Announcements
New Discussions
Previous Thread
Next Thread
Print Thread
Rate Thread
Hop To
daggarboards #249135
06/04/12 11:19 AM
06/04/12 11:19 AM
Joined: Dec 2001
Posts: 5,590
Naples, FL
waterbug_wpb Offline OP
Carpal Tunnel
waterbug_wpb  Offline OP
Carpal Tunnel

Joined: Dec 2001
Posts: 5,590
Naples, FL
With all the talk about curved and RLB (ridiculously long boards), someone mentioned the same lift/lateral resistance could be achieved by moving the daggars forward.

Would anyone care to elaborate? If this theorum is true, would it make sense to just have shorter/straight boards further forward?


Jay

-- Have You Seen This? --
Re: daggarboards [Re: waterbug_wpb] #249136
06/04/12 11:37 AM
06/04/12 11:37 AM
Joined: Nov 2005
Posts: 141
M
mini Offline
member
mini  Offline
member
M

Joined: Nov 2005
Posts: 141
Originally Posted by waterbug_wpb
With all the talk about curved and RLB (ridiculously long boards), someone mentioned the same lift/lateral resistance could be achieved by moving the daggars forward.

Would anyone care to elaborate? If this theorum is true, would it make sense to just have shorter/straight boards further forward?


Ask Bill Roberts about this and the wild sucess of the 21 that sailed around Fl for a while I believe.

Re: daggarboards [Re: waterbug_wpb] #249138
06/04/12 12:33 PM
06/04/12 12:33 PM
Joined: Jun 2001
Posts: 733
Home is where the harness is.....
Will_R Offline
old hand
Will_R  Offline
old hand

Joined: Jun 2001
Posts: 733
Home is where the harness is.....
It's more complicated than fore/aft. The boards/rudders work in conjunction to provide the necessary lift (lateral resistance) to make the boat go forward.

At low hull speeds, the amount of lift created per area of foil is less than at speed (related as the square of the velocity, just like drag). Therefore at lower speeds, you need more board to provide the necessary lift to "stop" lateral slippage.

The only thing that moving boards forward or aft does (with conventional straight foils) is change the relative center of lift of the foils in relationship to CE/CL of the sails. You don't create additional lift, you only move it. i.e. if you move them further forward, you will load the rudders more and change the helm.

With regards to length, typically the designers are going for efficiency. The aspect ratio of the board is directly related to their efficiency. Longer boards are more efficient, but don't produce as much lift at low speeds and have a MUCH narrower grove. Short board provide more lift at low speed, however are less efficient, but have a wider grove.

One other factor is "tripping". Longer boards will fly a hull faster than shorter boards b/c of their increased lever against the hulls.

It's all a trade off for one performance gain against another. Build something that is theoretically more efficient, but won't ever hit it's range and it's likely to be slower than a less efficient platform that will be able to reach it's operational range.

Re: daggarboards [Re: Will_R] #249159
06/04/12 01:42 PM
06/04/12 01:42 PM
Joined: Dec 2001
Posts: 5,590
Naples, FL
waterbug_wpb Offline OP
Carpal Tunnel
waterbug_wpb  Offline OP
Carpal Tunnel

Joined: Dec 2001
Posts: 5,590
Naples, FL
Originally Posted by Will_R
It's all a trade off for one performance gain against another. Build something that is theoretically more efficient, but won't ever hit it's range and it's likely to be slower than a less efficient platform that will be able to reach it's operational range.


gotcha.. Figured as much. Build a high-performance boat with a narrow groove to keep the racers happy, but at risk of dissuading the general weekend warrior types who rarely find the groove...?


Jay

Re: daggarboards [Re: waterbug_wpb] #249162
06/04/12 01:48 PM
06/04/12 01:48 PM
Joined: Jun 2001
Posts: 12,310
South Carolina
Jake Offline
Carpal Tunnel
Jake  Offline
Carpal Tunnel

Joined: Jun 2001
Posts: 12,310
South Carolina
Originally Posted by waterbug_wpb
With all the talk about curved and RLB (ridiculously long boards), someone mentioned the same lift/lateral resistance could be achieved by moving the daggars forward.

Would anyone care to elaborate? If this theorum is true, would it make sense to just have shorter/straight boards further forward?


But then it won't tack W.A.P. (worth a poop).


Jake Kohl
Re: daggarboards [Re: waterbug_wpb] #249166
06/04/12 02:13 PM
06/04/12 02:13 PM
Joined: Jun 2001
Posts: 733
Home is where the harness is.....
Will_R Offline
old hand
Will_R  Offline
old hand

Joined: Jun 2001
Posts: 733
Home is where the harness is.....
Originally Posted by waterbug_wpb
gotcha.. Figured as much. Build a high-performance boat with a narrow groove to keep the racers happy, but at risk of dissuading the general weekend warrior types who rarely find the groove...?


I don't think they think about it directly like that, but I think that is the root of the process. A word comes to mind and that's "sailability". If the boat "sails well", it's design is probably pretty good and you'll feel it feel good more often. I sail on a boat with a super narrow grove and you can tell when you're not there. It is super fast, but you have to be on your toes at all times or you're not getting close to hitting your number.

Last edited by Will_R; 06/04/12 02:19 PM.
Re: daggarboards [Re: Will_R] #249171
06/04/12 03:15 PM
06/04/12 03:15 PM
Joined: Jun 2001
Posts: 12,310
South Carolina
Jake Offline
Carpal Tunnel
Jake  Offline
Carpal Tunnel

Joined: Jun 2001
Posts: 12,310
South Carolina
All I knew to feel when I started sailing was whether or not a hull was flying. I would have had as much fun on a spin-less F18 as my Nacra 5.2 and not known any difference. Now, finding a spin-less F18....


Jake Kohl
Re: daggarboards [Re: Jake] #249174
06/04/12 03:46 PM
06/04/12 03:46 PM
Joined: Jun 2001
Posts: 3,906
Clermont, FL, USA
David Ingram Offline
Carpal Tunnel
David Ingram  Offline
Carpal Tunnel

Joined: Jun 2001
Posts: 3,906
Clermont, FL, USA
Originally Posted by Jake
All I knew to feel when I started sailing was whether or not a hull was flying. I would have had as much fun on a spin-less F18 as my Nacra 5.2 and not known any difference. Now, finding a spin-less F18....


Found one, taking the spin off costs extra though.


David Ingram
F18 USA 242
http://www.solarwind.solar

"Do or do not. There is no try." - Yoda
"Excuses are the tools of the weak and incompetent" - Two sista's I overheard in the hall
"You don't have to be a brain surgeon to be a complete idiot, but it helps"

Moderated by  Damon Linkous 

Search

Who's Online Now
1 registered members (TimTT), 603 guests, and 90 spiders.
Key: Admin, Global Mod, Mod
Newest Members
Darryl, zorro, CraigJ, PaulEddo2, AUS180
8150 Registered Users
Top Posters(30 Days)
Forum Statistics
Forums26
Topics22,404
Posts267,055
Members8,150
Most Online2,167
Dec 19th, 2022
--Advertisement--
Powered by UBB.threads™ PHP Forum Software 7.7.1