The PO neglected to nip it in the bud, and also whoever installed the Maxwell Windlass foot switches didn't seal the holes, so now I've got three areas of my deck, probably 2'x4' each, that are spongy. So I'm going to do the good old peel and replace of the core and reuse the peel. 

Just wondering if anyone's been there, and can give me any tips. Like, where do I get marine plywood in Minnesota? What thickness is the plywood? It appears that the best way to do this is to use the plywood on 4"x4" sections, so I would like to purchase that and epoxy seal the plywood sections at home before starting the project, since home is 4 hours away. 

Also, the two other soft areas are at the chainplates. Any tips on working around them? Since I will have to scarf the fiberglass to to hide the seams, I think I'll have to work around them. Or should I just keep them in place and lift the fiberglass skin up while doing the repair, so I can be positive that there is a good seal?

My decks are terrible and faded, so I was going to go with Kiwi-grip even if I didn't have a soft deck. So timing is right for this job at least. I'd rather not have to deal with creating molds to recreate the current diamond pattern, and I've become fond of Kiwi on other boats because I prefer to be barefoot. Anyone have other suggestions? 

I plan on using West Epoxy, because I'm familiar with it, with 404 filler. Does anyone have another preference?

Also, should I scarf first? Then use the oscillating tool? Or use the tool first? 

After doing an exhaust riser and a full bottom job, I think this job should land about in between for degree of difficulty. Peel it, scrape nasty stuff out, put good stuff in, put the skin back on, scarf it, fill with strand and a top layer of biaxial, paint with kiwi next spring. 

I'm open to suggestions. This forum has helped me so much already, and the "been there, done that" tips received in my past projects has been invaluable. 

Thanks.