SailNet is a forum community dedicated to Sailing enthusiasts. Come join the discussion about sailing, modifications, classifieds, troubleshooting, repairs, reviews, maintenance, and more!

Compression Post Blues

2612 Views 12 Replies 5 Participants Last post by mitiempo, Oct 6, 2009

lavery

Discussion Starter · Oct 4, 2009

Sailors,
I would like to discuss a possible mast compression problem with people who have been there, done that, and have the t-shirt.

I am looking at a Southern Cross 31 with lots of deck crazing, cracking around stanchions etc. A survey has turned up no concerns about deck or hull integrity. My concern is the apparent slight crushing or dishing of the cabin top in the area of the mast step. Also, there are parallel cracks in the fiberglass surface where the cabin top meets the deck in the area of the mast.

The survey did not determine a reason for the dishing. The surveyor looked but did not observe a compression post problem.

First, does deck dishing around the mast step indicate a serious problem?

If so, might hidden compression post problems exist that require disassembly for observation? What parts of mast removal and compression post disassembly require yard expertise and what can be done by a do-it-yourselfer? What $ values might be assigned to different repair scenarios?

Any light you can shed is greatly appreciated.

Jim Lavery

Save

1 - 13 of 13 Posts

jmolan

· #2 · Oct 5, 2009 (Edited)

Lavery, I would post this question over at Brion Toss's site.

SparTalk - Powered by vBulletin

There is a number of riggers and plenty of boat guys there who check in. Good bunch.

Jack

Save

lavery

Discussion Starter · #3 · Oct 5, 2009

Thank you Jack. I'll do it.

Save

scottyt

· #4 · Oct 5, 2009

lavery over at sailboatowners.com there are also some post replacement right ups there too. they may not be for your boat but they can still help

Save

lavery

Discussion Starter · #5 · Oct 5, 2009

Thank you Scottyt - I'll head over there right now.

Save

scottyt

· #6 · Oct 5, 2009

lavery said:
Thank you Scottyt - I'll head over there right now.

i just looked... if you do a search on compression post you will get 4 pages of results. it will cover all boat types.

Save

mitiempo

· #7 · Oct 5, 2009

It's not a rigging problem, but a structural problem. Whatever post/bulkhead or beam that is designed to support the mast in the Southern Cross is failing. Find out what method was used by investigation. Sometimes there is a block under the cabin sole and if wood it can rot over time allowing the post to sink slightly. Sometimes the beam under the cabin top will sag. When you know how it was designed and built you can plan for a fix. Until then you are just guessing.
Brian

Save

Stillraining

· #8 · Oct 5, 2009

mitiempo said:
It's not a rigging problem, but a structural problem. Whatever post/bulkhead or beam that is designed to support the mast in the Southern Cross is failing. Find out what method was used by investigation. Sometimes there is a block under the cabin sole and if wood it can rot over time allowing the post to sink slightly. Sometimes the beam under the cabin top will sag. When you know how it was designed and built you can plan for a fix. Until then you are just guessing.
Brian

Agreed..Its either in the deck core or the post top or post base or what the post sits on above the keel. It ain't rocket science figuring it out... that's not meant meanly by the way..

..just check all the options and you will find the culprit.

Save

mitiempo

· #9 · Oct 5, 2009

I tried to research how the mast is supported but got nowhere on the web. I did find an original brochure on the 28 http://www.msogphotosite.com/MSOG/pdfpage/southcross28bro.pdf , but doesn't mention the mast support.
Brian

Save

mitiempo

· #10 · Oct 5, 2009

Here's a drawing of the layout showing what looks like a vertical post just to port of the head. I do know that some of these hulls were sold for owner completion so your interior may not be the same. If it is I think either the deck is crushed under the mast or the post's support under the floorboards may have issues. But I don't think the post could move much without affecting the bulkhead/door arrangement. If it moved the door(s) would not fit properly.
Brian

See less See more

Save

lavery

Discussion Starter · #11 · Oct 6, 2009

mitiempo,
Cool. Drawing correctly locates mast support. Agreed: problem is structural. Good point about the doors and bulkheads. I need to recheck them more closely because no distortion points to cabin top core. The head door operated well during survey.

Your comments as well as Stillraining's about investigation v. guessing are well taken. What I get from this discussion is exactly a sense of how the hardware is put together, where the problem(s) may be, and that with enough investigation the problem(s) will reveal themselves.

I now feel ready to take it to the next stage, which is a hands-on look and estimate by someone qualified to do the work. Seems to me you have been around this kind of work. Would you venture a guess of cost range to repair should the problem be below cabin top (post/support beam). $5k-10k? $10k-20k?

Thanks for your help.

Save

Stillraining

· #12 · Oct 6, 2009 (Edited)

Do it yourself for a couple hundred...I just becided to pay the yard to do mine just because it was winter and I needed the yards building to strip and paint my masts so I was already in there and they don't rent it out for DIY stuff anyway..so I told them to go for it. But it is easy to do once the stick is out Thats about 1200 to 1500 out and back in...so you might have 1500 to 1800 into it .

Save

mitiempo

· #13 · Oct 6, 2009

I do all my own work except welding, so I'd estimate also about 200-300 for materials. You'll need epoxy, colloidal silica to thicken and 17oz biaxial cloth. It's not hard for a beginner to do if you research and plan it well. There is a great deal of info on the web on various blogs and The Plastic Classic Forum • Index page.
Brian

Save

1 - 13 of 13 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.

Compression Post Blues

lavery

jmolan

lavery

scottyt

lavery

scottyt

mitiempo

Stillraining

mitiempo

mitiempo

Attachments

lavery

Stillraining

mitiempo

Top Contributors this Month