Author Topic: Windage for higher roof at high heal angle  (Read 2044 times)

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Offline claudiof

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Windage for higher roof at high heal angle
« on: January 07, 2007, 19:29:27 PM »
A higher roof on a mini is great for making a sailor happy inside, but the typical answer is that it is at the cost of increased windage. The increased windage is however especially harmfull for performance when close hauling, but in this configuration a mini has anyway a high heal angle (assuming windy conditions) and hence exposes mainly the bottom hull to the wind. So, can someone explain exactly how a higher roof may actually lower performance? See the Didi mini and cruise-mini options on www.dixdesign.com - about 10cm higher plus a cute dodger.

Offline GDesign

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Re: Windage for higher roof at high heal angle
« Reply #1 on: January 08, 2007, 14:01:16 PM »
windage a difficult question.
From my point of view
As you said, in hevy winds the hull will be exposed but this cant be change and every little thing adds on. You also have to take care that windage can be a real problem in light winds more than hevy ones. In heavy conditions you worry about controling the boat as it has enough speed anyway, it will be limmited by the hydros and stability. The real advantage is on light-medium winds where stanchions, coach roof, harware and crew will dramaticaly influence the windage.
In boats there is not only one solution but a compromise, so if you want a cruising mini, that means you are not planning to race the full year and aim to first place in the transat so... 10 cm interior space can make the difference between confortable and banging your head every time you get in and out!
hope this helps

Offline r.finn

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Re: Windage for higher roof at high heal angle
« Reply #2 on: January 11, 2007, 06:37:13 AM »
I seriously doubt it matters.  Go for what is practical and what you are most comfortable with.  Now I'm not a naval architect, but I feel safe saying that nobody ever won or lost a Mini race because of the upwind drag of their coachroof, but many races have been lost due to fatigue. 

Offline GDesign

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Re: Windage for higher roof at high heal angle
« Reply #3 on: January 11, 2007, 13:37:55 PM »
Remember there is another "trik" the higher you go with your coanchroof toy start loosing mast, as the maximun height, keel-to mast, is fixed so lower coachroof, lower boom so you could put more sail!
I think thats the reason why mini coachroofs are on the low side, apart from aesthetics, windage will not be a big thin on such a boat.

Offline claudiof

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Re: Windage for higher roof at high heal angle
« Reply #4 on: January 15, 2007, 08:54:15 AM »
Thanks everybody. I'll go with the cruise-mini roof. I'll try to prove the point by racing it in the class. By the way, have you guys seen the new race "Les Trois Continents" (Marseille-Malte-Alexandria)? Magnificent!

Cheers!