I was looking over the posts and noticed many about epoxy. Perhaps someone with more knowledge than I could point out what is wrong with the following reasoning: I use epoxy for boats, canoes, and wood surfboards. I do so not because of strenght, but for weight and brittlness. I can use the same amount of cloth with epoxy and get a lighter laminate that seems to be more lively. For foam surfboards I only use epoxy for large longboards where weight is an issue(old weak guys such as myself) and for shortboards where performance is an issue and money is not. Generally, I don’t use epoxy for an average board because of the price. It is about twice that of polyester but only provides a small increase in strenght - not enough to make a difference to a board put into the wrong spot on a wave. I apologize for taking up space if I have missed a post that addressess my type of reasoning. Thanks Patrick
Patrick, You need to catch up on epoxy prices. Now they’re only 5% to 15% higher than polyester resin prices, but you have to look. Try http://www.surfsource.net and choose “Manufacturers”. In boat repair and construction epoxy has more advantages than strength. Epoxy bonds better than any other resin known, and you can use it under water. I think your perception of epoxy surfboard strength is too low, but I can’t prove it. There are too many variables, age vs flex, breakability vs weight, hardness, etc. One of the best epoxy properties is the ability to use it with EPS foam. EPS doesn’t crush or delam under your deck dents nearly as badly as polyurethane foam. Yes, epoxy is stronger, but you unknowingly included the biggest evidence of epoxy strength in your statement. Epoxy is much lighter. That means you can use more glass for the same weight. And glass is way stronger than any resin. It’s tough to quantify strength increases in eopxy laminated surfboards, worn over time. But I can tell you that you can use epoxy to yield a way stronger surfboard than the 10% extra you spend on resin. But with epoxy you can choose whether to have a much lighter board with standard strength, a much stronger board with standard weight, or a board that’s a little lighter and a little stronger. Your choice. A person needs to use an epoxy/EPS board for a while to see and feel the advantages. But if you’re gonna build one don’t leave out the stringer(s). Stringers are needed for strength and flex, just like in poly boards.
Noodle, I want to build a 10’ longboard with epoxy and 2 pound EPS. I will be using a hotwire and glueing up a stringer. What do you recommend for stringer material and dimensions? Thanks, Gary
