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CS27 Survey

Having nearly rebuilt a 1977 CS27 from the bare hull up, I have reached a point where I have a pretty good idea about what is and is not vulnerable.  I've often thought to myself that I'm certain I bought the correct boat design, but perhaps I may have bought the wrong implementation of that design.  by that, I mean to say Ravat needed far more sweat and finance than I ever intended to invest.  In an effort to install a silver lining in that cloud, I thought it would be useful to put together information for people considering a CS27 so that they would know what they were getting into.

The content of this page is not intended to be authoritative or complete.  It's just a holding tank for thoughts I have and things I have encountered.  I am not a certified marine surveyor, nor should this list be used as a substitute for a valued professional opinion.  I do believe it could be a very useful indicator of what boats are worth investing in a survey and which boats may be passed by.  It could also be useful to someone who already owns a CS27 and would like some ideas on how to improve their fine yacht.


Hole Potting

None of the deck piercings in the CS27 are properly potted.  Almost no stock boats are potted, which is why we have so many structural issues with old boats.  I believe the best procedure for doing this is documented by MainSail at his Compass Marine site.  There are two article you need to read and live by:
If you don't do this, assume your decks will rot and become structurally unsound.  I'm serious.

Gate Stanchion Backing Plates

With the exception of the gate stanchions, all the stanchion bases mount on the toe rail completely.  This is an excellent load distributor.  In contrast, the gate stanchions extend into the fiberglass.  If the deck core gets wet, it can soften where the inner bolts pierce the deck and eventually fail to support the load and allow the upper laminate to crack.  This leads to a total side-deck replacement.  You don't want that.

The solution is to make sure all the deck holes are properly potted, and to add a nice backing plate to the stanchion bases.  Ideally while you are at it, add plates to all of the stanchion bases.  But at a minimum make sure you add them to the gate stanchions.

I made mine from structural pre-fab 1/4" fiberglass sheets bedded in epoxy thickened with colloidal silica.  I think 1/4" aluminum would be better, but all I could find at convenient locations was 1/8" stock, so I used fiberglass instead.  It was a beast to cut that stuff, but I guess that's a good sign of its strength.

Chainplate Openings

The cut-outs in the deck where the chain plates to through are much larger than they need to be.  As a result, the sealant is being asked to do much more work than is necessary.  As with the other holes, this is not potted and needs to be.  Use the standard Don Casey technique and gut out out, but we'll fill it a bit differently.

Load up a syringe with epoxy thickened just enough not to sag much.  That means you can suck it into the syringe, but just barely.  Now grease or wax the chainplates and loosely install them with screws.  Now, using the syringe, inject the thickened epoxy up into the gap from the cabin interior.  You should be filling approximately 1/8" of gap through the 1" deep deck.

The Don Casey cast-island method will not work with the CS standard chainplates, unfortunately, so make sure you pot the hole well, and watch the interior for leaks to catch them early.  Alternatiely, re-bed those plates eavery few years proactively.