Plywood Moth

alternative method:
http://www.moth.asn.au/building/gwise_concept_moth.html
MERRY CHRISTMAS
SHC

 

It's true, Andy
when cutting scarfs in stack it's easier to obtain the desired planarity of the joint as there is a wider support for the tool you are using.
Steve, I have built a Moth lookalike 3 mt. long in carbon/expanded polystyrene. The downside of the system is the inherent brittleness of the core. Sheating the foam with thin plywood will increase impact resistance for sure.
Best whishes for a Happy New Year.
Marco.

 

http://www.diecipiedi.it/Cernobbio 2005/PICT0005.JPG
Carbon/Foam 3 mt. Trimaran

 

Tri

Marco, Merry Christmas and Happy New year! You've showed me the tri before but everytime I see it it just looks terrific-you do good work!
-------------
edit: do you think removable hulls/buoyancy pods would be an aid in learning to sail a skinny Moth ? Maybe it's better to start right off with nothing-what do you think?

 

Hi Doug,
I can sail this particular boat on the main hull only but the sponsons are definitely too low on the water, they need to be at least 20 cm. higher to minimize interference with water surface. Sailing a Moth is very difficult indeed and learning sponsons would of course save many capsizes.
Having a lot of buoyancy out on the wings will render the boat more difficult to recover after a capsize when you need to sink a wing. Inserting the main hydrofoil would be more difficult and possibly became a two man work.
Moth foilers are achieving a very delicate balance, a change like this will alter them substantially.
Marco.

 

Too much buyancy in the wing tips causes immediate inversion and makes capsize recovery a very much longer duration exercise. Takes suprisingly little.

 

Buoyancy

But wouldn't some buoyancy prevent most capsizes while learning-or is even a little too much? Could a combination of removable masthead buoyancy and wing buoyancy work to reduce the "capsizeability" and recovery issues while geting a learner past capsizing too frequently?
Looking at the M4 they appear to have buoyancy in the wing tips and there is a discussion on the UK Moth site about the legality. Do any of you have any knowledge from first hand experience on a Moth with extra buoyancy on the wings or concerning the M4?
------------------
Here's the UK site discussion in case you haven't seen it:
http://www.int-moth.org.uk/IsthisamothSP.htm

 

foiling speeds

hey again everyone. Hope everyone had a great holiday time and has a great new years. Does anyone know where information regarding moth foiling speeds can be found? Perfect information would be the speeds at which with the current set ups foiling starts, and with what wind speeds they acomplish that. Im doing some work with a preformace software and this benchmark info would be awesome. Thanks again everyone~dan

 

Foiling speeds

This site and the UK site in my previous post have almost all there is on Moth hydrofoil performance. On the previous site you have to go back to the main page:
Australian Moth Class Forum http://www.moth.asn.au/forum/index.php?sid=b2984b019982eb0292321c902664a9d2
The boats take off at around 7-8 knots boat speed.They can hit 19knots in a 10-12 knot wind and the current record posted on the UK site is 23 knots. Big progress is being made in lowering take off speed-that seems to be one of the critical factors-getting foiling early is probably more important than top end speed in this class.You could write to John Ilett builder of the World Champion foils and originator of racing bi-foils in the Moth Class:
john@fastacraft.com

 

Doug,
what you are actually doing when learning to sail a Moth, I won’t call it sailing but swimming instead, so having two small hulls out on the wings could make the first outings less of a shock.
That’s all.
After this very initial stage sponsons will greatly detract from overall performance: increased weight, increased windage , increased wetted surface, increased stresses on the racks when capsizing, reduced water clearance, greater inertia, bigger foils, greater costs and so on.
Marco.

 

In my experience, not on Moths, but on something similar, all the problems with capsize recovery come in far sooner than much difference is made to survivability. Angling the wings so they skip across the surface touching at the stern first helps nearly as much without the downsides. I can't imagine anyone with the required skills to be getting into a Moth wanting to sail with 10 litres of foam at the masthead, and the weight would make the boat feel horrible.

 

Buoyancy Pods for Beginners

Jim, 10 litres of buoyancy at the masthead probably wouldn't be needed-maybe 20% of that but I haven't figured it yet. One thing seems certain: the boat would be highly unlikely to capsize in the first place.Marco, the buoyancy is not enough to hold the boat up above water. The nagging problem remains: what happens with a pitchpole? I doubt the boat would go inverted if it doesn't go inverted in a "normal" pitchpole.And if it does maybe a small amount of removable(after training is completed) buoyancy could be added high up.
Reading the UK site discussion that took place in 2002 at the Euro Championship a boat built by Freddie Duvoisin(well known Fireball builder) was entered with what look like 5" diameter carbon tubes with pointy ends forward. I estimate the buoyancy at 43 pounds(19.5kg) significantly less than the weight of a Moth. Four guys were asked for their opinions including Andy Patterson. David B, Doug Rybos(UK President) and Nigel Oswald.To a man they expressed that they felt such pods could be a usefull learning tool or words to that effect; they were opposed or ambivalent on the use for racing.A poll taken then was 2/1 for saying such an arrangement was a "trimaran".
The guy writing the article on the UK site said:"Moths with mini hulls at the wing tips would be much easier to sail and greatly reduce the skill differential between those who can balance their narrow hulls and those that can't. This may be a good thing or a bad thing."
I can't find any reference on the Moth forum to buoyancy in the wings so I don't know how this issue has been resolved since 2002 unless it was covered in the banning of Brett Burvil's surface piercing foils mounted outboard on each wing.
But I'm not suggesting that these be used for racing though I don't think that intentionally sailing "on" these pods(like a trimaran) would be anything but slow and that therefore a good argument could be made that these pods do NOT make a Moth a trimaran-they only make it easier to get started. That being said it seems that, at least in 2002, a lot of very experienced Moth sailors and designers thought that the pods would make it easier for beginners. So why not use them in order to get people who are really interested in foiling foiling sooner?? I read a story someplace where a guy said you'd better allow 6 months to learn how to sail a skinny Moth OFF THE FOILS. In todays world I'll bet a lot of people would say to hell with it before then. The pods could be removable and I'd be willing to bet that in the US,at least, they would make a huge difference in getting new blood into the Moth Class by allowing them to foil much sooner....

 

Nearly all Moths use some form of buoyancy at the wing tip in form of swimming pool noodles inserted in pockets. Everyone adjust their number to suit weight of the sailor and personal preferences but so to still enable sinking of the wing for capsize recovering. As long as buoyancy is not shaped in a hull shape and the boat is not consistently sailed wing in water it is allowed by the rules. I think that learning mini hulls, though banned by the rules, can be useful to learn to sail a lowrider Moth, which in my opinion you have to do anyway before graduating to a Moth foiler. At least that’s what I’m trying to do. I think that the one who graduates to a foiler should have the capability to sail on the (main) hull alone so rendering useless mini outer hulls. I don’t think it is realistic to jump on a Moth foiler and go, unless you are a very experienced sailor and than you have to expect anyway a lot of crashes which mini hulls couldn’t prevent .
Marco