Just want to say thanks for all the helpful information. As far as the probox installations, I do it the same as you have shown except in the past I didn't make the holes in the foam with the fin key. On my last installation I angled the cut into the foam a little to make the bottom wider than the top, and I also added a glass patch over the bottom covering the last quarter or so of the board. I pack the boxes with flour and added wax in the grub holes over the screws, but may try something instead of the flour next time.
I'm using 1lb EPS for a couple of boards, so I'm going to add either wood or high density PU foam under the lamination and sink the boxes into that. In the past I've broken the side glassed on fins and have delaminated the glass under others so I guess I am pretty hard on the side fins.
Wanted to share a simple way of picking the right fin by looking at the machine base of the fin. The reason for the difference in lay-ups is overses companies can not foil a fin right by hand, so they CNC cut which is why they use a smaller oz class which the CNC cutter can cut. But neglct to tell you it's heavier and stiffer flex which effects the preformance of the fin.
Fin Structure from Overseas in Black and here by Larry Allison in clear. These 2 fins are same outline but come from 2 different location. The black fin is made up using a 4or 5 oz fiberglass (small square looking) weighing 12 ozs, the one by Larry Allison is made up using a 7 1/2 oz fiberglass (larger square looking) weighing 9 ozs. Not only is the weight different but so is the flex, the black overseas fin is stiffer flex lack of projection hard to turn. The Larry Allison flex has more twang with a "S" flex with good projection and easy to turn. Next time someone compares weight makes sure you are comparing apples to apples! Look at the base of your fiberglass fin next time and notice the square size which is the weave, small square is heavy and big square is light!
WHAT do you feel with be the next major breakthrough in fin design[s] , in the future ?
- See more at: http://www.swaylocks.com/forums/shapers-hotseat-larry-allison-aka-probox-larry?page=5#sthash.BMV5wwW5.dpuf
Answer : Ben the answer depends on what Industry you are referring to Surf Industry or Sup Industry. The Surf Industry has gone backwards where corporate companies are so busy trying to change the surf history to legitimize them selfs. The Sup Industry has part of that corporate makeup but also has a new cutting edge side pushing forward, which you can see in some of my Sup Fins designs, http://www.standupfinsbylarryallison.blogspot.com/
Larry do you have an online site where you show the different fin models you sell?
That's really interesting about how heavier cloth produces a better flex.
1) How many layers of 7.5 oz cloth do you use for your fins that go into a Probox box? (thrusters, quads, twins)
2) And how many layers of 7.5 oz do you use for your single fins?
3) Do you always use E cloth with polyester resin?
4) What do you think about the flex in all these honeycomb fins verses solid fiberglass?
There is so much hype, smoke, and mirrors out there on the subject of fin design - is there a website, book, or other source you can recommend for understanding different fin designs and how they affect performance?
"Everybody is ignorant only on different subjects." - Will Rogers
Agreed Huck, the basics of fin design are often repeated but is there a more definitive explanation of fin design available ? Larry would be the go to guy for this ?
Question for Larry or ?
If the 7.5 OZ lay-ups are lighter, and I am assuming that the claim is accurate and in fact comparing equal fiber/fabric ratio, does going with even heavier cloth extend this advantage?
I.E. does 10 OZ cloth offer and avantage over 7.5 OZ cloth in regard to weight or flex properties?
I'm assuming that at some point, it is a matter of diminishing returns due to the texture/3-D effect of the weave... like maybe 7.5 is the Goldilocks answer.