Stringerless EPS.

General Discussion
1

I am about to embark on my first board. As it is my first.

I WANT TO KEEP IT SIMPLE!!!

I’ve got my foam block and I’ve just done up a few planeshape templates as well as rocker templates

that I’m very happy with.

If I just cut out a profile shape it up and epoxy glass it, aside from my shaping skills (or lack of) what will it

turn out like. What I’m trying to say is what are the pros and cons of building a stringerless EPS board?

How does it compare to a standard stringered pu/pe board?

OR should I just chuck in the KEEP IT SIMPLE idea and put in a bit more effort and go for the Balsa Rails approach.

I keep on coming across quotes like this from Bert.

"a true perimeter stringer ,all the way round your whole board…

even if you dont do a wood skin top and bottom …the performance key is still in the wooden rails.

no matter what i made , whether full p/u cores and p/e glass jobs , eps/xps combos or eps/pvc combos or eps/p/u combos ,the one thing that livened them all up was wooden rails …

"

Which gets me excited about giving it a go but then I get scared of by quotes like this.

"theres a few construction aspects that arent apparent…

in that the balsa has to be treated a special way so you get good resin penetration and an unbreakable bond between glass resin and wood …that aspect is the key to the strength of these boards…

not doing that will result in mixed results , depending on your balsa quality…you could end up with a disaster…"

Bottom line is that I don’t have the cash to make a “disaster”. If I can get away with making a stringerless board

that is comparable at least to a standard pu/pe then I probably should start with that.

Or is it worth the effort to go the balsa rails way?

any thought s would be great.

thanks, JD

2

i am also embarking on my first 2 eps boards, and from what i understand, if it is under 6’ you dont need a stringer, depending on the glass schedule of course.

however, i think i will split the blank, and put a fiberglass stringer in. shouldn’t be too hard. just cut the blank, roll some epoxy on one side, lay the glass, saturate, pull off excess resin, roll the other side, and clamp together. when it gels, trim the excess cloth off so it doesn;t cut my hands while shaping, etc.

in the archives, some have just used glue lines for stringers, some have put it wood. i guess it depends on what you’re shaping.

3

Interesting.

Almost NO windsurf boards outta epoxy styro tech use stingers. They seem to last just fine.

Of course, no stringer, you gotta lay some bigger laps and a little more glass to compensate.

4

"I WANT TO KEEP IT SIMPLE!!! "

hi there Justin !

…Maybe it’s just me , but I wonder if perhaps a close tolerance, ready rockered, ready stringered polyurethane blank would be simpler , quicker and easier to shape for your first ever board ? …

cheers

ben

5

yeah Ben considering I could get a poly blank from just up the road from my place it would have been easier

but I have opted not to.

If I wanted to build a standard shortboard I probably would have gone down that path but I want to make

something a bit different. With the block of foam I have bought I can easily get 4 boards out of it (maybe 5 if I do some glueing). I’m not looking at making anthing futuristic just something along the lines of the boards used

in Morning of the Earth or maybe a fish or maybe a longer beginner board. I can do all of these from this one block.

I think I would be limited if I got a poly blank.

PLUS. It only cost me $100 bucks. thats $25 a board. I think a poly would cost a bit more than that. Yeah I know epoxy resin costs more but atleast if I stuff up the shaping well I can try again on the next board without crying too much.

There so much info here on going the Epoxy EPS way that I thought I’d give it a crack.

I’ve just decided I think I’ll make the first 1 stringerless, the next with a stringer, then maybe try the balsa rails.

thanks,

JD

6

JD,

What density EPS are you using?

7

I have no idea.

I need to find that out. The place I bought it from is a big EPS warehouse. They supply it for all varied uses.

They called it “M” grade. Which I’m guessing is for “medium” grade as they had S grade which was lighter and had larger more spaced balls and then they had H grade which was heavier with smaller tighter balls.

Any ideas what density it might be?

