Can anyone tell me how much upward force a boat (say 24 feet x 8 feet, weighing 4000 lbs) exerts as it rises 1 foot on an incoming tide? My son asked me whether or not somone could hold the boat down as it tried to rise and I thought not but can't quite figure out how to quantify how hard it would be to try. Is it something that would strain a rope if you tried to hold it down (assuming no stretch)? Is "force" even the right term? Should I be asking how much work is done?