by dtc » Sun Mar 06, 2016 7:22 am
To follow up Big H - its either feet or physics. Its not feet, as you have moved around and have the same issue, so its physics
Basically, at rest, your weight is borne entirely by the buoyant force of the surfboard (buoyant force is essentially dependent on the volume of the board ie how big it is). As the board moves faster, it starts 'planing' and creates another form of lift beyond the buoyancy (displacement or hydrodynamic lift). Although the cause is different, its sort of like how an aircraft wing lifts the aircraft up once the aircraft is going fast enough.
you can see this effect by trying to stand on the water (fail...) then trying to barefoot waterski. Go fast enough and you can barefoot waterski, even though your feet cant support you when you are stationary. On the other hand, put something with enough buoyancy below your feet (eg a stand up paddle board, SUP), and you can stand up without any speed. A surfboard is somewhere between just your feet and a SUP.
So, with a surfboard, once you hit a certain speed, the board will support your weight standing and you will surf. Below that speed, there isn't enough lift (buoyancy plus 'other' lift) to keep you above the water and you will start sinking. (when you sit on the board while waiting for a wave, the board is probably below the water line - that's fine when sitting, but you cant surf a board that's below the water line).
So the solutions are either go faster or increase buoyancy (or a combination of both). Increase in buoyancy means you will stay floating even when going slow. This is simply a bigger volumed board (your board is something like 24L from the website, you probably want to look at something at least 10L bigger if not 15L bigger to really appreciate this; but even a few litres increase volume might help).
The other solution, go faster. As Big H says, there are many ways of doing this (you can do them all at the same time as well). Stay high on the wave and close to the shoulder (where the wave is breaking/curling) - these are the most powerful parts of the wave so you go faster. Learn to pump the board. Learn to surf up and down the wave. Surf only more powerful (bigger) waves etc
Unfortunately from the sounds of it I think you are just at a weight, in comparison to the volume of your board, where you are going to sink pretty much whenever you are in the white water (after the wave breaks and you are not still on the unbroken face of the wave) or if you have a weak/small wave. Certainly within the next few years, as you get older and heavier, you will definitely need a bigger board.
In any case, the 'simple' solution is a bigger board (this wont make you a great surfer, but it will more often put you in a position where you can practice your skills); the harder solution is to learn new skills when you don't have a board that is assisting you to learn those skills.