Foiling Moths...what's the thing hanging off the bow?

Greenheart

Greenheart

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I'd never want to sail one, but these foiling Moths are certainly startling, for the brief time they're in range to be visible...

...but what is the wirey thing hanging from the bow?

It appears to be just long enough to touch the water when the hull is fully up in the air...so I'm guessing it relates to trim in some way. Does it control adjustable foils, something like that? Or are Moth sailors all just very sloppy about tying off their painters? :confused:

http://www.youtube.com/watch?v=P_EpOyX-wDI
 
dancrane said:
Does it control adjustable foils, something like that?
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Exactly that, I believe. It operates control surfaces on the centreboard foil to keep the hull at the proper height. The helmsman has manual control of the foils on the rudder by twisting the tiller extension.

Pete
 
dancrane said:
Does it control adjustable foils, something like that?
http://www.youtube.com/watch?v=P_EpOyX-wDI
Click to expand...


yes, there is a mechanical linkage between the rod hangin down from the bow and the fin horizontal foil angle

the boat sinks, the rod is pushed backwards, increases the foil angle, increases lift.... the hull lifts out of the water, the rod becomes more vertical, the foil angle decreases

balance is eventually found :rolleyes:



there is a second horizontal foil on the rudder blade tip, its angle is trimmed by twisting the tiller stick


had I a better back, a boat I'd have ready to go :(
 
It's automatic? I see, thank you gents. Although, I'm a little disappointed. I had supposed those Moths took some actual skill to sail...:D
 
dancrane said:
It's automatic? I see, thank you gents. Although, I'm a little disappointed. I had supposed those Moths took some actual skill to sail...:D
Click to expand...


I talked to a Moth distributor, asking things like how long does it take to "fly", the answer from the salesman was oh, two three days

There was a moth sailor nearby, he winked, gently whispering "make that two three weeks", which in my case might well become two three months :D
 
looking at one of the Dutch Moth videos, I am surprised to see how small the hull foil is: it seems about the size of an A4 page.
 
Yup, it's a wand. It does give automatic ride height control in the manner described above, but it does take a lot of setting up and experience to get it right. Which is part of the issue as when you first start crashing moths you don't know what you've just done wrong!

On a modern boat there's a lot of parameters. Gearing is essentially how much does the flap move compared to the wand. Less important in flat water but essential in waves. Gearing is changed fairly permanently by changing linkage positions on bell cranks, but also by wand length...modern wands can be adjusted in the fly. For example, bear away in big breeze and waves and your boat speed will be well north of 20 knots, you need the wand to have less effect on the ride height, otherwise the boat will sense a wave, start to climb, only to pop out the back of it with nothing in the water at all. You can pull a string and shorten the wand as required.

Modern boats also have a bias adjuster, which essentially lengthens or shortens the pushrod in the cockpit, giving ride height adjustability. You will also notice that Moths have the wand off to one side...initially this was for ease of construction and watertightness...experiments were carried out with a central wand, however it was found that unless the leading edge of the main foil was getting clean water flow it cavitated, so the wand was moved back to one side to stop the wand paddle messing up the flow. As such, with the wand off to one side, the ride height is different on each tack (remember you sail with the boat cranked about 15 degrees to windward) so the ride height will be different...the bias adjuster lets you manually correct this.

You also have the wand bungee which controls the spring rate of the wand...in flat water you want high ride height and a lazy wand...the opposite in waves. Your weight is important too...as speed increases lift increases dramatically (water being 30 times denser than air and all that!) so on the bear away you bizarrely move forward (gulp) to keep the nose down. And there's also the matter of wand shape (some are bent), stiffness, paddle shape, and how far forward it hangs in relation to the foil position.

