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Jul 17, 2017, 05:12 PM
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Crunchy Frog's Avatar
Quote:
Originally Posted by KoneWone
Are there sailmakers out there that give specific information about mast pre-bend ?
My Jelacic sails came with a rig guide, including all specific measurements. This included the amount of pre-bend, and the distance (from the top) that the prebend should cover.
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Jul 19, 2017, 03:53 AM
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KoneWone's Avatar
Preparing to make 3 new Rigs & checked current IOM Class Rules 2017 and like to ask for clarification regarding lower mast mark height variation between A, B & C. e.g

C.7.4 Mast
(a) DIMENSIONS

Lower point to deck limit mark as defined in D 1.5 ... Min 60mm - Max 100 mm

Within these limits, the variation height of the lower point for each rig ... +/- 5mm


Do l understand correctly that we cannot have the lower mark for example an A Rig @ 60 mm from the deck and a B Rig @ 100 mm ?

Further, if this is correct, does anyone know why ?

Cheers Alan
Jul 19, 2017, 09:04 AM
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hiljoball's Avatar
This item has been discussed on the IOMICA forum

http://www.iomclass.org/phpBB3/viewt...heckstay#p3864

Sounds like lots of confusion, but I cannot find any 'official' clarification or ruling. I agree that the wording is ambiguous.

My take is that the lower limit mark for each rig must be +/- 5mm from the limit marks of the other rigs.

However with the modern trend for beat/run type courses with no triangle type reaching legs (where a low boom could drag in the water) there is little reason to set the lower limit mark higher than the minimum to get the lowest COE for each rig.

JOhn
Last edited by hiljoball; Jul 19, 2017 at 11:33 AM.
Jul 19, 2017, 03:04 PM
Registered User
KoneWone's Avatar
Thanks John, albeit l'm none the wiser ... neither will be a regatta measurer so will l keep the confusion going until an official clarifaction turns up.

On single day events where using a single rig, no-one would know as long as all rigs are between 60 - 100 mm
Jul 19, 2017, 05:17 PM
T_G
T_G
QAV250 - IOM - F959
I believe it's quite straightforward and we are over thinking it to see if we can exploit an advantage. It effectively puts your boom at the same height above waterline for all three rigs. The +/-5mm is a reasonable tolerance, and the 40mm allows for variations in deck designs. With current designs it's going to be close to 60mm otherwise you will have a huge well to fill with water.
Jul 19, 2017, 10:51 PM
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KoneWone's Avatar
I don't believe it is a matter of exploiting an advantage, anyone can do it. Just trying to clarify the rule of having 60-100 mm from deck mark to bottom band which becomes ambiguous when it says "variation height of the lower point for each rig ... +/- 5mm" does it mean between each boats 3 rigs or not ?

The well has nothing to do with the question excepting it defines the deck mark, example take a Cockatoo that has no well compared top a Britpop that does however, their Rigs will be different heights above the water line anyway.

It is purely a question if one can have a low A Rig (60 mm) and a high B Rig (100 mm) or must all 3 rigs be within +/- 5 mm of each other ... it's that simple !

P.S Reading the official rig certification measurement checklist (see attached PDF) it is not mentioned there either ?
Last edited by KoneWone; Jul 19, 2017 at 11:07 PM.
Jul 20, 2017, 06:48 AM
T_G
T_G
QAV250 - IOM - F959
Quote:
Originally Posted by KoneWone
It is purely a question if one can have a low A Rig (60 mm) and a high B Rig (100 mm) or must all 3 rigs be within +/- 5 mm of each other ... it's that simple !
No you can't have A=60 & B=100, otherwise the "variation height of the lower point for each rig ... +/- 5mm" would not be written in the rules. A=60 & B=70 around a nominal 65mm would be acceptable.

I believe you normally want a low CoE, so B & C should be low, same for a general purpose A rig - the only time you might want a high rig is for catching zephyrs wafting over the reeds. Heel angle is the enemy, the more you heel the shorter your rig becomes until it produces zero driving force when horizontal. Fin and rudder lose effectiveness with heel although some hull forms may benefit from certain hydrodynamic effects at moderate angles. The compromises are ensuring an effective vang angle, and dragging the boom in the water, we can also assume that wind is more turbulent at the water surface.
Jul 20, 2017, 03:23 PM
Registered User
KoneWone's Avatar
Quote:
Originally Posted by T_G
No you can't
Yeah right, thank you
Jul 20, 2017, 06:15 PM
Will fly for food
davidjensen's Avatar
Hood River Carnage is this weekend with 21 or more boats entered. Winds are predicted to be light to upper A with the possibility of B rig conditions later in the day both days. Pics and video to follow.
Jul 20, 2017, 08:09 PM
Registered User
Quote:
Originally Posted by davidjensen
Hood River Carnage is this weekend with 21 or more boats entered. Winds are predicted to be light to upper A with the possibility of B rig conditions later in the day both days. Pics and video to follow.
Looking forward to checking this event out. Wind has been great this summer we have been on B & C sails more then any other with our dragon boats.
Last edited by lavaandy; Jul 20, 2017 at 08:14 PM.
Jul 22, 2017, 10:09 PM
Registered User
1st day results hood river carnage? ron
Jul 22, 2017, 11:53 PM
Registered User
Here you go Ron,

Lots of temperature all day but also very good #1 rig winds and from a reasonably solid direction. Depending on th3e when you compiled the scores a lot of changes through the day but her is the end of day score sheet.

_Barry
Jul 23, 2017, 12:56 AM
Registered User
thanks, barry.
winning a race looks like it can't be repeated.
is j. brower really sailing a brit pop?
ron
Jul 23, 2017, 09:39 AM
Barry D USA 747
Yes Jerry is sailing a borrowed BP. Yesterday was a great days sailing marred by weed problems, got me 3 times, if you picked one up on the far side of the course, it was game over.
No weeds last year so not sure why this time around. Should get into B rigs today at some point hopefully.
Jul 23, 2017, 10:47 PM
Registered User

Hood River Carnage Final Results


All day long on good #2 rig winds. Another 9 races on the books and even a bit of the promised carnage. No one was exempt with even the winner having a dnf over what appears to be a duff battery.

Maybe some others will chime in but in the meantime here are the finals results.

- Barry


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