Dinghy development: mad moth idea

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mad moth idea

Printed From: Yachts and Yachting Online
Category: Dinghy classes
Forum Name: Dinghy development
Forum Discription: The latest moves in the dinghy market
URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=13585
Printed Date: 28 Jun 25 at 5:48pm
Software Version: Web Wiz Forums 9.665y - http://www.webwizforums.com

Topic: mad moth idea

Posted By: Gordon 1430
Subject: mad moth idea
Date Posted: 17 Apr 20 at 12:18pm

As I understand it Moths have started to cant the rig to leeward to compensate for the angle the boats are sailed heeled to windward.

Would it work to have the rig and wings on a sliding system so the whole rig and righting moment could be in a better vertical plane while the hull and foils stay heeled to windward to drive the boat up to windward?

It would also increase righting moment as well.

Sorry my sketching skills cant cope with how to draw this up.

Stupid idea but just something to ponder.

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Gordon
Phantom 1430

Replies:

Posted By: 423zero
Date Posted: 17 Apr 20 at 1:28pm

Sure something like this been done before, years ago, do you mean mast is always vertical?

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Robert

Posted By: Gordon 1430
Date Posted: 17 Apr 20 at 4:45pm

Yes Mast and wings would be on a single space frame so when moth is heeled to windward the whole thing could be rocked separately from the hull to bring rig and wings to a more vertical plain.

this would be more efficient I think.

daft idea to engineer and tricky to sail but so were foils

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Gordon
Phantom 1430

Posted By: The Moo
Date Posted: 18 Apr 20 at 8:29am

National 12 3489 Radical Edward started out life with a canting rig in the 2000s. It was the brain child of Mike Cooke of Aardvark fame who went on to do things in the Int Moth class

Posted By: Riv
Date Posted: 18 Apr 20 at 9:17am

Parasitic drag on a Moth must be large. So far I've not seen any effective way of streamlining the sailor. So in comparison the complexity and weight of a canting rig may not give as much advantage as extra research into drag reduction. On the other hand rig canting ideas can be pursued more easily at home.

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Mistral Div II prototype board, Original Windsurfer, Hornet built'74.

Posted By: Rupert
Date Posted: 18 Apr 20 at 9:32am

Isn't one of the ideas on windward heel that when you catch a gust, the mast goes upright, rather than to leeward, which would cause you to crash and burn. My poor understanding was that it was the combination of rig and foil angles that would cause the crash, but I'm clutching at ideas which are slightly beyond me.

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Firefly 2324, Puffin 229, Minisail 3446 Mirror 70686

Posted By: GarethT
Date Posted: 18 Apr 20 at 10:02am

I'd always assumed it was so the foil was lifting upwind as well as up out of the water.

Posted By: 423zero
Date Posted: 18 Apr 20 at 11:08am

They all appear to heel to windward in this short video. https://www.youtube.com/watch?v=WEj_xNcZXF0" rel="nofollow - https://www.youtube.com/watch?v=WEj_xNcZXF0

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Robert

Posted By: 423zero
Date Posted: 18 Apr 20 at 11:33am

Presumably the lift from foils while boat is heeled to windward also stops boat making too much leeway ?

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Robert

Posted By: Sam.Spoons
Date Posted: 18 Apr 20 at 12:18pm

With a fixed rig it's basically down to the righting moment balancing the heeling moment like any dinghy. It would probably be possible to sail the upright with the helm out on the wing but by heeling to windward you gain considerably more righting moment as the Centre of Lift/Buoyancy is further to leeward of the 'ballast'. Getting the mast vertical would reduce the lift component from the rig but will increase the drive component but I'd guess only a little. I think canting the hull with the rig would slightly reduce the righting moment so may not have any benefit.

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Spice 346 "Flat Broke"
Blaze 671 "supersonic soap dish"

Posted By: ian.r.mcdonald
Date Posted: 18 Apr 20 at 5:42pm

Being able to cant the rig radically to windward is essential- a shorter fall for me as I tip it in (yet again)

Posted By: giraffe
Date Posted: 18 Apr 20 at 5:57pm

the rig canted to windward gives more righting moment too - and I believe this aspect is considered to be highly beneficial - but I may be out of touch

Posted By: Sam.Spoons
Date Posted: 18 Apr 20 at 6:09pm

It's not the rig being angled to windward but the fact that the boat, when foiling, pivots around the bottom of the foils (the roll centre?) so leaning to windward moves the CoG of the boat plus helm further to windward of the 'roll centre', the righting moment works vertically downward (gravity) so the more you heel the greater righting moment you have. The opposite applies too as anybody who has allowed a Laser to heel too far and the point of no return comes when the sailor is above the centre of buoyancy (which in the case of displacement sailing is effectively the equivalent of the roll centre?)

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Spice 346 "Flat Broke"
Blaze 671 "supersonic soap dish"