HULL SPEED

[Tom G]

WHAT IS THE HULL SPEED OF A 1977 CAPEDORY 28, CAN ANYONE HELP ME WITH THIS QUESTION?

[Craig Curtis]

The square root of the length of your waterline multiplied by approximately 1.34. According to what I can see your waterline is 22' 2 1/2" . Therefore, your theoretical hull speed is about 6.3 knots. I hope you can spend a lot of time in that groove.

Craig Curtis
CD40 "Coalescence"
Chicago



Craig_Curtis@prusec.com

[Scott MacCready]

Here's a link to a neat tool to find out that info plus more about just about any sail boat. I can't take the credit for it, someone else posted it a few weeks ago.

<a href="http://www.image-ination.com/sailcalc.h ... lc.html</a>



scottmacc@coastalnet.com

[Catherine Monaghan]

You'll find a link to Carl's Sailing Calculator right on our own web site on the same page as the Cape Dory <a href="http://www.toolworks.com/capedory/ccdoi ... cations</a>.

Or, just scroll up to the top of the Cape Dory Board and click on the graphic "About Cape Dorys" or the link "Cape Dorys". Once there, click on the "Specifications of Cape Dory Boats" link. You'll find the link to Carl's Sail Calculator in that section.


Cathy
CD32 Realization, #3
CCDOA Assistant Webmaster

WHAT IS THE HULL SPEED OF A 1977 CAPEDORY 28, CAN ANYONE HELP ME WITH THIS QUESTION?

catherine_monaghanNOSPAM@merck.com

[D. Stump, Hanalei]

Captain Monaghan,

Thank you for reminding us that there is some really interesting stuff on this site that we don't often look at. I for one have not looked at the hull speeds for a CD-27, 28 or 30 (also, a 33, but who's looking?)in quite a while. I have just now, and I remain confident that I will remain.......your most HUMBLE servant...........

Dave Stump
Captain Commanding
s/v Hanalei CD-30C
CDSOA Number ONE ! ! !

[Neil Gordon]

>>The square root of the length of your waterline multiplied by approximately 1.34. According to what I can see your waterline is 22' 2 1/2" . Therefore, your theoretical hull speed is about 6.3 knots.<<

Further complicated, of course, because as the boat heels, the waterline increases. Now that I'm thinking about it, extra weight would raise the waterline and increase the length; that, too, would increase the theoretical hull speed.


Regards, Neil
s/v LIQUIDITY, BOston
CD28 #167



neil@nrgordon.com

[Hobbster]

Hull speed is the maximum speed that the boiat can go before the bow wave and the stern wave become one. The hull speed formula listed (1.34 X the square root of the waterline length) is almost correct. Different hulls make different wakes. You also have to multiply the answer by a hull coeffentent. The hull coeffentant for a fin keel will be differenf for a full keel boat. For the most part the number you get with the basic formula will be very close. Someone mentioned the fact that as the boat heels the WL will increase. This is true and the hull speed will increase as well. One America's Cup boat was designed with this in mind. The overhangs fore and aft were termendous and the WL almost doubled as the boat heeled over. Many think that the hul speed is the maximum speed the boat will go. Not so. To exceed the hull speed yopu need hoursepower such as a bigger motor or more wind/sail area.

So, when you have pushed your boat as fast as it will go and still are not in first place, have someone pull up the anchor, start the motor or tie on (or is that tie one on)to a faster boat.

Good luck,
Glen