Closing above the waterline thru hull

[LifesBetterWhenYoureBeating]

I'm removing an air conditioner from my boat so I'm gonna to need to plug its water outlet thru hull (above the waterline). It has no valve, just a simple fitting with a hose connected to it.

I'd like to close it permanently. The boat is in the water now and the thru hull sits around 1cm above the waterline. Should I just remove the fitting, tape it from the outside and fill the hole with some form of epoxy? If so, what exactly? If not, how should I do it?

Thanks in advance!

[ItDepends]

1 cm above the waterline? The ONLY correct answer is to remove the fitting and glass it over. A simple epoxy plug is not sufficient.

[LifesBetterWhenYoureBeating]

Originally Posted by ItDepends

1 cm above the waterline? The ONLY correct answer is to remove the fitting and glass it over. A simple epoxy plug is not sufficient.

Fair enough. Any suggestions on what to do with this thru hull until I haul out and close it permanently?

[ItDepends]

Not sure exactly what the plumbing arrangements are, but if it was my boat I’d put a pipe plug or cap (whichever gender works) on the thru-hull fitting until a permanent repair was possible.

[AKA-None]

Can you use one of those expanding rubber stoppers from the plumbing department?

[CarlF]

Cut the hose about 3" from the end of the thruhull. Get a hardwood dowel of the right diameter at HomeDepot. Cut to about 3" long, apply some caulk/sealand and insert. Use two hose clamps to secure it.

[Uncle Bob]

Or you could remove the threaded hose fitting and install a quality ball valve with a plug fitted to it, providing you with a useable hull fitting if you should need one in the future, for whatever reason.

[ItDepends]

Originally Posted by CarlF

Cut the hose about 3" from the end of the thruhull. Get a hardwood dowel of the right diameter at HomeDepot. Cut to about 3" long, apply some caulk/sealand and insert. Use two hose clamps to secure it.

Originally Posted by AKA-None

Can you use one of those expanding rubber stoppers from the plumbing department?

For heaven’s sake! You guys are going to the hardware store anyway! Why spend money on a half-assed solution, instead of the pipe cap to do it right?

I appreciate a clever, inexpensive solution, but when it saves almost no money and is just done to show off how cheap you can be at the expanse of the safety of the boat, that’s just silly. Do you SERIOUSLY think that your insurance company would recognize those solutions as meeting the standards of seaworthiness?

People just do not have enough respect for how much water can come in through a 1” hole in the hull of a boat.

[smj]

Originally Posted by ItDepends

For heaven’s sake! You guys are going to the hardware store anyway! Why spend money on a half-assed solution, instead of the pipe cap to do it right?



I appreciate a clever, inexpensive solution, but when it saves almost no money and is just done to show off how cheap you can be at the expanse of the safety of the boat, that’s just silly. Do you SERIOUSLY think that your insurance company would recognize those solutions as meeting the standards of seaworthiness?



People just do not have enough respect for how much water can come in through a 1” hole in the hull of a boat.

I guess the question is, does the thru hull fitting look like this

Or like this?

Once that’s answered maybe a good solution could be found?

[HeywoodJ]

Depends on the interior cosmetics. If this is below a floor board, behind a cabinet, or otherwise not in view:

1. Sand the interior surface of the hull around the hole to a diameter of 6-8" (150-200mm) centered on the hole. Get down to bare laminate. Clean up the sanded surface.
2. Tape over hole on the outside with very firm tape (I like to use the PVC pipe wrap tape that is quite thick).
3. Apply gelcoat to the back of the tape inside the hole
4. Fill the hole with a thickened epoxy. Use a structural filler such as fibers or silica.
5. When the epoxy is nearly cured, sand or trim on the interior until flush with the hole, then lay up fiberglass over the hole with epoxy. Use successively larger disks of glass until you reach the edge of the sanded area.

With the above you will end up with a "bump" over the hole on the interior. If that doesn't bother you then go for it, if it does then you do the same procedure from the outside, with lots of feathering around the hole, fairing, and finish.

As an alternative to laying up glass as described you can get a small piece of G10 and epoxy that to the inside of the hull in about the same dimensions using a structurally thickened bog.

Either way, it is a couple of hours work to fill in the hole in a way that will outlast the rest of the boat.

[LifesBetterWhenYoureBeating]

Originally Posted by smj

I guess the question is, does the thru hull fitting look like this
Attachment 266869
Or like this?
Attachment 266870
Once that’s answered maybe a good solution could be found?

It's the former, but with a couple indents.

It's behind teak panels so glassing over from inside is not something I'm willing to do. I guess until I haul out and can glass over from outside, I could try to fit a strong conical plug (with plenty of sealant) from the outside, making it flush with the outside part of the fitting, and a length of hose on the inside, going up, capped on the other end. Or replace the fitting with a threaded one so I can put a proper cap on it.

[smj]

Originally Posted by LifesBetterWhenYoureBeating

It's the former, but with a couple indents. I guess those indents are for installation purposes so the best I can do is secure a cap with hose clamps there?Attachment 266871

If threaded I would put a cap on it but be careful not to spin the thru hull while tightening.
If not threaded I would get a long piece of hose double clamped to the thru hull, try to find a cap with a male thread that would fit tightly inside the hose and hose clamp that. Then lead the house as high as possible and secure.
I’m sure there are many ways to skin this cat, just comes down to comfort level.

[Renoirpierre]

If a cap is purchased at the hardware store it is likely to be a pipe cap which will have tapered pipe threads where I believe the thru-hull will have straight pipe threads.

Any concerns mixing the two thread types?