Hi,
Just wondering what is the minimal size board that will be able to float with a rig and person on it?
I sometimes need to to uphaul starts, but rarly go out in winds under 15 knots so i would like to get a board with minimal literage.
I weight 75kg, and sail with 30% 430 mast
As a guessimate, I would say you could uphaul a 90litre, but fairly wobbly and even worse in chop. At 89kg I could uphaul a 99 Carve but it was messy.
Best get a more accurate recommendation from some 75kg.
I am a couple Kg lighter, and on a rented freewave 86 it was not a problem, though it was on a long period swell and no chop. I have tried it once on a 80 litre wave cult, and could not make it happen. If your uphualling at that 'advanced' level it is no longer just that it floats anymore, it is also how stable it is, particulcarly for and aft at complete rest, which it won't be! 
For me I would say 95 litres is the limit if you need to depend on it with no stress, and about 85 litres, if you situtation can cope with a few mistarts and you are prepared to practise it a bit, below that I would not want to be depending on it to get me home...
I am 75kg as well and i would say 90lt min. more importantly you should well on your way back to the beach if it's dropping like a stone.
i have no problem up hauling my JP freestyle wave 93 and i've up hauled my Naish wave board which is 89lt but it was a bit of hassle.
it's depends on the water state.
from my experience once you hit >120 litres uphauling is a problem, not only do you have the balance (left and right) but nose and tail sinkage makes things difficult.
if theres current or chop, it can end up with a swim in rather than an uphaul.
basically (i reckon) low volume boards require waterstarts, also knowing how to lightwind waterstart can save you a swim.
mind you, there was one board that stood out and that was a starboard go. its so freakin wide the thing wouldnt sink or topple! i think there 125 litres.
really easy to sail, could get a bit boring never falling off tho.....
I am 75kg and can uphaul a 8.5m KA Formula sail on my 105lt Hypersonic relatively easily (big chop makes it interesting though).
I can just uphaul on my 95lt sonic but its not fun.
It will depend on your board. Short, wide boards with most of the volume towards the rear of the board will be easier than the same vol board that is narrower and longer.
use this formula:
board volume - body weight - 15 kgs (for rig etc) = floatation
(for salt water add 10% to board volume)
if negative floatation = board will sink
if positive floation = board will float
eg:
Board Volume: 86 liters
Weight: 72 kgs
Fresh Water: 86 - 72 - 15 = -1 => board will sink if there is no wind.
Salt Water: (86 * 1.1) - 72 - 15 = 7.6 => board will float if there is no wind.
