MORE BOAT PHYSICS

• Have ever been in a boat and passed another boat which was very close by? Have you ever wondered why it felt like you were being pulled towards the other boat, which would surely end in a catastrophic crash in which you would most definitely drown? Well, the answer lies here. "Boats traveling on nearby parallel courses experience an attractive force due to the reduced hydrostatic pressure between them." (The Science of Yachts p.40) This means that it didn't just feel like you were about to crash with the other boat, you really were.

Diagram by Brenton Savikko

• Whale watching is a popular activity among Alaskans. One might ask themselves why there aren't more accidents between boats and marine mammals. A main reason for this is that most tour boats have jet engines instead of propellers. A jet boat has no moving parts that exist beneath it, unlike a boat which uses propellers, thus making the chances or hurting something far less. A jet propelled boat sucks water in, then shoots it out. Newton's third law states that for every force there is an equal and opposite reaction force. The boat uses it's pumps to shoot water backwards. The water reacts by pushing the boat forward. The size of the force on the water equals the size of the force on the boat.

• Next time you wonder why your gas bill for your boat has shot through the roof, take the effects of drag into account. Drag is the resistance force to motion in a fluid acting in the direction opposing the motion. For maximum speed and improved fuel consumption, drag must be reduced to a minimum. Boats of greater displacement will show greater hull drag simply because a greater volume of water is displaced. Boats with better streamline will produce less drag. Boats with less surface roughness (less crap on bottom) will produce less drag. So as a solution to your fuel bill problem:

a) Don't be lazy. Clean the bottom of you boat.

b) Think twice before using your square boat.

c) Get a smaller boat.

More drag.

Less drag.

Photos by Brenton Savikko

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