"DSK" wrote
| ... The Soverel 33 is renowned as
| a light-air speedster though, probably not a fair comparison. They make
| a wake you can hear from 1/2 mile off on days when the wind is barely
| enough to disturb cigarette smoke.

Capt. Mooron wrote:
Yeah Doug...and I can drink a keg of beer and not fall down.

Well, this winter why don't you snowmobile on down here and come sailing
on one... you'll see...


Oddly enough I don't see a bow wave on that vessel either.

The one that's anchored??



| Huh??? That's not at all how it works. The wave-making resistance of a
| hull increases with her speed in proportion to her Froude number, which
| is a fairly complex derivative.

That's not going to overcome friction/displacement and allow for a speed
faster than the wind pushing you is it?

??? It's easy to go faster than true wind speed. Beach cats and faster
monohulls do it all the time. It's not a question of "going faster than
the wind that's pushing you" it's a question of building apparent wind
and foil efficiency.

... Even on plane I doubt a boat will
exceed wind speed. That would border on the perpetual motion theory.

OK, after we go sailing on my friends Soverel 33, we'll take the Johnson
18 out. It's a hoot... and it's not perpetual motion.



Now that's odd..... hull speed is a figure of the hull's shape and wetted
surface.

No no no. "Hull speed" has nothing at all to do with wetted surface and
almost nothing to do with shape. Hull speed is the the speed at which
wave-making resistance, determined by waterline length, becomes greater
than any practical amount of power that can be applied.

Hulls experience two kinds of drag... surface friction and wave making.
Surface friction increases as the square of the velocity of the water
moving past the hull's skin, but it should be remembered that much of
this surface is going to be carrying water along with it (at least
somewhat) and this reduces drag. Surface friction is the major factor at
low speeds.

The key to understanding wave making resistance is to realize that the
faster waves go, the further apart their crests have to be. This is why
at lower speed, boats make waves at bow, 1/2 waterline length (or some
fraction of their LWL), and stern. When the boat is making only two
waves, at bow and stern, it is going at hull speed. Wave making
resistance increases at a somewhat higher exponential factor than
surface friction so at higher speeds it is more important.



Obviously we have a difference in interpretation of a wave here Doug. I
consider a six inch 'bow wave' as nothing more than a ripple. A bow wave is
when you have water curling off the bow.

And this can happen with waves less than 6" high.

... Upwind it's far easier to effect
this than downwind.

I don't think so, it seems to me that as far as the hull making waves
goes... the water neither knows nor cares if you're going upwind or down.

... I'm certain you've experienced the feeling of a heavy
boat cleaving a large wave on a downwind run and sending tons of water
aside.

Yes but it's more fun to feel a light boat getting ready to fly over the
waves.


I can move Overproof downwind easily at half her hull speed in 5 knots of
wind and only see ripples... not waves.

OK, if you're satisfied, I'm not going to argue that point.


| Jack Daniels? You can have my share... I've been hiding a bottle of
| single malt in the desk...

I found a bottle of cheap champagne in my cooler..... rum on Friday! ;-)

Rum mixed with champagne... hmm, sounds like a good morning drink all
right...

DSK