Gary, I’d use a 5/16" basswood stringer for easy shaping, or 5/16" spruce stringer for strength. You didn’t say what kinda surf you’re hunting, how much meat you wanna hang on it, or how you want it to float! I’ll take a stab at it and say average on everything… 4" square stern x 15"t x 24" x 18.5"n, wide point offset 3" forward of center, 3.7" tail rocker with moderate progression, and 4.9" nose rocker. Center foam 3.2" thick. Rail line .9" above bottom foam. .9" bottom roll, and moderate deck crown. I’ll throw in a deck template matrix for hot-wiring. It only gives you .1" extra foam thickness to shave: The rocker reference line is a bottom center tangent, stern=0. The rail reference line bisects the cross section at the rail line, stringer=0. Rocker template: Length , Outline , Rocker , Deck 0 , 0.00 , 3.70 , 4.89 0 , 2.00 , 3.70 , 4.89 0.5 , 2.54 , 3.61 , 4.87 1 , 2.98 , 3.52 , 4.84 2 , 3.69 , 3.35 , 4.78 3 , 4.28 , 3.19 , 4.73 4 , 4.79 , 3.05 , 4.68 5 , 5.23 , 2.90 , 4.63 6 , 5.64 , 2.77 , 4.58 7 , 6.01 , 2.64 , 4.53 8 , 6.35 , 2.52 , 4.49 9 , 6.67 , 2.40 , 4.44 10 , 6.96 , 2.29 , 4.40 11 , 7.24 , 2.18 , 4.35 12 , 7.50 , 2.07 , 4.31 13 , 7.75 , 1.97 , 4.27 14 , 7.98 , 1.88 , 4.23 15 , 8.20 , 1.79 , 4.19 16 , 8.41 , 1.70 , 4.15 17 , 8.61 , 1.61 , 4.11 18 , 8.80 , 1.53 , 4.08 19 , 8.98 , 1.45 , 4.04 20 , 9.16 , 1.37 , 4.01 21 , 9.32 , 1.30 , 3.97 22 , 9.48 , 1.23 , 3.94 23 , 9.63 , 1.16 , 3.91 24 , 9.77 , 1.09 , 3.88 25 , 9.91 , 1.03 , 3.85 26 , 10.04 , 0.96 , 3.82 27 , 10.17 , 0.90 , 3.79 28 , 10.29 , 0.85 , 3.76 29 , 10.40 , 0.79 , 3.74 30 , 10.51 , 0.74 , 3.71 31 , 10.62 , 0.69 , 3.68 32 , 10.71 , 0.64 , 3.66 33 , 10.81 , 0.59 , 3.64 34 , 10.90 , 0.55 , 3.61 35 , 10.99 , 0.51 , 3.59 36 , 11.07 , 0.47 , 3.57 37 , 11.15 , 0.43 , 3.55 38 , 11.22 , 0.39 , 3.53 39 , 11.29 , 0.35 , 3.51 40 , 11.35 , 0.32 , 3.49 41 , 11.42 , 0.29 , 3.48 42 , 11.47 , 0.26 , 3.46 43 , 11.53 , 0.23 , 3.44 44 , 11.58 , 0.20 , 3.43 45 , 11.63 , 0.18 , 3.42 46 , 11.67 , 0.16 , 3.40 47 , 11.71 , 0.13 , 3.39 48 , 11.75 , 0.11 , 3.38 49 , 11.79 , 0.10 , 3.37 50 , 11.82 , 0.08 , 3.36 51 , 11.85 , 0.06 , 3.35 52 , 11.88 , 0.05 , 3.34 53 , 11.90 , 0.04 , 3.33 54 , 11.92 , 0.03 , 3.32 55 , 11.94 , 0.02 , 3.32 56 , 11.95 , 0.01 , 3.31 57 , 11.97 , 0.01 , 3.31 58 , 11.98 , 0.00 , 3.30 59 , 11.99 , 0.00 , 3.30 60 , 11.99 , 0.00 , 3.30 61 , 12.00 , 0.00 , 3.30 62 , 12.00 , 0.00 , 3.30 63 , 12.00 , 0.01 , 3.30 64 , 12.00 , 0.01 , 3.30 65 , 12.00 , 0.02 , 3.30 66 , 12.00 , 0.03 , 3.30 67 , 12.00 , 0.04 , 3.31 68 , 12.00 , 0.05 , 3.31 69 , 12.00 , 0.07 , 3.32 70 , 12.00 , 0.08 , 3.32 71 , 12.00 , 0.10 , 3.33 72 , 12.00 , 0.12 , 3.34 73 , 11.99 , 0.14 , 3.35 74 , 11.99 , 0.16 , 3.36 75 , 11.99 , 0.19 , 3.37 76 , 11.98 , 0.21 , 3.38 77 , 11.98 , 0.24 , 3.39 78 , 11.97 , 0.27 , 3.41 79 , 11.96 , 0.30 , 3.42 80 , 11.95 , 0.34 , 3.44 81 , 11.94 , 0.37 , 3.46 82 , 11.92 , 0.41 , 3.47 83 , 11.90 , 0.45 , 3.49 84 , 11.88 , 0.49 , 3.52 85 , 11.86 , 0.54 , 3.54 86 , 11.83 , 0.58 , 3.56 87 , 11.80 , 0.63 , 3.59 88 , 11.76 , 0.68 , 3.61 89 , 11.72 , 0.73 , 3.64 90 , 11.68 , 0.79 , 3.67 91 , 11.62 , 0.85 , 3.70 92 , 11.57 , 0.91 , 3.73 93 , 11.50 , 0.97 , 3.76 94 , 11.43 , 1.04 , 3.80 95 , 11.35 , 1.11 , 3.84 96 , 11.27 , 1.18 , 3.87 97 , 11.17 , 1.25 , 3.92 98 , 11.07 , 1.33 , 3.96 99 , 10.95 , 1.42 , 4.00 100 , 10.82 , 1.50 , 4.05 101 , 10.68 , 1.59 , 4.10 102 , 10.53 , 1.68 , 4.15 103 , 10.36 , 1.78 , 4.21 104 , 10.18 , 1.89 , 4.26 105 , 9.98 , 1.99 , 4.32 106 , 9.76 , 2.11 , 4.39 107 , 9.51 , 2.23 , 4.45 108 , 9.25 , 2.35 , 4.53 109 , 8.96 , 2.48 , 4.60 110 , 8.64 , 2.62 , 4.68 111 , 8.28 , 2.77 , 4.77 112 , 7.89 , 2.93 , 4.86 113 , 7.45 , 3.10 , 4.96 114 , 6.96 , 3.28 , 5.07 115 , 6.39 , 3.48 , 5.19 116 , 5.74 , 3.69 , 5.32 117 , 4.97 , 3.93 , 5.46 118 , 4.02 , 4.20 , 5.63 119 , 2.74 , 4.51 , 5.83 119.5 , 1.81 , 4.69 , 5.95 120 , 0.00 , 4.90 , 6.09 Rail Template: Width , Deck , Bottom 0 , 2.30 , -0.90 1 , 2.30 , -0.90 2 , 2.30 , -0.90 3 , 2.30 , -0.90 4 , 2.29 , -0.90 5 , 2.28 , -0.90 6 , 2.24 , -0.90 7 , 2.19 , -0.90 8 , 2.10 , -0.90 8.5 , 2.03 , -0.90 9.0 , 1.95 , -0.90 9.5 , 1.84 , -0.90 10.5 , 1.53 , -0.90 11.0 , 1.30 , -0.90 11 , 1.30 , -0.90 11.1 , 1.24 , -0.90 11.2 , 1.18 , -0.89 11.3 , 1.11 , -0.88 11.4 , 1.03 , -0.85 11.5 , 0.95 , -0.81 11.6 , 0.86 , -0.75 11.7 , 0.75 , -0.67 11.8 , 0.61 , -0.57 11.90 , 0.44 , -0.41 11.95 , 0.31 , -0.30 12.00 , 0.00 , -0.00 Good Luck!
Thanks you very much! Gary
You can also buy epoxy from Resin Research. 321-779-2369. A bit more cost but a bit better product.
You got it. I’m just waiting for the weather here to get consistently above 75 degrees. Gary
The new fast hardener is fine above 50º. Additive F will solve many climate problems as well.
This is board #3 so I would like some extra lam time. BTW, any suggestions on glass schedule? Greg, I read in the archives that you say to use S-glass. Three bottom & two deck with 6oz? I would like to error on the endurance side rather than weight. Thanks, Gary
Noodle, Thanks for taking the time to write a detailed response. I did some checking and it seems you are correct about me not being up to speed on pricing. Given my most recent canoe is ten years old (seems like only yesterday) and most of my latest purchases of epoxy have been small amounts, I should have realized my knowledge was dated. Take care, Patrick
Since Greg hasn’t popped up I’ll take a stab at this. Lucky, You mistak…ed the glass schedule upside down. You should have said 3-6’s on top and 2-6’s on bottom. The industry pretty much accepts this epoxy schedule for laminating S glass over EPS foam. I would use 6 oz warp S for a little extra strength. More fibers interlock between layers. That makes the structure stronger and displaces resin. Epoxy is strong enough to laminate even stronger fabrics, like carbon and kevlar. Ortho polyester resin pretty much craps out when trying to bond anything stronger than E glass. I use 3 6oz warp E on bottom and 3 2/3 6oz warp E on top. It’s very strong, but a little heavy. And Steven has a good point about big longboards weighing alot.
That’s Patrick, not Stephen.
At less than 70º time is usually not an issue. Fast hardener has plenty of work time and you can still flip it in less than 5 hours. Slower curing agents like our slow or the surf source resin doesn’t allow you to flip in less than 12 hours, or even more, in cooler temps. Also when the resin doesn’t kick in a reasonable amount of time, bad things happen. Again Additive F eliminates these problems and a faster curing agent always gets better results in cool temps.