Volume in layman's terms


 Please some help here. Surfer weight 200lbs or 90.72 kilo

Let’s say we have 3 shortboards with the same dimensions except for thickness.

#1 is at 40 liters 

#2 is at 35 liters 

#3 is at 30 liters

Board #1 floats right on top of the water. 

Where would #2 float at? The belly button? 

Board #3 sinks to the chest? 

Is 5 liters a big drop if the dims/surface are the are the same?

Thank you


yes and no

shaping machines are all good!!!  sorry I still measure with measuring tape its a solid object not a liquid…hahaha  thought the  volume in beers is an interesting concept  hahah  peace

Wouldn’t adding a kilo of weight to the ‘system’ (rider sitting on board) approximate one less liter volume in the board?

Could this be tested with a 40 liter board and 10 kilos of diving weights in a swimming pool?



Good idea.

I have a board at 45l

Take some weights and test it myself.


Been a long time since I flunked high school Algebra.  I thought I was thru with the nightmare of solving for X.  Then YOU came along.  College??  Ugh!! Gag me with a slide rule.  Lowel

Haha. Sorry. I barely graduated high school.

That’s why I need something visible and relatable. 

I can’t wait to see the face of my neighbor when I ask to use their pool.

What’s that board ride like in your avatar pic?

It’s great. I grew up riding boards like this in the late 70’s 

The added fin in the back was to see if if can push the main fin forward as much as possible, but not spin  out. I really need to try this in more serious waves to know for certain.

Yes I was wondering about that board as well.  Well good luck with your calculations.  For years I have always tried to “scale” in four inch increments.  From short to long board.  Volume was automatic.  Lowel

Here are the results:
Board: 45.6L
Weight with wet wetsuit. 220lbs/99.79 sinks to ribcage line.

+10lbs/4.54k sinks 2 inches or 50.8 mm 

+20lbs/9.07k sinks 4 inches or 101.6 mm
+30lbs/13.61k sinks 6 inches or 152.4 mm to nippleline 
The first 10lbs/4.54k isn't really perceivable.
Now most calculators add 2 liters for every 10lbs/4.54k .
My original question was:

#1 is at 40 liters 

#2 is at 35 liters 

#3 is at 30 liters

Board #1 floats right on top of the water. 

Where would #2 float at? Guessing 5" of sinkage.

Board #3 sinks 10 inches.

Is 5 liters a big drop if the dims/surface are the are the same? No

10 liters is a big drop.

Lesson learned… That was a dumb question. But I had fun in the pool.

  10lbs/4.54k sinks you 2 inches or 50.8 mm

Actually I did learn something. The board I was considering was 37.6 L…a 8 L drop from my test board of 45.6 L

That would sink too much for me at current weight. Drop 20lbs would work.

Then there is planing speed.

Board 1 at 40 litres is going to plane higher on the water than board 3 at 30 litres.

Board 1 will pick up speed quicker and lose speed slower than board 3.

Volume is just a way of tuning the required speed you desire in a board.

Lower volume boards planing lower in the water are more reactive.

And take fast reacting surfers to surf them well. 

It’s all just tuning.

 Why older surfers sometimes need more volume.


I see some older surfers who do fine with small low volume boards, but also see some who struggle. I like higher volume boards for paddling around and for catching waves easier, for the extra stability on the pop up.  I don’t think “reactive speed” of the board is an issue in volume preference.  I think a steep critical wave is gonna be harder for the older surfer with slower reflexes and stiffer joints and body. 


Good link but he only talks about how volume effects paddling speed, he doesn’t go deeper and talk about volumes effect on glide speed.

Great footage of Devon Howard in that link, such a pleasing on the eye style.

I always thought it was more common to speak in volume to weight ratios rather than weight to volume ratios as in the link.

One example KS 72 kgs 24 L weight to volume ratio 3, whereas volume to weight ratio is .33 litres per kilo.

Comparing my prefered vol/weight ratio of .6 litres per kg, I like thick nugget type wide tailed shapes, volume at the high end of the spectrum for maximum glide speed and maximum drive from wide tail compression.

 That article helped me understand the variables of volume much better. My original question and experiment sprang from getting pounded at my local beach break because I couldn’t duckdive my heavily volumed shortboard. (not the avatar) I remembered what Bert Burger wrote about how having too much thickness in a shortboard is counter productive to wave catching and how surface area is more important for glide and catching waves. (Of course, there were counter arguments to his viewpoint.)

So I am trying to figure out is Bert correct? It would be nice to duck dive, yet reasonably catch waves. I know someone out there has tried wider thinner shortboards. What has been your experience?




High volume nuggets are a bugger to duck dive.

The only negative of the design in my opinion.

A thinner nugget planshape say 2 5/8’’ thick instead of the 3 1/4’’ I prefer would mean when I paddle my weight would be further forward and therefore when I jump to my feet they land further forward.

One of the unique aspects of wide tailed thicker nuggets is the volume is more in the back half (wide point below halfway) therefore   your feet land closer to the tail and therefore closer to the fins.

Whether Bert is correct, well for him yes, but I like how my weight is more over the fins, a feel that suits how I swing my weight.

And we all swing our weight differently so there is no one size fits all theory just varied tunings.