Hey Cajunsurfer,
I think its awesome you pulled it off, but I’m just wondering, with all those bayous and swamps…and houses with boat docks on those bayous. Isn’t there a supply of eps dock foam. So was this a exercise in being frugal, or an exercise in “Nana Nana Boo Boo, I’ll show you” Both are completely legit.
I want to see this blank…before it was shaped.
This is the stuff I was playing with. No doubt I could make a blank of it if I was so inclined. It wouldn’t be UV stable and wouldn’t save me any money considering what my time is worth.
http://www.uscomposites.com/foam.html
Mako - do you think this product would be viable for filling a hollow wood surfboard? If you were going to do it, how would you approach it, i.e. would it have to be done as you build, or would it be possible to fill a completed board with a few penetrations and patches?
I will post video’s and photographs when the project is completed. I hope you are online when I do. P.s. The camera loves me and my slight in your face attitude just gives me dimension. <3 one love
The problem with using pour foam to fill an enclosed space is that it expands with quite a bit of force. That is why blank molds are made of concrete and still held together with a powerful locking mechanism. When putting pour foam back in boats some people have deformed floors and hull sides because of the expansion in tight spaces. The trick to avoid this is small batches and having plenty of room for expansion.
On a hollow wood board the path to take might be to fill the board with foam and shave it down before putting the deck on.
Watch this one die.
Haha, I’m looking for 2 part pour foam simply for large ding repairs and came across this thread. Bump?
This is how I did my 4 piece collapsible…
Build a wooden frame, covered it with cardboard and filled it with can foam
https://www.woodboardforum.com/filedata/fetch?id=5628&d=1517686094
This was the result:
https://www.woodboardforum.com/filedata/fetch?id=5638&d=1517771748
and after some sanding, it sands much better than eps…:
https://www.woodboardforum.com/filedata/fetch?id=5656&d=1517900222
I the glued wooden veneer directly onto the “blank”, during the vaccuming of the veneer some slight dents appeared, but it finally is working.
My next project was a collapsible bodyboard for my wife. Here I glued on the Deck and bottom using 4mm balsa first and filled the frame with can foam too, prior to build the rails. the results are much better than with the cardboard, but unfortunately I only have pics of the final board:
https://www.woodboardforum.com/forum/design/workshop-tool-ideas/6169-new-bodyboard
(Watch the interesting connection between the collpsible parts; it workd out pretty well, the connection is solid and releaseable the only thing is you have to protect the connectors from saltwater. I had some saltwater contact, but finally nothing seriously happened, but I protected additionally with a lot of oil and cleaned everything after use)
My upcoming board for autumn will be constructed according to this method. wooden frame, deck and bottom planked, the filled with can foam. The expansion forces are not a problem at all, but this depends on the used foam. mine is very light, about 15g per litre final weight and its supporting deck and bottom well, and I leave the rails open for expansion. some areas where the foam is denser or has bubbles, but it works pretty well. since it will be encased in wood completely I do not see a danger from UV rays.
For me, this method is quite perfect, because you finally evitate to shape whatever kind of foam, no mexx at all, just cutting at the rails side, ready. the waterabsorbancy of the used foam is 0,3% but its better that everything is tight. My 4 piece collapsible sucked half a cup of water through a pinhole. Nothing seriously, but it demonstrated that under sucking pressure (if hot board gets into cold water, the foam is not really watertight, it must have at least some open cells. the shape comes from the wooden frame, which is easily done, especially if using balsa. the balsa deck will additionalyy veneered, here its a little bit tricky, because I’m using vaccuum and you need to have the pressure high enough to glue the veneer, but light enough to not deform the deck (and foam below). Otherwise you will have some dents between the ribs. If you look closely to the final bodyboard you will see what i mean:
https://www.woodboardforum.com/filedata/fetch?id=6211&d=1526208947 (a concave on deck from right to left was on purpose, to get more hold in the water…)
This is the “Surfdude/Olddudes” way of building his upcoming boards… Hope the next board will be my best one built ever. it will not be collapsible and should be at 8’3’’ length not heavier than 10lbs…
this is exacly what I do, using can foam. See post #26 in this thread, posted some minutes ago. I choose the used foam according to its specs. It was the lightest I found, with the lowest water absorbany rate. I think its ideal to fill a wooden frame. I tried it to avoid having valves in the HWS because I had problems with water intakes, due to forgotten valves…
The foam I used is call Wuerth Purlogic Top, 2 cans should be enough for even a malibu. It is highly epansible too, but the expanding forces are very light. If there is bigger opening it works flawless. thats why I will use it in future to fill an already bottom and deck planked HWS balsa frame, leaving the railside open. the only thing you need after filling is cutting it with a saw. I did it with the bodyboard with for me quite perfect results. Not a real mess at all.
I would not fill an existing existing board through some holes, because I would consider a larger opening for pressure release, although the expansion forces of this foam are quite low. I just repaired a water hogged board of my son, where I remove a 2 inch wide bottom plank from each side of the stringer and filled it with the foam between the ribs. this 2 inch opening was okay. Instead of replacing the removed plank, I just veneered the entire bottom, vennering onto existing planks and the foam filled voids. during vaccuuming the foam areas bend in by parts of a millimeter, but I can live with this. But planking a wooden frame completely and the foaming avoids this uneveness. As said in post #26 a three mm balsa deck should be enough, but I will apply a nice wooden veneer on my next project. this gives additional strength and the I can use less glass. I hope that 80gr/m² for bottom and 160gr/m² for deck will be enough (should be 2.5oz/sqy and about 5oz/syd for the deck) to protect the wooden foam construction from any usual dents in the knee and hands area. Actually the 4 piece collapsible made of wooden frame, foam and 1mm veneer, did not show any after 14days of use. https://www.woodboardforum.com/forum/design/workshop-tool-ideas/5597-my-new-project/page5
I used spray foam to fill the sections in my first hollow balsa. I did it before adding the deck skin and was only able to fill a small part of the board with one can. I found that it ended up heavy so I dug out the foam. I left some foam in the tail section, but added XPS where the fins would be.
Without the proper molds, spray foam can’t get the compression it needs to get good density. It develops a hard crust, but under that it is very soft. I found it better to cut EPS or XPS pieces to fill the voids.
I think it is possible to build a simple rockered and profiled mold that you could use to make slab style poly blanks. Once you get the amount of mix figured out, you could make your own blanks. Is it worth the effort, might be if you live far away from blank sources, but have access to the 2 part mix.
Funny—. I just read an interesting history of Jeff White and White Owl Surfboards. He was the first and only to pour/mold his blanks in the Santa Barbara area. This was around the time that Clark got started. That would put Jeff White in the same company as Dave Seet, Grubby and Harold Walker. White had three molds that he used to produce longboard blanks. I’ll see if Ican find it again and post the link. Lowel
With more than one stringer it is getting complicated… With one stringer you can plank deck and bottom and leave the railside open. I tried the EPS pieces too, but I glued them in using PU glue, if you have to shape it, you are running into problems, because the glue is harder than the EPS/XPS. By now I do not have any long time experience, but the results with the used spray are such promising, that I will use it in the future. You need less wood, less glass, , but all depends on the used spray foam. The Wuerth Purlogic Top is highly expandable, one small can gives up to 40litres of fine celled foam, it weighs only 15-20gr/litre wihich probably is 0.5oz/quart. But its support a thin wooden deck equally.
