how to build hollow balsa blank?

hi swaylockers,

after building some foam boards I’m  thinking about building my first balsa board. I already watched around how to build balsa blanks and I found a picture that looks realy interesting to me (

Seems to me that these blanks are pre-chambered respectivly glued together with these chambers. 

Can anyone tell me more how these blanks are built? And how next steps are? And how to prevent thinning out the deck balsa towards the rails while shaping? Seems to have some advantages towards later chambering like less work and less balsa needed for the blank.

Best regards,


I don’t know if you will find it in the Archives;  but this Topic has been previously discussed at length.  Those past threads were so exhaustive and exstensive that it is doubtful anything could be added in a new thread,  Jim Phillips , Balsa Bill and others documented the whole process with photos and excellent step by step instruction.  To the archives you go!  Maybe someone will dig up the necessary links got you.  Lowel 

Agreed. Search on Balsa Bill for the most recent. The blank in that pic is being built by the “plank and rib” method which makes a sturdy blank buy requires some production tools. The rails are built up separately after the very rough outline is cut by wrapping boards along the rails and clamping. Balsa Bills method is more suited to the one off home builder. 

I’m building a fish from one of the plank blanks now and will post a build thread in a week or two. 

I have a long board and a fish blank I’d consider selling if you PM me and throw gobs of money at me. But you’d miss the joy of building your own blank and finding your own wood. For both you’ll need expert skills. I am not an expert but happy to tell you what I know. 


hi greg, looks really fine!

do you have some pictures of the blank without the covering balsa? “normal” HWS interior looks very fragile, wondering the thickness of your balsa ribs and planks. And the distance between the ribs.

No. Your picture shows the inside best. I got the blanks finished and ready to shape. Finding good light weight balsa is the first adventure in building a balsa board. I chose to skip that step this time. 

All the best

I haven’t been on too often lately, but here I’ll bite.

As you’ve seen, there are really several ways to go. Glue up a blank, rough shape, break apart, chamber, reglue and finish shaping. Or, build it up in one of many variations of a hollow structure. 

As McDing and Greg said, there is a ton of info in the archives.

Without repeating myself and others, I’ll say that the first method allows the greatest freedom for most of us. Building a blank on a framework requires a lot of prethinking where your deck will transition into your rails, same with your bottom curves, to ensure that you have enough but not too much material and that your blank stays balanced. I prefer to bandsaw my rocker in, then glue up a blank, cut my outline…shape and then chamber. A lot of work, but not more for me than the frame methods.

I’ve built à la Simmons with a foam core, on a frame à la Kosminsky, and the old tried and true. Skip’s blanks, Shark Bay… should have ordered from Kayu a bit ago but got really distracted with things like work. His work looks insanely nice if you’re thinking of ordering a blank.

All have their advantages and disadvantages depending on the quality of wood you have, the quantity at your disposition, and your tools and woodworking skills. A lot depends also on what your end result is intended to be… some shapes are more forgiving than others of construction techniques! Oh yeah, and your budget…

I’m sure others will chime in with their two cents worth.

Do an Instagram search for toddredwoodsurfboards.

Francis doesn’t build balsa but is an amazing builder who shows the whole process of building chambered boards.

AndiHL , the photo is the widely used South American method…if you want some deck camber , just cut the required curve into the deckside of the transverse bulkheads…this is made much easier to do , if you build a flat rocker bed to match your bottom curve , then clamp everything down to that curve . …here’s some board porn for inspiration.Outer Island News Letter: Balsa Gallery

kayu , I dont know what to say after looking at those balsa boards but , WOW

Thanks for inspirational replies!!

@kayu (and all others): do you have any hints dimensioning the bottom & deck planks, the bulkheads and the distance between them?  I’m considering building a balsa sandwich. How much thinner can I go with maybe 2oz glass under the plank and 6oz on the outside. Or is that too much (or too few).

Kayu, that is gorgeous work. Is it yours? Love the Bolt  

I will say that shaping balsa will really advance your shaping skills. I’m a better foam shaper as a result. 

All the best

…it’s the work of Mitchell Rae , a shaper from Nth Coast NSW…a bit underground …his work has always been first class , as long as I can remember.

…the method used in Ecuador is not the best; the best way is the “California” way; like J Phillips etc does. I had imported lots of planks from Ecuador and the guys phone called about the rocker; when I told them the measurements (and at what intervals to measure) they really did not understood; also did not understood that I needed only the planks not the blank chambered that way or not chambered.

I did the shapes pre shaping then spot glue et all, like other members mentioned.

You cannot tweak the rockers or the rails with this other method.

True, Reverb. That is why I went with the fish. Very little rocker needed. 

All the best

One thing that I should add:

Balsa is a neat wood to work with and has a long history but… I don’t know your skills at all. A really functional board can be made of samba, or even cedar if you choose your wood carefully using the treaditional chambering method. Getting really close to your finished shape before you break it up will allow you to really get in there and remove stock.

A friend of mine, Marc Bilion (Atao surfboards up in Brittany) made a great little egg from local pine a few years ago and while it was heavy, not unreasonably so after he chambered the heck out of it. I’ve seen poplar used the same way but never tried it myself.

My avatar board is chambered sugar pine. Went from a 60 lb. blank to a 23 lb. finished board. Lots of chambering, and probably coulda taken out even more. Shoulda started with a lighter wood species.

I have had good luck with getting my blanks made in Ecuador…But I have a finished board for them to copy. I also watch over the wood they use. You can get a pretty good board made with the way they do it but it depends on who you go to to get the blanks. ‘‘Afro’’ the guy in the picture has been making blanks since my first time in Ecuador 1979. He has never surfed. So getting what YOU want without being here in Ecuador can be interesting. Their knowledge of rockers etc is limited to what they have been taught or seen. I see some good boards made and some not so good. Most get bought from tourist and taken back to hang on walls.

IMO , balsa is the best of surfboards hands down…there isn’t a surfboard than won’t perform better if it’s made from balsa…sure , there’s some negatives , but the ride cannot be equaled by any other wood or material that I’m aware of . Some years back I restored a very old Matt Kivlin board that was polystyrene cored with 5mm skins top and bottom , with solid balsa rails…it was dated in 50’s…now that’s what I call wayyyy ahead of it’s time !

Kayu, I remember that board from a posting long ago. Fell in love with it!

Still a pretty darn good way to make a board.