ODay 25 forward deck recore

Aug 25, 2014
21
O'Day 25CB Claremore, OK, Redbud Marina
It all started out with a plan to replace a vent over the anchor locker. Upon removal of the offending vent it was clear the core in the vicinity was rotten and delaminated.

I considered making an epoxy paste and jamming it into the gaping void in lieu of more serious surgery and slept restlessly on it overnight. The next day I began surgery.

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I cut a perimeter around the suspect area with about a two inch clearance to the toe rails. I then cut one straight line across the deck to for a large triangle. I carefully lifted off the deck lid to reveal total and utter carnage. 38 years of decay lay before me in the form of black rotten end-grain balsa.

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I removed the rotten material carefully with my angled oscillating multi-tool and carefully scraped rot out of the edges around the cut.

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At home, I cut a large bag of 1/4" pressure treated plywood in 2X2" squares. I know marine grade is preferred, but getting marine grade ply in Oklahoma is like buying roughneck boots in the East Village. Hard to find. Besides, the whole mess was about to be sealed in epoxy and would be a lot better than what was there already.

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I began by cutting 1.5oz fiberglass mat into some random shapes to fill the blisters that had formed on the bottom layer of fiberglass and tacked them in place with Aeromarine epoxy (300/21 mix). After carefully taping the holes for the hawspipe, vent, and assorted through deck bolts from the inside, I then laid two sheets of fiberglass over the entire cutout, making sure the first sheet tucked into the side cutouts. I saturated each layer of mat well with epoxy, pushing it into the fiberglass with the end of the chip brush. No rolling, I wanted it "fluffy."

Next went in the plywood sections. I made most of the pieces in 2X2, but I made some 4X2 as well. I used the 4X2 pieces as a bridge to link the cutout area with the existing edge, pushing about 2" of each 4X2 deep into the lip after first buttering the area well with a peanut butter expoxy mixture. The next piece in the lip would be a 2X2, then another 4X2 and so on. I tried to match the existing layout by inserting a solid section of plywood up the centerline of the deck as it appeared to be during deconstruction. When I'd added all the whole pieces I could, I fit smaller triangles of plywood into the gaps. Each of these pieces was carefully pressed into the epoxy soaked fiberglass below it, often adding fresh epoxy in between as the bedding began to stiffen and kick.

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When all the pieces were in place, I flooded the entire area with a loosely thickened epoxy mixture that poured about like ketchup. I thickened with Cabosil, by the way. Then I went home for the night, or slept on the boat... I cant remember. I was exhausted!

The next day, I ground and sanded off any high points on the replacement plywood inserts until they were fairly even. I then drilled small holes around the perimeter of the original deck skin to accommodate the use of screws and washers in holding the skin to the same depth as the existing edge. I next added two additional layers of fiberglass mat to the whole area and one stripe of 4" fiberglass cloth down the centerline to approximate the additional thickness of the original plywood backbone and filled the area generously with epoxy until it could hold no more.

On went the skin:

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By tightening the screws it was fairly easy to get good compression on the skin and the area stayed true to the original deck thickness.

Tape removed to reveal the scars:

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The seam was manageable. I ground a bevel around the area about four inches wide about 3/16" deep and scarfed the seam with fiberglass mat strips. When these had hardened, I sanded and faired the seam (twice, actually) with a mix of cabosil and microspheres.

I ended the project by slopping on some cheap exterior epoxy paint by Rustoleum and reinstalled the hardware. I'll have to add a pic of the completed job, I started getting frustrated with getting epoxy on my iphone and didn't take many pictures towards the end of the job.

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All told, the project took the better part of a week and was made more miserable by 105 degree days here in Oklahoma... but it was worth it!