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Old 06-12-2012, 19:09   #1
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Need Advice For Compression Post Support

Hello,

Long time lurker - really appreciate all the shared knowledge here and what it takes to make it happen!

My 1980 Cal 2 25 may need some help. Sheís got some stress cracks with slight sagging of the cabin sole around the compression post, however, there are no stress cracks or detectable deformation on deck around the mast.

In the cabin sole photo a hollow U shaped stringer can be seen that runs athwart ships between the salon and V berth with an aft extension for the compression post. The bilge photo reveals unsupported areas between the cabin sole and the hull as well as a small piece of 2x6 that is glassed into the stringer and supports the compression post.

So, should the bilge area under the compression post be beefed up and if so is just Fiber Reinforced Epoxy (FRE) enough or does she need a stainless bar and FRE, or some other option?

Thanks for your help,

gus
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Old 06-12-2012, 19:37   #2
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Re: Need Advice For Compression Post Support

With that much damage under the compression post there must be some indication around the deck plate for the mast.

I would definitely pull the rig and then take a look at what needs to be done. I think I would extend the compression post down to the keel. You will at least need to jack up the support beam and then epoxy/glass it to repair the damage. Get some high density foam (beveled edges) under the beam (on the hull sides) and then epoxy glass the beam and hull, making a nice taper on the hull sides. I'm unsure of all the construction details so I can't say much more than that. If there is a Cal 2-25 user's group get in touch with them. There is likely someone that has already done this.

Edit: is that black mold under there? If so you might as well make some nice holes in the sole so you can clean and then install hatches over the area that you cut out. Make the forward one a ventilating hatch.
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Old 06-12-2012, 19:48   #3
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Re: Need Advice For Compression Post Support

I suspect that water may have entered the wood filled cavity and rotted the wood. This along with the long term stresses would push the mast down into the structure. When you pull the rig and explore the crushed area you may decide you can excavate, remove the wood and fill with solid glass. You may want to add structure below as well but make sure water can drain past - possibly embed a tube at the bottom. Looks like a relatively simple repair. It will take longer to fix the stress cracks.
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Old 06-12-2012, 20:42   #4
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Re: Need Advice For Compression Post Support

Yikes! My Cal 36 has similar construction. And some stress cracking - but nothing like that. I figure it is from my teenage days when we thought it was fun to sail with the rail underwater in the slot at the Golden Gate Bridge.

I now just reef much earlier.

You might repair and thicken what is already there. Tough working under the pan though. I'd be a little concerned about where I directed the load. The skin at the keel may not be up to it. The force needs to get to the chainplates. Normally that is thru the crossbeam hull and the bulkhead. You might just stiffen the external surfaces with some tidy glass work over that whole structure. I think a boatbuilder might be valuable for advice.

The good news is nothing is actually broken. Just tired of the stress. Shouldn't take much to stiffen it. And modern epoxy/glass work is far more durable than the polyester, no?
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Old 06-12-2012, 21:12   #5
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Re: Need Advice For Compression Post Support

I would call that cross beam broken. It just hasn't failed to the point where the mast has come through the deck yet.

reefed, check the bulkhead tabbing around the mast/chainplate area to make sure that the standing rigging hasn't been reefed down hard and caused damage in those areas. When you have the mast down it would be a good idea to thoroughly check the chain plates as well.
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Old 07-12-2012, 06:04   #6
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Re: Need Advice For Compression Post Support

Greetings and welcome aboard the CF, reefed.
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Old 07-12-2012, 06:38   #7
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Re: Need Advice For Compression Post Support

Re DeepFrz comment: From what I see the beam is intact. The island that the post rests on is cracked vertically. And the floor pan, which is non-structural in theory, is stress cracked.

On my Cal 36, which seems to have similar construction and the same type of problem, the port bulkhead is substantially attached to the compression post. On a heavy air port tack everything is happy because the cap shroud chainplate attaches to the same bulkhead. The beam feels little stress (and the head door can be opened).

On a heavy air starboard tack things get complicated because the starboard bulkhead is not fixed to the compression post for the doorway forward. I think the designer figured the hull, stiffened by the beam, would carry the load. In practice FRP is too "rubbery" for this to work well. The hull flexes. The door cannot be opened. The starboard shrouds pull the starboard side of the hull upwards and the doorway skews. Things stress crack. The tabbing breaks. The Cal 40 has a steel beam down there to help. But that has proved problematic as well.

Reefed: So how is the port bulkhead attached to the post, and has the tabbing to the deck and hull survived?

