Cap off a thru-hull?

I have a thru-hull with a 1.5" tapered cone seacock that is not being used. The seacock is broken so I need to take action and remove it. Is there an obvious reason that I am missing why I shouldn't just remove the seacock and cap the the thru-hull off with a bronze 1.5" pipe cap? I have read where others recommend putting a new seacock in then using a bronze plug on the seacock. What's the difference other than about $150 ? I also do not want to pull thr thru-hull and glass it over permantly. Thanks.

SeaBreeze said:

I have a thru-hull with a 1.5" tapered cone seacock that is not being used. The seacock is broken so I need to take action and remove it. Is there an obvious reason that I am missing why I shouldn't just remove the seacock and cap the the thru-hull off with a bronze 1.5" pipe cap? I have read where others recommend putting a new seacock in then using a bronze plug on the seacock. What's the difference other than about $150 ? I also do not want to pull thr thru-hull and glass it over permantly. Thanks.

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Put a new valve on it in case you find a need scuttle the boat. WINK WINK

I have done the cap thing before. I sealed the threads with 5200 so it won’t ever come off. Also if you have a bonding system don’t forget to bond the through hull.

Its the seacock that locks the thru hull in place, correct?
You might need a big bronze nut to secure the TH, without the valve.

Yes, you do need the nut.

Removing the seacock and not putting another seacock or glassing over should never pass a good survey and is not really a "safe" way of fixing the problem.

On the hard I had one removed and glassed over. Looked like he did a good job.

It was in our storage compartment (aft of the engine compartment) exposed to gear adrift and something heavy could have knocked it off and presented a big job for our bilge pumps. Now it’s just flush hull bottom (inside) and no danger.

psneeld said:

Removing the seacock and not putting another seacock or glassing over should never pass a good survey and is not really a "safe" way of fixing the problem.

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I don't like unnecessary holes in my hull. I had a below water line through hull that was not being used, which I removed and the hole fixed at the yard. I believe the repair was with CSM and vinylester. My hull is solid fiberglass with no core.

I think all of the above advice is good, especially about the nut.
One thing to keep in mind is that the threads on the cap won’t fully engage the thru-hull. The cap will have tapered threads and the thru-hull straight.

I’ve thought about filling the thru-hull with epoxy and then capping it. Probably over kill.

I had a survey fail, with a seacock installed, but no hose on it.
The open hole, wherever it sits, needs to be capped off.

Leave the broken sea cock in place and cap or plug the outlet with a bronze cap/plug. No need to replace or repair the seacock.

In addition to capping off, I drive a wood plug from the outside. My current boat had 3 marine heads that I replaced with Incinolets. Each head had an inlet and outlet thru hull. I capped and plugged. No issue with any survey.

I forgot to say that before I installed the through hull, I filled it with thickened epoxy. Then used 5200 to glue that cap on.

We hauled boat and removed all old seacocks and thru hulls repaired and sealed holes no longer needed and replaced all others with all new first quality marine bronze hardware. Bottom done.

Why not remove it? Takes less than an hour, reliable, and you can redrill it at a later time in 15 minutes.

Only reason I’d cap it is if I was going to need it in the next year and did not have a haul planned.

I'd cap it for now, and repair the hole properly next haul out. In fact, that is exactly what I did eight or so years ago.

Fixing a hole isn't that big of a deal. Everything you need to know is in the West Epoxy Fiberglass Boat Repair Manual. Worst part was grinding the bevel prep. Not even a half day job.

HopCar wrote;
“I’ve thought about filling the thru-hull with epoxy and then capping it. Probably over kill.”

For a hole the best could be “Chaulk Fast” (Sp?) as it dosn’t shrink.

If you are to fill it with epoxy or seal it with 5200 that means you don't want to use it anymore, ever. In that case better to do it right the first time and remove it before filling the hole. If you think you may ever use it for anything else, better to just cap it and seal it with something removable.

L

psneeld said:

Removing the seacock and not putting another seacock or glassing over should never pass a good survey and is not really a "safe" way of fixing the problem.

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I glassed over 3 trough hulls with no problems. Just have to know how to do it properly.

psneeld said:

Removing the seacock and not putting another seacock or glassing over should never pass a good survey and is not really a "safe" way of fixing the problem.

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Please help me understand how a seacock is any safer than a sealed brass cap? Also help me understand why it wouldn’t pass a survey. Is there a regulation that states it can’t be capped or is it just a surveyors opinion?

Ski in NC said:

Leave the broken sea cock in place and cap or plug the outlet with a bronze cap/plug. No need to replace or repair the seacock.

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That’s what I did with two of mine. The top of seacock should have the correct tapered pipe threads for the cap.

nodestination said:

I glassed over 3 trough hulls with no problems. Just have to know how to do it properly.

