How well a skin will take impacts and how easily your skins will crack is related to the Toughness of your resin. Strength and Stiffness are BAD indicators for how well a resin resists cracking.
Edit: The only claim I am making is that a resin with a higher toughness will
be more resilient to cracking…not breaking, delaminating, buckling
or denting…and may or may not surf better. If there are two identical surfboards( the shape, foam, cloth) but one board has a resin that is tougher than the other (while stiffness, bonding, strength and other properties are the same), the tougher board be more resistant to cracking. This is a hypothetical, because often toughness changes with the other properties.
If you plug in the numbers for polyester resin, you’ll quickly see what you already know. The Toughness is very low, which is why it cracks VERY easily.
One other thing:
I am not saying that a resin is good if it has a high level of Toughness. All I am saying is that it will be more difficult to crack. Performance and durability are two separate things. Stiffness, damping and bonding attributes determine the performance (and probably another thing that is coming to mind right now).
You don't even need all da mathanatikal stuff to know that epoxy is more rezilient to dem dings. All U gots to do is bend a little peice of fiberglass with da epoxy, den bend a little piece o fibermaglass with da poly. One like to bendo, da otha don't like bend so much
Everybody know how to make a mo better surfamabord, it just no guys like taking mo time, or dem folks scared o the new stuff.
paddle yo surfmabord out into da line up and listen to folks talk about da witchcraft on eeepoxie surfmabords. U think dat de talking about a new sputnik rocket type ship.
I wish designing a surfboard was as easy as designing sputnik. Surf guys say proudly about some board tech, “this is NASA engineering” or some people say that work experience with NASA qualifies you to do anything else. Someday, it will be the other way around…NASA will be recruiting surfboard designers.
When you break a surfboard how did you determine what was lacking: the resin, the cloth, the foam, the shape…or whatever else? Or when you bend a piece of epoxy impregnated fiberglass in your hand, how are you determining if the cloth or the resin dominated in behavior?
Let’s pretend that there exists only 10 types of resin, 10 types of cloth, 10 types of foam and 10 shapes. How many unique boards can you make by combining these 4 things in different ways? Answer: 10^4…10,000 unique boards!
For a given person, in a given set of wave conditions, one board will be better than the rest. If the only way you determine if a board is good or not is by building to full scale every time, then! the only way you can determine that your on the best board is by building 10,000 unique boards. And certainly, some people took this route and have been successful. An alternative route is to determine what the properties are of each component and determine how the individual properties interact with each other in the composite. You’ll quickly see that 9,990 of those combinations will definitely not produce the best surfboard. Test the remaining 10 and you’ve found the best board. I think everybody is roughly in the middle of these two extreme methods of R&D. But IMO, people that are tilted toward the second route, find truth faster than the others…Mike Daniel and Greg Loehr as examples, though there are many others on this forum.
Using the knowledge of how the components affect the composite, a person can determine how a board performs and breaks before it is even built or even before they’ve touched the materials. That seems pretty cool to me, but if it’s not interesting to you, no worries.
I have worked with RR epoxy exclusively for years. Recently I did a rare fin upgrade on a bud's pupe, put a new sharp blade on it and was shocked at how cracks propagated away from the blade, before i was even able to cut thru it. What a joke! Brittle is the word. I had to wheel cut it.
