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Old 11-03-2013
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Re: Beamy modern boats and offshore cruising.

Quote:
Originally Posted by EricKLYC View Post
No doubt about that: the extremely wide and aft beam of the Pogo gives excellent control downwind, especially in waves.
Much better than e.g. the IOR typed Dehler 39 we sailed extensively before (less beam positioned much more forward, narrow transom).....The Dehler was quite a roller and rolling movements cause a lateral imbalance between the center of effort (sail) and the center of resistance (hull), generating a rotating couple of forces that constantly must be compensated at the wheel. These rudder movements even reinforce this imbalance and that’s why inexperienced helmsmen can induce a broach or a gybe by overcompensating at the wheel.
....
You give the impression that the Dehler 39 (a recent design, the previous model regarding Dehler 41) is a bad boat

Well it isn't, it is even today a very good performer even racing. It is not designed for IOR racing (I guess you don't mean that) but for IMS racing, the ratting that perfected give today's ORC. About the Dehler 39 some opinions:

A Rollicking Good Ride
"..Now comes the racy Dehler 39. Designed to the IMS rule by Judel/Vrolijk (a firm known for its Admiral's Cup successes), the 39s occupy the performance end of the cruiser/racer continuum. But her cherry interior and separate shower stall won't let you forget that she's built for comfort."

Cruising World, by Tim Murphy


Go-Faster cruiser

"..The Dehler 39 is a fast, responsive, classy package"

SAIL, by Tom Linskeyn and Bill Springer


Style and performance in a highly engineered racer-cruiser

"..We got onto open water, and the moderate northeaster started kicking up a chop on top of some residual swells from the previous day.

The Dehler didn't mind at all. It bit into the waves and powered through, holding its speed and showing no tendency to pound upwind. When we took the boat through a series of tacks, the Dehler came through the eye of the wind cleanly and was very forgiving on the occasion that I timed things perfectly to stick the boat's nose into a particularly sharp wave..
All in all, everything about the Dehler says it is a boat both designed and constructed to perform"

SAILING, by Adam Cort


This is not mean to take away anything you said. Obviously because you have owned a Dehler 39 and now own a Pogo 12.50, you are in an ideal position to compare both boats, it is just to give more emphasis to what you are saying:

The Dehler 39 was and still is a great boat, the fact that the Pogo 12.50 performs much better upwind and with following seas show how suited for those conditions those hulls are, when well designed.

An older narrower design would roll even more downwind and will require a good hand at the wheel ion trying and difficult conditions.

Quote:
Originally Posted by EricKLYC View Post
Of course all this comes with a price: less pointing ability and an uncomfortable behavior sailing upwind against seas, because of the lack of inertia and wave drag (I can’t find back your excellent earlier post about this, Paulo ).
But of course “gentlemen do not sail upwind”… .
Let me point out that there is another reason for the two rudder setup on very beamy boats with all the beam carried back. Those boats when heeled have an asymmetric water plan and a central only rudder would be way off the center of that plan, while the two rudder system is designed in a way that one of the rudders is right on the middle of that plan when the boat is heeled. That gives to the rudder a much bigger efficiency and allows it to have a much smaller wet surface and therefore less efforts on the rudder and on the wheel.

These designs (by Finot) are very old and I am not sure if twin rudders were used already but they show clearly the problem and why twin rudders are more efficient on these hulls.





Originally with these designs Finot wanted to show that a beamy boat will have, when heeled, a biger LWL than a similar sized narrow boat. both boats with the same LWL on a not heeled position.

Regards

Paulo
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Last edited by PCP; 11-03-2013 at 07:45 AM.
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