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NowWeTryItMyWay

Repairing Split / Cracked Hull Panel

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In unfolding and weighing down the hull panels last night, I made a mistake which resulted in a small split or crack on the outside of the starboard bottom panel, about 19" back from the bow.  Would appreciate any advice or suggestions on how to fix.

 

What happened was, at the step of the instructions where you put some weights on the bottom panels to open them out to the shape of the cradle, I got the bright idea to combine it with the step where you lay scaffolding across the stringers so the weights wouldn't be resting directly on the plywood.  This seemed to go OK until I bumped one of the weights putting another one in, and it slid off of the scaffolding and fell about 2" onto the panel, cracking it.

 

The crack is about 7" long.  As the hull opens up (curving that section of the panel more) I am imagining that the crack itself is opening up and getting wider.  It doesn't go all the way through the board (yet), the plys on the inside aren't cracked.  At the moment, sighting down from the bow, that part of the panel is just barely not fair (by a few millimeters).

 

I was thinking of possibly wetting out that section with clear epoxy and a scrap of fiberglass, and then bracing it from underneath with hopefully enough pressure to push the bulge in slightly.  If it was glass rather than wood (like a windshield), I might drill a hole at either end of the crack, and then fill the hole, to stop it from spreading further, but not sure if that would be smart or not with plywood.

 

 

IMG_1903.png

Edited by NowWeTryItMyWay
English grammar

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I enjoyed watching your time lapse video, you are doing a great job.

 

I am sorry about your little glitch. It is not a big deal and will not compromise the boat. Unfortunately it is right around the maximum curvature where the ply is under the most stress and will cause a slight outward bulge.

It needs to be epoxied back into place but you need to apply force to get the cracked veneers back to the fair shape. I would cut a piece of 6mm ply about 9" long and 7" wide with plastic sandwiched between the ply and the hull and screw it over the damaged area to force the hull back to its fair shape until the epoxy cured.

 

Because the 6mm ply bottom that you are screwing into does not have enough thread bearing area to absorb the force needed to draw the cracked area back to a fair shape, you need to use some blocks to screw into, like 1 1/4" squares of 3/4" ply. Put some duct tape on the underside of the blocks. 

 

You should do a dry run to check that it works like you want. If it does not quite bring the surface back to fair, try thicker ply.

 

I presume that you will glass the outside of the hull before painting. I would glass a patch on the inside and you will be back to full strength.

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I think this surgery was successful.  I mostly followed the instructions.

 

To make the cast, I used 3/4" ply on both sides - on the outside I big rectangular piece as suggested, and on the inside I used 2" squares.  I pre-drilled through both the big piece, the boat itself, and enough through the little pieces to get the screws to start.  In an attempt to try and mostly get the bulge to go away, after I applied the cast I propped a stick up under the boat and the ground so there was some outside pressure "in" on the bulge.  I think this worked, when I sight down from the bow I don't see any bulge where the crack is.

 

When I'm inside the boat (soon) to fillet and glass the keel, I will fill the screw holes and put a glass patch on the inside of the crack as suggested.  I will be glassing the hull outside as in the instructions so looks like this should work out just fine.

 

 

IMG_1916.png

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During construction, I fell from the bridge deck into the cabin floor and my knee made a divot very similar to yours,  fixed exactly the same way, absolutely can’t tell where it was.  You are good! 

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