I am finally making the foray into foam fins (to minimize weight) and I was wondering how many layers of 4 oz. I need to lay up in order to have some durability but still be ultra light. Also interested in any potential pitfalls. Thanks, Magoo P.S. Herb, I’m unable to post responses right now because of a password problem (I forgot it – duhhhhh). Just wanted to tell you that I am very happy for you and the family. It is hard to find the right person to share a lifetime with – the key of course is to compromise. Your two beautiful daughters are very lucky to have you two as parents. Good luck to you and your family. I think it is fairly evident that your virtual brothers at Swaylocks are all pulling for you guys . Peace, Magoo
I am finally making the foray into foam fins (to minimize weight) and I > was wondering how many layers of 4 oz. I need to lay up in order to have > some durability but still be ultra light. Also interested in any potential > pitfalls. Thanks, Magoo>>> P.S.>>> Herb, I’m unable to post responses right now because of a password problem > (I forgot it – duhhhhh). Just wanted to tell you that I am very happy for > you and the family. It is hard to find the right person to share a > lifetime with – the key of course is to compromise. Your two beautiful > daughters are very lucky to have you two as parents. Good luck to you and > your family. I think it is fairly evident that your virtual brothers at > Swaylocks are all pulling for you guys .>>> Peace,>>> Magoo Hi Magoo, First cut your template/ templates out of foam; choose one that is your favorite. By the way what kind of foam are you going to use? The number of initial layers in the lay up will be dictated by the fin depth and template size – the bigger the more layers of glass of course on the flat side or in the spine of the fin accordingly. But just as a general rule: Symmetrical fins get the same number of layers in the spine and the depth measurement of the fin in inches. Asymmetrical fins get 2/3 the number of layers as depth. If it’s gonna be a box fin include the tab that will be at the base of the fin in the cutout if you use the same glass weigh I’m using. I use 6 oz & 5.7oz carbon fiber every other layer in epoxy for my initial lay-up with the glass on top for the flat side of asymmetrical fins and glass on the outside of the sandwich for the spine between two layers of 1/8" high density foam for symmetrical fins. You need enough material in your work to have a substantial leading and trailing edge. The project can be done with polyester sanding resin just go with 30% more thickness in the middle cause It’s not as flexible and strong as epoxy. After this is cured good and hard, sometimes a couple of days depending on weather conditions if you use epoxy, you can do a rough foil and build the shell around it of 3 to 5 layers of 4 oz depending on the depth of the fin with a few extra pieces in the bottom half of the forward part of the foil to add strength where the fin gets the most torque stress. I can give you more details but I don’t want to pile too much on at once. As to pit falls – It’s a labor-intensive process, but well worth the effort in my opinion; they should float when you’re done. The results add performance by reducing weight. All other things being equal, if you have the cosmetic end of things under control, they’ll add a touch of class to a well-shaped stick also. Better Surfing, Rich
Hi Magoo,>>> First cut your template/ templates out of foam; choose one that is your > favorite.>>> By the way what kind of foam are you going to use?>>> The number of initial layers in the lay up will be dictated by the fin > depth and template size – the bigger the more layers of glass of course > on the flat side or in the spine of the fin accordingly. But just as a > general rule: Symmetrical fins get the same number of layers in the spine > and the depth measurement of the fin in inches. Asymmetrical fins get 2/3 > the number of layers as depth. If it’s gonna be a box fin include the tab > that will be at the base of the fin in the cutout if you use the same > glass weigh I’m using. I use 6 oz & 5.7oz carbon fiber every other > layer in epoxy for my initial lay-up with the glass on top for the flat > side of asymmetrical fins and glass on the outside of the sandwich for the > spine between two layers of 1/8" high density foam for symmetrical > fins. You need enough material in your work to have a substantial leading > and trailing edge. The project can be done with polyester sanding resin > just go with 30% more thickness in the middle cause It’s not as flexible > and strong as epoxy. After this is cured good and hard, sometimes a couple > of days depending on weather conditions if you use epoxy, you can do a > rough foil and build the shell around it of 3 to 5 layers of 4 oz > depending on the depth of the fin with a few extra pieces in the bottom > half of the forward part of the foil to add strength where the fin gets > the most torque stress. I can give you more details but I don’t want to > pile too much on at once. As to pit falls – It’s a labor-intensive > process, but well worth the effort in my opinion; they should float when > you’re done. The results add performance by reducing weight. All other > things being equal, if you have the cosmetic end of things under control, > they’ll add a touch of class to a well-shaped stick also.