Let's run the numbers. Archimedes' priciple states that the volume
immersed in the water will be equal to the total weight of boat, motor,
gear, etc. Assume the boat is perfectly rectangular 14 ft by 6 ft,
that's a total bottom surface area of 84 sqft. Water weighs approx 64
lbs per cubic ft. You don't say how much the boat weighs but lets
assume 300 lbs or so. So, total weight equals about 300 (boat) + 475
(people and gear) + 70 (small OB and fuel) = 845 lbs. Divide 845 by 64
to get cubic feet of water, about 13.2 by my calculator. So,
immersion in feet will be 13.2 divided by 84, about .157 feet or 1.89
inches. Round it up to 2 inches for good luck and then subtract from
your lowest point, 16 inches at the transom for an answer of 14 inches,
or 19 inches of freeboard at the side (21 minus 2).

Hope that helps.