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-   -   Can planing hulls exceed hull speed upwind? (http://www.sailnet.com/forums/general-discussion-sailing-related/91276-can-planing-hulls-exceed-hull-speed-upwind.html)

peterchech 08-23-2012 04:41 PM

Can planing hulls exceed hull speed upwind?
 
Now the theoretical hull speed for my boat is about 5 knots, but I regularly hit 6 knots upwind, and I know that this is not unusual. I have gone 9 knots downwind on a 26' non-planing boat under spinnaker, with the transom sucking down and all. So hull speed can be exceeded somewhat in most boats I get this.

But many sportboats advertise "multihull speeds in a monohull". Multihulls don't have the same transom-sucking hull speed limitations that monohulls do. Now downwind a sport boat can jump on plane, and a 21' viper will easily do 14 knots in any decent breeze. This is almost 3 times the theoretical hull speed, and getting close to being as fast as a similarly sized cat or tri. But what about upwind?

Can these sportboats, with their planing hulls, do anything close to what multis can do on points of sail from a reach to upwind? ie can they jump on plane and significantly exceed hull speed upwind? Or is that $50,000 melges 22 gonna be just as slow as my hunter on anypoint of sail above a broad reach?

Jeff_H 08-23-2012 04:47 PM

Re: Can planing hulls exceed hull speed upwind?
 
Both multihulls and and some sportboats are capable of acting as semi-displacement boats upwind. In other words, they are designed to miimize the size of their bow and quarter waves and so can achieve speeds which exceed their theoretical hull speed. But besides hull speed is not an absolute brick wall, it is only a point where dynamic drag rises very steeply.

Jeff

Loki9 08-23-2012 05:27 PM

Re: Can planing hulls exceed hull speed upwind?
 
Yes, they can.

Barquito 08-24-2012 12:18 PM

Re: Can planing hulls exceed hull speed upwind?
 
1 Attachment(s)
I would add to Loki9's response the following:

aa3jy 08-24-2012 12:32 PM

Re: Can planing hulls exceed hull speed upwind?
 
Yep..seen it done. When the Coast Guard tows in a strickened sailboat(displacement hull) under power of the CG cutter..just about destroys the boat at 20knts+..:eek:

rgscpat 08-25-2012 12:53 AM

Re: Can planing hulls exceed hull speed upwind?
 
Extreme example: foiling Moth (hydrofoil).

WDS123 08-25-2012 05:57 AM

Re: Can planing hulls exceed hull speed upwind?
 
Yes,

Schock 40

Ultimate 20

peterchech 08-25-2012 10:22 AM

Re: Can planing hulls exceed hull speed upwind?
 
That ultimate 20 looks like a really fun boat! But what kind of speeds are we talking upwind? I mean a multi is doing 10 and up no sweat, what will that ultimate 20 do upwind?

WDS123 08-25-2012 10:47 AM

Re: Can planing hulls exceed hull speed upwind?
 
The Ultimate 20 was originally comiisioned by a group of Santa Cruz Hobie Cat sailors who were aging out of their Hobies.

Jim Antrim designed the boat to be a monohull that reached multihull speeds.

U20 Class Association

Flybyknight 08-25-2012 02:16 PM

Re: Can planing hulls exceed hull speed upwind?
 
Quote:

Originally Posted by Loki9 (Post 913410)
Yes, they can.

Big Time!


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