Author Topic: What tail?  (Read 5881 times)

Henrik F

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What tail?
« on: January 11, 2013, 02:48:20 PM »
Hello!
I am going to build a board for flatwater and whitecap waves. I haven't yet decided if it is going to be 12'6" or 14' but I need som thoughts of the boards tail. Can anyone please explain the pros and cons of a pintail or a "squaretail" in those conditions? Please help me out. I don't want to start off the wrong way.

Thanks

Henrik F
crosswater.se

DavidJohn

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Re: What tail?
« Reply #1 on: January 11, 2013, 03:18:55 PM »
Put a square tail on it and it's almost like having a 15' board that's only 14' long.. or a 14' board that's only 12'6" long.

IMO its really that simple.. Paddle a board without looking back and you could not tell what shape tail it is.. Pin, round, diamond or swallow tail.. It's not like a suring board so you might as well keep it simple and just go with what almost everyone else does now.. a square tail.

DJ

DurhamSUP

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Re: What tail?
« Reply #2 on: January 11, 2013, 04:28:47 PM »
Yup, I would go with square as well. The benefits of the stability out way the reduced drag of the pin tail. I have found that the pin does release the water cleaner with less turbulence, so if you were only ever paddling in pure glassy conditions, the pin would be better.  ...and stability wouldn't be an issue.
In normal conditions, the square tail is the way to go.
I do remember seeing a video of Joe Bark talking about a pin tail dominator that he no longer (or rarely) makes any more. I think the rationale was that everyone preferred the square.

Just be sure to make the edges at the tail as sharp as possible for clean release.

Henrik F

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Re: What tail?
« Reply #3 on: January 11, 2013, 10:29:08 PM »
Ok thanks. Squaretail it will be then  :)

Henrik F
crosswater.se

Jethrow

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Re: What tail?
« Reply #4 on: January 12, 2013, 02:51:34 PM »
As a follow up question, does a square or diamond tail increase stability over a pin tail?

Here's why...
I built a 16' pin tail flat water board and I am having stability issues. I haven't fallen off in normal flat water conditions but I do this running on the spot thing (alternating weight rail to rail quite fast) every now and then to try and stay on and this can't be fast. Any sort of side wave from a power boat or such would definitely see me in the water.

If I cut the board down to 14' with a square or diamond tail will this increase or decrease the stability? I'm just shy of 100Kg's and the board is 70cm wide with a rounded bottom shape (probably too much round).

I've spent the weekend cutting foot wells into the deck to get my center of buoyancy lower but haven't tried out the results yet.

Thanks
Jethrow

DavidJohn

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Re: What tail?
« Reply #5 on: January 12, 2013, 03:49:49 PM »
As a follow up question, does a square or diamond tail increase stability over a pin tail?

Here's why...
I built a 16' pin tail flat water board and I am having stability issues.

If I cut the board down to 14' with a square or diamond tail will this increase or decrease the stability?


No change IMO... Maybe even slightly worse.

DJ

Jethrow

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Re: What tail?
« Reply #6 on: January 12, 2013, 04:03:13 PM »
Yeah DJ, that's what I thought deep down :'(

pdxmike

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Re: What tail?
« Reply #7 on: January 12, 2013, 04:20:58 PM »
Think of it this way--if you started with a 14' board with a square tail--which is what you have "buried" within your 16' board, then added 2' at the back in any shape--pintail or whatever--could it possibly make the board less stable?  It seems like at worst, it would have no effect on stability.  So going the other way, starting at 16 and cutting down, you'd either break even or get worse like DJ said. 

Jethrow

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Re: What tail?
« Reply #8 on: January 12, 2013, 11:52:05 PM »
I was thinking more along the lines of the sharp corners of the square tail pushing through the water and making an impact rather than the board pivoting on the pin tail but I'm clutching at straws. Hopefully the foot wells make a difference. I guess if it doesn't work then at least I have an excuse for doing another board.  :D
« Last Edit: January 12, 2013, 11:53:41 PM by Jethrow »

DurhamSUP

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Re: What tail?
« Reply #9 on: January 13, 2013, 05:01:56 AM »
Like pdxmike said, the area of the square tail is still in your 2' of pin tail. That area is already helping float the board, plus the added float from the pin tail area. Since the surface area of the pin is close to the centerline of board it adds very little stability, but it can't reduce stability. At least at the speed that a board is paddled. I'm not sure what happens at really high speed.
 It would suck to do all that work to the board and not change the stability and possibly slow it down just a bit.
If you want to cut into the board, you could add some foam and make a 16' square tail.
I like the idea of new board build.     ;D
...keep us posted.

SUPpaddler

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Re: What tail?
« Reply #10 on: January 13, 2013, 12:58:36 PM »
On a flatwater board, what does "clean release" mean, and why would sharp rail edges be more efficient?  I thought those concepts were for planing conditions.  Since the rails stay submerged in flatwater, wouldn't rounded sufaces do better since they have less surface area to create drag?

DurhamSUP

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Re: What tail?
« Reply #11 on: January 13, 2013, 02:34:33 PM »
If the rails are round at the tail, the water will want to follow the curve of the rail and create more drag and turbulence. With a hard rail the water will leave the tail and not be able to follow the radius of the sharp edge.
The rear edge of tail can even go farther and have a chisel shape to the rail to be sure there almost no chance of the water following that angle.
Normally with a flat water board the tail will be just at the surface of the water, so the edge will not be submerged.

DavidJohn

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Re: What tail?
« Reply #12 on: January 13, 2013, 10:36:57 PM »
IMO the rails don't need to be super sharp but the edge along the back of the board does.

DJ

SUPpaddler

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Re: What tail?
« Reply #13 on: January 14, 2013, 02:57:58 AM »
Glad this topic came up since I was finalizing a flatwater design and wondering about the tail.  I was going to curve up the last inch of the tail so that in case I had miscalculated the waterline height, it would still curve up to meet the water surface.  But based on what you guys are saying, perhaps it should have a clean edge, and maybe the last few inches of the side rails should also be sharp.  That seems to be the conventional wisdom.

Henrik F

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Re: What tail?
« Reply #14 on: January 14, 2013, 06:47:02 AM »
What happens if we take the side rails sharp even further forward?

Henrik F
crosswater.se

 


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