I have some through hulls that I'm disconnecting as part of a plumbing upgrade and, since I can't dump on the great lakes, I would like to reclaim the area they in without the fear of something knocking into them. Any thoughts on using epoxy and G-10 discs to plug the holes?
G-10 discs for thru-hull
- Thread starter bob45
- Start date
Using just plugging the hole will not have a large bonding area, so it will be weak. The correct way, is to feather the inside and outside of the hole to achieve a 12:1 scarf and build up layers of glass and epoxy on both sides.
Or cap the through hulls and go sailing.
Or cap the through hulls and go sailing.
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 23,146
Yes. That is an option...but:
The strength of your hull to resist fracture and maintain water inegrity is in the laminate structure of the hull. Fitting a plug in the hole then covering over it with fiberglass will leave a lump on your hull surface and a weakness at the edges of the plug/hull joint.
The prefereed method is to sand a taper back from the hole edge and then rebuild the hull by layering fiberglass circles of gradually larger diameter onto the hole repair.
Here is a 3 part video by Andy of BoatworksToday demonstrating the process.
Structural Fiberglass Repair Part 1 | Boatworks Today
This is part 1 of a 3 video series outlining how to repair structural damage to your fiberglass boat. Make sure to watch all 3 in order! Otherwise you will be totally lost :-) These video'
www.boatworkstoday.com
Good luck
I’m hearing you guys, thanks! I think cap ‘em and go sailing is gonna win day!
I did something similar with a broken, leaking paddle wheel sensor a few years ago. @dlochner and West Systems provided me with excellent advice. The process went something like this:
- Remove through hull
- Drill out hole to a standard size
- Make a roughly 1/4" thick puck of straight epoxy the same size as the hole. I cut a hole out of a piece of wood, screwed it to another piece of wood to form the bottom, covered it in saran wrap and poured in some epoxy
- Taper the hull around the hole inside and out
- Epoxy the puck in the center (depth wise). I held it in with tape. I don't see why you couldn't use a layer of fiberglass cloth however
- Apply a few layers of fiberglass cloth
- Use fairing compound or your preferred concoction
- Sand smooth
- Apply barrier coat and bottom paint
This article from Steve D'Antonio arrived today. Thought it was timely for this thread. If you don't know Steve he is a highly sought after marine surveyor. He goes all over the world to over see new boat construction and to survey used boats. A subscription to his site is free and full of accurate informed advice.
Very timely! Random follow up question: any suggestions for a plug on a Marelon sea cock? Can any material work?
I’m removing my head overboard discharge, can’t use on the Great Lakes, want to keep the sea cock but need to remove barb and replace with threaded pipe plug. Just not sure if there is a material comparability issue with Marelon sea cocks
I don't think so, you could check the Forespar website or their tech support for a definitive answer.
The threads are probably strait threads, not tapered pipe threads. A plug off the shelf from a big box store will probably be tapered pipe thread. Defender, Fisheries, or West should have straight threaded plugs.
No material compatibility issues within the range of materials available for the plug you may end up buying.
dj
There is a risk of applying unneeded Modern Digital Precise Result thinking to such problems.
Remember that your hull (unless made of alum. or steel) is made of "fiber reinforced plastic" or "FRP." The material that Forespar uses for its excellent valves is also FRP.
Epoxy bonds forcefully to this material. You can always just remove the OEM thru hull and patch the hole with layers of glass and epoxy at the normal 12 to 1 cut back. G10 could be used for an inside reinforcing plate, but it would take a wide area of coverage around the hole to approach the strength of the simpler patch done the right way.
Our Series 93 Forespar thruhull seacocks are actually bedded in thickened epoxy, and were installed in the 90's. Changing them out, someday in the future, will involve a hole saw and a grinder. (No so much different than having to remove old thrufulls glued in with 5200...!)
Having the bases be "one with the hull" is a great way to have full structural integrity with no worries about leaks.
If you want to eliminate the OEM thruhulls, you can certainly do so. A short trip to the yard for a day will be needed, and best be done when hauled for a bottom paint job. (IMO, and YMMV)
Remember that your hull (unless made of alum. or steel) is made of "fiber reinforced plastic" or "FRP." The material that Forespar uses for its excellent valves is also FRP.
Epoxy bonds forcefully to this material. You can always just remove the OEM thru hull and patch the hole with layers of glass and epoxy at the normal 12 to 1 cut back. G10 could be used for an inside reinforcing plate, but it would take a wide area of coverage around the hole to approach the strength of the simpler patch done the right way.
Our Series 93 Forespar thruhull seacocks are actually bedded in thickened epoxy, and were installed in the 90's. Changing them out, someday in the future, will involve a hole saw and a grinder. (No so much different than having to remove old thrufulls glued in with 5200...!)
Having the bases be "one with the hull" is a great way to have full structural integrity with no worries about leaks.
If you want to eliminate the OEM thruhulls, you can certainly do so. A short trip to the yard for a day will be needed, and best be done when hauled for a bottom paint job. (IMO, and YMMV)