I'll be boarding right through the winter this year and I want to know if I can get away with a 3 or a 4mm full suit for Rhode Island this winter or should I buy a 5mm? Second, who makes the best suits for boarding in your opinion? I was looking at these but I'm not too sure they're thick enough.
I can (barely) get through the winter in southern NC in a 4/3 wetsuit with taped seams. For RI, you're gonna need about the thickest wetsuit you can find. Of course, everyone tolerates the cold water differently, but it gets awfully cold up there.
Water temps in your area in mid winter are in the mid 30's. If it were me i'd wear a 6/5/4 with 7mm booties and gloves but talk with a local shop and see what they recommend.
Some guys actually wear 4/3's all winter around here believe it or not, but I'd recommend a 5/4 minimum, 6/4 if you want to be a bit more toasty and don't mind losing a little flexibility. I find the 5/4 to work perfect for me, but for RI a 6/4 is probably the call. 5mm boots ans gloves minimum, although you my find you want 7mm.