Hi Ted,
Sorry about taking so long to get back to you, last night was one of those ‘doc has a glass-and-a-half of wine and falls asleep early’ nights. Sad, getting old. Or maybe the right word is ‘pathetic’…
In any event-
Cutting glass- you know, what I like to do is cut away most of it or score it well with something else before I attack it with the utility knife. 'Cos the glass plus hotcoat plus gloss is pretty hard stuff, and pushing hard to cut it always seems to lead to something ugly. So what I’d do is go at the cut with a veneer saw or something similar, cut 'til not quite through, then finish it with a knife.
Run this little guy against a straightedge, it’ll do the job for you.
They also make a tool for scoring plexiglass, that works well too. Either tool is under ten bucks at a good hardware store or tool place.
Uhmmm - normally, I’m prone to leaving things attached that are attached at all, but in this case I might make an exception , as there’s going to be a lot of work going on here and reglassing: the less in the way the better, especially if the fins are kinda marginally attached.
So sand away the glass and such at the bases of the fins and carefully take 'em off. I’d also take your sander and sand the sides of the fin low down ( once they’re off, that is ) so the extra glass and glass rope that were used to attach 'em goes away. It’ll make reattaching them cleanly a lot easier.
Oh, and use some cardboard or something to make a template of where the fins went and their angles and such. Then you can feel comfortable about being able to get 'em back in the right spot.
Replacing/extending the stringers…well, something occurred to me last night. Namely, why in hades would somebody have a strange-stringered blank like that made, or use it? Especially Hank Byzak, who is no dummy. Then light dawned over Marblehead:
Quick, inaccurate and dirty sketch, but hopefully it’ll make sense. The narrow swallowtails that were popular on twinnies like this was originally, well, what better way to do 'em but with the stringers going right to the tips. While a non-centerline vee-shaped stringer setup like this would suck from the point of view of laying out a roundtail or such from templates ( it’s not centered, it’s not paralell to the centerline) , it’d make a lot of sense for a narrow swallowtail.
Now…strengthwise, stringers don’t do diddly, so extending something from your practice blank piece into the old foam wouldn’t accomplish anything beyond making life difficult. And inletting the old stringers into one piece of new foam…y’know, I wouldn’t want to try that. Especially as they taper apart: to fine-fit the foam without adding great gobs of filler the new foam would wind up going further in, the taper cuts for the old stringers would have to get wider and globbed full of filler, train wreck.
But cutting along the existing stringers is easy, and adding onto them is too.
If you have, or have access to, a small tablesaw, you’re pretty well set. Just cut a couple of strips of wood that’s reasonably close in appearance, spruce or pine or something, that’s the same thickness. And that’s thin. It can be lots wider than the old one ( taller, that is) and stick up beyond the foam, you’ll be cutting it down when you shape the foam anyhow. It doesn’t have to be anything beautiful or perfect, just ‘good enough’.
Cut out the foam in the center, between the stringers, nice square cut at the end. Remove that.
Do a scarph joint in the new pieces or any cut at all, really, that gives you a fair amount of glue surface stringer-stringer, use those as your cut templates for the old ones ( a nice sharp utility knife should do it ) and stick it together with glue when it’s done, both sides. Stuff the new piece of foam in there to hold it in position while the glue dries ( use wax paper between new foam and glued stringers) , then glue up the center foam piece when the stringer extension glue has dried. Then, cut out the sides as needed - I might make a template for the cuts on those, then cut two identical pieces of foam, stick them in, cut outline and shape as needed, glass, reattach fins and there ya go -
Gawd, cobby drawing, isn’t it. But hopefully, it shows what I’m thinking about here.
The advantages are that it’s small jobs that are really not all that hard individually and it all proceeds in stages to bring back something like the original blank. Fitting the new foam very cleanly is relatively easy. It keeps most of the looks of the original too. I mean, why go frankenstein if you don’t have to.
See, I originally trained as a boat carpenter. That’s my real trade. And the cool thing about doing boat repairs is this; you have to understand the original construction, why they did it that way. Then, why does it have to be repaired? What went wrong with the original? Last, given the constraints of the tools and materials and skills you have access to, how to improve on the original construction so it does the repair and at the same time corrects what was wrong with the original system…'cos after all, it needed to be fixed, right?
This is kind of the same thing. Why was it done this way in the first place, what was right and wrong with the approach, how to fix it clean, as easy as possible so it does what it was meant to do originally.
Which is fun, ya know?
Hope that’s of some use
doc…
