Repair split in hull

[Rocky S]

I built a boat that is a combination of a Kara and my old Duracraft aluminum fishing boat. The Duracraft is very efficient in the water for rowing or using a small motor, so I used the hull designer software that someone posted on this site a while back to approximate the Duracrafts hull.

The boat worked out pretty well, but I do have one problem. I used 6mm Okume plywood with 6oz fiberglass cloth, which evidently wasn't stong enough because the hull split while I was unloading the boat off the trailer. The trailer has a roller at the back and as the boat rolled off the trailer the plywood on either side of the roller split.



What is going to be the best way to fix this?

 

[Eric Caswell]

I would cover the split with a strip of plywood 4-5" wide.

Use a utility knife to clean up the torn wood and cloth to sound plywood. Try not to cut through the outer layer of cloth unless it too is damaged. You should have a small vee shape. The idea is to just clean it up. Wet out the repair with unthickened epoxy resin. Fill the vee to level with thickened epoxy using a dense filler like cabosil, talc or wood flour. A combination of cabosil and wood flour would be my choice. Cover that with cloth wide enough to give 1 1/2"-2" of coverage on both sides of the vee. Over that epoxy a strip of the same ply as used in the construction, allowing at least 2 inches overlap of sound wood on [font=Verdana,Arial,Helvetica]either[/font] side of the vee. Fillet all edges (of what will now be much like a butt block) of the strip and cover with cloth out to a couple of inches all around the strip.

Too help prevent and strengthen the area I wouldn't fillet the block but fair it in with wood flour epoxy mix to about 1 1/2-2"s out to help distribute the stress of the roller over a wider area and then cover it with cloth.

Too help hide the strip I would end it against a bulkhead if practical fore and aft.

This assumes the splits are wide enough apart to do it this way and that the damage is localized to the split. (A small 1/4" vee) Any place the cloth is damaged on the outside of the hull (delaminated, torn,etc.) additional steps will have to be taken to clean, repair, fill , fair and sheath.

This is what I would do based on what I see in the close up pic.

Eric