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Re: Hull Design Philosophy [Re: ] #161452
11/26/08 05:44 AM
11/26/08 05:44 AM
Joined: Jun 2001
Posts: 9,582
North-West Europe
Wouter Offline
Carpal Tunnel
Wouter  Offline
Carpal Tunnel

Joined: Jun 2001
Posts: 9,582
North-West Europe
Quote

But then if you fit T foils as they are currently being fitted (ie no control mechanisms) you are adding drag to all but the optimum case.



I feel the magnitude of this drag is negligiable. At least I never felt slower when I sailed on a boat fitted with these.

I also believe that in ALL conditions, except the absolute extremes, that the boat is optimal when sitting perfectly on its intended waterline. You achieve this attitude by shifting your weight around I you angle your T-foils to that attitude then I don't see what they at large drawbacks to the design. You make it is out as if their is only attitude among many at which the T-foils are not a drag but I seriously doubt whether many different attitudes of the boat (hulls) are really used in real sailing anyway.

I more strongly feel that lots of sailors dismiss the T-foil rudders on unfounded reasons. From my experience these things are really as good as sliced bread. Afterall, we can have similar arguments about fitted daggerboards or not. Still we all know that the advantages of having these far outweight the drawbacks in the way of performance. T-foils are the same way. Hell, even in lighter wind conditions the stabilizing of the rig (less swinging back and forth) could already be enough to ofset for the added drag. That is what John Pierce feels is the case and I can not find fault with that from my personal experience with T-foils.

I say try them before you knock them and don't look at A-cats. There are more things they don't do but works really well on other designs nevertheless.

Personally, I'm convinced in them enough to want to fit them to my own F16 when my budget allows that. I feel they will transform my Taipan F16, which has the least bow volume and freeboard of all F16's except Altered !

Wouter


Last edited by Wouter; 11/26/08 05:46 AM.

Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
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Re: Hull Design Philosophy [Re: Wouter] #161479
11/26/08 12:39 PM
11/26/08 12:39 PM
Joined: Sep 2007
Posts: 571
Hamburg
Smiths_Cat Offline
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Hamburg
After all I think that the effect of hull shape and T foils on performance are overestimated.
If T foils would be a game changer, Stealths would dominate all F16 events, but my impression is the current F16 design a quite comparable in perfomance.
Same for hull shapes. On the last A worlds many different hull design philosophy were present from Marstrom to LR2. Taking into account that the best sailors have in general the newest material, I would conclude that no particular hull shape is a must to win. The vintage style Tornado hulls are another example.

Performance is one factor (water line length, Sears volume distribution and low pitching motion are the key factors), however most F16 sailors are recreational racers, more for fun than the ultimate racing boat (at least my impression). A low free-board (the distance from the water plane to the trampoline, don't know the english word) should not be forgotten: How easy is the boat to right and how easy is it to come back on board depends on that. This is important for smaller and lighter persons. Unfortunately designer consider the standard US or European man. My wife had problems to come on board a Tiger, because the hulls are to high. And to be honest I and many friends need more than one attempt to come back on larger cats like Ts or F18s. A wave slapping against the rear beam or the tramp at 5 Bft costs me how many seconds? Is my week end fun reduced because of it? Certainly not.

Cheers,

Klaus

Re: Hull Design Philosophy [Re: Smiths_Cat] #161495
11/26/08 05:44 PM
11/26/08 05:44 PM
Joined: Apr 2003
Posts: 1,669
Melbourne, Australia
Tornado_ALIVE Offline
Pooh-Bah
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Pooh-Bah

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Melbourne, Australia
Each wave slap can cost you several boat lengths, not to mention assisting in nose diving as the boat decelorates and transom pushed up. Not so much of an issue in flat water but when there is large chop..... It is not pretty.


Re: Hull Design Philosophy [Re: Tornado_ALIVE] #161499
11/26/08 06:28 PM
11/26/08 06:28 PM
Joined: Oct 2005
Posts: 951
Brisbane, Queensland, Australi...
ncik Offline
old hand
ncik  Offline
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Posts: 951
Brisbane, Queensland, Australi...
Freeboard is the correct English word.

Consider a rope ladder for getting back onboard cats with high freeboard. This was of major concern for the F12 I designed for solo kids.

Re: Hull Design Philosophy [Re: ncik] #161514
11/26/08 09:15 PM
11/26/08 09:15 PM
Joined: Sep 2006
Posts: 586
Hobart, Tasmania, Oz.
Dazz Offline
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Dazz  Offline
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Posts: 586
Hobart, Tasmania, Oz.
I found the tiger easy to get back onto. the capricorn is higher out of the water, I would imaging the viper being so similar would be about the same.



C2 AUS 222 by Goodall design
"Darph Bobo"
Re: Hull Design Philosophy [Re: Dazz] #161522
11/27/08 01:06 AM
11/27/08 01:06 AM
Joined: May 2003
Posts: 4,451
West coast of Norway
Rolf_Nilsen Offline

Carpal Tunnel
Rolf_Nilsen  Offline

Carpal Tunnel

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West coast of Norway
http://www.youtube.com/watch?v=W4Y5z_pZmNE

And it is even easier from the water with a solid platform to pull/push on smile


Fit females can do the same thing, with style:
http://www.youtube.com/watch?v=n4A5sQ-2Cgw


If sailing two up, one just walks up the hull while righting. Then helps the partner up. Best and safest if both are able to boost themselves up. My favourite spot to enter the boat from the water is at the intersection between mainbeam and hull. Nice triangle to pull/push on and no scratches/holes on the boat. Also a place very close to you after righting the boat.



