What size through-hull fitting? - SailNet Community
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post #1 of 6 Old 05-19-2019 Thread Starter
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What size through-hull fitting?

I need some advice on what to do with my head through-hull...

I pulled my marine head, all the plumbing, and holding tank to replace it with a composting toilet. I also removed all through-hull fittings and ball valves for replacement. I plan on keeping the head through-hull as I would like to add a wash down pump and water maker and that would be a perfect spot for it. Or I might change my mind and would like to add a marine head in the future. My current issue is this:

Do I leave the through hull at its current size, or do I downsize it? It is currently set up for a 1 3/4" through hull which I think might be quite large. How large would it need to be to accommodate the watermaker and anchor wash?

If I downsize, I will have the added advantage of space under the sink in the head as the valve is so large. I will also not have to not grind some of the wood from the inside of the cabinet door to make it fit the new valves of the same size (instead of adding backing plates where there were none, I just thickened the hull with some colloidal silica and glass). However, I will have to modify the hole which could be a lot of work especially considering I have a looooong list of jobs to do as I near the deadline for this refit. If I plug the hole with colloidal silica and redrill it slightly smaller will that suffice?

Note: my through hulls are countersunk (flush-mount?) and had a layer of glass over the top to finish.
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post #2 of 6 Old 05-19-2019
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I think you answered your questiin with....option ti add marine head in future
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post #3 of 6 Old 05-19-2019
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Re: What size through-hull fitting?

No need to shrink the penetration. Just replace what fits.

I doubt that combining the washdown and watermaker is a good idea, but maybe with a y-valve, which I would personally forget to set properly.
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post #4 of 6 Old 05-20-2019
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Re: What size through-hull fitting?

Yes, if youíre cutting a new hole make it as small as necessary but if itís there already, live with it.
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post #5 of 6 Old 05-22-2019 Thread Starter
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Re: What size through-hull fitting?

Whats a traditional size for a head thru hull and a galley one 1-1/2 1-1/4 is there no such thing as standard or recommended size?
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post #6 of 6 Old 05-22-2019
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Re: What size through-hull fitting?

If your through-hull is over-sized, you can install an adapter to step it down to the proper size for your hose, but you can't go in the opposite direction if your through-hull is too small.
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