How to Reinforce a Keel Sump to Support 22,000 Lbs?

[Jim Pendoley]

Hello everyone,
I have an interesting design/repair challenge on my new to me Pearson 424 and I'm looking for a well thought out plan to repair/rebuild the keel. The back story is my boat was improperly lifted on a trailer and the sump was cracked. The design (Pearson-Bill Shaw) is an 1980 cruiser with a long keel and detached rudder on a skeg. Displaces 22,000 lbs. The keel has a four-five foot long, deep and obviously hollow sump. Ahead of and behind the sump is well encapsulated lead ballast. The sump has been repaired well (from the outside in) by removing laminate and then relaminating biax and epoxy from the outside of the keel. I've done a fair bit of glass work and I'm convinced the repair is as good as factory BUT this area from the factory is a vulnerable spot in a grounding and because the sump is so long it makes hauling with a trailer at a ramp very challenging. I am at a DIY yard with only a ramp and trailer-no travellift-trailer hauling is a requirement and I want to remain here.

Question is this:
what would be a viable way to reinforce the sump from the inside such that I can lift the boat on a trailer with the sump resting on the trailer crossbeam? A respected fibreglass repair man recommended laminating white oak to fit in the cavity snugly as possible and then covering the whole assemby with "pourable transom". This sounds like RJAY 6011 and some other products I've seen used for coring on transoms. He suggests of course abrading all surfaces and laminating the oak with epoxy first. The wood would not rot (he supposes) as it would be encapsulated.

I have a few concerns:

1" This suff seems to have a lot of compressive strength but lesser bonding strength. Also for a supporting beam, I would think tensile strength would be more relevant.
2. Adhesion-this would be a secondary bond-wouldn't epoxy be a better bond?
3. Heat-I imagine the beam would be at least six inches tall by four to five long. Thats a lot of epoxy or "RJAY 6011 or "pourable transom"-how to I deal with that?

Has anyone done a similar repair with good results? Can anyone suggest a better approach or confirm the utility of the proposed fix? All imput much appreciated.
Jim

 

[gonzo]

You can make the piece of oak to fit fairly well so it only needs thickened epoxy to set it in. I would think that a 1/4" gap all around is easy to do. Then laminate over and overlap on the sides of the keel. Can you post the dimensions of the sump?

 

[Jim Pendoley]

You can make the piece of oak to fit fairly well so it only needs thickened epoxy to set it in. I would think that a 1/4" gap all around is easy to do. Then laminate over and overlap on the sides of the keel. Can you post the dimensions of the sump?

Fitting the oak laminate in place will be a pain, laminating glass will be harder-that’s why the pourable transom product is appealing. Typical older design, the sump is about four feet deep, four and a half feet long and tapers from ten or eleven inches wide at the fron to a few inches wide at the back. I can abrade the walls with a grinder on a stick or a drum sander on a long extension, but laying glas down that deep would be next to impossible-thus the interest in the pourable products. I have no experience with them.

 

[gonzo]

It is a rough fit. Take a few measurements and then shape the wood. As far as laminating, wet the fabric and then lay it on top of the wood. You can use smaller sections. A bubble roller with an extension pole should get the fiberglass laying nicely.

 

[Rumars]

Fill the sump with reinforced concrete, use a lightweight aggregate like foamed glass to keep te weight low.