Old 14th October 2008, 09:11 AM   #21
Roger
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Hi JohnK and Bazza,
OK, I'd like both of you to get a piece of string a bit longer than your board, and put some sort of light weight on one end.
Now stretch the string along the fore and aft centerline of the bottom of your boards
(2002 Start for Bazza.... Mistral nTrance for JohnK) with the weight hanging off the tail.
Notice how the board is basically flat (front to back) near the tail and then somewhere around the front footstraps in their back and outboard positons, the string no longer touches your board because you have reached the "rocker transition" in your board.
Take a little electrical tape (bright red or yellow is the most visible) and put a little tape
"arrow" near the top of each rail at this "rocker transition" point in the bottom of your board.
So, if you keep your weight far enough forward that the "rocker transition" (RT) never gets up and clears the water, you aren't getting the nose up and the Angle of Attack (AOA) of the bottom of your board will not promote easy planing because the RT (and any part of the board forward of the RT that's in contact with the water) is causing an immense amount of drag.
This is why it's so important to get your weight all the way back on the board so you can set the AOA at the optimum angle to promote early planing.
Can I tell you what that angle is...... no, sorry, I've never made a "test fixture" to discover that.
Probably between 1 and 5 deg. and it probably varies with different board designs.
How do you "set" the AOA
Move the mast foot forward and back until you find yourself back in the rearmost and outboard footstraps and the board planes really fast and is easy to control.
So, if you don't move back enough, you won't get the AOA you need to plane early.
If you use the tape "indicators" I suggested above, you can look at the water coming out from under your board and know if you need to have the nose higher to plane off.
If the water comes out significantly "ahead" or forward of your marks you need to move back further and or move the mast foot futher back.
If the water comes out just behind the rocker transition (about under the front footstraps and front foot) you will feel your board "light up" like never before.
Getting on plane will become far easier.
Hope this helps,
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Old 14th October 2008, 10:08 AM   #22
bazza
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So I've checked my rocker line and although my intermediate strap settings are inboard they are still on the flat part of the board. This seems to be good! I will need to move them to the outboard positions and practice with them there until I get comfortable.

I will move the mast further aft also and work on my sail and fin pumping. I suspect that I'll need to adjust my harness lines so that I'm not raking the mast back too far.

Thanks again Roger!
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Old 15th October 2008, 03:51 AM   #23
johnk
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Quote:
Originally Posted by bazza View Post
So I've checked my rocker line and although my intermediate strap settings are inboard they are still on the flat part of the board.
I've found the same with the intermediate strap position on my NTrance as well.

Roger, thanks for helpping us get the most out of our existing equipment!
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Old 15th October 2008, 08:15 AM   #24
Roger
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Hi Bazza and johnk,
Guys, have fun, and work your way all the way back and out at your own comfort level.
No way I can describe for you the improvments in performance and control you'll get when you get all the way back on the board, get the rig to support your weight and get the power directed through the mast foot.
For Bazza, yes, be careful not to rake the rig back too far as this can turn you upwind so some degree.
Remember, you can keep your rig failry open and not raked back much to get the max. power to get going.
Be sure you aren't raking back and sheeting in too soon.
This is a case where later and less is usually better.
At some point this will all come together and you will simply "flow" through all these little
nuance "steps" and it will look like you just slide back on the board and onto a plane.
Hope this helps,
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Old 13th July 2009, 10:01 PM   #25
johnk
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Hi Roger,

Just wanted to provide an update on my quest for early planning. I ended up picking up a lightly used 2006 Bic Techno Formula 170 with 70 cm fin for $450 over the past winter. I have been on the water blasting around as much as time will allow.

Two Saturdays ago I went out in a gusty breeze... winds were 10-15 mph with gusts 20-25 mph as measured at the local iwindsurf station. I rigged my 2000 Retro 9.5 which became unwieldy in the gusts and made it extremely difficult to get back upwind. This past Saturday, I rigged up my 2006 Retro 9.0 in similar conditions and found the newer sail less powerful in the low end, but much more stable in the upper end. So, while the sails are only 1/2 meter apart in size they obviously favor different conditions.

At my weight of 185 - 190 pounds, it seems like I need a 15 mph breeze to get planning with my current gear, which is a big improvement over my previous Mistral N'Trance. As 10+ mph winds are more common around here then 15+ mph conditions, I'm questioning the need/benefit of a larger rig to drop that planning threshold even further. Seeing how stable/controlled my 2006 Retro is, I was thinking about getting a newer 11.0 Retro to boost the lower end. Do you think a larger sail would do much to lower my planning threshold?

Thanks as always for your invaluable advice.
JohnK
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Old 14th July 2009, 06:52 AM   #26
Roger
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Hi John,
How much you gain by increasing your rig size is always a bit puzzling.
If you have an older 9.5 Retro, you may not find a huge gain by going to an
11.0.
Are you using an adjustable outhaul on your 9.0 and 9.5 m2 Retros?
That could do alot to "power up" the low end on both sails, but allow you to
trim them a bit flatter once you are planing.
Part of what makes this difficult to predict is that you will increase the weight
when you go bigger.
The 11.0 m2 Retro needs a 520 or 550 mast. Your 9.5 rigs on a 490 I believe.
So combine the 520/550 mast with a longer heavier boom and you gain a few pounds in the rig.
Also, I think one reason you aren't planing earlier is the Bic Techno formula is only 94 cm wide.
That's a really good width, but unless you have mastered pumping, giving up the 6 cm between the '06 Techno Formula and a full on 100.5 cm wide formula board can really move the planing threshold up a bit.
At 185 lbs. I'd think you should be planing (with pumping) in 10-12 knots(11.5-14 mph).
What fin are you using..... not enough fin could be really keeping you from planing super early.
So, I do not have a definitive answer.
The 11.0 might be a really good thing and get you planing a couple of knots earlier, but learning to efficiently pump onto plane on your older 9.5 Retro might get you to the same place.
The 11.0 Retro is kinda FE/Formula racing oriented, so I'm not sure it has the basic "grunt" that your older 9.5 has.
Hope this helps,
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Old 15th July 2009, 05:55 AM   #27
johnk
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Quote:
Originally Posted by Roger View Post
Are you using an adjustable outhaul on your 9.0 and 9.5 m2 Retros?
That could do alot to "power up" the low end on both sails, but allow you to
trim them a bit flatter once you are planing.
Yes, I've been using the strap/buckle style adjustable outhaul from Sailworks. I am likely sailing with too much outhaul tension in the light breezes. How do you gauge the outhal trim for maximum power... should the sail be so soft that it touches the booms?

Quote:
Originally Posted by Roger View Post
What fin are you using..... not enough fin could be really keeping you from planing super early.
I'm using the supplied fin which is a 70 CM Select.

Quote:
Originally Posted by Roger View Post
Hope this helps,
I really appreciate your advice and suggestions.
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Old 15th July 2009, 09:47 AM   #28
Roger
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Hi Johnk,
Retro's need a little outhaul (perimeter tension) but when you want the max. low end
it's OK for the sail to touch the boom a little.
The best gauge is the positon of the front of the batten above the boom
For max. power you need to set that batten at the midpoint (front to back)
of the mast or even slighty ahead of the middle.
Then just a couple of cm's of outhaul to just tighten things a little.
Hope this helps,
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