I want to start a discussion regarding the characteristics of different materials used to create surfboards; here is a bit of background information as to why I have come to this forum.
I am a novice shaper, having only shaped and glassed 35 boards in the past two years. My day job is at Rainbow Distributing (An East Coast distributor of surf supplies, including Rainbow Fins) in Indian Harbour Beach, FL, which puts me in direct contact with the best shapers and surfers in our area on a day to day basis. In our area, there has been a resurgence of traditional longboard enthusiasts seemingly hell bent on riding heavy logs shaped ONLY from polurethane foam and glassed ONLY with polyester resin. A traditional log absolutely cannot be shaped from EPS foam, so I am told.
In my experience, two boards shaped and glassed exactly the same, one with a polurethane core (Medium to Heavy Density) and the other with a 2lb density EPS core will show a noticeable difference while paddling and surfing. EPS foam has better memory, rigidity, and float quality than Polyurethane, which results in a stiffer board that tends to sit more on top of the water than within the wave.
After this long preface, my simple question is:
Is it possible to build an EPS board that can essentially pass as a poly/poly board and fool a hardcore poly/poly traditionalist?
Let me know your thoughts, and please, correct me if anything I have stated is incorrect.
First basic physic (Archimède) is float : at same volume and same density float is the same. Heavy old school pupe big boards have lot of materials and they are thick so they are stiff, not so much different than an heavy eps epoxy one. So for this kind of shape i think you can make a valid board by using hi density EPS. I make guns like that and guys seems to like them.
Round and round we go on this…I have fooled more then one old narrow minded surfer with my eps/epoxy custom boards. Making a poly board and eps board with the same glassing does not work the eps board comes out too light. Glass the eps board “heavier” I use trible glass 6 oz decks /double bottoms, heavier density eps and get boards that feel just right in the water and under the arm. I have 3 test boards Balsa wood, poly and eps similar shapes same lengths widths etc. The weights are close it is interesting to “feel” the differences of the ride changes in materials. Poly has a middle of the road friendly feel. Eps/epoxy has a little more of a “popping” feel and tingly paddle sound. Balsa starts out slow and secure but BUT just starts going faster like nothing is going to stop it. Balsa goes thru under over waves better, than poly and last Eps. These are all 8’ boards. The differences are subtle due to the weights being so close. So glass em heavier put a nice stick in the board shape it like a log do not tell anyone it is EPS/EPOXY until after they ride it and like it. Poly is much nicer to shape an old style board out of but thats just me. I have a pretty even mix of EPS and Poly boards in the yard.
This horse has been beaten to death around here for years. I prefer to shape, glass, repair and ride Poly any day of the week. I’ve used both and went back to poly.
I am intrigued by the versatility of being able to cut my own blanks from EPS foam at a small fraction of the cost versus buying a blank from USBlanks.
My shaping is completely funded by my day job, so I’d like to explore alternative materials and methods that may help me keep production costs down while still getting the same traditional feel. I realize this may be impossible, but I figure someone out there has tried it!
Thanks for sharing that information. I had assumed a heavier glass job would be in order for an EPS board to have that same solid feel.
I gather from your tests that more weight on the EPS foam will help it sit more in the wave, but only to a certain extent. For experimental purposes, would you think that a moderate deck concave from nose to tail would help remove some of that extra float from the EPS without changing too much how the board rides?
if you want to make an eps core ride like a a log, put thick wood offset stringers in it and glass each side with an extra layer of glass to get the weights equal. if you compare two boards of equal shape and volume and equal weight they will have the same level of ‘float’ (water displacement) no matter what they are made of. the dampening (vibrations) of the eps will feel a bit different no matter what but getting the core denser with the extra stringers will help. and yes the water will sound different as it hits the board. do an opaque tint so you cant see the foam. jim philips gave a trick that he seals an eps blank with resin and baking soda which makes the crust of the blank look like urethane foam then he can do a really nice clear laination or translucent tint.
but i am with the rest of the crew if you want an old school log get us blanks to glue up a nice heavier density blank with lowered rocker and interesting stringers, then glass it with 8 oz. if you make an eps one, post it here let us know how it goes
I am not sure what set up you used to make your own blanks, but I put one together in roughly 30 minutes during my lunch break. Of course you do have to let the glue harden overnight before shaping (if using a stringer), but I wouldn’t call that labor. If I had made it stringerless, I would have spent a whole 15 minutes cutting the foam which is hardly a pain at all. I actually enjoyed it.
Sure, I did mention the cost of the production in my last reply. But cost isn’t my only concern:
-In the glassing bays I currently have access to, regulations do not allow the use of polyester resins. I have to use Epoxy resin no matter what, so making my own blanks does save me money in the long run no matter how you look at it.
-Wait time for a custom blank from US Blanks is one month. I don’t want to wait that long.
-This is an experiment. If it works, it works. If it doesn’t, then I won’t do it again.
I appreciate your feedback, but I would like to know if you have ever attempted to create an EPS board that rides and feels strikingly similar to a board with a Polyurethane core?
I agree. I also prefer shaping polyurethane, glassing with polyester, and the overall feel of the finished product. Current limitations in my working environment have pushed me to experiment with alternative methods. After all, there is always more than one way to beat a horse to death.
Any two boards of similar design , and similar weight , will perform the same…regardless of the core material . The often-referred-to “corkyness” of EPS foam , is just because they are usually much lighter than the poly equivalent …although poly blanks are generally preferred by most shapers , because of their clean shape-ability .
My own observations of eps vs poly ride performance is one of perception. Different sound, yes. Different feel, yes. Different performance, questionable. To me it’s more of a perception issue if the weight is comparable.
Thank you for the constructive reply. I’ll have to give that baking soda trick a try on my next build and I’ll post it here.
Since EPS foam is more rigid than Polyurethane foam and will require more glass to reach the same weight, would’t the end result be a board much stiffer than the Polyurethane equivalent? I was thinking of making a stringerless blank to equal out the flex a bit in the finished product. I have seen other shapers make stringerless EPS longboards, but I haven’t found someone who would comment on how it affects the board in ride and durability.
EPS foam is not “stiffer” than pu foam of same density. EPS foam is more elastic than pu foam wich is more plastic. EPS can deform and come back more and quicker than pu foam wich deform and return slowly or keep it’s new shape (ie plastic déformation). EPS act more like a coil while pu act more like a damper. For surfboard it play essentially on vibratory response. Différence reduce while weight and overall stiffness increase.
Search in archive, some good post about stringers.
There’s a 3rd option that you didn’t mention. Get your heavy pu blank and glass it with epoxy. That way you get the ride of pu and can glass within your restriction. I’ve done a few pu/ epoxy s shortboards/ fishes and works for me.
Going back into the archives. All of these boards were poly blanks glassed using epoxy resin and the same cloth schedule I’d use with poly. Epoxy is just a resin. If I didn’t tell you, average joe would never know they weren’t glassed with poly other than that they dent more so than shatter when dinged. If glassing with poly resin is a problem for you and you want the performance and weight of a poly board, this is the way to go.
I’ve done this as well with great results. I’m not sure exactly why it is, but every board I’ve done with this construction comes out nearly indestructible. I haven’t done a lot of research on the strength of different resins, but I have heard from other glassers that Epoxy resin becomes stronger with age whereas Polyester resin becomes more brittle.
I’m more interested in experimenting with the EPS foam because of the versatility you can get by making your own blanks and the low cost of the material. I can cut each blank specifically for the board and not have to worry about fitting my shape into a premade blank. I’d like to try to get the weight and flex of an EPS board to be about the same as a Polyurethane.
