I read once about setting glass on fins in a groove that was routed into the bottom of the board. I think it was Greg Griffin that described it… Anybody have the details on this? Steps, how-to, etc?
I want to do glass-on bamboo fins in this way on one of my upcoming builds.
Extend the base to sink it to the deck .
Mine were about 1/4" narrower for the base to sit on the bottom .
Scrape the foam off inside the slot on the deck for contact and add a patch to the bottom in the fin area
Fin needs to be made stiff since no aditional glass is being added like a glass on .
Thanks Greg!
Ok, I think I get it.
The router bit would need to be about 1/4 and kinda long right?
I’ve done a couple after used a slightly larger bit to allow space for resin around the fin fairly shallow cut then carve foam out by hand to allow for cant. Made the fins oversize test fit and cut to suit. They are tied to the deck
skin so very strong. The ones I’ve
done are in 1lb eps a bonzer
centre and a twiny used and
abused for over a year. Also scored under the glass around the slot. Inspired by one of Greg posts on the other forum. And a strong dislike of sanding 
hahaha, yep that’s me too Tom
thanks for the tips
I’ve got more time than common sense, so I often find the hard way to do simple things.
I’ve done several rout-in installs (I like them a lot), but I use HD PU inserts that I set into the blank prior to shaping. I usually run them from bottom to deck. I use Gorilla Glue to set them because it’s easier to shape than epoxy glue lines that usually also saturate the surrounding foam.
Shape, glass and finish as normal and rout the slots (w/cant) as the last step. I run the bases of my fins deep enough to have some hold but I don’t attempt to tie them directly to the deck. Usually 1" or more on the bases, depending on how much depth I have at that area of the core. Most of them I’ve done I’ve run full-length bases, but on the last one I did I cut 1/4" notches so that the leading and trailing edges of the fin sat on top of the deck instead of going all the way through it. I found it easier and less work to finish the area around the base that way. Greg Griffen had mentioned that before and I aspire to pay attention when the experts give advice.
The fins are completely finished when I install them, and I don’t use roving or patches around the base. I use the head of a screw to roll a slot into the foam under the skin around the perimeter of the slot so as to fill it with resin when I set the fin. Epoxy with slow hardener, of course. I usually wrap the bottom half of the fin tab itself with fiberglass cloth, cutting it short so as to avoid any strands near the skin. On my next one I may try veil instead, to get the extra adhesion.
The next time I do one I’m also planning on skipping the extension of the insert from bottom>> deck plug because I think that might be overkill, and it’s kinda ugly anyway. Instead, I’m going to try routing 1" deep on the plug instead of all the way through, and face the core-side of the plug with a couple layers of cured fiberglass before gluing it into the blank. After shaping, I reckon that layer of fiberglass will be about 3/4" deeper than the skin, so that when I rout through it for the fin base I’ll get a secondary point of stabilization. In theory.
Rout in HD plugs may not be any lighter than a finbox install but they feel really solid upon completion. I think they’re a killer application for setting glass-ons into any bottom with heavy contours, like bonzer runners or channel bottoms or Mc-Coy’s dome bottoms. You finish the bottom as normal without having to work around any fins and do the fin install last. Plus, there’s no danger of sanding into the exterior skin around the fin, and you retain the original shape of the board.
The reason I like the HD foam insert for the rout-in install goes back to what Larry Allison mentioned one time when we were talking about it: he believes that most fin install failures are due to the failure of the surrounding foam, not the skin or the box (or plug or glass-on). The lighter density foams simply flex more, which in turn stresses the box or plug, or otherwise delams the surrounding fiberglass. I don’t do FCS plugs but if I did I’d want to insert them into oversized HD plugs the way Josh Dowling does with his paulownia bottoms.
I’m still trying to think my way through this so if anyone has any tips or pointers to add I’m definitely eager to learn more.
Amen to that. What great resources we have yah?
Thanks for the tips GDaddy… I’m looking forward to trying this!