Is balsa much heavier than PU foam?
if it is heavier, with construction methods (hollow) can you make a balsa board as light as a PU foam board? and how would it perform comp’d to same pu shorty?
shaping a fish or modern shortboard with balsa - is it much more difficult?
what is the drawback to balsa? (expensive Stateside? )
I, to, would love to work with balsa!!
It really depends! The weight of balsa can vary across a fairly large range from 6# per cu.ft to as much as 19# per cu. ft. Of course these weights are all a lot heavier than straight PU foam. So the key for them to be light is that they either have to be hollow or chambered, with the hollow being the lightest.
My experience is that for larger boards like some of the guns I shape, a hollow balsa board is comparable in weight, but a lot more durable and with a lot less glass. The 12’ balsa gun I just finished shaping is going to have a single 4 oz. on each side which should bring its weight in very close to that of a similar sized PU board but it will be a lot stronger and should have a much longer lifespan.
With shorter boards I’m not sure you can get them to be lighter than a PU board, in fact I’m pretty sure that you can’t. That is if you are building them out of hollow balsa, not a composite balsa which will easily be able to be as light and more durable.
In terms of shaping them, it is not necessarily that they are more difficult it just takes a different technique and to some degree different tools, and a different mindset. I tend to use my power planer a lot less and my hand planers a lot more, because I tend to get sucked into the fact that I’m working with wood. You also have to be more tuned into things like the direction of the grain so you don’t always get to flow the same way as you would with PU. But that is what makes them so much fun to shape as you have to create the board out of the wood, you aren’t just shaping the skin off a close tolerance blank!
One thing that I have found is critical is that you really want to keep your tools as sharp as possible, makes a big difference. I also find I use a wide variety of hand tools, from block planes to spokeshaves to smoothing planes, but that could be because I love working with those tools! You also have to be careful when sanding them as you can create a lot of work for yourself if you sand across the grain, so I always flow with the grain. Balsa has a tendency to furr up when sanded especially against the grain, so it can be a challenge.
Balsa definitely surfs very differently than a PU board because they tend to be a lot stiffer, in bigger boards this is a plus, but for a modern short board it might not be everyones cup of tea. Personally, I love the way they feel in the water.
Of course the really positive thing about a balsa board is how awesome they look, they really are a joy to look at! The other thing I love about balsa is that when you are done shaping them you clean out the shaping room and dump the shavings in the garden as mulch, that makes one feel really good, knowing its not all going to the dump!
The balsa blanks can certainly be expensive, but then you don’t make a balsa board as something disposable, they are built to last!
They are a lot of work to shape but well worth the effort!
Hope this helps!
-Robin
I’ve only built the one balsa board and I’ll back up all of what Robin has written. Mine was solid, wide and long so…heavy, real heavy. When I build the next one I’ll just tack the sticks together, rough shape it then split the sticks apart and go phsycotic with a hole saw. Should lighten it up a tad!! I only glassed mine with 2 oz but given the density of balsa and the 3" thick board she should be right.
OK - thanks for those answers. Balsa is pretty cheap down here, and now with this clark business it might be a good time to experiment with it.
One more question fellas - you mention ‘composite’ balsa contructions – balsa and what?
any chance someone can post a pic of the tools you need for working balsa? I know you mention them, but I probably know the spanish names better.
Composite balsa construction involves the vacuum bagging of thin strips of balsa over a foam core using epoxy resin, the typical core being one of the polystyrene foam types like EPS. Typically the rails are solid balsa and when the bagging is done and everything is cleaned up the board is glassed but with much lighter layers. It produces a very strong and light board and they tend to look really nice as well.
There are many discussions of this construction techinique on Swaylock’s so if you are interested just do a search through the archives.
-Robin
Most balsa is right around 7-9 lb /cu ft.
But only needs one thin layer of glass…
i want to make a balsa board myself.
on average, how much does a 9 foot balsa longboard weigh.
and can they have a finbox or is it only glass on fins?