re-coring question

[swhfire21]

I had a delamination around the mast and cut it open this morning. I removed all of the wet balsa and now have a 3 in. lip around the hole. I need the 3 in. lip to feather in the repair.

Any hints on how to slide the balsa in and make sure there are no voids, while avoiding any overheated epoxy issues.

Thanks,

[Jeff and Sarah]

Why not cut out that fiberglass that you left around the mast and just lay a full sheet over your new core? You could easily cut out the mast hole afterwards with any number of tools.

Perhaps there is a complicating issue that isn't clear in the photo.

[Markst95]

Cut the balsa out to as close as filling the space as possible. You will have to do it in sections. Wet out the whole area with unthickened epoxy first then use epoxy/ colloidal silica mixed to jelly consistancy and spread out in a area putting some on the balsa edges as you work. Use enough to let the epoxy squish between the gaps. After an hour or so fill in any voids and start laying up the glass on top. You should have all the edges feathered beforehand. You should remove the hinges on the hatch to give you enough room to feather there as well. Put some tape underneath the screw holes to keep the epoxy from oozing through.

[swhfire21]

Jeff - I actually thought about that approach, but still need a surface to bond the new fiberglass to the original structure. I don't want to wrap the glass into the hole as there is already a complex joint in there (inner to outer skin) and not a lot of excess clearance for the mast. Also, this boat has no head liner, so whatever I do on the underside of the deck is visible in the cabin.

Mark - I was leaning towards you approach. I'm trying to figure out how the hatch hinges are fastened as there are no through bolts. In order to keep things dry as possible I'm going to pull the hinges last thing. This way if the hinges are not fastened to a tapped metal plate (adhered to the hull) or tapped epoxy plug I can at least get into the space from the core repair area to fix them.

Thanks

[jbenagh]

You are going to need to grind a 1.5 inch bevel around the edge of the existing glass. I think you will need to remove the hinges to do that. If you do grind the mast step away, the new glass should provide all the strength of the existing structure.

In my cockpit sole I found it a lot easier to just lay new glass on top rather than reuse the piece I cut out.

Jeff

[tjr818]

I have often wondered if there isn't some kind of spray foam that could be used to fill some of those areas between the top skin and the bottom skin. Something dense enough that would not expand with too much pressure.