>>> Better Surfing, Rich Thanks Rich, I appreciate the detailed response. You always come through! I am using regular poly foam and resin – I haven’t ventured into the epoxy realm as of yet. Are you identifing the Spine as the leading or trailing edge? I am thinking about laying a narrow bead of fin rope and resin around the leading edges to help in the foil (and I think that it will work aesthetically). However I have the foam already foiled thinking that would lead to less layers and less weight. Is this going to cause some durability issues? I remember reading that three layers of 4 oz.is stronger than two layers of 6 oz. Would you be able to confirm that? I am making your basic thruster glass ons - no box. In looking at Pauls work and his discussion points in the past I am wondering how an extreamly thicker leading edge would affect the characteristics of your basic 6’9" thruster(How’s THAT for a run-on sentence?). Follow-up on the Star Fin: Still working on the test chamber. Right now it is a circular (donut) tank with a view window at the fin point of entry. I have been testing different pumps looking for a minimum of turbulence and maximum of thrust (minimum cost is always an issue of course). So far the large fins work best with the angles you recommended. I am testing the small canards with one angle and two angles. Real surf has been limited while I have been in town so I have limited results recorded at this time. Ahhh, the perils of working in the transportation industry with the Teamsters… I will let you know of any epiphanies as well as failures as they come along. Final note: The cosmetic end is always a challenge for me. If I had the gift that Jim, Herb, Gene, CDB, Noodle, Ramon (Hermano Cubano), Tom S, You and the rest of the gang I would be blessed. As it is I muddle through and hopefully get better as I go along. Thanks for all the insight. Magoo
Thanks Rich,>>> I appreciate the detailed response. You always come through! (((find me here)))>>> I am using regular poly foam and resin – I haven’t ventured into the > epoxy realm as of yet. ((((You gonna have to make some perfectly flat pieces of foam))>>> Are you identifing the Spine as the leading or trailing edge? (((The spine runs clear through the center of the fin. It’s the only way to give it any strength.)))>>> I am thinking about laying a narrow bead of fin rope and resin around the > leading edges to help in the foil (and I think that it will work > aesthetically). However I have the foam already foiled thinking that would > lead to less layers and less weight. Is this going to cause some > durability issues? (((Forget the fin rope you don’t need it the spin provide with the shell over it provides the leading and trailing edge strenght.)))>>> I remember reading that three layers of 4 oz.is stronger than two layers > of 6 oz. Would you be able to confirm that? ((That’s true I’m sure.))>>> I am making your basic thruster glass ons - no box. In looking at Pauls > work and his discussion points in the past I am wondering how an extreamly > thicker leading edge would affect the characteristics of your basic > 6’9" thruster(How’s THAT for a run-on sentence?). (((How you foil the fin is critical. Do some studying on aqualocomotion on the net and you get some good ideas about foiling. Then just try something you think will work.)))>>> Follow-up on the Star Fin:>>> Still working on the test chamber. Right now it is a circular (donut) tank > with a view window at the fin point of entry. I have been testing > different pumps looking for a minimum of turbulence and maximum of thrust > (minimum cost is always an issue of course).>>> So far the large fins work best with the angles you recommended. (((Were these angle the completely neutral 120 degrees between each fin surface?))) I am > testing the small canards with one angle and two angles. Real surf has > been limited while I have been in town so I have limited results recorded > at this time. Ahhh, the perils of working in the transportation industry > with the Teamsters… I will let you know of any epiphanies as well as > failures as they come along. (((and many to follow in both realm to be sure))>>> Final note:>>> The cosmetic end is always a challenge for me. If I had the gift that Jim, > Herb, Gene, CDB, Noodle, Ramon (Hermano Cubano), Tom S, You and the rest > of the gang I would be blessed. As it is I muddle through and hopefully > get better as I go along.>>> Thanks for all the insight.>>> Magoo (((Carry on, Rich)))