Compression Post Blues

[lavery]

Riggers,
I would like to discuss a possible mast compression problem. I’m looking for 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 for 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 parts 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
s/v Polar Bear

[Brion Toss]

Hello there,
The surveyor did not determine a reason for the dishing? Really? Was there some conjecture that it might have been built-in as a birdbath? This is never a good thing to see, and always, it seems, directly related to mast compression, or rather the failure of the support structure that is supposed to oppose that compression.
Sometimes the deck is cored under the step, and the core slowly compresses over time. This in turn leads to cracking, which leads to water intrusion, which leads to rotting core, sometimes across the entire deck.
In other cases there is a wooden spacer at the top of the compression post that rots or sags, and in still other cases the post itself might buckle or rot. And finally sometimes it is the failure of the step that the post is sitting on. Or some combination of some or all of the above.
Recommendations? First of all, feel free to have that surveyor contact me. If there is something that makes this genuinely puzzling, I'd sure like to hear about it. If, as seems more likely, the surveyor simply doesn't understand what is going on here, I will presume to offer my opinion for their consideration.
Some posts are easy to remove -- with the mast out, of course -- by dint of a screwjack or wedge arrangement. Others are driven into place, and must be driven out, perhaps with the aid of a hydraulic jack to ease pressure. It's the kind of thing you want to learn about by working on someone else's boat, so I recommend getting good help for this one.
Finally, if we discover that the surveyor was, um, ignorant on the step issue, it raises the question: what else did they miss?
Fair leads,
Brion Toss

[Rick M]

There are a number of things that could cause the dishing around the mast step, some have been mentioned and there are none I can think of would be good. The surveyors role on a condition and value survey is to find areas of concern and make recommendations. If there is an obvious reason for a finding, then the surveyor may recommend a specific cure. If the cause of the finding requires further investigation to determine (as in this instance), then the surveyor may and should recommend a qualified specialist investigate. Surveyors are generalists, if they were doctors they would be General Practioners, they can tell when something is wrong but may refer the patient to a specialist for diagnosis and treatment.

Rick Milner, AMS

[Douglas]

I agree with both Brion and Rick . Surveyors can be illusive ,,,, like , they say things in their reports,,,,,,,, such things as ,,,, "what I can't see , I can't inspect" ,,,, means that if they don't go up your mast,,,, nothing can be sure, up there,,,, ect .,,,,, or, sometimes they just say,,,,,, "we reccommend replacing,,,,,,,,,, (SS structural fittings),,,,,,, every 10 years, without inspecting any of them !

There is a problem, with that compression, that needs to be addressed,,, period , as it wasn't ment for it to be there !

Douglas

[JohnV]

I looked at 3 or 4 SC 31's in the past couple of years before I settled on my Alajuela 33. I recall seeing a couple of boats that had problems in the mast step. I had none of them surveyed.
One showed signs of leaking around the cabin ceiling below the step, another showed signs of an odd-looking repair. Fortuitously, the latter boat's owner had posted something online long before, to the effect that her mast was 'punching through her cabin top' or some such thing.
I looked at the bottom of the compression posts on all the boats and they appeared dry and sound. The post is integral with the head doorframe and reachable via a small hatch in the head or v-berth sole, if I remember right. I was left wondering if there was a common structural vulnerability in the cabin top.
Some suggestions--
There's an SC owners' group in USSail or Yahoo or one of those.
You probably know about the SC owners' website.
Clarke Ryder, the builder, also has a website and may be willing to offer some thoughts if you email him.
I thought the SC 31 was a great boat overall and would have been happy with one had the right one come along. Good luck in your search.
John V.

[lavery]

Thank you Brion, Rick, Douglas and John for your valuable comments.

Now that I know more, it is time to update this thread.

Brion,
I appreciate your comments regarding conjecture. The survey indicates that the cabin top, mast, and post "as accessible appear sound," then suggests that "the condition may have existed since manufacture." Then there is some rambling about how the forward rake when corrected may "relieves stress sufficient to allow a return to a fair shape."

On the other hand, when I delivered the boat to a good fiberglass guy in another town it took him about...oh...3 seconds to recognize the signs of rotten core in the cabin-top. Repairs are now underway.

By the way, I have a pdf file of the page of my survey that deals with the mast support area of the cabin-top if you are interested. Please tell me how to get it to you.

Rick,
Yes a specialist could have helped. The small Alaskan town in which I bought the boat had no fiberglass specialist. Besides, finding problems could kill the sale. This would be counterproductive for the surveyor and the used boat dealer who recommended him (that's my conjecture and I am sticking to it).

Douglas,
You are right on target. The surveyor did not go up the mast, did recommend replacing rigging on the basis of time-in-use, and did not raise any serious concerns around "areas not now visible."

John,
Yes my compression post appears sound. Also, the head door frame to which the compression post is attached is still square. If there is a common structural vulnerability in the cabin top, it might be as Brion suggests that over time the core collapses and ultimately cracks the fiberglass. A quirk of the SC31 mast support system is that the mast is not directly over the compression post, but is instead somewhat cantilevered. The original core was plywood. If the original engineering was sound, then consider the result of punching holes in the cabin-top for mast electricals and hardware, and leaving the boat out in the rain for 30 years without proper sealants.

All,
So I would leave you with the following 2 questions:

1.) Do I have any legal recourse in the case of a survey that really did not do the job?

2.) I pulled my chainplates and found some cracks. I have opted to replace all 8. Is 316 stainless steel the best material for chainplate duty, or should I call for a different specification?

Thank you for sharing your experience and expertise.

Jim Lavery
s/v Hoku Ke'a
Southern Cross 31

[Brion Toss]

Hello again,
Sounds like you now have a complete idea of what you need to address. I wouldn't recommend legal action; the deck is stacked in favor of all but the most heinous surveyors. Lovely little phrases like, "as accessible," and, "may have existed," are outs, even when, as in this case, any remotely competent person would see a dangerous situation. I don't expect surveyors to make definitive pronouncements without definitive evidence. I do expect surveyors to pay attention, to not be in the broker's pocket, and to communicate clearly and completely. It is a high calling, so perhaps it is no surprise that good surveyors are rare. Yes, surveyors are generalists, but even GP's will know appendicitis when they see it.
The worst thing from your quotes, to my mind, was that business about how, "... the forward rake when corrected may 'relieves stress sufficient to allow a return to a fair shape.'" So on the one hand everything is fine, and on the other a little change of rake will correct the step's collapse.
Did the surveyor have anything to say about chain plates? As for what to replace them with, consider titanium, which is now the same cost as stainless, or less, and cannot crevice corrode.
Finally, once you get that boat to a denser population area, see about finding a better surveyor to go over things with you.
Fair leads,
Brion Toss

[lavery]

Brion,
Thank you for your comments.

I agree that legal action would be futile. I'd rather put my energy into the boat.

Regarding chainplates on the survey, some chainplates were cited for evidence of leaks below decks. Recommended was "All shroud chainplates should have the cover plates and remnant caulking removed to examine the chainplate and deck materials beneath. Repair or replace as found necessary; and reseal."

I pulled all 8 chainplates and found a couple of small cracks. I also found a good deal of rust on the hidden faces of the leakiest chainplates. This exploration also yielded more mushy core. Repairs are underway here as well.

Titanium chainplates - what a concept! I like it. I'll check with my local fabricators for availability and expertise. Likely I will go with whatever is most expedient as my weather window for repairs is closing in.

Yes my intention is to head initially toward denser population areas. I'll stop in when I get to Port Townsend.

Jim Lavery
s/v Hoku Ke'a
Southern Cross 31