Author Topic: Keel box repair at Elkhorn Composites  (Read 188 times)

Bob Comstock

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Keel box repair at Elkhorn Composites
« on: April 13, 2022, 01:01:31 AM »
Due to repeated collisions with underwater rocks, my flange had separated from the keel box and a crack was visible on both sides of the keel.  Water was leaking into the inside tank during the summer when the boat is sailed often. 

Per Craig Smith's direction, I removed the putty from the flange gap with a buzzy tool (same as used for drywall and general vibratory cutting).  I then applied masking tape around the area to be repaired to ensure I didn't get epoxy outside of the desired area.  I used a putty knife to repeatedly push toughened epoxy (ask Craig for the correct product) into the gap and then smooth the inside surface (adjacent to the keel).  After curing, I filed and then sanded the epoxy to match the keel box.  The entire repair took two days. 

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Re: Keel box repair at Elkhorn Composites
« Reply #1 on: April 16, 2022, 03:47:05 PM »
Tools and materials mentioned in the webinar:

Tool for cutting out the old caulk/putty is an Oscillating Saw.  Made by Fein or other vendors.

3M 5200 - Super strong adhesive, sealant caulk.  Do not use in applications where you want it to come apart in the future:  https://www.3m.com/3M/en_US/p/d/b40066983/


ProSet Toughened Adhesive Epoxy mentioned int he webinar: https://www.prosetepoxy.com/wp-content/uploads/ADV-176_ADV-276.pdf


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Link to Richard Hunt's Keel Box Repair Procedure!
« Reply #2 on: April 16, 2022, 03:48:24 PM »
Keel Repair - Richard Hunt

Bayview had this problem with all six boats You can grind out the keel box two ways 1. drop the keel out of the box using a crane 2. take the keel plate off put the boat in the water and lower the keel out of the way (not to far) Dremel works great to grind out the cracks , clean out all the debris I used Epoxy with 406 adhesive filler to fill the cracks, a syringe is helpful to inject into the cracks then put 2" tape over the cracks to keep the epoxy in place and the sanding to a minimum. Then spray a little gelcoat over that for looks I also put 10 thought bolts in the keel box (5 a side) ,the pictures I sent show 4 total around the wedge area of the box ,these are old photos. 5 bolts a side help keep the keelbox from moving or flexing , epoxy does not like to flex . In photo 001 you can see the bolts going thought to the G-10 which is a good backing plate to hold the keel box together I did countersink the bolts Drill the holes for the keel bolts first before you epoxy the cracks The epoxy putty USI uses is ok it works . but even a boat that sees very little use will eventually leak into the air tight compartment I will take some more pictures if any body would like to see the 10 bolt system Richard Hunt.