I have asked before for suggestions about the bulkhead on my C36 (MK II) that has dry rot. I was undecided as to whether to replace the entire bulkhead or simply cut out the dry rot and repair it. I had decided on the second choice until this morning, when I started in on it. It seems that there is some dry rot behind the lower part of the chain plate (see photo). I didn't know about this before. I'm thinking I'll have to pull the entire bulkhead now. Below are some photos. What do you think?
Bulkhead - What's Your Opinion?
- Thread starter John
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Ouch!! I can't believe that happened in less than ten years. You would think the factory bedding would survive 5-6 years which means that damage occurred in only 4-5 years time...
I think it's new bulkhead time $$$:cussing: Fortunately they are screwed in and not tabbed!! It may not fit into the cabin in one piece though. Call Catalina they may be able to ship you a pre-cut (done with a CNC machine) bulkhead. Of course it won't likely match the rest of the interior but in time they will all settle into a similar patina..
It seems to me that the dry rot goes about six or eight inches up behind the bulkhead. I'm basing this on the fact that it goes up bout four or five inches alongside of it.
As far as the time - if water sits behind there for four to six months per year for four years or so, it doesn't surprise me that this would cause dry rot. What does surprise me (or more like annoy me) is the fact that the previous owner would allow this to happen. He was even a live-aboard so he must have seen it.
I've already talked with Catalina. They don't stock this bulkhead, but I don't think it would be a great problem to make a new one out of a piece of marine grade plywood, using the old one as a pattern.
As far as the time - if water sits behind there for four to six months per year for four years or so, it doesn't surprise me that this would cause dry rot. What does surprise me (or more like annoy me) is the fact that the previous owner would allow this to happen. He was even a live-aboard so he must have seen it.
I've already talked with Catalina. They don't stock this bulkhead, but I don't think it would be a great problem to make a new one out of a piece of marine grade plywood, using the old one as a pattern.
It does look pretty bad!
As Maine Sail says, luckily it's bolted in! As for repair or replace, there will be a LOT more work involved in repairs and then you'll have a seam, may as well replace it and have it good all the way through.
Good time to work in any changes you'd like to make.
Started to tear out the ice box on my ariel the other rday, It was dry rotted around the cockpit hatch and lower side by the bulkhead. Everything was tabbed in and the fastenings were under the counter top's formica, so after looking it over decided it was much easier in the long run to peel -everything- out and make a few changes to improve the usability.
Luckily your's looks like a straight forward replacement!
Ken.
As Maine Sail says, luckily it's bolted in! As for repair or replace, there will be a LOT more work involved in repairs and then you'll have a seam, may as well replace it and have it good all the way through.
Good time to work in any changes you'd like to make.
Started to tear out the ice box on my ariel the other rday, It was dry rotted around the cockpit hatch and lower side by the bulkhead. Everything was tabbed in and the fastenings were under the counter top's formica, so after looking it over decided it was much easier in the long run to peel -everything- out and make a few changes to improve the usability.
Luckily your's looks like a straight forward replacement!
Ken.
Yup... time to replace it. 
Also, take a look and see if you want to make any modifications to the cabin bulkhead or surrounding area, since this is the time to do so.
Also, take a look and see if you want to make any modifications to the cabin bulkhead or surrounding area, since this is the time to do so. 
I've seen a posting from somebody who replaced this same bulkhead on the same model boat, so I assume it will fit through the companionway, or else I am sure he would have mentioned this.
Is the bulkhead "loadbearing"?
Is it an intergral part of the structural design that keeps the deck up?
If so, I do not thank you want to take it out unless you are taking the mast down.
Surely so other Catalina 36mkII owner can help.
Bill
Is it an intergral part of the structural design that keeps the deck up?
If so, I do not thank you want to take it out unless you are taking the mast down.
Surely so other Catalina 36mkII owner can help.
Bill
The masts are keel stepped on the 36's but it still may be a good idea to de-tune the rig a bit and let some tension off the hull..
if there's a chainplate on the bulkhead...
...it's most certainly bearing a load.
John, I don't see where you have any option but to replace that bulkhead due to the proximity of the chainplate. You'll never be able to trust the rig in heavy weather until you've done that.
Bummer, dude.
...it's most certainly bearing a load.
John, I don't see where you have any option but to replace that bulkhead due to the proximity of the chainplate. You'll never be able to trust the rig in heavy weather until you've done that.
Bummer, dude.
