solid balsa float etc questions (with hull undercurrent)

I just wondered (include Paulownia in the questions below, if you know anything about that stuff)

if solid balsa planks are available in say 7 foot length by 24 inch width by 4 inch thick anywhere?

how thick a 7 foot board would have to be to float a 200#er. And a reasonable guess how heavy would that be, if I finished it with only linseed oil? Or sealed it minimally

if the wooden hull in the TSK Stubby article quiver shot had any story to it? (KP, Matt, Lee, anyone?)

float how? sunk to armpits? belly?

you won’t find 24 inch wide balsa…unless you grow it yourself maybe…

I’d prefer belly. What is the biggest balsa/paulownia stock available you know of? What about 12" width and 7 foot length, 2 inch thick?

The biggest balsa sticks I’ve seen were maybe 8’ x 6" x 6". Balsa grows straight and tall but doesn’t get that big around. You pretty much have to live with scarfing pieces together.

paulownia is next to unavailable in the USA so far.

7’ and 8’ balsa lumber is not impossible to come by (sometimes 9’ or 10’ even) but typically it’s 4"x4" or maybe 4"x6" at biggest. Never seen a balsa 2x12 myself. That’s what glue is for, though…

you could get hemlock in that size.

When I bought the balsa wood for my project I got boards that were 3.5’’ x 4’’ x 10.5’. I bought them locally at a lumber yard called Frost Hardwood. The density of balsa varies quite a bit. Look for wood with a density of about 11 or 12 pounds per cubic foot. APS 3000 allows you to estimate the volume of your surf board, so you can easily do the math to predict the final weight of your board. It gives you the volume in liters, so you’ll have to do the conversion (There are 28.32 liters in 1 cubic foot).

The equation of the buoyant force is as follows:

See the following link to learn about buoyancy:

Adjust the volume parameter so that your new board requires the same amount of force (F=mg) to overcome the buoyant force as does a foam board of equal weight.

Thanks for the help guys

I wonder how the guys used to make balsa LBs?

I built 17 riders for a documentary surf movie, 4 of them semi-chambered.

Zeph, his friends and some surf stars rode Quigg reproductions at Malibu last fall, I thought they would be sinkers, but the solid boards floated amazingly well, catching waves as easily as a foam board of much less weight.

You see old photos of the San-o era with a guy and gal, both knee paddling the old wood boards, they obviously float very well

Thanks for your reply, JimTheGenius


How big were they?

What board stock was used and where was it sourced from?

Do you think a 7 footer could float a 200# rider