I am in the process of repairing the deck of my boat around the mast base. I have a Columbia 26T which has a mast mounted in a tabernacle mounted on top of the deck. This past year I noticed it was "sagging" at the base. After reading many forums, I am attempting to repair it myself. I have removed the fiberglass skin and all of the rotted/wet balsa core. My plans are to replace the balsa with Core cell and then reapply the skin then glass in the seams. My question is: Should I consider glassing in a piece of aluminum or stainless steel plate between the skin and the core material to strengthen the whole area? I could use anywhere from 1/8" to 1/4" thick. Will the epoxy stick to the metal or am I asking for more delamination? Is there a corosion issue? I am also planning to build up the area under the tabernacle on top of the deck with a glassed in piece of 1/2" core or marine grade plywood. Thank you for your responses.
Deck core damage
- Thread starter ncsailor634
- Start date
Sounds like a plan ! 
Only thing I did differently was to replace skin entirely. I used 1/2" ply as original and went over it w/ 5 lamms of 1708, appropriately beveled; then a couple of brushed coats of (borrowed) white gel coat, just to UV-proof it for now Figured it was easier than trying to get intervening lams just right for replaced skin to lay to height!
Address all points of the system from there down, too. Could be a sagging below sole, a limp compresssion post, a bad crush between overhead and bottom of deck........ no real familiarity w/your model. It'd be a shame to do listed repairs and *still* have issues. My step under the sole was a 1/16" low and the overhead about the same. Since theyhadn't moved substantially in 30-some years; I simply added an eighth up top
HTH,
Paul
Only thing I did differently was to replace skin entirely. I used 1/2" ply as original and went over it w/ 5 lamms of 1708, appropriately beveled; then a couple of brushed coats of (borrowed) white gel coat, just to UV-proof it for now Figured it was easier than trying to get intervening lams just right for replaced skin to lay to height!Address all points of the system from there down, too. Could be a sagging below sole, a limp compresssion post, a bad crush between overhead and bottom of deck........ no real familiarity w/your model. It'd be a shame to do listed repairs and *still* have issues.
My step under the sole was a 1/16" low and the overhead about the same. Since theyhadn't moved substantially in 30-some years; I simply added an eighth up top HTH,
Paul
If you want to use a metal to strengthen it, you should probably look at expanded metal, or some other form of perforation. That will provide a good bond, as well as make it lighter. Can't really say if adding metal is necessary though. If you are worried about tear out, use Kevlar.
Thanks for the information. I did drill a several holes into the plywood above the interior liner and although it seemed damp there is no evidence of rot. I believe "most" of the sag is from delamination of the top skin and the balsa underneath. I read another forum that said to coat the stainless in epoxy then sand w 80 grit then bed it in thickened epoxy. As far as the top skin goes, I am a little nervous about trying to lay up new glass and getting it right. It seems easier to lay down the old skin however I know there could be issues there too. I have the work area out of the weather and am periodically running a heater to make sure it is dry. I also considered using a hole saw to drill out 1 1/2" holes in the 3/4" plywood where the tabernacle bolts go through to the cabin and replacing with epoxy coated 3/4" thick x 1 1/2" round. I happen to have some spair hardwood.
I used 2-3 inch squares of 1/2 inch Corian counter top to recore the area below the mast step on my Cat 22. Yes, I know it isn't light but it is very strong and didn't do more than about 1 1/2 square feet.
The main stress from a mast should be simple compression. Side loads are relatively small.
I would think once you are satisfied with the compression part you are good to go. I've never heard of a boat with a plate under the mast and I question just what the benefit would be. The compression post, wall or whatever is used in your boat should bear the load. Also if you make the cabin top higher the rigging must also be lengthened.
Ken
I would think once you are satisfied with the compression part you are good to go. I've never heard of a boat with a plate under the mast and I question just what the benefit would be. The compression post, wall or whatever is used in your boat should bear the load. Also if you make the cabin top higher the rigging must also be lengthened.
Ken