Author Topic: Balsa vs foam -float  (Read 1289 times)

NorthJerzSurfer

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Balsa vs foam -float
« on: February 09, 2020, 12:41:29 PM »
Question for you shapers. I just had someone tell me that a balsa board (ie sunova xxx construction or several other brands that do full balsa over foam)  will float like a slightly higher volume board.

In my case a 114l balsa being closer to 118 foam and glass...

Can anyone weigh in if they think this is true?  One balsa shaper said this on line when I searched the question.

DOES BALSA FLOAT BETTER THAN FOAM?

Surfboard flotation is a function of the ratio between the volume of the board and the weight
of the board. Period. A balsa board and a foam board of the same basic dimensions and
weight, will float exactly the same. If one of the boards is lighter, it will float better.

I tend to agree with the above but if a balsa board gets me a little more float in a slightly more compact shape I'm all ears

burchas

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Re: Balsa vs foam -float
« Reply #1 on: February 09, 2020, 02:18:42 PM »
I tend to agree with the above but if a balsa board gets me a little more float in a slightly more compact shape I'm all ears

Well, if you're going to subscribe to this why stop at fake Balsa construction, go full on Balsa wood chambered construction. With all the added Balsa your 114L board will float like 180L  ::) And while on the subject you should want to consider the holy grail in hollow construction, surly air floats better than foam and Balsa then your board will float like a 228L Board if I'm going by the same calculation. Make sure to mention the name of that shaper, I'll want to run it by him first just to make sure I did the right math in my head ;D

If that's your way to justify in your head buying a new Balsa board because you just dig the look then go for it. The extra stoke will double your float. Now that's a fact for you ;)
in progress...

exiled

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Re: Balsa vs foam -float
« Reply #2 on: February 09, 2020, 03:28:24 PM »
Volume numbers on almost all production boards are whatever the computer spits out based on the design for the blank. When you see 100L on your board, think 100L of foam. The glassing that comes later adds to the volume, and the thicker the layers added, the more volume you get. Balsa adds more thickness than a normal glass job, so a board with the same amount of foam will float more because its simply a little thicker.

TallDude

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Re: Balsa vs foam -float
« Reply #3 on: February 09, 2020, 04:58:56 PM »
An object floats in water because of buoyancy or buoyant force. Buoyant force only depends on the density of the fluid (salt water is denser than fresh water) which the object is submerged, the acceleration due to gravity ( the weight of everything like foam, wood, glass, fins, wetsuit, and your weight ), and the volume of the displaced fluid ( the volume of everything below water line).
Take for example a standard shape board that 8’ x 32” x 4” thick and 100 liters vs a similar shape board that is 8’ x 27” x 5” thick and 100 liters and they both weigh the same, if the same person stands on each board separately of course, they will displace the same amount fluid (water and maybe trash) that they are floating on or in.  Here’s the difference, because our ability to balance requires a certain amount of buoyant force where our feet are, the wider board will be easier to balance on. The type of material doesn't mater, but the weight of the material does.
« Last Edit: February 09, 2020, 05:00:42 PM by TallDude »
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Fishman

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Re: Balsa vs foam -float
« Reply #4 on: February 09, 2020, 07:29:21 PM »
The type of material doesn't mater, but the weight of the material does.
This /\

Which ever you can make that is lighter per litter of volume will float better.

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NorthJerzSurfer

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Re: Balsa vs foam -float
« Reply #5 on: February 10, 2020, 04:14:18 PM »
Gracias - Thanks Fishman- that what I thought

PonoBill

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Re: Balsa vs foam -float
« Reply #6 on: February 10, 2020, 08:28:05 PM »
Yeah, it's totally bullshit. The lightest Balsa is six times heavier per unit volume than 1# EPS, medium hard balsa is 11 times heavier, hard is 18 times heavier. There's no point in using light Balsa since it squishes easier than EPS. Furthermore, most of those boards are made with a thin veneer. If it were made from some kind of anti-gravity unobtainium it wouldn't make a bit of difference. And the balsa isn't sealed with microbaloons so it looks nice. It sucks up a pint or two of resin before it takes on a good hotcoat. 

There's a hollow balsa gun Dave Brewer made hanging on the wall at Ponohouse. It's not light. I made sure to screw the hangers to the studs.

And Talldude, you mean the density, not the weight.
« Last Edit: February 10, 2020, 08:33:32 PM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

TallDude

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Re: Balsa vs foam -float
« Reply #7 on: February 10, 2020, 11:16:46 PM »
Yeah, it's totally bullshit. The lightest Balsa is six times heavier per unit volume than 1# EPS, medium hard balsa is 11 times heavier, hard is 18 times heavier. There's no point in using light Balsa since it squishes easier than EPS. Furthermore, most of those boards are made with a thin veneer. If it were made from some kind of anti-gravity unobtainium it wouldn't make a bit of difference. And the balsa isn't sealed with microbaloons so it looks nice. It sucks up a pint or two of resin before it takes on a good hotcoat. 

There's a hollow balsa gun Dave Brewer made hanging on the wall at Ponohouse. It's not light. I made sure to screw the hangers to the studs.

And Talldude, you mean the density, not the weight.
I meant what you knew ;)
It's not overhead to me!
8'8" L-41 ST and a whole pile of boards I rarely use.

 


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