Bilge Compression Block was Mud.
- Thread starter BillyK
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okay, after all is said and done has snbody out there ever heard of a mast coming down because of failure of this block?
finally found what i was seeking. the interational catalina 30 website says, under changes through the years, lists 'boat 5397, first non-wood mast support.' case closed for those boats.
I am hull number 5800. I know that I have a metal compression post. That block may just be a filler.....Why set a metal post on a wooden block that will end up rotting away because it will see water. They didn't seal the block either.
What I found on my '84 was that the wood rot began first in the mast compression "block" (under the compression post), but more of a problem was that this block and my bilge plywood were connected all the way thru. That is, from the block under the post, all the way through to the last keelbolt under the engine.
I had seen the "Catalina Smile" during the initial survey and after a 1st summer of sailing, I investigated why there was always water in the bilge. I had water leaking up from around the keelbolts. I found my plywood was soaked by drilling a core sample with a hole saw.
One reason water intrusion into the block happened is because Catalina factory drilled a hole thru my compression block so they could snake the mast wiring, that comes down the compression post, back to the electrical panel via the bilge. The worst of the block rot was right through the middle of the block where the wiring went. I highly recommend adding an aluminum plate to cap off the top of the masthead.
The other issue, just as related in my opinion, is the Smile/Keelbolt/BilgePlywood situation. The wood is continuous. As I demo'ed the bilge ply, I did my block at the same time. I don't think it's always necessary to handle these together, but it was in my case. I had leaks coming in and visible gelcoat cracks, inside the cabin at both the top and bottom of the compression post.
Rig tension to the post, applied straight down to a moving, squishy base. Keel weight held by bolts in wet plywood. Summary: neither mast nor keel had a catastrophic failure and I am very happy that I completed the repairs before they did. Learned a lot about the boat's structure and about the engine when I yanked it out to get at everything.
Rob
I had seen the "Catalina Smile" during the initial survey and after a 1st summer of sailing, I investigated why there was always water in the bilge. I had water leaking up from around the keelbolts. I found my plywood was soaked by drilling a core sample with a hole saw.
One reason water intrusion into the block happened is because Catalina factory drilled a hole thru my compression block so they could snake the mast wiring, that comes down the compression post, back to the electrical panel via the bilge. The worst of the block rot was right through the middle of the block where the wiring went. I highly recommend adding an aluminum plate to cap off the top of the masthead.
The other issue, just as related in my opinion, is the Smile/Keelbolt/BilgePlywood situation. The wood is continuous. As I demo'ed the bilge ply, I did my block at the same time. I don't think it's always necessary to handle these together, but it was in my case. I had leaks coming in and visible gelcoat cracks, inside the cabin at both the top and bottom of the compression post.
Rig tension to the post, applied straight down to a moving, squishy base. Keel weight held by bolts in wet plywood. Summary: neither mast nor keel had a catastrophic failure and I am very happy that I completed the repairs before they did. Learned a lot about the boat's structure and about the engine when I yanked it out to get at everything.
Rob
the bulkhead next to the compression post won't support any weight. Plywood has near zero compressive strength on edge. the design of the boat is to transfer all downward force of the mast to the keel via the compression post and then the compression block directly underneath.
I'm curious. Does the mast have to come down to tackle the compression block?
Could I loosen the shrouds enough to give an 1" or so play and then cut out the old block. Perhaps build a temporary post to spread the weight of the mast onto the floor while I'm working on the old block and installling the new one?
I didn't take the mast down this winter but I would certainly look at tackling this project over the next few weeks.
Otherwise, it'll go on the list.
Could I loosen the shrouds enough to give an 1" or so play and then cut out the old block. Perhaps build a temporary post to spread the weight of the mast onto the floor while I'm working on the old block and installling the new one?
I didn't take the mast down this winter but I would certainly look at tackling this project over the next few weeks.
Otherwise, it'll go on the list.
I have never seen a picture of the aluminum beam support used after #5397. Are they glassed in, under the post? I wonder if they used plywood as filler for the void between the structure?
Regardless, I wouldn't worry after #5397. Any plywood in that area isn't structural. And if you haven't seen keel movement or a "Smile", I wouldn't worry about plywood in the flat part of the bilge (bearing the keelbolts), either.Rob
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- Feb 5, 2012
- 183
There's a 1988 C-30 at my marina here in Nashville that has just had the same repair; I didn't see his compression post, but I suspect it's just like the one on my 1990. The guy fixed it by creating a new foundation of fiberglass, which he sanded down and then reset the mast. He had pulled the mast up about a foot for the repair.Bad Obsession said:
Bob
longterm
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- Feb 5, 2012
- 183
Actually, not true; the guy here made a sort of a-frame on the boat, loosened the shrouds, and lifted the mast about a foot so he could make the repair. He didn't take the mast down, but made a new foundation of fiberglass, onto which I assume he put the compression post. I saw it before he lowered the mast, but before he replaced the post, took him about a week...BillyK said:
Bob
That sounds pretty amazing. He had to lift the mast with a crane, right? And suspended it vertically, one foot above the deck? The shrouds were loose for a week and, long enough to remain attached to the chainplates?
Nah, pics or it didn't happen...
I'm losing something in translation here...
longterm
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- Feb 5, 2012
- 183
No, he didn't use a crane at all; he made a neat triangular frame with 2x4's; he used ropes, tied them to the cleats on the mast I think, lifted the mast off the compression plate. I was considering buying that boat, so that was how I came to look at it.rbmcintire said:That sounds pretty amazing. He had to lift the mast with a crane, right? And suspended it vertically, one foot above the deck? The shrouds were loose for a week and, long enough to remain attached to the chainplates?
Nah, pics or it didn't happen...
I don't remember how the shrouds were, but the mast was standing the whole time. He may have attached the shrouds somewhere else while he was doing the work, but I didn't really look that closely.
He made a big mound of fibreglass, then sanded it down once it was dry; I didn't see it before he replaced the compression plate.
Next time I see him I'll ask how he kept the mast up; it was a pretty impressive bit of mechanics.
Bob
Was this repair down in the bilge or did the guy repair the fiberglass underneath his metal deckplate, up on deck? If so, he may wonder why it sunk down?
longterm
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- Feb 5, 2012
- 183
Didn't look dangerous, actually; this guy works on all the boats at our marina, so he's a bit of an expert at boat repair, painting, etc. I'll be using him to work on mine as needs arise.BillyK said:
He told me they often use two boats to put p a mast--a line from the top of each mast, I think, to hold up the mast between the two boats. I haven't seen it done, but suspect its a common technique.
The guy who transported my boat has a crane built onto his trailer, holds up to 1100 pounds; all he transports are sailboats. Here are photos of him working on my boat:
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