Termainating a thru-hull?

[71Irwin32]

My boat has a central AC and I'm getting rid of it. What the best way of removing and sealing the thru-hull.

This boat is strictkly hand laid fiberglass. Anybody done this?

Thanks!!

[sailingdog]

Lots of people have done this. You wil have to haul the boat. Then you grind the area around the through hull to a 12:1 taper, preferably on both the inside and outside...then laying glass starting with a patch the size of the repair area and then slightly smaller each layer.

A 12:1 taper means that if the hull is 1" thick, you would taper the hull area for a RADIUS of 12" around the through-hull.

Use epoxy resin. A good source for it is www_epoxyproducts.com. Get your fiberglass from www.fiberglasssite.com.

A good book to walk you through this are Don Casey's This Old Boat. A good website to refer to is the West Systems epoxy website.

[brak]

Sailingdog's method is a Bible of doing this.

In a pinch, however, for relatively small holes you can simply glass it over from inside with a layer or two of glass roving/cloth, then fill the hole from outside with epoxy mixed with filler. This construction is certainly no less strong than the thru-hull that was previously in that hole.

[LandLocked66c]

Here's a nice how to...

[sailingdog]

I would reverse this.. and do the glassing over from the outside and plugt the inside.... If there were a problem with the patch... the water pressure would be far more likely to hold it in place this way, rather than pop it out...

Originally Posted by brak

Sailingdog's method is a Bible of doing this.

In a pinch, however, for relatively small holes you can simply glass it over from inside with a layer or two of glass roving/cloth, then fill the hole from outside with epoxy mixed with filler. This construction is certainly no less strong than the thru-hull that was previously in that hole.

[hellosailor]

One might argue that this is a case for "good enough" rather than perfection. Clean up the through-hull, insert a durable plug from the outside, bedding it with a serious sealant (like 3M 4200 or 5200) and then trim it flush and paint over it. On the inside, fit a cap on the thru-hull, secure it, and leave it in place in case you ever want to undo the project and use that same convenient hole in the boat in the future.

[danielgoldberg]

Originally Posted by sailingdog

then laying glass starting with a patch the size of the repair area and then slightly smaller each layer.

I think you have this backwards. Start with a layer just larger than the hole, and then add layers slightly larger as you move out towards the edge of the beveled area. This way you are creating a true plug and building up the layers with lots of contact area.

[mitiempo]

Sorry, but sailingdog has it right. When you sand after laying all the layers the largest layers remain intact. If you start with the small layer the largest will be compromised during final sanding.

[danielgoldberg]

Originally Posted by mitiempo

Sorry, but sailingdog has it right. When you sand after laying all the layers the largest layers remain intact. If you start with the small layer the largest will be compromised during final sanding.

You know what, I stand corrected. I find this counterintuitive, but upon reflection I think you are right.

[sailingdog]

Originally Posted by danielgoldberg

I think you have this backwards. Start with a layer just larger than the hole, and then add layers slightly larger as you move out towards the edge of the beveled area. This way you are creating a true plug and building up the layers with lots of contact area.

while Don Casey and others used to advocate this, most have changed their position over the years for the reasons mitiempo has stated.