Congrats on the nused boat 'dog....Fo' Shizzle! Here's my cursory assessment:
The "cheesy" cracks look like common gelcoat stress cracks. As long as there's no softness indicating delamination, I'd forget 'em. (If needed, search http://www.hobiecat.com/community/index.php?c=2 and http://www.catsailor.com/forums/ubbthreads.php?Cat=0 for an explanation of and fixes for delamination.)
The good news regarding the damage where the rudder pin goes through the deck just above the transom: That hole through the deck (~1/2" dia.) was simply there for the pin (3/8 " dia.) to pass through. The deck itself is not involved in holding the rudder assembly on (only the gudgeons are....see below), and that hole should not be bushed. There is actually no need to restore the deck back the way it was (other than looks). You do need to seal it up to prevent water from getting in the laminate, though. Get rid of the loose stuff and seal with epoxy or polyester. Again, you can search the forums cited above for info on using these materials. I use epoxy simply because I got familiar and quite handy with it before I ever knew the difference.
The bad news regarding the damage where the rudder pin goes through the deck just above the transom: It wasn't caused by lack of a bushing; most likely a gudgeon failure (TRAUMA!). The gudgeons are the little bracket things that are screwed into the transom and, along with the rudder pin, hold the steering assembly to the boat. All four of these need to be checked carefully for stripped threads, cracks, etc. If they are stock, they are fastened with #12 stainless screws (hard to find locally!) that go into a threaded aluminum plate that's glassed into the transom on the inside of the hull. If you use my imagination (not sure about yours), you can see the plate here:
http://www.thebeachcats.c…pictures&g2_itemId=10745
Because of dissimilar metal corrosion, the SS screws are sometimes fused to the aluminum plate. Be careful about shearing them. Being a machinist, that may not bother you, but it's a nightmare for us mere mortals. If necessary, the holes can be easily tapped to 1/4", and it's easy to obtain 1/4" SS screws. The gudgeons originally had an aluminum insert/bushing thing where the rudder pin goes through, but yours are probably badly worn or missing. If it was me, I'd just replace any gudgeons that look suspect. If nothing else, take 'em off, inspect them, seal the screw holes (silicone or 3M Marine 5200), put something on the screws to inhibit corrosion, and put 'em back in. Reseal the drain plug housing too.....the transom fittings are a common cause of leaky boats.
Be careful about bushing the rudder castings too tight. (A little slop isn't going to affect performance.) In my opinion, none of these components were built to very tight Q/C tolerannces. If you bush every hole and/or shim the rudder blades too tightly, you'll never be able to reassemble it or it will bind badly and the rudder won't kick up properly.....which causes...that's right...transom damage! For good info on rudder kick-up/adjustment, search the above cited forums for "rudder cams".
One last piece of advice: It's a $600 boat....spend as little time working on it as possible and as much time sailing on it as possible!
Hope this helps...good luck....let us know how it goes!
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Jerome Vaughan
Hobie 16
Clinton, Mississippi
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