If your son's 16 he should already be using a fiver. i'm not sure how experienced he is but i don't think the wind would be that big for him 2 be using smaller ones. i'm 14 and I use a five sq m (52 kilos, about 110lbs). unless he's a beginner, let him try it and let him decide. if he is a beginner or doesn't windsurf, yeah, he can use it when he's learning if there isnt a lot of wind or later on when there's a lot of wind as well....