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v deep or rounded plaining??? #127133
12/28/07 12:16 PM
12/28/07 12:16 PM
Joined: Feb 2007
Posts: 78
rictorn Offline OP
journeyman
rictorn  Offline OP
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Posts: 78
i think we all know that all realise a rounded plaining hull is more efficient that an v deep one but as v deep ones such as a quattro or a pixie are so much easier to homebuild i was wondering

for a boat with the same rig how much slower how many points on a handicap system would a v deep hull be

or alternatively how much extra sail area would you have to put on the to make say f16ish cat to make a v deep hull go as quick???

-- Have You Seen This? --
Re: v deep or rounded plaining??? [Re: rictorn] #127134
12/28/07 06:56 PM
12/28/07 06:56 PM
Joined: May 2006
Posts: 954
Mumbles Y.C Wales U.K
Mark P Offline
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Mumbles Y.C Wales U.K

Cats can't plane...they just goooooooooo fast.


MP*MULTIHULLS
Re: v deep or rounded plaining??? [Re: Mark P] #127135
12/28/07 08:26 PM
12/28/07 08:26 PM
Joined: Jun 2001
Posts: 12,310
South Carolina
Jake Offline
Carpal Tunnel
Jake  Offline
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Posts: 12,310
South Carolina
oh they plane. Ever had the kite up in 20?


Jake Kohl
Re: v deep or rounded plaining??? [Re: Jake] #127136
12/28/07 08:51 PM
12/28/07 08:51 PM
Joined: Feb 2007
Posts: 78
rictorn Offline OP
journeyman
rictorn  Offline OP
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ok maybe a cat won't get fully up on the plane, but there is a speed on rounded hulled cats and even 1/2 rounded ones where they, lift less there is noticably less wetted are and thats sort of what i was wondering about any ideas???

Re: v deep or rounded plaining??? [Re: rictorn] #127137
12/28/07 09:06 PM
12/28/07 09:06 PM
Joined: Feb 2005
Posts: 4,118
Northfield Mn
Karl_Brogger Offline
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Northfield Mn
I haven't done been able to do it yet but my boat is supposed to plane. The hulls have a really flat bottom.

Re: v deep or rounded plaining??? [Re: rictorn] #127138
12/29/07 12:31 AM
12/29/07 12:31 AM
Joined: Oct 2002
Posts: 307
maui
jollyrodgers Offline
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jollyrodgers  Offline
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maui
i'll take the position that v hulls are not slower than rounded or flat hulls. in fact it is possible that there are conditions that a v hull would be faster.
the v hull is preferable in rough conditions because when you land the jumps the hull cuts right in rather than pounding.
when a v hull leans over you have a planning surface, and will just keep building speed.
in triangle racing the beats are important so dagger boards are preferred by most designers. a hole in the bottom of the hull is required for that which creates drag. designers live with the drag because the advantage gained on the beat is worth the cost of a hole in the hull.
if you could figure out a way to design a v hulled boat that was at the top mark in good shape you would have a competitive cat since you would at least be able to hold your own if not pull away on the downwind. they say it can't be done, but the are stories of the gcat 20 hanging with the tornado upwind.
it is job to develop a new design. got lots of time, experience, money, and dependable testing conditions?

Re: v deep or rounded plaining??? [Re: rictorn] #127139
12/29/07 02:56 AM
12/29/07 02:56 AM
Joined: Jul 2006
Posts: 1,147
Bay of Islands, NZ
W
warbird Offline
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warbird  Offline
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Bay of Islands, NZ
My Paper Tiger planed and so will my Tiger Shark....both V with hard chine.

Re: v deep or rounded plaining??? [Re: jollyrodgers] #127140
12/29/07 04:26 AM
12/29/07 04:26 AM
Joined: Jun 2001
Posts: 9,582
North-West Europe
Wouter Offline
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Wouter  Offline
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North-West Europe

I'm mostly with Jolly on this one.

The speed difference between a well designed Deep V-ed hull and a rounded keel hull is surprisingly small. No I wouldn't design a deep V-ed hull for racing in the F18 class, because it will be at a disadvantage on the start and upwind leg but that still doesn't say the disadvantage is very large.


Wouter

Last edited by Wouter; 12/29/07 04:32 AM.

Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
Re: v deep or rounded plaining??? [Re: warbird] #127141
12/29/07 06:54 AM
12/29/07 06:54 AM

A
Anonymous
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Anonymous
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A



Thought you had the TS back on the market. Was I wrong or did you change your mind?

Re: v deep or rounded plaining??? [Re: ] #127142
12/29/07 02:40 PM
12/29/07 02:40 PM
Joined: Jul 2006
Posts: 1,147
Bay of Islands, NZ
W
warbird Offline
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warbird  Offline
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Posts: 1,147
Bay of Islands, NZ
Sold one and bought another.
It has the larger 30 foot rig. Have changed all trim mechanisms and rudder set up. Sailed for first time yesterday in 5/8 knots and was flying a hull and going surprisingly fast. My changes so far are very sweet so I can continue.
Have a second mast that I am cutting to almost mast head and raking back like Hobie 16. Will cut sail like the rig pictured but larger for the 18 feet.
One hull has had a big hit but proff repaired. I still want to find better hulls but will use this to develop what I can.