I’m going to call them and find out more info.

regards, JD

8
Quote:

Morning of the Earth or maybe a fish

yew thats what i’m talking about! excellent choice in boards there jdhogg.

big, thick, sqaures of eps are a bugger to shape. ( i just made a 3’6 fish that detererated when i put wood stain on it…crazy proffeser stuff). close tolerence blanks sound delightful too me.

good on you for having a go at it!

9

Stringerless can be done…

It can be bigger than 6’ too

stay away from balsa rails to start

there’s a couple of options some easy some cheaper…

Easy way…

1.8lb stringerless Richardson molded EPS preshaped 7’6" standard Jeff Johnson “funshape”

Just clean it up and make a 7’6" Jeff Johnson classic funboard single to double to vee

or reshape it in a 7’4" Stubb Vector

Or go buy and glue up some .75lb Lowes 4’x8" insulfoam sheets and make them out of that

6’6" 5 fin redX bonzer (waterskate outline)/7’4" thruster Bonza(hourglass) bottom

So obviously you don’t have to stay under 6’ for stringerless even at less than 1lb density…

But to tell the truth, I don’t like these really super light boards

If you cut your own it’s easy too but with out a stringer shape the board on an ironing board or board reinforced racks to keep the flopping down to a minimum. You’ll see…

Thats why we bag on the bottoms before finishing the top

It’s really not that hard to put a center stringer in as well

Best of luck!

10

JD,

If you are in AU or NZ then M grade is about 20 kgm3 which would be a bit dense for sandwhich construction, but ok (if a bit on the light side) for standard epoxy/glass layup. If sealed you could do a double 6 top and 6 bottom which would hold up ok and would be super light. With that weight EPS you could do perimeter stringers and still have a pretty light board. Personally I’d go for the perimeter stringers becuase there is a real performance advantage - boards feel lively and positive so you can go a bit wider. The extra density in the rails makes it easier to sink the rails in turns so there’s no corkyness and strength in the rails makes the boards less prone to snappage. From a beginners perspective I think an EPS blank with an accurately cut profile and balsa rails is probably easier to shape than a thick PU blank with a centre stringer.

11

Thanks Pinhead.

I’ve been off with the flu for the last few days so I haven’t gotton around to calling the EPS factory.

I was going to go for the 2x6 top and 1x6 bottom.

Will I need to put in a vent plug with this M grade foam?

I’d like to get away without one but i’ll put one in if it’s necessary.

I was going to get the H grade stuff but they told me that it was too heavy for making surfboards.

Is this correct?

It looked like it would be easier to shape.

thanks, JD

12

If you leave the board in the car on a hot day then a vent would probably be safer with M grade. If you’re careful you could maybe get away without one. H grade is OZ is 23 kg m3 which I think would be best for non-sandwich construction. I don’t think it would be too heavy - PU is 38 ~ 45 kg m3 so H would still be a lot lighter than a PU blank.

13

Thanks heaps for your info Pinhead.

You have helped me out heaps.

Cheers, JD

14

instead of a “stringer” could you maybe put some carbon fiber strips on the perimeter after shaping? It would stiffen up the perimeter (not to the extent of balsa sure) and wouldn’t be any more work since you’re already glassing at that point. Anyone try this?

Rio

15

Thread revival…

Just wondering if folks have used a double 6 top and bottom with longer EPS boards with success.

(no carbon fiber or balsa, just 2 lb stuff with a stronger glass schedule…)

16

Well I just went through the same questioning process. I decided to walk before running. Having said that I still managed to screw up 2 blanks.

In the end the finished board was 2lb eps, with a glue line stringer using normal brown gorilla glue. The glue line seemed to add a bit of rigidity to the blank while shaping. The brown glue sands well when dry, the white glue didn't sand as well.

Glass schedule for my 5'10" was 2 layers of 4oz s cloth on the bottom and the deck was one layer of 6 oz E topped off with a layer of 4oz S

In the end the board is relatively light, the flex is about normal. I rode it the other night and it went well.

 

For the next one I was going to see about the same process but going with 1 layer of 4oz on bottom with some carbon fiber strips

and 6x4 top. After that if all goes well I might look into a more advanced process.