Topsides core repair

[George ( Triton #236 )]

Hi All,


I'm talking over a used C&C 40 with a yacht broker and it is in need of core repair in the topsides area around the bow lights. ( C&C 40's have cored hulls ) The damage covers a three foot diameter circle on both sides of the bow.

I have good experience in recoring the deck of a boat. Working with a vertical surface looks like it might be a bit trickier. Any ideas or tricks of the trade when undertaking topsides core replacement?

Also, the topsides are painted with a green Imron paint. Any thoughts on Imron paint and how easy it is to repair?


George

[Tim]

The process should be about the same on the hull, though of course you have gravity working against you. But any issues that come to light because of the vertical nature of the repair should be easy enough to overcome once they arise. Obviously, epoxy putties and such will need to be mixed thick to prevent running, and reattaching the outer skin, after it's cut off, will be a bit more of a challenge and will require some means of restraint. If you have inclination to learn how to vacuum bag, this sounds like a perfect application.

To that end, I would consider laminating new material over the core repair, rather than using the outer skin. I think it will end up being easier to install and no more difficult to fair in with the surrounding hull, when all is said and done.

I read somewhere (and this means nothing at all) that Imron is easier to patch than Awlgrip. I have no idea if this is true or not. Awlgrip is notoriously difficult to patch imperceptibly, though it's possible. The older the finish, the more the repair will probably show.

Maybe you can paint flames or a shark's mouth in the bow sections to hide the repair! There's a thought for you... :<)

Or maybe one of these color-fusion paint jobs...

[George ( Triton #236 )]

Hi Tim,

Thanks for the info. That's pretty much what I thought except for not re-using the exterior skin. Isn't it much easier to re-use the top skin rather than to try building one up from scratch on a vertical surface? I would think that since the existing skin has the proper curve built in, it would be easier than trying to get the curve right using fresh materials. Thoughts?

George

[Tim]

Six of one, half dozen of the other.

I'm not sure which one will end up being easier; it depends on the circumstance. I would by all means try to reuse the top skin. Remember, though, that those top skin pieces will probably be quite heavy and awkward, so shuffling them into place with gravity working against you could be a challenge. That is what I was thinking of when I suggested using new material. You can wet out large pieces (and several layers, depending on overall size and material weight) in advance, and then drape the whole nasty wet thing over the patch and roll it out. Obviously there are some practical size limitations for this. You can also even roll the material up over a length of 3" PVC pipe or something, which might allow you (and a helper?) to more easily apply it. Once the material sticks, if it's wet out enough, it'll stay there. This is a technique worth practicing before attempting on large pieces, though. But stuff like 1808 (which is used in the 40) manages to hold its shape pretty well when wet with resin.

The point mainly was that if you ended up needing to build up new material, it probably wouldn't end up being that much more difficult to fair in. Remember, your new core will be curved more or less in keeping with the curvature of the surrounding area, so any new material laid over the top will of course also follow that contour. You'd have to fair to smooth out the texture of the cloth, of course--but there will be a bit of fairing involved with the top-skin replacement method as well, so I'm not sure how much practical difference it makes. Either method will work fine once you overcome whatever obstacles there are in a given situation.

Any repair you make on the topsides will require more intensive and careful fairing than deck repairs, since the glossy topsides surface and water reflections will highlight any errors or undulations. Break out the longboard!

[George ( Triton #236 )]

Thanks Tim!

George Jones
Triton #236 "Ca Ira"