Decommissioning through hulls?

[PorFin]

They don't call them "best practices" for nothing -- I don't think Stumble's solution would qualify.

Med -- I think your plug idea will work fine. Good joint compound on the threads, and then close the seacock and remove the handle. You'll still want to exercise it periodically, so keep the handle available.

[fryewe]

I think I would plug it as you are thinking but leave the valve open after it is plugged and exercise it open and shut occasionally. If left shut the downstream side will likely fill with water due to seat leakage and there is a slight possibility of overpressure with temp changes or damage due to freezing. The properly installed plug (tape or pipe dope on the threads) will not leak inboard and is plenty strong - likely stronger than the hull.

[mitiempo]

Originally Posted by misfits

The proper way to do this.

Duct tape & plastic over thru hull hole inside the boat. Grind back the hull on an angle, 4+" around the thru hull. Cut fiberglass mat in circles, each one a little smaller than the next. Start w/ the largest & keep pilling on the smaller patches in sequence. Once you're at the desired thickness, slap the fairing compound on.

Most mat is not compatible with epoxy. Biaxial roving is a good choice as would be heavier fiberglass cloth. As posted by others the epoxy only plug is not a very good method. The proper method is shown below. Note that the largest patch is put on first. This eliminates the chance of sanding through it during finishing weakening the repair.

[Watercolor]

My wife and I have done a lot of fiberglass hull repairs on our boats. It's not rocket science. There are a lot of good books on the subject that can take you through the process step by step, follow them closely, but don't be anal about it. Don't be impatient (let the layers cure). Don't skimp (especially on the hole size preparation). And above all recognize that you can rectify a mistake.

Having said all that, I'd say your in good shape leaving the seacocks in place, giving them a good greasing before closing and plugging them. It wouldn't hurt to even exercise them on occasion.

The only reason I'd leave them in is potential resale. No matter how good some people feel about composting toilets, others don't have the same warm and fuzzy felling about them. If you're looking to sell the boat later on the ability to convert back, if the new owner so chooses, is a selling point.

[eherlihy]

I'm thinking of pulling my old through hull transducer, and going the fiberglass & epoxy route. I replaced the old Signet depth sounder and 1¼" transducer with a Garmin fishfinder. I mounted the new transducer inside the hull on a bed of silicone glue. Works great!

Can anyone think of any reason why I might want to leave the 1¼" hole?

[mitiempo]

No.

[SkywalkerII]

I was given advice that is a blend of the above. Grind/bevel the hole. Duct tape the outside. Mix up some Fiber Hair and fill from inside. Cover inside and out with fiberglass cloth. Makes a nice, strong sandwich.

I've done this a handful of times over the years with god results.

[DonScribner]

The term Best Practices comes into play

BEST - Hull ground outside and inside, glass replaced on both sides
GOOD - Hull ground on inside, glass replaced
MARGINAL - Epoxy in hole.

Since the epoxy is a different density and flexibility than the surrounding glass, the edges will be under greater stress and will want to shear or tear. Will it happen? I don't know. This method would probably work fine, but I'd stay with time proven methods if you go far offshore. Pick up a book by Don Casey. Easy read, step-by-step. Even a Geico advertising icon could do it.

[MedSailor]

For the record I'm not considering the epoxy in the through-hull idea. I don't see the advantage over the pipe plug.

I'm leaning towards the pipe plug and leaving the through hulls in place for 2 reasons. First I might use them again. Second, I think my first real fiberglass job shouldn't be on the under-side of my hull.

Perhaps at the next haul-out, or the one after, I'll have a better idea of which ones I want to keep and I may have a few "above the waterline" fiberglass projects already completed.

MedSailor

[Watercolor]

Sounds like a plan. Just check them like you would any other seacock/thru-hull you have.