Re: Hull Design Philosophy [Re: Rolf_Nilsen] #161524
11/27/08 02:16 AM
11/27/08 02:16 AM
Joined: Mar 2008
Posts: 201
Adelaide, South Australia
simonp Offline
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simonp  Offline
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Posts: 201
Adelaide, South Australia
After capsizing three times 2 weeks ago I learnt that lots of free board does have it's downside. It's bloody hard to get back on the boat. The stingray was lower in the water and narrower so i could put one hand on the hull and the other on the spinaker pole and push my self up over the mainbeam. That doesn't work on the blade. I had to swim around to the side of the hull, jump up to the trapeze handle and pull my self up from there, which i think is a slow and risky way to do it. (as I found out when the boat sailed away from me*). On my third attempt I thought about a rope ladder off the mainbeam, has anyone successfully tried this before?


* big thank you to the rescue boat who picked me up and quickly put me back on the boat


Simon
BLADE F16 AUS405
Re: Hull Design Philosophy [Re: simonp] #161525
11/27/08 02:51 AM
11/27/08 02:51 AM
Joined: May 2003
Posts: 4,451
West coast of Norway
Rolf_Nilsen Offline

Carpal Tunnel
Rolf_Nilsen  Offline

Carpal Tunnel

Joined: May 2003
Posts: 4,451
West coast of Norway
Did we not have a long righting thread about a year ago?

Re: Hull Design Philosophy [Re: Rolf_Nilsen] #161527
11/27/08 04:03 AM
11/27/08 04:03 AM
Joined: Jul 2002
Posts: 539
taipanfc Offline
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taipanfc  Offline
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Posts: 539
You can set up a rope climbing ladder attached to the front beam with a bungee holding it under the tramp. Couple of boats in Singapore use this as some of the crews can be quite small and struggle at times getting up onto the Taipan.

Re: Hull Design Philosophy [Re: ] #161529
11/27/08 05:21 AM
11/27/08 05:21 AM
Joined: Sep 2005
Posts: 893
W
waynemarlow Offline
old hand
waynemarlow  Offline
old hand
W

Joined: Sep 2005
Posts: 893
[/quote]

Hi all,

"Altered" performed with less than A class bouyancy, better than it could have been expected. Of course it did best upwind but still performed OK downwind to a point. I would look for more freeboard primarily, as excessive forward bouyancy on the water line may make it hard to drive upwind. My guesstimate from experience on "Altered" It was the beams hitting the water that stopped it as often as not. [/quote]

From memory on Altered you cut length off the bow, as a single hander if you left the bow long as per the A's and cut length from the rear part of a A design, would we not have a good compromise, foward boyancy to handle the spinnaker and the A's good hull design ?

Re: Hull Design Philosophy [Re: waynemarlow] #161530
11/27/08 05:27 AM
11/27/08 05:27 AM
Joined: May 2003
Posts: 4,451
West coast of Norway
Rolf_Nilsen Offline

Carpal Tunnel
Rolf_Nilsen  Offline

Carpal Tunnel

Joined: May 2003
Posts: 4,451
West coast of Norway
Here is the old righting discussion I remembered: http://www.catsailor.com/forums/ubbthreads.php?ubb=showflat&Number=88315

Better to continue discussing righting there instead of in Scarecrows hull design philosophy thread.

Re: Hull Design Philosophy [Re: taipanfc] #161548
11/27/08 10:34 AM
11/27/08 10:34 AM
Joined: Jun 2004
Posts: 1,479
Thailand
Buccaneer Offline
veteran
Buccaneer  Offline
veteran

Joined: Jun 2004
Posts: 1,479
Thailand
The Taipan? Never heard of such a thing but if the taipan is tough to re-board then the viper must be nearly impossible.;-))

Originally Posted by taipanfc
You can set up a rope climbing ladder attached to the front beam with a bungee holding it under the tramp. Couple of boats in Singapore use this as some of the crews can be quite small and struggle at times getting up onto the Taipan.


"House prices have risen by nearly 25 percent over the past two years. Although speculative activity has increased in some areas, at a national level these price increases largely reflect strong economic fundamentals." – Ben Bernanke – 2005
Re: Hull Design Philosophy [Re: Rolf_Nilsen] #161574
11/27/08 08:31 PM
11/27/08 08:31 PM

S
Scarecrow
Unregistered
Scarecrow
Unregistered
S



Originally Posted by Rolf_Nilsen
Here is the old righting discussion I remembered: http://www.catsailor.com/forums/ubbthreads.php?ubb=showflat&Number=88315

Better to continue discussing righting there instead of in Scarecrows hull design philosophy thread.


With all due respect Rolf, this does all impact on the hull design and is perfectly welcome.

Re: Hull Design Philosophy [Re: ] #161583
11/28/08 04:18 AM
11/28/08 04:18 AM
Joined: May 2003
Posts: 4,451
West coast of Norway
Rolf_Nilsen Offline

Carpal Tunnel
Rolf_Nilsen  Offline

Carpal Tunnel

Joined: May 2003
Posts: 4,451
West coast of Norway
By all means, your thread smile

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