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Wow, sorry.....maybe I was confusing with a double negative.
Meant that a working, plugged seacock or glassed in are the 2 most accepted methods. They should pass muster... Others are subject to rejection.


As to why a sea cock over a capped through hull.... It can break off more easily and no wquock way to properly stop wyer ingress.


A plugged broken sea cock may be acceptable, depending on what kind of "broken" and overall condition..


A thru hull with no seacock is really never acceptable.....tons of internet stuff on the subject and whether it will pass survey or not.

Greetings,
Aw SNAP! I recently had 2 unused thru-hull transducers replaced with capped Marelon (sp?) thru-hulls. I figured that was better than leaving the transducers in with deteriorated wooden faring blocks. I also figured by going with Marelon I wouldn't have to worry about bonding.

This thread still going??
One issue with taking off the Seacock and dealing with the TH stub is the likely stub length. Since u will need a proper bronze nut to add, there may not be adequate length to add the tapered bronze cap on the straight thread thruhull.
If it does assemble secure, fine. But on my plastic boats, the project ends with no metal and a proper hole patch.

On my boat (the boat being discussed) there are over 1.5 inches of exposed threaded pipe. It is an in-line seacock with a tapered cone valve. The nut is already there securing the through hull. The seacock tapered cone broke in half which means the handle and half of the valve can just fall out and flood the boat. Other than hauling and glassing the hole (which I don’t want to do) the only options are to replace the entire inline seacock then plug OR remove the seacock and cap the pipe. So far no one has shown me anything that says it shouldn’t be done or is unsafe or unacceptable. It may be unacceptable in a surveyors PERSONAL opinion but that means nothing to me. If there is a code requirement or a really sound logical safety reason I hope someone will provide it.

I think your plan is sound. No one in there right mind can survey a piece of a boat remotely.
The pertainate spec for this type of thing is the 300lb side load test and a reasonable seal that wont depend on a rotting piece of wood plugging etc.

The PO of my boat put a plastic thru hull exactly at the waterline for the A/C discharge. Besides it would spray discharge water at the surface and was obnoxiously loud, I didn’t want a plastic thru hull near or below the waterline. Unfortunately there is almost no way to access the inside of the hull to glass the old hole closed after I moved the discharge water thru hull up about 4” so it is above the waterline. Since I could not glass the inside of the old hole in order to close up the hole, I went with a bronze thru hull and filled it with thickened epoxy and then capped it with 5200 on the threads so the cap won’t ever come off. Some surveyor may not like this but in order to even be able to see it you have to spend about 2.5 hours removing the house bank of batteries and build a scaffold so you can slide down to get close to the thru hull.

SeaBreeze said:

On my boat (the boat being discussed) there are over 1.5 inches of exposed threaded pipe. It is an in-line seacock with a tapered cone valve. The nut is already there securing the through hull. The seacock tapered cone broke in half which means the handle and half of the valve can just fall out and flood the boat. Other than hauling and glassing the hole (which I don’t want to do) the only options are to replace the entire inline seacock then plug OR remove the seacock and cap the pipe. So far no one has shown me anything that says it shouldn’t be done or is unsafe or unacceptable. It may be unacceptable in a surveyors PERSONAL opinion but that means nothing to me. If there is a code requirement or a really sound logical safety reason I hope someone will provide it.

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Do you plan on getting hull insurance?


If you do, the surveyor's opinion WILL count.

SeaBreeze said:

On my boat (the boat being discussed) there are over 1.5 inches of exposed threaded pipe. It is an in-line seacock with a tapered cone valve. The nut is already there securing the through hull. The seacock tapered cone broke in half which means the handle and half of the valve can just fall out and flood the boat. Other than hauling and glassing the hole (which I don’t want to do) the only options are to replace the entire inline seacock then plug OR remove the seacock and cap the pipe. So far no one has shown me anything that says it shouldn’t be done or is unsafe or unacceptable. It may be unacceptable in a surveyors PERSONAL opinion but that means nothing to me. If there is a code requirement or a really sound logical safety reason I hope someone will provide it.

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So you didn’t have a flanged seacock? Just a valve screwed onto a thru-hull?
I’d say you’re safer with a cap on the thru-hull than you were with the valve.

The fact that the cone broke is kind of scary. I’ve never heard of that happening.

Are the rest of your thru-hulls this way? If so I suggest you start replacing them with flanged seacocks or Groco flanged adapters and Groco valves.

SeaBreeze said:

Please help me understand how a seacock is any safer than a sealed brass cap? Also help me understand why it wouldn’t pass a survey. Is there a regulation that states it can’t be capped or is it just a surveyors opinion?

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Brass rots away far faster than bronze.