James Boyd Photography / www.thedailysail.com

Latest foiling Moth hardware

The Exocet and Mike Cooke's new Rocket

Thursday March 7th 2013, Author: James Boyd, Location: United Kingdom

On display at the treasure trove that is the annual RYA Dinghy Show last weekend was of course the state-of-the-art foiling Moth hardware.

The boat of the moment seems to be the latest Kevin Ellway design, the Exocet, built by Maguire Boats in Lymington. The boat made its debut last summer with several examples competing at last year’s World Championship on Lake Garda. At the RYA Dinghy Show various Exocets were scattered around the halls, including Simon Reynolds’ new boat on the Harken stand.

We wrote about the Exocet last year prior to the Worlds (more about it here), however it was good to see an example in the ‘flesh’ and understand some more about its basic concepts. One of the most interesting aspects of the boat is that unlike say the Mach 2, which has an almost catamaran-style hull section with a flat bottom (and slab sides) for planing, the Exocet has taken a step away from this.

Simon Reynolds explains: “The Exocet has a lot of rocker and a lot of curve on the hull, because the boat gets up of the foils effectively in displacement mode and a displacement hull is quicker at slower speed than a planing hull, so you don’t need a planing-shaped hull.”

The foils on the Exocet are particularly impressive. While there once was a trend for having foils with as high an aspect as possible, for a while now people have been reducing the size of the foils on the basis that they are generating excessive lift. The Exocet’s foils have a ‘nose’ and their span is wide, but tapers both in terms of chord and thickness – and this with a full-width flap running along its trailing edge. In short a masterpiece in carbon fibre, the rudder a smaller short-span version without the flap.

So noticeably different sailing it to the Mach 2? “The thing you notice is the ease of use and the foils allow you to have greater hang time in the tacks and gybes,” says Reynolds, echoing what Rob Greenhalgh told us a couple of weeks back. However since acquiring his Exocet in November he’s only had a chance to sail it five time.

Generally detailing on the Exocet is very good. All the controls are led back from the mast to the wings where the sheet ends are pulled into the wings by bungee, while the sides of the tramps feed into neat recesses in the wings.

Chris Rashley’s Exocet finished eighth at last year’s Worlds - the top position for a boat other than the still massively dominant Mach 2 design. Will this still be the case this season?

Red Rocket

An even newer addition to the Moth fleet is the Rocket from Aardvark Technologies, their latest model following on from the Kevin Ellway-designed Ninja.

The Rocket is a design by Aardvark’s Mike Cooke and the significant difference from the boats preceeding it is that it is an artificially ‘large’ Moth. The rig and daggerboard have been moved forwards in the hull, while the separation between the main lifting foil and the wand has been maintained by hanging it off a bowsprit which is apparently allowed under the Moth rules.

“You can have a maximum on each end of the boat – 500mm at the front and 500mm at the back,” explains Cooke. “So the fact that you can do that is what has allowed me to move the foil forward because you are able to maintain the spacing between the wand and the daggerboard.” This same rule also permits the more familiar aft gantry from which the rudder is slung.

The effect of moving the rig and the main lifting forward by around 150mm is that it increases the separation between the two lifting foils and this improves the fore and aft stability when foiling, Cooke maintains.

“Moving the rig forward means that you have to bring some volume forward just to get the boat to behave while it is low-riding, because the low-riding dynamics change quite a bit. But when it is foiling it just behaves like any other Moth, only bigger.”

The hull shape at the bow is also more Veed. “I wanted something more punchy for going through waves. I find the U-sections to be quite sticky. Then aft there is plenty of rocker – when you are going through the take-off transition, it just keeps the wetted area down – the bow is already out of the water at that point...”

The Rocket also dispenses with the steel push rod link mechanism between the wand and the lifting foil. Instead it has a carbon fibre tube running from the wand on the bowsprit back to the top of the daggerboard.

“It gets rid of some slop, because there are no push rods or linkages,” says Cooke. “If you look at the older systems there are lots of stainless steel bits all held together with bolts and you can’t help but get play in that eventually. This dispenses with all of that. This has really solid connections and there is no friction either - you haven’t got a rod sliding in a tube, it is just floating around in there. The whole thing acts as a massive bottle screw, so that is your basic push rod length adjustment.”

Ride height is adjusted by changing the wand length. This is typically used to adjust ride height upwind and downwind (you make the wand shorter downwind because the boat is going faster). It also allows differences tack to tack to be evened out (through the wand mechanism being mounted on the starboard side).

In addition to this the length of the carbon fibre pushrod can still be altered and there is also of adjustable gearing that alters the degree to which wand movement affects the flap on the aft side of the lifting foil (ie useful for adapting to different sea states). “Changing the push rod length changes the gearing and it messes around with quite a lot of things all at once. I like to set it for the day and leave it alone,” says Cooke.

With the foils for the Rocket (which we didn’t get to see at the show), Cooke says he has scaled their aspect back from the ultra-high aspect foils used on the Ninja, although he points out that the new foils are generally scaled down rather than just having a section loped off each end.

The Ninja, he says was pitched more at the European market in anticipation for the Worlds on Lake Garda. “We found being able to tack without touching down wasn’t particularly advantageous. If you can tack and you can come out the other side with 5-6 knots of speed you will be foiling again pretty soon anyway, it is not going to lose you a lot. Having so much lift that you can sail around on the foils isn’t that useful and we were paying for it in straight line speed. So I have pulled the spans in a little bit, although the aspect ratio is still fairly high.”

When we spoke to him about the Ninja last year, Cooke was saying that he wasn’t using the pitch adjustment on the rudder that all of the other Moths feature. The Rocket however will feature this. “It is personal preference. I have got it on this one, but I’m not using it. It helps being able to tune it up quickly, but then I just leave it alone.”

The price tag on the Rocket is around £11,000. The first example, in an Alfa Romeo red, was on display at the RYA Dinghy Show and according to Cooke they are shortly to finish the second and have orders for six – including one going to Team GBR 49er sailor Dylan Fletcher.





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