I've never really thought my boats problem was a big issue. It is sound. I have replaced the tabbing a few times. She's been sailed very hard, and only slightly less so now. My only visible failure is the upper surface of the step is warped several millimeters downward and the tabbing is moved a bit in the same direction.

Not sure what reefed should do. Either ponder the forces and bending for a while and come up with a modification. As I wrote earlier, putting the force into the keel may not solve the problem as it gets the force no closer to its destination at the port chainplate. Or contact a boatbuilder for a review.

Reefed: Do you have forward and aft lower shrouds, or just two?
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Old 07-12-2012, 08:39   #8
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Re: Need Advice For Compression Post Support

In the bilge photo, towards the right end and bottom of the 2 by, are those not open cracks in the U beam? Maybe I am seeing more than is there.
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Old 07-12-2012, 09:14   #9
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Re: Need Advice For Compression Post Support

There are those here who will shoot me down for this post but here goes. I would damn the section off under the compression post install a drain tube and fill the the void under the post with concrete. Yes I said concrete, when you think about this from an engineering point of view it makes perfect sense as concrete has great compression strength (just what you need here) is water proof (great for in the bilge) and is cheap and easy to work with. you could spend thousands to to do what concrete cad do for less than 100. FRP and FRP filler is plastic and will flex and compress under long term load, concrete will not. I have seen several repairs done like this and all worked great. I know some will say this is nuts but it works and this is a 30 YO coastal cruiser not a hi end racer. Pour concrete let it set for a week and go sailing!
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Old 07-12-2012, 10:30   #10
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Re: Need Advice For Compression Post Support

First of all, I am surprised there seems to be a void under the post - no wood block, no solid grp??? Or has the support/block been removed for taking the images?

Or else what did the designer/builder think of the loads? Puzzled.

Then I would (with the mast off the deck) remove the post and cut the support grp form open and then I would build a solid filler all the way to the top of the space wood, grp, or as someone noticed concrete perhaps. Then replace the post. Then re-stepp the mast and tension the rigging.

If the roof area is unsupported over a larger stretch there will be no cracks there.

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Old 07-12-2012, 16:49   #11
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Re: Need Advice For Compression Post Support

Quote:
Originally Posted by DeepFrz View Post
In the bilge photo, towards the right end and bottom of the 2 by, are those not open cracks in the U beam? Maybe I am seeing more than is there.
Maybe. We don't know.

The concrete is a clever idea. Very "shadetree." But we are not dealing with those magnitude of forces. And there is the real possibility that the hull and keel area there is not designed to take the load. Cal's have thin layups wherever they can. The stress would just move to a new area. Like I said above: the stress needs to go from the step to the chainplates. That's how boats work. A rod and turnbuckle from the step to the chainplate would be better, but probably blocks the doorway.
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Old 07-12-2012, 20:01   #12
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Re: Need Advice For Compression Post Support

Thanks for the welcome and all the replies.

Less the 400 2 25s were built and I havenít found a user group. No doubt somebody has done this repair but finding themÖÖ.thatís whatís so great about this forum!

I agree using foam and epoxy in the bilge may strengthen things and Iíve read several threads about using concrete to replace the wood compression post bilge block but as pointed out spreading the load is critical.

I looked over the tabbing this afternoon and it looks good Ė no breaks, separation, cracks, or deformation that I can tell. After thorough inspection again around the mast there are no stress cracks or deck sag Ė maybe Iím wrong but if the mast step was compressing and pushing the post down I would think there would be signs of deformation on deck Ė weíve all seen it in many other threads. With no deck sag Iím a little hesitant to jack up the floor which would raise a deck that hasnít compressed.

Maybe stiffening the crossbeam and spreading the load is a possibility.

I did ease the rigging when I got the boat - it was really tight and could have contributed to the problem. From what I can see of the chainplates they're in good condition, the aft lower shrouds are bolted to the side of the cabin trunk and there are no stress cracks around them. The forward lowers are bolted to the vee birth bulkheads and appear good as does the tabbing.

The starboard salon/head bulkhead is attached to the post but the port bulkhead doesnít - tabbing looks good. The head door slides athwart ships.

I hope there arenít cracks in the u beam, I felt around this afternoon and didnít feel anything - but the big stress crack in the cabin sole is visible in the bilge photo.

Iím surprised thereís a void under the post too! I donít think anything ever was there. And Iím concerned about moving the problem (stress) to an area that wasnít designed for it.

I do like to put the rail down, however, sheís in Lake Wallula and only gets into swells when we go down to McNary dam so thereís usually no pumping.

Thanks for all your thoughts!
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