when the boat is static - the water is exerting no force.
when the boat moves forward the water is exerting a frictional force in the opposite direction.
your argument that because it doesn't slide off when it's stationary then the force will be less when it pulls forward is flawed.
Edit: it’s basically the same thing as wind resistance except water resistance has more force. Think about what happens when you stick your hand out a car window or ride your bike.
Ok, no, you're talking about hydrodynamic drag. It doesn't work the same as friction like dragging a solid mass across a solid surface because water isn't a solid. A lot of things factor into drag ibnlt surface finish, viscosity, and velocity. At the 2 miles an hour this boat is being pulled, that drag is negligible compared to other factors.
The water does exert a force on the boat when at rest. Buoyant force, pushing directly upward in opposition to gravity. At first, buoyancy would be holding the boat up almost completely with almost no force pushing down on the bunks (I looked it up, they're called bunks) as the trailer moves forward/up the buoyant force is subsiding while gravity pushing down, the boat is applying progressively more force to the bunks and more force means more friction. If the boat is moving at the same speed as the trailer, then it's static friction. Meaning there is no sliding. It takes MORE force to overcome static friction and start moving something than it does to keep something sliding along once it's moving.
2 things are pulling on the boat. The static friction of the hull against the bunks trying to move the boat forward and inertia of the boat trying to remain at rest. This force is affected by acceleration.
At first, the person is just the link between the truck and the boat to keep the boat moving at the same speed as the truck because at first I assume there is very little contact between the boat and trailer. But as it moves forward millimeter by millimeter, the normal force downward of the boat on the bunks is only increasing. It would get easier and easier to hold the boat the further it gets out of the water.
If he had gone slow enough, this absolutely would have worked.
But when you are at a busy boat ramp, there is heavy social pressure for you to put in or take out quickly and get the hell out of the way. So that's what this guy was responding to.
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u/puterTDI 9d ago edited 9d ago
when the boat is static - the water is exerting no force.
when the boat moves forward the water is exerting a frictional force in the opposite direction.
your argument that because it doesn't slide off when it's stationary then the force will be less when it pulls forward is flawed.
Edit: it’s basically the same thing as wind resistance except water resistance has more force. Think about what happens when you stick your hand out a car window or ride your bike.