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Squaretop & Spin - what's it rate?
http://www.hobie.com/au/en/forums/viewtopic.php?f=13&t=17987		 Page 1 of 1
Author:  smv [ Mon Dec 07, 2009 10:19 pm ]
Post subject:  Squaretop & Spin - what's it rate?
I'm looking forward to next season and getting the chance to race against some other H18's a bit more than this past season. My hope is to organize a handful of events where we race the H18 in one-design fashion and set up a series to encourage others to join us, hopefully we can get some folks back into the travel events.

Here in Michigan however, most people have moved into other classes and I expect to go to at least a few events where we are the only H18 on the beach. For these events I'm thinking about putting together a separate sailplan which would include a squaretop main and spinnaker so that we can keep up with the rest of the fleet. I know that the portsmouth system has a ratings adjustment for these modifications but haven't really spent the time to figure it out. Has anyone else gone down this road? How did it go and what IS the rating with these mods (and how do you convince the PRO that it is all correct)?
Author:  MBounds [ Tue Dec 08, 2009 11:02 am ]
Post subject:  Re: Squaretop & Spin - what's it rate?
It's actually pretty simple (at least in concept).

Basic D-PN for a Hobie 18 is 71.4

SP (spinnaker) modification is 0.960

MN (main) modification is 0.995 (if the sail is the same area as a class legal sail)

ML (larger main) modification is 0.980 (if the sail is larger than a class legal sail)

Multiply them together to get your modified D-PN:

71.4 x 0.960 x 0.995 (same size sail) = 68.2

For reference, that's about the same rating as an FX-One (68.5) and just a bit slower than a Hobie 21 w/o spin (67.0) and a Hobie 20 (65)

In actuality, it's a bit more complicated as each boat has four D-PNs (one for each wind range) and four associated modifiers for each wind range. On an 18, you really want them to use the modifiers; you'll do much better in light air. There are also adjustments for being over / under weight on the boat.

There are a few 18s that race out of North Cape YC in Toledo, and some on the west side of the state in the Muskegon / Ludington area as well as a few in the Kalamazoo area (Austin Lake).
Author:  Karl Brogger [ Tue Dec 08, 2009 2:45 pm ]
Post subject:  Re: Squaretop & Spin - what's it rate?
I don't think it'd sail to that number though Matt. A guy in my fleet has a square top on an SX with a chute, and I get him both ways. His spinnaker is odd and freakishly large, in light air he pretty much owns me down wind. I'm not saying you're wrong in your math, just that it'd be tough to get it there.

But, I also know for a fact that the FXone number should be lower than that too. I can sail it to the number pretty damn consitently.
Author:  ncmbm [ Tue Dec 08, 2009 7:49 pm ]
Post subject:  Re: Squaretop & Spin - what's it rate?
I race mine with a 66.8 number. I have a SX mast on a SE platform plus the squaretop, spin and self-tacker. I have argued that I should sail with a SX corrected number, the SX gets a spin with no hit. My boat would be a open class ringer with that number, I might even correct out over F18s and I20s. The EMSA guys aren't having that! I make so many mistakes that it wouldn't matter what the number was anyway. :D I am currently using a Tiger jib which is a little small on my boat so I plan on having Chip make me a custom jib. The Tiger is shorter from the bridles to the x-bar than the H18 so the jib needs more foot and height.
Author:  SicosDave [ Wed Dec 09, 2009 12:37 pm ]
Post subject:  Re: Squaretop & Spin - what's it rate?
Do the ratings change much when sailing solo? (underweight)


ncmbm - for the difference in jibs click http://www.facebook.com/photo.php?pid=774239&l=040c3b7144&id=1452677617
Author:  J_Eaton [ Wed Dec 09, 2009 3:03 pm ]
Post subject:  Re: Squaretop & Spin - what's it rate?
SicosDave wrote:
Do the ratings change much when sailing solo? (underweight)[/url]


http://www.ussailing.org/portsmouth/tab ... ions08.asp
Author:  ncmbm [ Thu Dec 10, 2009 10:57 am ]
Post subject:  Re: Squaretop & Spin - what's it rate?
Sisco, solo the H18 cannot sail to the number. Genmar has tried to campaign the 18 solo and it just can't beat anything in open class, the 16 is a better solo boat numbers wise.

Thanks for the pic of the jibs. I run a self tacker on the front x-bar that will limit the foot size but I do have more room for a larger foot than the Tiger sail. Its going to have to be custom but it will still be less sail area than a stock jib.
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