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compression post step collapsing
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2013-11-09 at 10:47:21 PM GMT
Posts: 19
compression post step collapsing

Greetings from La Paz.  Marathon is a 1985 Beneteau Idylle 11.5 and we have recently discovered that the compression post step seems to be collapsing. The post sits on top of a glass stringer that is glassed to the hull, and between the stringer and the hull, immediately under the post, is a wooden block. It seems that the block is compressing and causing the stringer to show  signs of collapse.

 One suggested solution involves a custom made piece of stainless steel to reinforce the stringer fore and aft of the attachment point of the compression post. The post would sit on top of the steel insert which would be installed after slacking the rig and jacking up the cabin top. Any comments on this approach, either positive or negative?

For example, the steel brace will flex differently than the stringer or the hull to which it is attached. Will this be a problem?

All comments and suggestions will be much appreciated.




S/V Marathon

La Paz, BCS, Mexico

2013-11-10 at 12:40:25 AM GMT
Posts: 7
Mast Step Repair

Since the mast step area is prone to corrosion problems, aluminum is a better choice than stainless. This will necessitate a greater thickness of plate on the step than you would have if using stainless. The exact thickness will depend on the extent of the damaged area. That flexing fibreglass has given up some strength, as has the wooden core under it. There are lots of variables here, and possibly some not-so-visible damage. Why not look up former BCA member Rob Cross, who has a boat repair business at Marina Palmira, La Paz? 

2013-11-10 at 1:57:42 AM GMT
Posts: 16
If wood works for 30 years or so, you could just go that way again. Bronze is the best material if you can find someone to cast there, aluminum second, ss a distant third due to corrosion issues. Good luck!

2013-11-10 at 4:53:18 AM GMT
Posts: 8

Maybe use fiberglass?

I had a similar issue on my Spencer 35.  

My compression post was made of Douglas Fir glued to an adjoining bulkhead.  It sat on the plywood sole. Under the sole was a block made of several layers of ply glassed together.  This block was tabbed to the top of the integral fiberglass water tank.

Water intrusion from an old leak from the mast wiring had rotted the bottom of the compression post, the plywood sole, and the top plywood layer of the laminated plywood block.

I jacked up the cabintop and removed the compression post and a section of the sole.  Then I removed the entire laminated plywood block and replaced it with one I made up out of several layers of 1" fiberglass sheet that I got from McMaster Carr and epoxied together.  Probably overkill, but I didn't want to have to do it again in another 35 years!  I then replaced the section of sole with epoxied ply, and made up a new post out of yellow cedar.

I figure the new fiberglass block should be plenty strong and rot proof.  Only downside I see is a bit of extra weight (and a a few extra dollars) compared to wood.

2014-01-10 at 7:11:24 PM GMT
Posts: 19

Many thanks for the advice and apologies for not having responded earlier. I wrote the original message in La Paz and then sadly had to return to work in Canada.  One of the people that I have consulted on this problem is Rob Cross and his partner Will Immanse.  They are keen to use ss but I'll discuss the metal options presented here as well.  The second group of consultants are keen to go fibreglass and rebuild the entire step.  Hard choice.


thanks again.

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