BIG Ole Chunks Of Styrene - Where?

Kinda surprised. I went by my local Home Depot fully expecting to find the big pieces of foam board used for insulation. Zilch, nada… walked out with money still in my pocket and nowhere to go!

I am lost. Any direction appreciated. :slight_smile:


How big?
May want to check out a local lumber yard and find the polystyrene foam that they sell for dock floatation. I believe it is 2’x2’x8’. Works well with epoxies, but not polyester resin. Are you taking a stab at shaping a ski?


That’s what I am thinking – 7’10"x24" with a much more aggressive rail profile. I like the shape of the Tsunami Airski’s. Fairly deep to offer forgiving bouyancy but tapering to very aggressive rails. I think I can do it. I don’t think I can get it to be perfectly smooth like the production skis but smooth enough to work, I am sure. (I am more into quick and dirty rather than long and perfect.)

2x2x8 feet block would be exactly the right size! Which lumberyard around your way carries these? Locally we don’t have any yards that carries these. I am in the city, remember? :slight_smile:


Well, Lumber yards are everywhere up here in Maine!

When I buy EPS for making plugs I get it at Ricci Lumber in Portsmouth, NH. They sell the big blocks for dock floatation.

You may want to do a search on the web for EPS foam. I seem to remember there being a lot of sources in the Boston area. That way you could possibly get a white block of foam instead of Dow Chemicals blue.

Are you going to put a stringer in the ski? Have you thought much about how you are going to shape it? Planer, hot wire?


White Foam
is EPS? Okay. Yes, prefer that so coloring won’t be an issue.

I plan on getting rough shape with hot wire cutter (home made). Hand shape final shape, blog, sand again.

I haven’t figured out the stringer. I am wondering if it’s really needed. If so, I was thinking of getting near the final shape, cutting the block in half and then installing a stringer made from multi-layers of glass/epoxy, and glueing it back together again.

What do you think?


comes in so many different formulations. Perhaps there is a chemical engineer who could chime in, but generally for glassing, you want something that will not react with the chemicals in the resin.

I think a stringer would be wise as EPS is very flexible and the stringer will act to strengthen the length of the ski. You may want to look at surf and sailboard blanks to see if there is something that will fit the dimensions of your shape. They come with a stringer already in place and probably would be cheaper and faster to shape. Check out


Stringer “Issue” Resolved.
Gotta love Google!

Apparently older and even some newer style boards use wood stringers. It’s possible for me to laminate a good piece of 1/4" luan with glass and create (what apparently would be) a strong enough stringer to handle longitudinal stess that would be exerted by my weight and wave forces.


They might be out of it … our H.D.
seems to discontinue it ( no tags or ghosts of where it was showing) only to have 3/8" - 2" in stock a week later… Check Lowes too … architectural foam cutters will have “billets” 4’ X 4’ X 8’.

The 1" - 2" inch slices are real nice as you can keep things symetrical by watching the rings ( like rings on a tree) change shape as you work the foam …

DO NOT bond all the layers in a ton of places … only need to tack them together in order to shape the boat ( if you have a huge glue line everywhere you will be kicking yourself as you try to deal with the hard glue line showing up on every stroke)… no worries to get a fine edge as the foam lays pretty flat.

Suggested tools: Surform ( the flat blade w/ plane like handle not the low file type which inhibits free hand movement). Use 40 grit 8" or like heavy fabric backed sanding discs for conformable-yet -stiff-variable-radius shaping tools. Use only paper sandpaper with blocks and sanding pads as it lays flat.

If trimming for a stringer cut, reverse and use the nice flat factory cut to rebond stringer… which BTW is not ness. and will torture you as you try to get a nice rocker line without buggering up the soft foam … a planer is nice for this. Even better is to use High density foam instead of wood. Since the ski is already pretty thick ( as opposed to a surfboard) much of load is going to be in the skin. Gotta get some high density foam or “woodies” around the fin boxes to spread the loads though … footstrap plugs will hold just fine in foam glass for seatbelt…

Call me if you want.

Thanks, Pat.
that was my original idea – to bond sheets together with gorilla glue (which does a fine job of bonding styrene!). A big chunk obviously saves glueing time but I would have to draw out line grits to make sure I have reference points and then make the hotwire cuts.

I was thinking of creating a two forms with the center profile of the ski that can be stuck on the outside of the blocks to guide the hotwire cutter. I would then hand shape the rails and slopes from the middle. One of the forms can then actually serve as the “stringer.”

Anyways, I’m playing with the process in my head and making notes. I probably won’t get to this project 'til spring and want the ski ready for late spring early summer.

Thanks for the offer of help!


Styrene ain’t very healthy for you
Now polystyrene, that’s a different story. :wink:

Link on Western Waveski Page
Sing do you have the link from the western waveski page on building a waveski from foam? I can find it for you when I am at home if you don’t have it. It’s very detailed (and a little discouraging too). I knew you were going to turn into a ski builder. The Singmoyski I can see it now. My wife is taking a trip this spring and I’m thinking about trying it when she is not around to see the mess.

Actually easy to find …

Try commercial Insulation suppliers

– Last Updated: Nov-09-05 3:56 PM EST –

Hi Sing
Try to get at least an 8" thick piece. It comes in 8" X 4' X 8' sheets. If you try gluing a bunch of 2" thick pieces together it's going to be a lot of extra work and weight. It is amazing how fast weight can add up...a little here...a little there and all the sudden the light weight high performance wave ski is a slug. In the length you are talking about it should not weigh over 15 lbs...13 lbs if you really pay attention.

