Author Topic: What tail?  (Read 5882 times)

Dwight (DW)

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Re: What tail?
« Reply #15 on: January 14, 2013, 06:55:18 AM »
What happens if we take the side rails sharp even further forward?

Henrik F
The board gets clumsy. More fun when softened.

Henrik F

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Re: What tail?
« Reply #16 on: January 14, 2013, 07:00:12 AM »
What happens if we take the side rails sharp even further forward?

Henrik F
The board gets clumsy. More fun when softened.

Ok!

crosswater.se

TWsup

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Re: What tail?
« Reply #17 on: January 15, 2013, 02:42:31 PM »
IMO the rails don't need to be super sharp but the edge along the back of the board does.

DJ

check. this is what I believe is correct in regards to efficiency.
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Fanatic Allwave 9-2
Naish Keiki 9-0

TWsup

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Re: What tail?
« Reply #18 on: January 15, 2013, 02:52:59 PM »
Henrik,

take a close look at photos of the new Fanatic Falcons. they have rounded rails all the way back and only a sharp release at the rear edge on the tail. supports DJs statement.
this is how a displacement hull is designed.
adding tighter/edge rails to last meter of so ( like Bark competitor et al ) allows board to plane on waves easier, and I suspect easier to tail turn. The larger surface area as a result of harder rails planes easier.

I'm sure there are multiple interdependent design factors like rocker, bottom shape in cross section width and outline ( plan form) that effect this too.

in theory, absolutely best displacement shape is near cylindrical  cross section with pointy ends. but you can't stand on it...
Bark Competitor 12-6
Fanatic Allwave 9-2
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Henrik F

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Re: What tail?
« Reply #19 on: January 16, 2013, 01:51:01 PM »
Henrik,

take a close look at photos of the new Fanatic Falcons. they have rounded rails all the way back and only a sharp release at the rear edge on the tail. supports DJs statement.
this is how a displacement hull is designed.
adding tighter/edge rails to last meter of so ( like Bark competitor et al ) allows board to plane on waves easier, and I suspect easier to tail turn. The larger surface area as a result of harder rails planes easier.

I'm sure there are multiple interdependent design factors like rocker, bottom shape in cross section width and outline ( plan form) that effect this too.

in theory, absolutely best displacement shape is near cylindrical  cross section with pointy ends. but you can't stand on it...

Hello. Cannot find any photos and the rails but I see what you mean. Like an old Div II windsurfingboard. Sort of. But I don't understand why their new 14' is almost a pintail?

Henrik F
crosswater.se

DavidJohn

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Re: What tail?
« Reply #20 on: January 16, 2013, 02:52:19 PM »
Check out my pictures of the tail of last years Fanatic.. Here.. http://www.standupzone.com/forum/index.php?topic=10610.0

Compared with my latest pictures of the tail of this years Fanatics.. Here.. http://www.standupzone.com/forum/index.php?action=profile;u=229;sa=showPosts;start=210

See how very different they are..

I'm guessing that because the board gets tipped from side to side often when paddling if you have sharp rails in the tail area you get a lot of resistance resulting in drag and slowing you down.

With the very soft rails (not just soft but actually rounded) the board can be tipped from side to side without disturbing the water so much (even though it might be more tippier) there should be less drag.

Maybe there's more to it.

DJ
« Last Edit: January 16, 2013, 02:54:56 PM by DavidJohn »

DurhamSUP

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Re: What tail?
« Reply #21 on: January 17, 2013, 06:21:43 AM »
This is interesting.Looks like there is a lot of belly in the board too.
I always did hard rails on the last 12-18" of the board, depending on the outline. I'll give the round rails a try on my next flat water board. I sure do hate glassing hard rails anyway.

Henrik F

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Re: What tail?
« Reply #22 on: January 17, 2013, 12:54:09 PM »
Hmm. I have to sit down and talk all these things through with the shaper I am going to work with  ???

Thanks!

Henrik F
crosswater.se

TWsup

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Re: What tail?
« Reply #23 on: January 20, 2013, 12:27:21 PM »
at this point, I'm pretty convinced DJ is right. My boat design study from 30 years ago is coming back...
board will be less stable but heel angle changes don't effect efficiency as much.

those hard rails will be best when planing on DW rides.

when I start on my 16 footer it will have these kinda rails.

back to having square tail. having square tail will add buoyancy to tail allowing it to raise when swells overtake you from the rear. a pin tail will be better in total flat, but may make board yaw and broach in following seas.

wish I had my sketch books from 1982. I remember clearly drawing ideas for displacement windsurf boards that looked like these Fanatics. never built one tho- didn't have the facilities.
Bark Competitor 12-6
Fanatic Allwave 9-2
Naish Keiki 9-0

supuk

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Re: What tail?
« Reply #24 on: January 20, 2013, 12:45:57 PM »
the problem is theres a line between a board being very efficient but tippy and being able to efficiently paddle a board. i paddled the  falcon at the bop which has the rounded rails and found it a right handful in chop having to take nearly every other stroke to catch myself were as the 2012 board was stable as a rock in any condition far worse than that of the bop. The thing is finding a compromise between everything for the conditions you intend to use a board in.

Henrik F

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Re: What tail?
« Reply #25 on: January 20, 2013, 01:12:24 PM »
the problem is theres a line between a board being very efficient but tippy and being able to efficiently paddle a board. i paddled the  falcon at the bop which has the rounded rails and found it a right handful in chop having to take nearly every other stroke to catch myself were as the 2012 board was stable as a rock in any condition far worse than that of the bop. The thing is finding a compromise between everything for the conditions you intend to use a board in.

"The thing is finding a compromise between everything for the conditions you intend to use a board in." It is just that...  :-\

Henrik F
crosswater.se

 


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