OMC Stringer Mount Repairs

I have a '67 Slickcraft SS-235 I use on Lake Huron, she is in stellar shape, stored most of her life with less than 500 hours on the clock, until I bought her 4 years ago and have been using it for Great Lakes fishing. Last weekend I was 5 miles out in 140' of water off Grindstone City MI. I heard a thunk and the boat steered hard right. Thinking I broke a steering component, I came to idle and inspected the engine compartment to find both front mounts had pulled loose from the stringers! The manufacturer had used non-stainless bolts and the body of the bolts had corroded and let go. Needless to say we had a 4 hr voyage back to the dock doing 5 knots. Saw a beautiful sunset though.

Yesterday I did an in-slip repair using longer stainless bolts (originals 2" I went 3") and Marine-Tex packed in each bolt hole and threads of each bolt covered in Marine-Tex before installation. Of the 8 bolts I did, 3 were completely stripped to the point I could insert them by hand with some force. I am hoping if used gently I can make it thru the rest of the season (aka Labor day).

I also added an old circle track trick and chained the engine on both sides (4 places total) from the exhaust heat exchangers to bolt eyes I threaded into the stringers and used a turnbuckle to tighten each chain. I am confident this will work for the rest of the season.

I found the stringers are in good shape 2" away from the mounts. They did not seal these motor mount bolts when they installed them and over the years the moisture was able to get in and corrode the bolts, soften the wood adjacent to it and cause the failure. I am planning on making permanent repairs to this in the fall.

Several very old threads on this website have discussed using the following technique to fix this condition successfully:

What I interpret from those threads is using a gallon of liquid poly resin (maybe more) mixed with chopped fiberglass in a bucket, mixed to slurry thickness poured into holes or rectangular holes cut where the engine mount meets the hull to basically "fill and flood" the area below the floor between where the engine mount rests on the affected stringer and the adjacent stringer under floor. At least that is what I think they are doing by using a gallon or so of mixed resin per mount.

Anyone speak to the success of this repair? Back in '06 when the thread was written several folks seemed to be happy with the results just wondering if anyone can speak now as to the performance of a similar repair.

 

I recommend using epoxy resin instead of polyester for such repair now. Epoxy will bond better to wood and to existing cured glass surfaces.

 

FMS, Thank you!