Rotting Bulkhead - AGGGHHHH

[sailingdog]

Glad to help. If you look at some of the lower quality, older boats, you'll see vertical ridges where the bulkheads attach on the interior. The fiberglass laminate on the hull would then tend to flex more at that one specific point, weakening the hull where the bulkhead is attached. A gap of about 3/8" should be plenty.

The foam you insert into the gap will also help you create a well faired joint, which will make the fiberglass in the tabbing stronger than it would be if you had a sharper radius bend. The strength of the bulkhead is created by the glassing of the bulkhead to the hull. You will need to sand the hull interior down to bare fiberglass to do the tabbing. The distance should be about 6-8" on either side of the bulkhead position.

Also, use marine grade plywood. Yes, I know it is more expensive, but it is far less likely to delaminate and it won't have any voids on the interior.

I hope this helps.

Originally Posted by Finallybuyingaboat

See that is why I like this forum. I would not have known to put in a piece of foam between the hull and bulkhead, I would have just glassed it right up against the hull. Thanks sailing Dog, you just saved me making an enormous mistake!

I may be asking a lot of questions on this forum that seem very basic to many of you, but I am here to try and learn, and the knowledge base here is pretty helpful.

[US27inKS]

I don't know if you have a source for marine ply near you, but in the midwest it's hard to come by. I bought mine from http://noahsmarine.com/html/united_states.html
I got good quality wood for less than I could find it elsewhere. I also bought epoxy in the 5 gallon bucket from them as well as the appropriate fiberglass roving etc.

[Dihydro77]

If you get a chance post up some pics of this repair. Trying to learn as much as possible here too.
Good luck

[Finallybuyingaboat]

Originally Posted by Dihydro77

If you get a chance post up some pics of this repair. Trying to learn as much as possible here too.
Good luck

I have so many projects on this thing I am going to have to set up a website to keep track of it all!

[rsn48]

If you can start a web site on your upgrades, they can be amazingly helpful to others who own the same boat. Below are two Catalina examples I resource a lot:

http://www.blumhorst.com/catalina27/...nahomepage.htm

http://members.aol.com/bobdeurer/mod-.htm

[Finallybuyingaboat]

Since I am going to be replacing the bulkhead anyway, I was thinking, what if I could open up the cabin a bit. If you were in the main cabin looking towards the V berth, the left bulkhead is only about 16 inches wide. The one on the right (the one I need to replace) is about 3 feet wide. If I were to replace the right one with one that was the same size as on the left, it would really open up the boat. My kids are 3 & 5, so privacy for the porta potty is not an issue. Could this be done without risking the structural integrity of the boat? I see nowhere that the deck is actually supported by the right bulkhead, the only structural issue is for the front bench, but I can add a small piece of plywood to replace the missing bulkhead there. Other than securing the chainplate, this bulkhead seems to serve little purpose other than a wall to break up
the space. I could run a piece of ply across the underside of the deck , from bulkhead to bulkhead if need be. Any ideas?

[sailingdog]

You would probably want to run a beam across the top to spread any load. One thing to remember though, a bulkhead adds considerable torsional rigidity, much of which would be lost if you enlarge the opening in the bulkhead considerably. One way to regain the torsional rigidity in spite of the larger opening is to use a slightly thicker material for the new bulkhead.

Ideally, you should talk to a marine architect about making such a change, but YMMV.

[Finallybuyingaboat]

Normally I would worry about the torsional rigidity, but there ia a secondary bulkhead about 18 inches farther up the hull, on the other side of the locker. I will tie into that, glass in the seat fairly heavily and tie into that. Then, I will run a beam across the top of the arch and tie that into the mast support. I will also tie into the mast support at the bottom, so theoretically it should be like cutting a 2x2 foot hole in the buklhead. I'll get someone that knows this stuff better than I do to take a look though.

[sailingdog]

Sounds like a workable plan.

Originally Posted by Finallybuyingaboat

Normally I would worry about the torsional rigidity, but there ia a secondary bulkhead about 18 inches farther up the hull, on the other side of the locker. I will tie into that, glass in the seat fairly heavily and tie into that. Then, I will run a beam across the top of the arch and tie that into the mast support. I will also tie into the mast support at the bottom, so theoretically it should be like cutting a 2x2 foot hole in the buklhead. I'll get someone that knows this stuff better than I do to take a look though.