Answer:

Explanation:
The impulse theorem states that the product between the force and the time interval of the collision is equal to the change in momentum:

where
F is the force
is the time interval
m is the mass
is the change in velocity
Here we have
m = 84 kg


So we can solve the equation to find the force:

If you run your boat aground, the first thing you should do is to calmly assess the situation. In case you have passengers on your boat, you should have them don PFDs (personal flotation devices). Afterwards, you should turn off the engine, check if there is any damage, and generally see if everything is okay.
In rivers that are close to sea