inlet. These “inlets” (and outlets) are actually called “thru-hulls” because they go through the hull of the boat. And each thru-hull has a valve on the inside of the boat so that if something goes wrong in the plumbing, you can stop the flow of water by closing the valve. However, there’s the rub. All those valves are a potential source of trouble. Windbird has had trouble with three of these. The first, we repaired over a year ago. The second I replaced while in the water just a few days ago. The third defied all attempts to repair or to remove it without destroying the whole thing – which we did finally by hauling the boat out of the water and cutting the valve off the top so the thru-hull could be removed. We then attempted to install a new thru-hull with valve. Twice we thought we had it and twice we were lowered into the water to discover it leaked!
Since we had so much trouble getting a new thru-hull not to leak, we decided to simply plug the hole with epoxy and run a water line from the existing thru-hull that already feeds the aft head, the water maker, and the air conditioner. So we now have two thru hulls that bring water into the boat: one provides cooling water to the engine, the other provides all other salt water needs on Windbird.
Now if only I could figure out how to have all the discharge hoses exit through one thru-hull we could cut the number of holes in the boat to three. Fewer are always better – less maintenance and less chance of a failure at an inopportune moment. But given the separation between the three sinks and two heads, it is not likely. So we will likely be replacing more old thru-hulls in the future.
A bit late for your recent seacock woes, but a very good and informative website nonetheless: http://www.diybob.com/diySeacock.htm