Thanks Sharkcountry, I’ll figure out how to find that thread. Just the sort of feedback i was looking for. i wonder if Robin has posted some sort of basic formulaic chart like McKees. i beleive that Robin has stated that he has particular fins in mind when designing a board, and that by placing the fins out closer to the rails less fin base or less fin is needed to create the same amount of hold, minimizing drag. moving them closer together would loosen them up, unless you get them too close, or at least thats my understanding.
ps. sick looking fins
pps here’s Sharkcountrys thread with great info and diagram
That diagram comes from Robin “Handshaper” Mair - If you go back and read what he wrote, maybe it was on a thread linked in this thread, he spells it out:
The placements are on the diagram above - one of the most important things I learned from Robin is the fore/aft spread of the fins should be from 7/8"-1 3/8". I can really feel the drag set in once the spread is over 1 1/2".
The “secret” may be in what Robin wrote about fin area and template - the aspect I’ve been thinking about is having the lest amount of fin area without loosing drive, and how the back fin provides more of the “pivot” - I’ve been digging less/no rake on the rears.
The other thing I’ve thought about a lot is a thread, I think it was the Greg G. fin template thread, where one of the fin guys said something to the effect, “No board decelerates like a three fin.” This one has really made me wonder what people do to get the speed of an edge finned quad under control the way one can dump speed on a quad - without sacrificing the top end speed available on the quad…
Just want to add that the diagram was for the fins I show above on a 6-4 to 6-6. There may be issues for more traditional fins. I used the same setup on my 5-10 with different fins and I liked it. But I only had that board in the water twice.
Be sure to notice that the tow is different for front and back. Robin has a 1/8" difference in the triangulation. He also had me go with more can’t on the front fins, 6 degrees up front and 4 degrees in back. I can add more can’t to loosen the board up, or go the other way.
If you like this setup please thank Robin Mair, it’s all from him. Maybe you can buy a set of his fins and boxes. Proboxes are great boxes.
Now for a warning… Beware that you may be building yourself a crazy wild ass great board that will out surf you (if you’re over 50 and outta shape like me). I had such a great time riding my board that I got all nuts and surfed harder than I had in years. After 3 solid sessions and then 2 days of working around the house my back was a mess and I could hardly walk. Don’t know if I twisted my back surfing or did something in the backyard. That was 2 weeks ago and I’m still not OK. Missing a lot of good surf.
TaylorO what do you mean? “The placements are on the diagram above - one of the most important
things I learned from Robin is the fore/aft spread of the fins should be
from 7/8”-1 3/8". I can really feel the drag set in once the spread is
over 1 1/2". "
where are you measuring fore and aft? sorry to be dim.
I think he means the space between the front and rear fins or fin boxes.
My front fins tilt back more than traditional fins, so they seem to be closer from edge to edge, but the front of each fin’s base is where his numbers are. My fins actually overlap a little. 16’ to the front of the front fin’s base, and 11" to the front of the rear fin’s base.
Now there’s another thing to be aware of. Set the back mark for the rear fin 1" from the rail. If you have a lot of curve in the outline of your tail, your rear fin will be further in towards the center than if you have a straighter outline. I saw this on his eggs, but he said the important thing was to keep the back of the fin 1" from the rail.
What I did was draw a line for the front marks at 16" and 11", then I drew a triangle using 4 1/8" with 1/8" of tow for the front fins, and 4" with 1/8" of tow for the rear. Just line up the back of the triangle at 1" from the rail.
You can probably go with the tow you like and all that, but I wanted to try to be as close to what he recommended for those fins. I could be off on my calculations, but I’m not complaining. The boards are working, just have to get my body working again.
Greg - The main point to me is the distance between the trailing edge of the front fin and the leading edge of the rear fin, measured at the bases… That distance fore and aft - say, measured along a line parallel to the stringer (not the litteral distance between the fins bases) should fit those numbers…@ 1"-1 3/8" +/- 1/8". It’s hard to tell from the diagram, as Robin uses the leading edge to set the front fin. This is based off his knowledge of where he wants the fin action to start, coupled with his knowledge of the fins he will be using. I’ve basterdized the concept by working with the spred, but I still set my front fins from the trailing edge 'cuz that’s what I’m use to. As you can see, the spread is just one piece, but it’s the one that I noticed the most difference from experimenting with…