At the other end, the ruder will have a flap controlled by a twist grip tiller extension, or the more modern fixed flap design where the AoA of the whole rudder is controlled by the twist grip...I will be converting my boat to this system. Some boats have a fixed rudder that can only be adjusted by a spanner, where weight position is critical however this is quite rare now. Basically, as you go faster, the boat will climb, so you need to get more lift from the rudder to keep the nose down. Irritatingly, the fence has fallen off my rudder, so I had the unusual experience of foiling along at 20 knots the other day and not being able to steer as the vertical part of the rudder had ventilated.

So yeah, simples, really ;)
 
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Quick video from a training event the other week...with my slightly older boat and my own "heavy winds optimised" build, it was a bit marginal, but still shows that foiling in naf all wind is possible!

http://youtu.be/8P95oZZ5oKQ

Oh, and with regards to "how long to foil", if you have come from something narrow light and fast such as a skiff, or RS300, you will be foiling in minutes. If you have come from a heavier traditional class it will take a lot longer. Either way, the tricky bit is time on the foils between crashes, and corners. But when you first get on the foils and stay there for a mile and start to relax, look round and enjoy the ride, there really is NO going back...
 
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I've never been tempted myself, but my God they're impressive wee boats. Kudos to their pilots, too. I've an ex workmate with a much older one who still sails it in his 50's, but he's a lot fitter and more lithe than I am. I've seen a couple of crashes in the Solent over the years and they were pretty spectacular.
 
Weights range from 60 to about 90. Obviously, the salad dodgers will take off later and get marmalised in the light stuff, but will be much faster in big breeze. You'll be fine.
 
Looks good. It was designed by Andy Paterson on the IOW, the Ninja foils were designed by Kevin Ellway (who also did the Arup Skiff women's Olympic triallist) and built by Aardvark technologies. They are a modern foil which is an expensive upgrade for that boat. Standard stuff, foil alignment, cracks on foil joins, watertightness of the hull, controls all work, sail/mast condition, tramp condition etc. Remember they are fragile but being carbon anything can be repaired easily.

What have you sailed before and where are you planning on sailing it?
 
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Iain C said:
What have you sailed before and where are you planning on sailing it?
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thanks for the informations


Small boats not much: the usual Laser, a bit of Hobie 16, 470, I owned a Star but it's a completely different animal (well still own it but it's 2000km away), all at "have fun" level, no serious racing. I have been an instructor with Lasers but it was >20years ago and I was in my mid-20 :o

Sailing area, to have wind and a flattish sea there would be a number of such places: the bay of Lorient has maybe too much traffic but the lagoon of Gavres nearby would probably be ok, the bay of quiberon just E of the land spit would seem perfect with the frequent westerly winds, or inside the gulf of morbihan, going at 15-20kt against 8kt of current must be something :D

just playing with the idea for the moment
 
A picture is worth a thousand words:

74906d1349441862-idea-small-low-cost-bi-foiler-moth_diagram-sail.jpg


It looks like an enormous amount of fun. I wish I had the time, money, and a suitable body of flat water to sail one. I suppose I should revisit my failed attempt at learning to windsurf before I attempt to sail a moth.
 
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That's nearly right...the control rod comes straight off the wand block and through a tube through the bow tank and exits at deck level in the cockpit, rather than the right angled thingy floating in mid air above the bow. The top of the main foil is also flush with the deck, rather than poking up above it. The wand also pokes up a few inches above the pivot/block, and the return shockcord runs from there, over the wing bar, and down to the deck.

Roberto, go for it, you will enjoy it, but no matter how good you were in Lasers you will find it a big step up. Make sure you sail with someone, or have rescue cover, and a VHF. There was a well published incident of a badly prepared Moth sailor getting swept through Hurst Narrows due to rig failure, and even the very best in the country were having to get a helping tow into Hayling the other day at an open meeting due to not being able to make much headway against the ebb in a dying breeze.

And now for my favourite moth video...one day I'll foil gybe like those guys...:rolleyes:

http://www.youtube.com/watch?v=3LFLfH9j1PE
 
I was watching one at Blackwater recently. Amazing thing, I imagine you would get plenty of swimming practice at first.
What happens if a foil hits something, say a jellyfish, at high speed?
 
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