If you end up gluing any pieces together forget the gorilla glue and use epoxy thickened with only glass bubbles (no cabosile) don't just do dabs...use a very thin full coat...Back in 1971 I had a surfboard I made out of three layers of urethane foam glued you are talking about...where the different layers of foam come together it forms a small bump in the glass...when you sand out the hot coat it weakens that area...well after surfing in for a few months I kissed the bottom with it at low tide in small must have berely fractured along the joint line...then a beautiful glassy day of head high waves... I drop in and the whole front bottom of the board explodes...I come up and there is foam floating all over the place. Trust me..I have been building and experimenting with materials, designs and construction methods of boats/surfboards/sailboards/kayaks and wave ski's since 1968. It has cost a lot of time and money. I will share anything I have learned if you are interested.

You are definitely on the right track with making hot wire templates to fasten on the sides of the foam bullet. Use masonite for this...if you use plywood the wire will hang up, if it stops for even a mili second it will burn a grove down into the foam and will ruin the predetermined shape.

If you get the heat just right on the wire, and your template is perfectly smooth and will only have to shape any concaves or v's into the bottom (you can do the V with the hotwire too). When done right it will be a smooth and true as the factory surface. Spend a little time and get the templates perfect...or you spend a lot of time trying to fix the imperfections after the fact. If you do it right the thickness flow of the ski will give you a very true surface to work from to get your rails right and you deck curve symmetrical. If you take your time you can turn out a ski as good as any custom shop.

One of the big differences between a pro shaper and a novice is the pro works on one thing at a time...the bottom, the deck, the rails...the amateur will work a bit on the bottom and then move onto the deck and do a little bit...a bit on the rails...before he realizes it he has lost all points of reference. Once you round off the rails you have lost all your hard edges and have nothing to work from...That’s why a pro shaped board looks fair when you hold it up and sight down the rail...and the amateur’s rail looks bumpy and lumpy. If you take two passed on the left side ...take two passes on the right side. Don’t try to finish shape one side of the ski and then try to match up the other side...that’s a nightmare.

Use only two layers of 4oz S-glass...DO NOT USE E-GLASS it is not strong or stiff enough. Do not be tempted to use three layers of glass... it will be too heavy. Forget Carbon its way over rated in this application...too brittle.
Forget stringers...unnecessary weight, complicates shaping, causes delamination.

Good luck on your project, it is an awesome feeling to shape something out of is so three will thoroughly enjoy the experience. think of building a wooden boat as 2D and out of foam and glass as 3D.


Styrene short for poly-s…
Several plys of foam tacked together ( dabbed) as Waterat used is a better term) work great and other than said dabs, do not add extra weight. Seeing the ‘loft’ lines as you go … priceless. Especially for someone with a good yet untrained eye.

Why is it ye old “I’ve been shaping and building ( surfboards) since before you were born” guys always state catagorically if you don’t do it their way , it must be wrong ?

Too funny
"Why is it ye old “I’ve been shaping and building ( surfboards) since before you were born” guys always state catagorically if you don’t do it their way , it must be wrong ?"

So true. There are endless possiblites on how to do anything. It just takes imagination and patience to find what works for you or a better way.


It was for Sing…

– Last Updated: Nov-08-05 8:36 PM EST –

“Several plys of foam tacked together ( dabbed) as Waterat used is a better term) work great and other than said dabs, do not add extra weight. Seeing the 'loft' lines as you go ..... priceless. Especially for someone with a good yet untrained eye.

Why is it ye old "I've been shaping and building ( surfboards) since before you were born" guys always state catagorically if you don't do it their way , it must be wrong ?”

If that is all you took away from my post, it is much more revealing of your mind set than mine.

Onnopaddle and Straz-Kayaks you seemed to miss “It has cost a lot of time and money. I will share anything I have learned if you are interested.”

So your not interested...the post was to Sing…maybe he is interested…

Tell me…you think Wave Master or Island Wave ski is piecing together foam to make their custom wave skis? It’s a no brainer that if you want to get professional results with the least amount of expense, time and problems, you will use the technique and materials the professionals use. I am in no way trying to discourage experimentation… but life is not long enough to learn all the answers by personal trial and error…that’s why we have an educational system.


Tim what do you think is going on …
Is everybody on the internet passing kidney stones today or what?

Just was reading BT with Vince throwing a tantrum.


Guess I’ll just go surfing tomorrow morning.

Stringer material

– Last Updated: Nov-08-05 9:44 PM EST –

Hi sing...
If you check the wood that is in the is the stuff they make popsical sticks (beachwood I believe)out of...and its not plywood in the traditional sense of the word. If it was more than one piece it would be multiple laminated pieces running in the same direction (0 degrees)rather than traditional plywood where the layers alternate between a 0 degree and 90 degree axis. In fact it is usually single piece (sawn lumber).

Luan would not make a good stringer for two reasons...most luan is made with a glue that is non if you get a ding or there is any porosity in the laminate the luan could and most likely delaminate...second the only part of luan that is doing any good is the two outer skins which are running longitudaly...the core...which usually makes up 50 percent of the thickness is running vertically in the stringer situation providing no strength longitudianaly. So out of the 1/4" thickness only about 1/8" is actually doing any thing to reinforce the ski from buckeling.


Thanks All!
Lots of ideas here. Pretty much stacked or one piece foam is going to be determine by what I get my hands on.

I need to think out shape, rails, etc, and get the form materials and cut, etc. I’m pretty excited about doing this. At the same time, I lucky not to be any rush to complete this thing. Can we say freakin’ freezin’ water in another couple of months? I’ll be back in my Venom probably from December through April.


I don’t know?
I didn’t ask for it that is for sure.

Looks like we may have some swell for Thursday. As long as it is warmer than the 26 degrees (air temp, water is still 51) that it is right now, I’ll be out.