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Managed to snap a Kaholo bulkhead while planing
I was planing the sheer clamp on a side panel of my Kaholo 14 (to level sheer clamps, bulkheads, and stringers before installing the deck). I managed to clip a bulkhead with my relatively dull plane. The bulkhead (#9, about 2 feet aft of the center of the board) snapped between the outer stringer and the sheer clamp, leaving a piece about 5"w x 3"h missing from the bulkhead. I cut a wee bit more out with a Japanese saw to leave a straight-edged "hole" of missing plywood with a shelf on one side and then cut a piece of 4mm Okoume to replace it using the plans. I achieved a snug fit and installed the replacement piece using thickened epoxy. I almost added a sandwich of small backing blocks to span and reinforce the joint but decided to wait. Should I add something like this, add fiberglass tape, or just assume it will be stronger than the bulkhead was in the first place given that I got plenty of thickened epoxy to squeeze out and the joint doesn't seem dry? Obviously I don't want to wonder whether the board will buckle in a weak spot later, so my inclination is to add some kind of reinforcement.
3 replies:
RE: Managed to snap a Kaholo bulkhead while planing
I wouldn't bother with the reinforcement for the folowing reasons:
1. Those bulkheads are there to resist the compression caused by the paddler standing on the deck.
2. A joint such as you described in your repair is very strong in compression.
3 The addition of the deck and stringers will form a box beam and immobilize the bulkheads, greatly reducing the possibility of shear and torsion, especially in normal operation.
The weakness of the bulkhead that let you break it is a temporary thing that occurs only during construction. You were just unlucky enough to encounter it.
All that being said, if you're not convinced and still want to reinforce it, I'd suggest a glass patch rather than blocks of wood.
Laszlo
RE: Managed to snap a Kaholo bulkhead while planing
Thanks, Laszlo. I feel pretty confident that it will be OK without reinforcement. I wiggled it around a bit after two days of curing, and it is a lot more rigid than the other side, and I can't imagine that it won't have higher failure strength under atandard use. I'm not gonna bother with a patch because I agree it is unnecessary.
RE: Managed to snap a Kaholo bulkhead while planing
» Submitted by HerbieRidesAgain - Wed, 3/13/24 » 9:40 PM
I intend to sharpen my block plane and try to use it again to bring the sheer clamp and stringers down to bulkhead level, but I'm thinking I'll switch to a sanding block earlier than I'd previously hoped. I remember seeing a warning about snapping a bulkhead like this, so I was already being pretty cautious (I thought!).