Cracks under non-skid plates in engine room

[BroadCove]

We've just purchased 2005 Grand Banks Eastbay 47. Although the boat was in good clean condition, while following the surveyor around, I noticed typical bilge "gunk" under the non-skid plates. So, following the sale, I pulled those up and cleaned it all out.

I noticed the support for those plates have longitudinal cracks all the way along. As best I can tell, these are not structural in any way (except for supporting the deck plates). It appears that they are just 2x4 lumber or similar glassed in on top of the hull.

Nevertheless, liquids can clearly intrude/seep in there. Would you fill them? I'm thinking simply silicone if I do. The boat has been out of the water for months now, and I cleaned the bilge a month ago, so it's as dry now as it's going to get.

 

[Redhook98]

Are these what your non-skid deck plates rest on? If so, dry em out, put some wood hardener in there to solidify and kill any dry rot, then seal with 4200 or 5200. Could use a thickened epoxy also.

 

[Comodave]

Don’t use silicone, almost nowhere on a boat. I would grind the cracks out and use thickened epoxy.

 

[PM]

What Dave said. Both about the silicone and the thickened epoxy.

pete

 

[Comodave]

I use a Dremel tool to grind out cracks like those. Use a shop vac to suck up the dust as you go and it won’t make a huge mess.

 

[rgano]

We've just purchased 2005 Grand Banks Eastbay 47. Although the boat was in good clean condition, while following the surveyor around, I noticed typical bilge "gunk" under the non-skid plates. So, following the sale, I pulled those up and cleaned it all out.

I noticed the support for those plates have longitudinal cracks all the way along. As best I can tell, these are not structural in any way (except for supporting the deck plates). It appears that they are just 2x4 lumber or similar glassed in on top of the hull.

Nevertheless, liquids can clearly intrude/seep in there. Would you fill them? I'm thinking simply silicone if I do. The boat has been out of the water for months now, and I cleaned the bilge a month ago, so it's as dry now as it's going to get.

Silicone would be a BAD idea. I would route it out somewhat to see what is going on with the wood before soaking it with lots of Clear Penetrating Epoxy Sealer before filling in with thickened Epoxy, yeah, like Dave said.

 

[wkearney99]

Wood rot can migrate quite a bit. I'd give a shout to the Grand Banks folks to get a better explanation of that support. If it's just a piece of wood glassed-in to act as a support for the floor plate then grinding out the crack and checking for how far the rot has spread is probably a good plan. But if it's "more than that" you'd want to know before getting too far into exploration.

I have an EB47 and pulling up that plate is on my to-do list. You worry me with a discovery like that...

 

[C lectric]

Skid PLates?????
I suspect they are anti oil canning reinforcement for a too flat part of the hull that showed a tendency to "oil can" when the boat was running and it was somewhat rough.

If I am correct they are in fact structural reinforcement.

Talk to some one knowledgeable with boat repair work to confirm or deny what I am suggesting.

If I am correct it needs more than just a bead of caulking. The wood needs to be DRIED out properly and completely.
Yes maybe to the sealing of the wood with something like CPS , then filled with thickened epoxy and then the cracks should be closed with glass and resin so the wood can act like a reinforcement and not rot out.

THe wood could simply be a form for the glass shape above but the cracks have compromised the shape and strength of the glass overlay. It may well be the glass must be laid up MUCH thicker.

But talk to someone as I don't think you just want to seal and forget it.

I hope they are simply a riser to support the deck plates but FIND OUT.

 

[BroadCove]

Thanks for the replies, great advice! I'll definitely grind it out and take a look, and follow Comodave's advice (echoed by others) to go the epoxy route. And, Bill, if I learn anything from grand banks, I'll let you know! But I'm almost positive these are just straps of wood glassed onto the finished hull to support the non-slip plates.

The plates themselves are definitely not structural. I'm probably not describing them correctly. It's just a few sections of 1/8th inch aluminum fastened to the boat with two inch long screws each that make for a flat, non-slip surface to walk on between the engines, (instead of the slippery, rounded bilge).

 

[Comodave]

If you are worried about structure then lay on a couple of layers of 1708 after you put the thickened epoxy in the cleaned out crack. Good luck.

 

[BroadCove]

C lectric, I realize I misread your response. Definitely going to have the surveyor inspect tomorrow. But I feel pretty confident the risers aren't structural. They are short, irregular pieces that are only under the plates

 

[SteveK]

Was the photo taken while the boat is on the hard?
That looks like the centerline, keel under blocked. sure it can be fixed but why did it crack like that should be discovered.

Eta If it is loaded too much repairing in place may cause other issues when back in water. Surveyor may be of help in that.