Hull forms

Here' a couple of links I dug up from my old computer.

They deal with computer modeling low drag K1 hulls.
Possibly a bit out of date now, as they refer to the now defunct minimum width rules, but the physics never change.

Worth a read

linked from the first link, also worth a read


Another good basic read in plain english.

Even more hull shape stuff


And for the curious amongst you, how much drag when your boat is on your roof?

Much less than I imagined

The main drag on my roof comes from the roof rack not the ski in my case. With the ski on the rack I actually feel some improvement in drag

With the somewhat underpowered hybrids that I've been driving lately I can really feel the difference with and without a roof rack. My roof rack adds about 25% fuel consumption penalty at moderate highway speeds (65 or so mph). E.g. instead of getting about 50 miles per gallon I get down to 40 or so. The "imperially challenged" can do their own conversion, he-he, but I gather 50mpg equates to something like 4.8 liters per 100 km (roughly). Or eaquivalently, to maintain close to 50 mpg (e.g. ,the same resistance as without the roof rack), I need to drive about 10-15mph slower with the ski/rack than without them.

How do I know? My car has a fairly accurate consumption monitor and I've been tracking my real mileage/consumption at the pump enough to be comfortable with the car computer's estimate to within 2% of reality on average.

After I have the rack installed, adding the ski does not seem to make much of a difference, except I get less wind noise than with the rack alone so it's got to be good to have it on...