adding volume to Soft top

Hi, I recently purchased a used softech rocket launch 54"/4'6 in length. It has about 35 Liters of volume but was wondering how I could add some volume to it? I was thinking getting some foam/polypropylene from online and then gluing it to the deck. Thoughts?

Thanks

What are you trying to do?  Because merely adding thickness is the least effective way to make a small board paddle faster.   Better to add widths.   

You would be adding weight to the board, but if thats what you want .

trying to add more volume for more float, 35 liters is not enough for me haha, trying to beat the lifeguards with their restrictions

Hollow it out and put a fiberglass board inside of it. 

thats pretty smart, I was thinking about adding sometype of core but didnt want to cut away at it, anyone know of any type of foam I can reinforce it with?

Buy a used Wavestorm, cut the tail off and use the rail material from the offcut to seal your cut.  Move the fin plugs onto your remaining length and you’re done.   

Making a short/narrow shape thicker won’t do much of anything for your paddling.