Surface of bilge cracking/crumbling

Feb 17, 2021
1
oday 1978 25 burrard civic
Hi everyone! I have a 1978 25 foot Oday. I’ve had her for two years and it’s been great and I’ve been learning so much! I’ve noticed that the surface/substrate of my bilge is cracking/crumbling. I’m planning to pull her out next month and will have someone come and take a look at it, but I was wondering if any of you have encountered this? I’m not sure what this material is that is cracking. Not sure if it original or was done by a previous owner.
 

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Feb 21, 2013
4,638
Hunter 46 Point Richmond, CA
Welcome to the forum!!

Your plan to have a qualified boat contractor look at it is good and I would be prepared to to remove the surface cracks and re-glass it.
 
Jan 24, 2017
666
Hunter 34 Toms River Nj
welcome to the forum,

lots great info and helpful fellow sailors here.
Looks like some water saturation between the Fiberglas resins and layers of Fiberglas has delaminated. I had similar issue, not as much as your pictures.
doesn't apear to be structural,

Question?
Do you keep boat in climates where temperatures get below freezing?
My issue I believe was caused by ice that expanded where the water infiltrated the layers of glass.

Repair:
I think that all you need to do is scrape away to lose chips, clean with good solvent, then mix up some thickened epoxy and fill in any voids and give area good Côte of epoxy. After area has been given a good Côte and drys then paint with bildge Côte paint.

Did mine about twenty years ago, no issues.
If you are in a freeeze zone put a splash of antifreeze in the bildge in the winter,
I've been doing this for years and never had any issues sense.

Hope this helps.
 
May 24, 2004
7,129
CC 30 South Florida
Like the Cap says it is likely water that infiltrated the fiberglass, froze and expanded cracking the glass. Before repairing I would check the holding of the keel bolts.
 
Feb 5, 2015
37
O'Day 302 Ottawa
Hard to tell from pictures unless you have seen this exactly as it is. What do the cracked pieces feel like? Hard? Soft? Brittle? If delaminating fibreglass, I would expect to see glass fibres and I’m not seeing that. Is the cracked material under or level with or over the keel bolt washers? If under, I would think it was part of the bilge structure (original). If under the washers, then you might be looking at removing bolts and washers, cleaning out the bilge to solid material, building the thickness and strength back up to design specifications.
If the material is at level with top of or over the washers, then I would think it occurred after the factory build. Could be a previous owner applied this to ensure the bilge was waterproof and safe from water intrusion and delamination. Or it could just be a spill or leak of something that has been in the bilge a long time. The size of the cracks in the material suggest to me some kind of contraction as if the material has dried out or reacted badly - like a material or substance not designed for outdoor heat, cold, contraction, expansion or maybe a bad epoxy mix and pour. If it can be determined that this material is not part of the original bilge structure or added to solve a real problem with the original bilge, that the keel bolts are tight and secure, then I would just clean the stuff out and get back to sailing.