T&T: Why do longer boats go faster?

[John Blackburn]

Hi Marin:

Boat resistance has two parts, friction and energy lost to making 
waves.  The bulbs do add surface area and as a result increase energy 
lost to friction, but they also (at cruising speed and designed 
correctly) can create a wave that is 180 degrees out of phase with the 
bow wave that cancels out the bow wave and you don't waste energy in 
creating the bow wave.  So it takes less energy to push the boat through 
the water at design speed.

John Blackburn
44 DeFever "Yak Rack"
Deale, MD

Faure, Marin wrote:

>I was told by someone who designs ships that the bulbous bow on a ship
>is there primarily to alter the waterflow around the forward portion of
>the hull and reduce hydrodymanic drag, which allows the ship to be
>driven through the water more efficiently.
>
>______________________________
>C. Marin Faure
>GB36-403 "La Perouse"
>Bellingham, Washington
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