Yes, the bulkhead is load bearing as among other things a chain plate is attached to it (as you can see in the photo and as I mentioned). And, yes, I'll be pulling the (keel stepped) mast if for no other reason than that the bulkhead can't be removed with the mast in place. My original thought of just doing a cosmetic repair was when I thought the rot was only along the bottom of the bulkhead. Seeing that it goes under the chain plate that is attached to this bulkhead, it seemed to me that this is not an option, but I wanted to check with those more knowledgeable than me on this list first.
Actually, if it weren't for the cost and the fact that I won't be able to take the boat out for a little while, I'm kind of looking forward to it -- just one more learning experience!
Actually, if it weren't for the cost and the fact that I won't be able to take the boat out for a little while, I'm kind of looking forward to it -- just one more learning experience!
Replace standing rigging too?
One other question that I forgot to ask: The boat is eleven years old and still has the original standing rigging. It's been on salt water all this time. I'm wondering, while the mast is down, if I should replace the standing rigging at this time? What I'm thinking is to get it inspected by a rigger and then decide. Any opinions on this?
One other question that I forgot to ask: The boat is eleven years old and still has the original standing rigging. It's been on salt water all this time. I'm wondering, while the mast is down, if I should replace the standing rigging at this time? What I'm thinking is to get it inspected by a rigger and then decide. Any opinions on this?
Waterproof the new bulkhead
You should be able to waterproof the new bulkhead by coating it with west system epoxy, especially along the edges to prevent water absorption. Then you can stick the teak veneer onto the waterproof plywood. I built a sailing dinghy of marine plywood and all of it was waterproofed in this way. Once the bulkhead is cut and fitted just mix a small amount of epoxy and using a plastic squeegee spread it around and let it cure, you may want two coats as it goes on really thin and soaks into the wood. I'm sure after all this work you won't want to do it again in a few years.
You should be able to waterproof the new bulkhead by coating it with west system epoxy, especially along the edges to prevent water absorption. Then you can stick the teak veneer onto the waterproof plywood. I built a sailing dinghy of marine plywood and all of it was waterproofed in this way. Once the bulkhead is cut and fitted just mix a small amount of epoxy and using a plastic squeegee spread it around and let it cure, you may want two coats as it goes on really thin and soaks into the wood. I'm sure after all this work you won't want to do it again in a few years.
http://www.rotdoctor.com/products/cpes.html
If you want to go one step farther, use cpes to seal the wood, then epoxy. Stay away from 5200, think 4200. My $.02
If you want to go one step farther, use cpes to seal the wood, then epoxy. Stay away from 5200, think 4200. My $.02
If you're going to use epoxy, there is no need to use CPES, which is just a proprietary type of epoxy that is sold to seal wood. There is absolutely no need to buy it if you have West System or any other good marine-grade boat-building epoxy resin.
Bulkhead bonding
I'm not sure using a sealant is going to add much structural strength to the bulkhead or boat. The sealant would be in shear and probably doesn't have much strength anyway. Glassing the bulkhead basically will stiffen the whole structure as the hull will be stiffened in the area of the bulkhead. Most bulkheads I've see are screwed top and bottom but not along the side along the hull. If you look at a Pacific Seacraft for instance the chainplate is screwed directly to the hull, they make the boat a little narrower but it limits your sheeting ability for upwind work. Check out the website for Caliber and they describe how they tape the bulkheads to the hull. I think Island packet does also. Since the bulkhead is trapped between the hull and deck adding a sealant isn't going to do much. If it is a tight fitting joint the wood hull and deck are likely taking all the load, not the screws. They probably are there just to hold the bulkhead in position versus load carrying capability. Especially since the ones i've seen are wood screws not through bolts.
I'm not sure using a sealant is going to add much structural strength to the bulkhead or boat. The sealant would be in shear and probably doesn't have much strength anyway. Glassing the bulkhead basically will stiffen the whole structure as the hull will be stiffened in the area of the bulkhead. Most bulkheads I've see are screwed top and bottom but not along the side along the hull. If you look at a Pacific Seacraft for instance the chainplate is screwed directly to the hull, they make the boat a little narrower but it limits your sheeting ability for upwind work. Check out the website for Caliber and they describe how they tape the bulkheads to the hull. I think Island packet does also. Since the bulkhead is trapped between the hull and deck adding a sealant isn't going to do much. If it is a tight fitting joint the wood hull and deck are likely taking all the load, not the screws. They probably are there just to hold the bulkhead in position versus load carrying capability. Especially since the ones i've seen are wood screws not through bolts.
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