Compression post and block

[ElMico]

Hey everyone,

I'm working down the project list on my '83 C30 over the winter. This boat was completely refit by a previous owner and mostly in good shape. It has a few issues that I'm trying to improve, one being the well known compression block in the bilge.

The original compression post between the deck and floor pan has been replaced, and the new one looks good from the outside. I drilled into the compression block in the bilge, and it's quite wet. I've read up on this fix quite a bit, but still have a couple of questions.

1. Can I replace the compression block with the mast still standing?
2. Can I remove the aft side of the compression post to inspect inside and look for a leak point? Again, with the mast standing?
3. The plywood in my bilge is collapsing. This plywood extends under the compression block, correct?

Thanks again!

 

[Stu Jackson]

Try here, it's new:

https://groups.io/g/catalina30

 

[weekendrken]

El, See ** below.

1. Can I replace the compression block with the mast still standing?

**yes it is possible.

2. Can I remove the aft side of the compression post to inspect inside and look for a leak point? Again, with the mast standing?

**The sides of post are screwed together and the holes bunged. It can be disassembled. But the place to look is the mast tabernacle. You likely are letting water down the wiring conduit. There’s a fix for leaks there.

3. The plywood in my bilge is collapsing. This plywood extends under the compression block, correct?

**Yes

IMHO the C block should be replaced with various options OTHER than WOOD. There are differing opinions.

There’s a lot of C post, C block, bilge plank (and many more) resources including CTY factor drawings on the official IC30A forum that Stu linked to. C’mon over.

 

[Elysium_Van_Isl]

ElMico,
Mine is an '82, so there's a strong possibility that we were constructed the same way. They mad a LOT of changes in methods over the years, most of which weren't documented so it makes it tough to do direct comparisons boat-to-boat.
But, I have mine apart right now and here are my observations:
I tried to properly shore up the cabin sole and compression Post area to replace the oak compression Block a couple years back. I couldn't get a satisfactory support set up which still allowed access to the work area. Some people have managed though... so yes, it 'can' be done.
My mast is currently off (see my other recent post) and just yesterday I pulled out the compression Post. I put 2x4's in place beside the post and used my car jack to lift the headliner along the transverse beam. It took quite a bit of pressure on the jack to raise it enough to allow the post to be removed... and that's without the mast, so I can't imagine how much pressure must be on there when it's in place! But again...people have done it...
You say you don't have an original post. Whats going on there? Any idea of why the old one was replaced? Mine is made of some seriously thick solid teak boards. They would be worth a fortune today! What has yours been replace with? And do you know if your wiring harness has been run through the centre cavity of the new post? Originally (for our time period) Catalina laminated the mast wires into the deck and did not run them down the post to the bilge. If your post has been replaced you want to know if wires were re-routed at that time.

As for why your compression block has rotted - do you know the culprit? Many of our boats have a constantly wet bilge, which is an obvious source for water entry... but other boats, like mine, use a dry shaft seal and so the bilge does not get wet. Regardless, I know CatalinaDirect sells replacement oak blocks, but like others have said - I would personally go with something other than wood.

One final thought - the teak bulkhead connecting to the compression post on my boat is ALWAYS wet along the bottom. Even in August when it hasn't rained for weeks and weeks. I am currently trying to sleuth out the source of this. The whole reason I pulled out my compression post was that I thought water was coming down from the deck and wicking along at the base of the post. When I pulled it out there was still perfectly dry original sawdust from the installation. So I am searching elsewhere for this water source. I guess all I'm saying is that you want to be absolutely sure that water is coming in from the mast step before going to all the effort of pulling it apart when that mast is still up.

 

[ElMico]

Thanks Elysium,

Yeah, lots of changes throughout the years and lots of changes by previous owners to mine - most good.
I think I saw your pics of jacking against the deck, might try something like that. I was thinking it would be easier to pull the aft plank of the post rather than the mast to check if that's the source of the water. My compression post (along with the rest of the interior) wad redone with oak. My wiring now exits the side of the mast a few inches above the deck and goes through the deck through a couple of fittings. Wiring then runs behind trim at the bulkhead/deck. I did get the aft plank wedged away by a little, might be able to see up to the deck and see if the original wiring hole was plugged.

I'd like to replace the block with a large bolt/nut/tube as I've seen here.

My bilge has always been wet. Boat is out of the water now and I get a quart or two every time it rains. Trying to find that leak without much luck.

 

[Elysium_Van_Isl]

My bilge has always been wet. Boat is out of the water now and I get a quart or two every time it rains. Trying to find that leak without much luck.

Oh man do I ever hear you there!! That wet area along the teak plywood I spoke of is only one of my topside leaks. The port windows have recently been letting massive amounts of water in when it rains. Since bringing the boat home I have completely taped the outside edges of the windows and yet it still manages to rain inside! So the water is getting in elsewhere and travelling along the plywood deck to exit at the window which is a low point.
A few years back, when it was only a slight drip from the windows I removed almost all of the deck hardware and did MaineSail's method of over-drilling and epoxy filling each hole. I think I did....maybe 90% of the deck fittings and rails... But clearly I missed something. Everything is off the deck as of yesterday and I taped over every single hole. Now - IF the drip stops (and God help me if it doesn't) - I will start replacing deck fittings one by one until things start to leak.