As to up wind etc.
This project is simply to gain a high terminal reaching speed but I will attempt planing up wind. I don't pretend to understand the advantages for buoy racing. I am doing this only to create enjoyment for myself and discussion about planing cats.
My aim is 25 knots over 500 meters.
I will used no specific equipment developed after the design of the boat.
That is to say, yes it will have more powerful down haul out to the shrouds for example but use gear that was available then.

Attached Files
Re: v deep or rounded plaining??? [Re: ] #127143
12/29/07 02:55 PM
12/29/07 02:55 PM
Joined: Jul 2006
Posts: 1,147
Bay of Islands, NZ
W
warbird Offline
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warbird  Offline
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W

Joined: Jul 2006
Posts: 1,147
Bay of Islands, NZ
sold one and bought another with a bigger rig.
Have changed all of the outdated trim mechanisms and rudder set up. Tested that yesterday and all is great including an 8:1 mainsheet I set up with a free floating ratchamatic with tapered line.
Boat was flying a hull in 5/8 variable. Boat weighed in at 114K at birth so I am saying 120 now after a proff repair to damage.
I am still looking for goo hulls but this platform is good enough to develop idea of high terminal planing speed.
I have second mast I am cutting down to almost mast head and will rake that like a Hobie. See photo for sail style envisaged.

I am doing this for my own fun and satisfaction. Aim is 25 knots over 500 metres.

I do not pretend to understand any more than that I believe these old V hulls will plain more steadily and with a faster terminal speed that the round hulls.

I decided on this project after watching the World Tornado guys trying to get high speeds and was shocked at how unstable the platform became at only 22 knots.

I believe I have sailed one of these boats at over 20 knots with grunt and stability to spare and so am putting my efforts where my mouth is.

Attached Files
128899-Maricat.jpg (80 downloads)
Re: v deep or rounded plaining??? [Re: warbird] #127144
12/29/07 04:09 PM
12/29/07 04:09 PM
Joined: Feb 2005
Posts: 4,118
Northfield Mn
Karl_Brogger Offline
Carpal Tunnel
Karl_Brogger  Offline
Carpal Tunnel

Joined: Feb 2005
Posts: 4,118
Northfield Mn
What about all the speed you loose with a boat that tacks slowly, like a H16/14?

Re: v deep or rounded plaining??? [Re: Jake] #127145
12/30/07 02:10 AM
12/30/07 02:10 AM
Joined: Jun 2001
Posts: 1,459
Annapolis,MD
Keith Offline
veteran
Keith  Offline
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Joined: Jun 2001
Posts: 1,459
Annapolis,MD
Out of the boats I've owned/sailed, the only one that I would say that I have experienced true planing on is the N-20. In the rough, with wind, the boat picks up and gets quiet, and keeps hauling more butt. It feels great - get set, flick it upwind a tad to heat it and drive down fast and smooth. The first time we had the boat out in a lot of wind we shot down the Bay under main only, and with every gust it pick up, get quiet, and take off.

The N-20 hull section is fat and flat aft, and the hulls are canted. The bows, although flared pretty dramatically at the deck, are pretty standard stuff at and below the waterline. The bouyancy in the bows is a wonderful thing, but maybe not so good going out through surf. Other than that I wouldn't trade them.

My 6.0 never felt like it was planing, although it is plenty fast. Rounded hulls, decent bouyancy, not as fat as the N-20 hulls. These hulls cut through just about anything, just power through it. But again, never had the planing sensation like on the N-20. Same goes with the H-20, and H-18.

So, I'm fairly convinced that most of the rounded hulls at best semi-plane (like semi-displacement, semi-planing power boats). As for the v-hulls planing when heeled - that depends on the boat. Most v hulled boats are asymmetrical - the outside of the hull is flat and fairly vertical. I believe you'd have to heel pretty far to get planing action on such a hull. A symmetrical v would give you that action, and the less deadrise the quicker that would happen - but would it be as good upwind? And the chined v, with smaller amount of deadrise will present a planing section earlier, with boards might be the better of both worlds. I'm not convinced that on a decently made boat that the dagger slots should present a lot of drag relative to everything else.

I'm very intrigued by the hull shape of the Blade F-16 - with flat sections going all the way out to the bow stem. To me, the Blade is to the T-4.9 as the N-20 is to the N-6.0. Although I've not sailed the 4.9 or Blade, it appears that like the 6.0 and N-20, there are times when the 4.9 is faster, but on the whole the Blade is the faster boat. The main differences being the flatter hull sections.

Re: v deep or rounded plaining??? [Re: Karl_Brogger] #127146
12/30/07 01:42 PM
12/30/07 01:42 PM
Joined: Jul 2006
Posts: 1,147
Bay of Islands, NZ
W
warbird Offline
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warbird  Offline
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W

Joined: Jul 2006
Posts: 1,147
Bay of Islands, NZ
The Hobies could never be accused of planing but the sailors sure have the 16 maxing out to its potential on a reach.
The Tiger Shark is 18 feet with dagger boards and tacks easily.

My fast run was on the face of a 20/25 knot front coming in over a flat sea. I was planing on both hulls with a 5/10 degree heel only. A witness said the boat appeared flat.
It was smooth like a speedboat, not touchy at all and showed no signs of nose down etc. A note is that the chap on the trap that day will simply not get on that boat again.....it might have been my wild cheering that created his aversion. : )


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