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Does anyone know how the Mark II hull is constructed. I am wondering about stringers and the keel stub specifically. I can see 6 inch wide bands running across the hull through the bilge(2 or 3). Is the hull solid glass between the bottom of the bilge and the keel? Any help would be greatly appreciated.
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All 27 hulls are solid glass throughout. The bands you see in the bilge are most likely tows of Lyasil, which is a bundle of un-woven (hence straight) strands of glass. These would give the rigidity necessary to keep the keel from swinging from side to side. Normal glass cloth is woven, hence crimped. Under load, the fibres straighten along the load direction, which means the whole structure stretches in that direction. With time, the bond between the glass and the resin breaks down, weakening the layup. By using Lyasil, the designers minimize the movement of the keel and the stretching of the layup, ensuring longer life for the hull.
BTW, I'm guessing that they used Lyasil, but it seems a reasonable guess, because the stuff has been around since the beginning of time and all the C&C alumni whose work I'm familiar with used it in later work.
David Weatherston
Towser, Toronto
C&C 27 Mk IV
David Weatherston
Towser, Toronto
C&C 27 Mk IV
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Separation of the glass and resin occurs within the laminate and would not normally be reversible. Think of a single strand of glass that has been separated from the bonding resin - then multiply that strand by the hundreds of thousands or millions - fixing that simply isn't in the cards. The alternative is to build a laminate strong enough that very few of the glass fibres ever approach working load - minimal movement = minimal separation. And that's why overbuilt boats like ours just keep on going, while the built-to-safe-minimums boats like Mumm/Farr 30's and Farr 40's start getting soft after 5 to 10 years.
I don't know what evidence you have for thinking that the keel is moving, but before you start mucking about with the structure and the sole - which after all is part of the internal liner, which has a structural role of its own - that you speak with a naval architect who knows how C&C built boats. I suspect you risk opening Pandora's box.
David Weatherston
Towser, Toronto
C&C 27 Mk IV
David Weatherston
Towser, Toronto
C&C 27 Mk IV
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About 40% of the weight of your boat should be on the base of the cradle (in other words, the keel should be firmly grounded on the baseplate). So there's one possible explanation for your problem - the keel isn't moving in relation to the hull, but the hull is flexing because the boat isn't properly supported. If on the other hand, there really, the keel is moving in relation to the hull and the connection between them is so loose that can be initiated by hand, you have another problem. Both are serious.
Either way, I suggest that you stop thinking about your problem and call in someone with a greater depth of knowledge, who can inspect the boat and advise you how to proceed. I suggest you look for someone with a good reputation for a) fixing boats and b) (if it comes to this) telling people honestly when a problem is beyond fixing.
It may sound brutal to suggest that your boat is a write-off, but if you really do have a sow's ear, you don't want to be throwing money and time at it, trying to make it something else. Boats are unbelievably cheap right now as the overextended unload their toys in order to salvage what they can (like, their homes). If your boat is as badly damaged as you suggest, you may be better to cut your losses on a damaged boat and move on so you can enjoy sailing instead of spending summers with a roll of glass and a pot of resin.
David Weatherston
Towser, Toronto
C&C 27 Mk IV
PS Don't be too despairing if the boat turns out to be unrepairable. Parts like the keel (for its lead), the winches, engine, blocks and spars retain significant value.
Last edited by (2010-12-03 09:36:39)
David Weatherston
Towser, Toronto
C&C 27 Mk IV
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As to finding someone to help you diagnose your problems, why not ask here? Getting answers is what the Forum is for. Also, this is why you are asked for a home port or club in your profile, so that geographically sensitive questions can be intelligently answered.
How much of the galley sole is structural? I have no idea; that's why I suggested calling in a pro (but deal with the keel issue first). I will say that having looked over various boats under repair, the area in boats that is meant to be hidden is best left hidden. You think the sole isn't attractive? Wait until you see what's under it. Again, you risk opening a Pandora's box if you start chipping away at bits and pieces without understanding clearly what you are getting into and how to get out of it without compromising your sailing time and your boat's value.
The best solution to the bare-sole problem I've seen was aboard a Mk II whose owners had laid down a short length of oriental carpet. It looked nice and could be taken up any time the going got rough or when they wanted to clean it.
David Weatherston
Towser, Toronto
C&C 27 Mk IV
David Weatherston
Towser, Toronto
C&C 27 Mk IV
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I’ve seen many C&C 26’s & 27’s of all ages and have never seen one with a weak keel box area. Echoing what David indicated, you may find that the problem is not with a weak hull box area at all. The problem may be in the keel to hull joint which is serious but a less messy issue to resolve. My boat has the heavy “wide bands” you describe and David accurately explains. I’ve tugged on my keel when it was in the travel-hoist slings (while it was hung just above my trailer’s posts for obvious safety reasons) without any noticeable effect of hull flexing. Your description of the test for hull flexing and subsequent descriptions begs many more questions (including the point that David makes regarding why it sounds like your keel was “hanging” and not seated on the center base of the cradle) and we could go back and forth with questions and answers for a long time. But your questions and concerns are best answered by the personal inspection of a marine repair professional while it’s in the slings with proper safety measures. Hull flexing when the keel is pulled side to side from the bottom is a common problem among San Juan 24’s, 28’s, Ranger 28’s and many other makes and models including J-Boats. I was privileged to be given access when a local facility “stiffened” a San Juan 24 hull around the keel box area. (The “stiffer” hull made a remarkable difference in performance on Wednesday nights.) In this case the sole was cut away so the interior of the hull could be fully accessed. After the hull was “stiffened” using modern, high-tech materials, the sole was replaced by tabbing stringers on the interior hull which were also tabbed to the remaining interior pan so as to maintain the original structural integrity of the interior hull liner/pan. The stringers also added “stiffness” to the hull. A plywood teak & holly sole was fastened to the stringers and the whole repair was very nicely finished. Because the facility had done this before, they knew what they were doing and thus the cost was mitigated and considered to be modest. The owner liked the boat and felt the repair was a good investment long term. After the first few weeks of use, he was very happy with the result. If you don’t need to destroy the cabin sole portion of the hull pan, don’t. There are many solutions to an “unsightly” cabin sole without “replacing” it.
As already suggested, it’s best to talk with a repair facility that is familiar with, and has fixed the problem on other boats like the case referenced above rather than a run-of-the-mill fiberglass repair shop.
Scott Schoeler, MKIII, "Scot-Free"
[Scott is a marine surveyor with significant knowledge of boat construction. See http://www.c3marine.com/ . - Admin]
Last edited by (2010-12-05 13:45:03)
Scott Schoeler, Hull 858, "Scot-Free"
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