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Old 20th May 2008, 11:49 AM   #2
Roger
Dream Team - School Guru
 
Join Date: Aug 2006
Posts: 2,092
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Hi Jamespr43,
I'm going to paste in your questions here and deal with them one at a time....OK?

1- "It's a 48 cm fin appropiate for a 7.5 sail and 145 board (Im 198 pounds weight)."
48 cm would seem about right for a 7.5 m2 rig, at your weight, but the tail width of your board, the type of sail you are using, and a couple of other things can combine to make the 48 cm fin less appropriate.
Also, if you want to plane earlier, and use a larger sail, then a deeper span fin, and a wider tail width are probably the best keys to success.
You can go with a big fin, but if you do not have the tail width to use it effciently and control it when you get up to speed, the big fin doesn't get you much.

2- "Did you gain performance and speed with a top quality fin (like tectonics), even if it's the same size as the standard fin ?"
Normally, the answer to this is yes, if you buy a CNC machined G-10 fin it's probably alot closer to it's "design profile" than a molded fin.
Virtually all fins are "hand finished", but the "set over" Dennis Parton uses at Tectonics is the smallest in the industry so Tectonics fin are always very high quality due to very little "hand finishing".
But, the other "fin artists" (Deboichet, Chuck Ames, Wolfgang Lessacher, Curtis Hesselgrave, and some others) can hand finish a fin from scratch, using templates and come up with the same quality or better because they can look at and feel tiny imperfections that make all the difference in a fin's performance.
So, buying a top quality fin normally gives you better performance, but not always as there are numerous things that come into play that can make one design or concept in a fin work really well, or not so well.

3- It's there a rule to select a fin size for a specific sail size?
There are some rules or formulas for calculating what size fin works with what size sail, but none of the formulas I've seen take into account the tail width of the board.
Some "fin size calculators" introduce sailor weight into the formula and I've found this to be very important.
So, the answer is that there is nothing that's specific and measureable enough to work in all cases.
Good guidelines are available, but again, the guidelines may or may not apply to your situation.
Experience counts for alot here. If others where you sail are using a particular brand; model; and size fin with sail sizes similar to what you have, these would be very good fins to "check out" because it's easy to see that they are working in your conditions.

4- "Did a cams sail makes a difference in early planning"?
This depends entirely on the "type" of sail your no-cam sail is.
If you have a Free Race sail (Sailworks Retro; and a number of other "no-Cam" free
race designs from other sail lofts) then the cambers may not make a great deal of difference in early planing.
If you have a regular "recreational" sail without cams, then yes, I would say that a cambered "free Race sail would be better for early planing.
And, this all depends on if both your sail, and the cambered sail are rigged on truly appropriate masts. If you don't have a mast with bend characteristics that match the
design of the sail, then you aren't getting the full performance or full range.
And, how you tune your sail can make a huge difference in it ability to provide you with
early planing performance.
This is one reason I don't find the annual "sail tests" in the magazines to be particularly "helpful".
They are fairly non-objective, and someone from the magazine (who we hope knows something about rigging sail) rigs them up.
It varies from magazine to magazine and even sometimes to individual testers whether or not the sails ever get "tuned" for different condtions.
So you can have a sail that's really good in light winds (from a good design and lots of testing by the R&D folks that made it), but it gets tuned initially on a higher wind day, and never gets "retuned" to bring out it's early planing performance. So, it gets poor marks for "early planing". A bit of tuning, to enhance the light wind performance, and the results might be very different.
The problem is that the folks at the magazine never tell you how the sail was tuned, or if it was ever "tuned for the current conditions".
Hope this helps, and I'm sorry that I cannot be more specific, but if you tell me what board and what fin, your sail brand/type/size, and the conditions (wind speed and chop height and type of water (sea water vs freshwater) only then can I give you a more specific answer
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