Through-hull: stay or go?

[Simply Sailing]

Originally Posted by Lepke

Leave the thru hull. Not everyone likes composting toilets. It allows a new owner an easy option of reinstalling a marine toilet.

We fiberglassed over ours in both boats that we installed Air Head composting toilets in. One is our "forever" boat, so we're not concerned about resale, and the other one sold for twice what we paid for it. The composting toilet actually helped the sale, IMO. Like many things boat related, it's a matter of preference. We didn't want to risk having extra holes in the bottom, but some people are more comfortable with things like that. We know we are on the extreme side of caution usually, but it's a personality trait. If you're just looking for opinions, that's our 2 cents.

[CHM]

What Stu said.


Sent from my iPhone using Cruisers Sailing Forum

[Chat de Mer]

This discussion was really useful, especially because of the variety of opinions. We are contemplating the same question, and now are clear that capping is best in the short run and any fiberglass work on the hull should be left to those with professional training and experience.

Do people have uses for a spare thru-hull other than a toilet, watermaker, or wash down? Assuming we like the composting toilet, we would not leave the thru-hull for a watermaker or wash down as we already have those. Unless there are yet more uses for thru-hulls, I am thinking that for us (assuming we like the composting toilet), the decision will be some function of the probability that we will sell the boat (and someone else might want a seawater flushing toilet) and the probability that something could go wrong with the capped thru-hull some day.

And does anyone care to speculate on the relative probability of a leak in a capped thru-hull vs. problem with a professionally removed & fiberglassed thru-hull?

[Don C L]

Originally Posted by Chat de Mer

And does anyone care to speculate on the relative probability of a leak in a capped thru-hull vs. problem with a professionally removed & fiberglassed thru-hull?

On mine I removed the valve and capped the thru-hull, and there is no problem with leaking. I'd put something on the threads to prevent corrosion that would make it hard to remove some day. I did something else in mine, I filled them with silicone, (not on the threads.) The silicone is fairly easily removed later with a small round wire brush on a drill, and will help ensure that even if there were a leak, it won't be a fast one. I think I mentioned earlier that the advantage of glassing it over is that you don't have a weak spot in that any heavy thing that falls on the thru-hull could still conceivably damage it causing a leak. Other than that I don't see any major advantage to glassing it over.

[Chat de Mer]

Thanks for the reply Don C L. Not sure if this is a dumb question, but to cap and fill with silicone - which sounds like an excellent idea to slow down any leak - you had to have the boat out of the water, right? Our boat is a big catamaran, and very difficult to haul. Or can you cap a thru-hull while the boat is in the water?

[rwidman]

Originally Posted by Chat de Mer

....................

And does anyone care to speculate on the relative probability of a leak in a capped thru-hull vs. problem with a professionally removed & fiberglassed thru-hull?

I had a hole in my transom where transducer wires once entered. It was above the waterline.

I was having some fiberglass work done on my boat by a "professional". I asked him to repair the hole.

Just recently I was having more fiberglass work done by another professional. The yard manager was talking to me and asked about the previous repair. He pushed on it and it fell in. Just because you pay someone, doesn't mean he will do a good job.

I had the second guy "professionally" repair the hole.

[rwidman]

Originally Posted by Chat de Mer

Thanks for the reply Don C L. Not sure if this is a dumb question, but to cap and fill with silicone - which sounds like an excellent idea to slow down any leak - you had to have the boat out of the water, right? Our boat is a big catamaran, and very difficult to haul. Or can you cap a thru-hull while the boat is in the water?

You can cap a thru hull when the boat is in the water. There is a valve on it right? Close the valve, remove whatever is attached to it and install a cap. If there is a hose barb you might have to remove it and install a threaded cap or plug. Use pipe dope on the threads.

If this doesn't make sense to you, hire someone.

[Simply Sailing]

Originally Posted by Chat de Mer

And does anyone care to speculate on the relative probability of a leak in a capped thru-hull vs. problem with a professionally removed & fiberglassed thru-hull?

There is NO risk of a problem with a correctly fiberglassed thru-hull. It becomes part of the boat as much as any other part of the boat. It's sort of like a broken bone: it's stronger at that point than at any other. The only reason it would need to be done "professionally" is if you're not comfortable working with epoxy in order to do it yourself. Gougeon Brothers has an excellent book on working with West Systems. There are industry standards that are fairly easy to follow. (We removed and faberglassed over our thru-hulls. I can send you a copy of the Sail Magazine article I wrote about how to, if you'd like.) If you don't feel comfortable with it, then yes, have it done professionally. But there is always a risk with simply capping a thru-hull. I certainly wouldn't feel safe offshore with one that was just capped, though I'm sure plenty of people do.

[Don C L]

Originally Posted by Chat de Mer

Thanks for the reply Don C L. Not sure if this is a dumb question, but to cap and fill with silicone - which sounds like an excellent idea to slow down any leak - you had to have the boat out of the water, right? Our boat is a big catamaran, and very difficult to haul. Or can you cap a thru-hull while the boat is in the water?

Well you could beach your cat at low tide and work fast! But if you don't mind swimming a bit, you can either jam in a cone of very soft wood from the outside, or they have these foam rubber cones too to jam in a hole in case of emergency, that would work too. Then you can remove the hose and valve, clean it and dry it from inside and cap it off. Personally I would not leave the valve on it, though I'm sure you could. Then just go back out and pull the cork out. We had a boat many years back that disappeared on a very breezy day, a Cal 24, same size as mine at the time. We were both out at the same time and though I did not know the folks personally it hit me hard to hear they were lost. Some months later a fishing boat snagged the boat with a net, it was recovered and they found a thru-hull had been broken off by something heavy falling on it, presumably a dive tank or unsecured battery, and presumably the folks did not realize they were sinking till it was too late, there was no mayday call as I recall. So since then, I see thru-hulls through different lenses. I think all thru-hulls should be easily accessible and easily visible, capped or not. As far as glassing, I have done that too. I think, if you are going to do it, it is important that the repair be as strong as the hull itself if possible so that if that area is struck by something it would not break more easily than the hull. But most repairs are not that strong, and boats sail around for years with them.