Hull damage from trailer roller/ Ballast Replacement

[brackish]

Something to consider since you are going to do it anyway.  You might build in your battery box and leave out the amount of ballast that would be replaced by the weight of the batteries.  That has been done before, but to my knowledge only with an inboard.  In fact, if I was starting with a project boat I would probably consider an electric inboard and batteries as part of the ballast.  This D model has the battery box on top of the ballast.

http://cpyoa.geekworkshosting.com/forum/index.php?topic=10364.0

[H2operator]

Thanks for the suggestion, My plan may have changed, I was too quick to jump to the conclusion that the concrete was totally gone. As it turns out the sump was full of granulated concrete and I thought that was the ballast. I pulled the sole out and removed the concrete dam that formed the bilge sump. There was some dampness but the ballast was in pretty good shape. There was some deterioration along the sides of the keel but it seems like it may not go back very far. So the big question is where did the granulated concrete come from? The ballast was completely sealed and I can't see how it could have gotten in there. I'm wondering if there was a shallow pour in the sump? That would make sense as it would be exposed directly to water.
Any ideas?

[Bilge Rat]

Would be interested to see photos.

[JTMeissner]

16 owner here, and I can attest that several years of freeze/thaw cycles can pulverize the concrete in the keel to a sand-like consistency.  I'm traveling, so can't add pictures (lost to Photobucket), but I dug out at least 50 lbs of sand after cutting through a layer of solid concrete into the depths of the keel during refit.  My "sand" did have scrap metal odds and ends mixed in as well, though.  I emptied  down all the way to the fiberglass in the bottom.

I used the scrap and a 50 lb bag of lead shot mixed together with the concrete mix when filling the void.  So, likely heavier than what I took out, but not too much compared to the total ballast. I'd guess I have about 500 lbs versus the stock 450 for a 16. 

The link below will pop out a picture from another thread.  You can see the scrap metal taken out of the void in the bottom left, some of the sand and gravel out on the right.  Looking at the keel, you can see a layer of solid concrete, but then the sandy mix with scrap metal sticking out underneath that.  The stuff on the sides of the void was all pulled out from the keel.  I have a picture from the stern that might show it better.

http://cpyoa.geekworkshosting.com/forum/index.php?action=dlattach;topic=10384.0;attach=1282

-Justin

[H2operator]

Keel ballast dam area. I got another message back from Gerry Hutchins regarding the granulated concrete in the bilge area, His guess is that some concrete spilled over into the sump and was never cleaned out. He also thought that this was pretty typical condition for a boat this old. There's no doubt that there are multiple voids between the trunk and the concrete so I'm still on the fence regarding replacement of the concrete!   

[H2operator]

Ballast, gap between concrete and keel trunk. (photo is sideways)

[H2operator]

View of the bilge sump with granulated concrete

[H2operator]

Top of ballast forward area

[Bilge Rat]

I am no expert on this issue, but it doesn't look too bad.

I don't know what you had to dismantle or take apart in terms of  flooring etc, to get the access you have, but assuming it's not too much work you could always put things back together and keep an eye on it over the years and if it breaks up further you could do the repair down the road.  I assume you didn't have to take the deck off to gain access to the keel area like the 16-owner did who replaced the concrete?  I don't know how you would manage that yourself on a 23.

[Tim Gardner]

If it were me, I'd clean out the loose crap in the bilge, seal up the sides of the concrete where the gaps are almost to the top, and pour slightly acetone-thinned epoxy into the gaps and such until no more will go in.  you can smooth out the top of the concrete with  self leveling grout primer and grout (like under tile over a concrete slab) & seal that with epoxy and be done.
Just my 2 cents.
TG

[H2operator]

Thanks for the suggestions, I always have these dilemmas when I do projects. I could roto hammer out the concrete and re-glass the trunk in a weekend. Bagged 5000 psi concrete would cost around $100. Otherwise the boat has good bones so I'll sleep on it again for a few nights! My plan with the boat is to do coastal cruising and short crossings, I'm pretty hard on boats so reliability is an issue.
Thanks again, Lance