Roger Long:

One of these days I'd like to look into the derivation of hull speed.
Can you suggest a very basic explanation (a source thereof). I'm just
curious as to when it applies. Like:

Does it apply to non-rigid hulls (hulls that might flex in the middle)
Does it apply to totally submerged objects?
Does it apply to towed objects, like dinghies?
What happens when an object exceeds hull speed?
Is there any way to "fool the water" into acting as if the boat is
longer than it is?

Thanks

David OHara


Wayne. B wrote:
On 12 Apr 2005 11:46:08 -0700, (Matteo) wrote:

I'm thinging of dirty hull (green slime), incorrect weight
distribution (bow tends to "point" upwards even when crossing small
waves).

==================================

A dirty bottom and/or dirty props will definitely slow you down.
It's
also save to say that the effective waterline length of a 40 ft boat
is actually less than 40 ft. Another factor is something called
prismatic coefficient which if a fancy way of describing how sleek
your hull form is. Obviously it's going to take more power to drive
a
40 ft square box through the water than a 40 ft sailboat. The
equation of 1.34 SQRT LWL is realy nothing more than an approximation
and is not written in concrete.