Jeff, You may have missed a couple of my points. Let me clarify...
coats I suggested were: (3 on and one or two sanded off, twice). It ends up with minimal unburried glass spots, and about 2 coats over the just barely burred glass job. It gives more consistent results, because if epoxy
is sanded lightly, but not first leveled, then due to an "orange peel" surface from the epoxy roller, one is only sanding
the hills, while the valleys, (= 50 +%) remain un-prepped.
Remember... Epoxy gets "0" chemical bond, and ONLY the tooth from being completely glazed over makes it work. I have done peel experiments with strong glass to confirm this... For the most part, the 50% sanding
job, (resulting in a 50% bond), that most builders do, seldom falls apart, but future failure could be reduced in likelihood to ZERO, by sanding surfaces totally flat, before the next process, (IF its beyond the chemical bond window).. That's why I put on 2 or 3 coats ON THE DAY I GLASSED IT, 45 minutes apart. Then sand perfectly smooth the next day, almost exposing the glass, but not quite. Now the glass is filled, totally flat & glazed over, and has NO topcoats beyond that. To give a cushion for future paint
job required standings, future glass tape feathering, etc... I put on 3 more coats that second day, 45 minutes apart. On the third day, I sand again, removing one of the 3 coats. Then I have basically 2 additional top coats, but over a previously filled and flat glass job.
The additional glass I recommended on the CB, its trunk, and the rudder
/ skeg, are a small area only, and in order to avoid problems here, which Searunners are VERY prone too. I'd say that over half of the one offs with centerboards have had problems with them or their trunks, after 30 years. If they'd do as I suggested, then having a CB starts to be maintenance
tolerable, and the advantages win out. Most boats with problems here have owners that don't know, until its been getting wet in there for many years! Then they try to remove the board, but can't, because its swelled.
Climate makes no huge difference regarding structural failures, btw... its impacts, stresses, and the decades of time, that do these areas in. With paint
, yes for sure, the tropics is brutal. Our boat
has held up better in the tropics though...
The same extra glassing with bias tapes, btw... actually applies to all of the radii, chines, and seams... Its the impacts, point stresses, and time, (more than anything), that does these areas in too.
It was John Marples who first pointed out to me how we all need additional glass on these areas, and this was from the feedback to him of hundreds of boat
owners, over decades...
By far, the wing tunnel's, mid, longitudinal seam, is the most vulnerable. This hard spot, has the panel on each side flexing when pounded, and it hinges here!!!
My new engine
location, runners moved forward, fewer winches, sailing as a sloop
, 4' taller rig, and switching to "dry" wing locker hatches, were also all John's ideas. They were all great ideas...
While the UVs in the tropics is harder on the rig, epoxy and paint, (making opaque primer more important), in higher latitudes, the puddles of water
on the low end of every single
stringer, (from condensation), becomes a primary issue. Most rot
of these boats, is from fresh water condensation
. It can collect a few spoonfuls, on each of say... 50 hard to reach places, OVER ONE NIGHT. This is why really good epoxy jobs on the interior
is so important, and why CC hulls, (with fewer frames and no stringers), are so much less vulnerable. They can be more completely sealed, are easier to wipe and paint, and have fewer moisture traps. As a slight improvement, my SC 28 had stringers with horizontal top surfaces, which prevented pooling, and helped solve the problem. I believe that Roy put huge fillets on the top of his, for the same reason.
Another thing with cold climates... If it freezes, it is really hard on hatches, as well as nooks and crannies that can contain water. The expanding Ice can wreck havoc.
I did try Systems Three's water based LP in the cockpit's sub floor. I had done year long experiments first, and knew it had poorer UV resistance than AwlGrip, but this area was totally out of the Sun. It has one big advantage! Unlike regular LPs, (that get little blisters
if water pools on it for months), The flat looking Systems Three stuff is HARD, tough, and impervious to blisters
. It is now 18 years later, always wet in there, and gets fuel
all over it. STILL PERFECT. I'm hoping better products come out soon. I understand that a new AwlGrip product, (not AwlCraft). is on the drawing board. It is supposed to be as tough, but more repairable.