Hi Tom, How about 2 1/4 gallons? That is the amount that goes with the CLC cheasapeake kits. Some people have a half gallon left over, some people need another 1/2 gallon, and that's on the same kit, whether it's a 16ft or 18 ft so that tells me there can be a wide variation according to layup,wood porosity,pre-sealing or not,whether fillets are part of the construction,etc.,,,oh and neatness.