On 13 Apr 2005 20:55:30 -0700, "Rolf" wrote:

I own a Newport 33 which has a waterline length of 27 ft. According to
the formula, the theoretical speed for the boat is 6.96 knots.
I have a 16 HP diesel with a 2 bladed impeller, and a maximum engine
RPM of 3300 RPM. Running the engine at 2700 RPM I can readily reach 6.5
knots.

I have a Viking 33 with same waterline. My direct-drive Atomic 4 with
a two-blade can drive the boat at 5.8 knots in flat water at
half-throttle, but it's too damn noisy to get it to 6.4...that final
half-knot is simply not worth the gas or the noise, as the A4 is
quieter than a diesel at anything but full out.

In a good wind I can go to 7 knots. The maximum speed I have ever done
was 11 knots on the GPS surfing down a wave with full sails up on a
very broad reach in about 30 knot wind. Many other boats of the same
design ( relatively light displacemnt, fin keel and spade rudder)
report he same thing.

Your results match mine. I can hit 7.1 or 7.2 knots SOG sustained in
25 knots on the right point of sail, but she'll "surf" to 10+ briefly
on a run.

snip

I think that traditional full keel boat with a high displacement would
have a lot of trouble getting close to Hull speed.

Not necessarily, but generally, that's correct. Full keelers can surf
on a run as well, but they frequently can't helm quickly enough to
maintain the right angle. On the other hand, in a three-day blow, I'd
much prefer to heave to in a full keeler.

Personal preference, location and experience play a huge role in
getting the most out of your boat. In a full keeler, you may never go
as fast as theory, but you may sail longer because the motion is less
whippy and exhausting. Personally, I like cutaway forefoot, skeg hung,
semi-full keelers. Best of all worlds if designed right. I even like
the still rare idea of canted fixed dual bilge keels with extendable
centerboards, but it's not common (yet).

R.