Have no idea how fast a Nordica 30 is, don't recall seeing phrf #'s. Never
attempted to do any reverse calculations, ie., how fast is a particular boat
based on it's phrf #, but I feel it is a useful tool when comparing boats of
similar length. BTW, more than one responder on the CR list told me they
didn't consider their CR38 to be a fast boat, no one, including the lake
sailors, claimed their boat would do 11 kts.

SPEED/LENGTH RATIO (V/ L.5): This is the speed in knots divided by the
square root of the LWL. For example, a 25 foot waterline sailboat moving at
5.5 knots would be at a V/ L.5 of 1.1. while a 400 foot LWL destroyer
travelling at 22 knots also has a V/ L.5 of 1.1. Both vessels would develop
about the same resistance per ton of displacement as they are both running
at the same V/ L.5.
The limiting speed for a pure displacement hull is a V/ L.5 of 1.34. Above
this speed the stern wave moves aft so that the stern loses bouyancy, the
hull squats, and great additional power is necessary for a small gain in
speed. In truth, the typical cruising sailboat probably averages a V/ L.5 of
about .9 - 1.0 and only gets close to 1.3 when reaching in a stiff breeze.
Tender boats may never get above 1.2 as the crew has to ease sheets when the
rail buries!

The modern beamy, super light ocean racer can have a stern wide enough to
resist squatting and the stability to stand up to a breeze so often achieves
speeds well above 1.4, but that is semi-planing and the boat is getting lift
aft due to its speed. My BOC 60 design exceeded 20 knots at times, a V/ L.5
ratio of over 2.6, but those are very specialised yachts.

Ted Brewer " Understanding Boat Design 4th. Edition"

http://www.tedbrewer.com/yachtdesign.html

John Cairns



"Capt. Mooron" wrote in message
...

John you can be as surprised as you like.... I'm certain of the figures
but
won't have the documentation to offer until well into the middle of next
month.

Insofar as the owner's response..... there is a Nordica 30 owner right
here with a sister ship to mine that claims he has never gotten beyond 6
knots of speed from the vessel. I understood that statement when I first
sailed along side him in my boat. His vessel will not do over 6 knots...
but
it has nothing to do with the vessel's abilities and all to do with it's
set-up and handling.

Now you'll tell me that a speed of over 9 knots sustained is impossible on
Overproof I suppose!

CM

"John Cairns" wrote in message
om...
| Don't remember that one, but I was surprised by Mooron's statement, so
| surprised that I let it pass for a while. When I first saw the statement
| "11kts in 6 ft of water" my initial reaction is that he was loaded and
got
| the numbers backwards. Then he insisted it was correct, and offered to
post
| proof in the form of log entries that he was going to post to his
webshots
| album. In any event, got some info from folks on the Cabo Rico list, at
| least one of whom indicated that the CR38 is slower than I imagined,
even
| got an offer to take a tour of a boat in Port Clinton, Ohio, hope to do
that
| before the season ends.
|
| "If you are going to windward, a 150 mile day is going to be hard to do.
On
| a
| reach or downwind with the right sails it is easy to do. The CR38 has a
29
| ft
| waterline so it does about 7kts if the wind and sails are right, and
| because
| it has a full keel (lots of wetted surface) the bottom needs to be kept
| clean"
|
| Quote from an owner, which were my thoughts about hull speed, too much
| wetted surface, too short a LWL. Still a great blue water boat, just not
a
| fast one.
|
| John Cairns
|
| "SAIL LOCO" wrote in message
| ...
| Claiming that a CR 38 will do 11 knots is
| a bit of a stretch, don't you think?
|
| Well you should remember that the Boobster told us he did 13kts in
8kts
of
| wind
| with his 70s era tub.
| S/V Express 30 "Ringmaster"
| "Trains are a winter sport"
|
|