Launching from shore.
The one going to the boat.
pushing a pram kicking a ball pushing the door pushing the car
Assuming that it is moving at a constant speed. Horizontally there is the thrust from the engines/oars/whatever is pushing the boat and the drag from the water and air it is being pushed through. Vertically there is the weight of the boat and the upwards force due to the water pressure pushing on the bottom of the boat.
You might propel a model boat by pushing it in the water or by attaching a sail to the boat. You might also propel a model boat using a motor and a remote control system.
The action is the girl propelling the rows in the water, and the reaction is the water pushing the boat forward.
wind or moving water
Same way an arrow works, the front is pointed making the water go around the boat instead of the boat pushing its way through the water.
The wind bows on it pushing it forward or any direction the boat is facing
A tug boat pushing a ship to direct it out from the port. A cart being pushed by a man. A footballer kicking a ball. Read more:
By getting under the boat while on the trailer and pushing up. If there is any flexing, the stringers could possibly be bad.
The keel is important because it forces the boat to move forwards when the force of the wind on the sails might also be pushing the boat sideways. The keel stops the boat simply going directly downwind.
the friction from pushing the hull through the water is not useful as long as you're travelling.