Interesting moth design

Doug Halsey

Member
335
97
That's a really nice-looking Moth!

I wonder just how low the faired portion of the gantry could be placed without being considered to be "an attempt at increasing waterline length" ? And how would the measurers determine the designed waterline?

NewMothGantry.jpg

GantryRules.jpg

 

jonas a

Super Anarchist
That's a really nice-looking Moth!

I wonder just how low the faired portion of the gantry could be placed without being considered to be "an attempt at increasing waterline length" ? And how would the measurers determine the designed waterline?
Yes interesting point. He wasn't shy about telling the purpose of the transom design

 

Phil S

Super Anarchist
2,602
229
Sydney
Some good ideas. Very well done.

I have discussed the bolt on one piece wings and deck stepped mast idea with some friends but no one I know has built one yet.

The Gantry seems to have enough gap and step in the water lines to satisfy most measurers. There are some Exocets which push the rule further and the class is in the process of re-wording the rule/interpretation/instruction to ensure more uniform rulings.

 

Reht

Super Anarchist
2,758
6
Pure morbid curiosity, do the moths sheet to the middle of the boat enough to make this a viable solution without a boom à la A class? Or is this going to be another funky-boom innovation?

 

BR3232

Member
271
2
Pure morbid curiosity, do the moths sheet to the middle of the boat enough to make this a viable solution without a boom à la A class? Or is this going to be another funky-boom innovation?
Mike Lennon tried it - seems like he was unconvinced, but someone might come up with a better design in the future

Moth-yny-ML4-lr.jpg


http://gpsailing.org/?p=13106

The WASZP has an end boom centric mainsheet without a track, used in conjunction with a wishbone boom, so that’s kind of half way in between.

WASZP-2015-12-22-1.jpg


AMAC and Co. reckon it works but the way you need to pass the tiller extension forward looks quite awkward to me, and most Mothies are running obscene amounts of vang upwind - I'm not sure if this designs allows the same amount. The round-the-back tiller swap that necessitates a middle boom sheet works pretty well for the way you manoeuvre a Moth… but the end boom centric arrangement relieves a lot of load that is concentrated in very small areas in the current design, there's a big advantage.

 
Last edited by a moderator:

17mika

Anarchist
949
226
Milan, Italy
I agree waszp solution is pretty clean, and it seems to work pretty well. If I get it correctly the north rig should work the same way,right?

Current moth kickers are starting to get obscene (some guys with 48:1 kickers this year in europe)

 

Reht

Super Anarchist
2,758
6
Passing the tiller forwards is just learning a different set of movements. Lasers have to do it, on a higher-performance note, 29ers often you single tillers, so the skipper learns to pass it forward "leading in" to the manoeuvre.

Elimination of the boom seems like a big step forward, with all the concern at the top of the moth fleet with drag minimization, can a wishbone really not suddenly add a lot of drag proportionally?

48:1 kicker is insane. How much travel does that give at the boom end?

 

Dave Clark

Anarchist
882
747
Rhode Island
Elimination of the boom seems like a big step forward, with all the concern at the top of the moth fleet with drag minimization, can a wishbone really not suddenly add a lot of drag proportionally?
Its not about booms so much as tip vorticies and moment arms.
DRC

 

17mika

Anarchist
949
226
Milan, Italy
Question to Dave: in your opinion does closing the deck slot really make a difference, or is it mostly about heeling moment?

Regarding moth kickers, 48:1 guys have to move the splice of the first cascade after rigging the boat, otherwise they don't have enough range of boom movement.

 

Dave Clark

Anarchist
882
747
Rhode Island
Question to Dave: in your opinion does closing the deck slot really make a difference, or is it mostly about heeling moment?
Yes. Also that's not an 'either or' question. According to our modeling, there are numerous positive consequences to sealing the tack to the deck. 1. it eliminates the capacity of the foot to generate tip vorticies, thus reducing drag. 2. It increases apparent aspect ratio (think of it as making the deck a scoop for the sail), driving the CoP profoundly downward, thus shortening the heeling moment arm and generating far greater thrust capacity in the overall system.
Moth sailors have been moving their sails down towards the deck and skewing the planforms low to incrementally lower heeling moment. Mr. Lennon's sail takes that to a new extreme with the faux endplate, but that's only beneficial on a geometric level. Aerodynamically, it's still a low sail with vorticies on both tips. I don't have data on how bad it gets once the sail truly endplates into the dihedral wings on the moth, but I suspect it's why neither Kevin elway nor Andrew macdougall have made forays into full endplating on moths as the A-class fleet has. The drag may be awful. It's one of the reasons why the UFO has an anhedral sealed deck. It allows us to gain the benefits of full endplating while keeping the junction drag as low as feasible.

DRC

 
Last edited by a moderator:

WCB

Super Anarchist
4,263
781
Park City, UT
I'm looking forward to seeing what Lennon is doing with their new Moth. We've gotten little views of it here and there. I'm ready to see what the whole package looks like.

 

Phil S

Super Anarchist
2,602
229
Sydney
Mike Lennon has gone back to a more standard rig. The sail from the deck sweeper rig is for sale on his web site.

 
Top