Tuning

As of Jan 2010, there are several hundred foiler Moths in action somewhere on the planet. This may be an underestimation but most aren’t properly set up.

With these complex and still experimental boats, you can’t simply unpack the box and hit the sweet spot. Even brand new boats require subtle modification to get the best out of them. Second hand boats are anybody’s guess, unless you just bought John Harris’ Bladerider – in which case don’t touch anything!

Yet set-up of a foiler is crucial to the ride. Speed, enjoyment and even safety are all dependent of fully sorting your foiler. Don’t underestimate what we are trying to do. Tuning any sailing boat is a complex task with many variables. But we’re dealing with unconventional rigs operating over a wider than typical speed range. That’s before we think about the foil set-up and control. The primitive wand, rod or cable and flap system can produce surprisingly good control when working perfectly, or it can give you an uncontrollable and dangerous boat only giving pleasure to the wise guys on the club balcony. So listen-up…

Here are the tips from four of the world’s masters of the dark art of foiler set-up. John Harris and Amac, number one and two at the worlds are the top two Bladerider sailors. Scott Babbage and Si Payne, are the top two Prowler sailors, 5th and 8th respectively. Their gear list is at the end.

What is the single most important part of the boat to set-up?

Amac: That is an impossible question, but easy adjustability would be my top criteria.

John: Getting the control system to work perfectly.

Scott: The skipper. Without doubt the most important factor in performance, and the biggest scope for improvement.

Si: Foil design and wand to flap ratio. Re adjustment – Lift set up, high upwind yet manageable down is fast.

The control system from wand to centreboard flap has been the subject of much experimentation. How do you set yours up and what have you changed to make yours work effectively?

Amac: It is very different to the standard setup, too much to describe. The paddle was a big factor.

John: Mine was pretty close to the standard Bladerider. Rather than reinventing the wheel I just tried to make it work as well as it could. I did the following:
- Put teflon washers inside the c/board on either side of the bellcrank.
- Ensured (with help from Simon Owen-Smith) that the arm coming out of the c/board bellcrank that attaches to the pushrod was perfectly aligned.
- Glued the pin that goes through the bellcrank into c/board with sparbond to make sure there was zero play
- Filed down the top of the bellcrank approx 2mm to get a bit more flap movement for given wand movement
- Replaced all pushrod connections immediately before worlds & made sure there was minimal play
- Lubricated all pushrods & moving parts
- Made sure bow fitting (bit that holds wand) was perfectly smooth & lubricated so it would swing without friction

Scott: I have changed it through many variations, both good and bad, but am yet to find the right solution. Some important things to consider are friction, play, power over the flap, flap range, and point in the range of maximum rate of change.

Si: Since the worlds I’ve changed the ratio of wand to flap movement. The flap now moves less for the same wand travel. I think it’s faster as the flap is less “jerky” and I also like having a paddle on the wand that gives better feedback and minimises cavitaion of the rudder. Unfortunately my best wand fell off yesterday.

How much do you use your rudder adjustment when racing?

Amac: A lot for trim, i.e from tack to tack, upwind-downwind, change in pressure, waves. Rarely, maybe never, for controlling the boat over waves

John: A little bit tack to tack (more bow down on s/board). I wound the bow down for the down-winds at Weymouth – mainly as I was playing it safe. Generally though not much.

Scott: Very little.

Si: Definitely regular adjustment, but only about half a turn here and there. Wind the bow a bit down upwind, wind it up downwind.

At Garda and Weymouth,the Bladeriders seemed to have better height control and more speed especially down-wind. Do you agree and how do you explain this?

Amac: Yes. More aggressive flap control and a foil designed around the flap.

John: Yes agree. I don’t claim to be an expert. I think like most performance gains it is a combination of a lot of things. Mainly though a better control system (correct ratios between wand & flap and minimal play in system) The foil shape (I guess??) and the larger flap being more effective.

Scott: Yes, I agree. In terms of control, they have a larger flap as a % of chord. They have more direct control through solid pushrods rather than cables and their gearing within the centreboard is more powerful. In terms of speed, perhaps their shapes are better suited to speed, or perhaps their speed was a function of their better control, and the resulting ability to push harder without failure.

Si: Yes I do agree. In a breeze this is the difference between the designs. Check out the Velocitek speed challenge times. The BR foils are clearly a good strong wind design, and spaced further apart than any other boat and the bigger flap means it has to move through less of an angle to keep control. Moths are about development, generally newer designs are faster. People learn.

John’s wand (left)showing radical forward of bow range. You get more flap angle change per unit height change the closer the wand gets to the vertical. Jean-Pierre Ziegert (right) tried twin wands to eliminate height difference between tacks. Why did he move them back to the centre-board?

Good flap response left – bad flap response right

The trend with rigs seems to be to use ever more kicker loads? How do you set up your rig?

Amac: With everything easily adjustable. It is important that there is no rule, it changes all the time. Put tell tales on the sail and get them to flow!

John: I think a common error when starting out is to not use enough vang. Above 20knots I pull it on as hard as I physically can. Make sure your system works really well (get sailingbits vang system!!!!!).I adjust cunno more than vang upwind. In Weymouth I did not even bother letting the vang off downwind…

Scott: Nothing special here. Plenty of vang.

Si: Badly if you look at the front cover of Yachts and Yachting… I’ve added an extra purchase to get more kicker on upwind. Downwind this year I’ve always been fast, I think this is largely because I don’t really let much off when I get to the windward mark… lots of people seem to turn their sail into a bag, but lots of the time downwind is only upwind but going the other way…especially in flat water. If you sail really accurately you can use the apparent to go fast, and where necessary low.

Even with the high vang loads used the sail still twists.

Do you adjust the spreader unit for different conditions?

Amac: No.

John: Bladerider is not adjustable.

Scott: Yes. Not a huge amount though.

Si: Yep drop it in in a breeze. Recently though I’ve been bending the mast more and sailing with an even flatter sail in light winds.

Is mast rake critical? How did you find the best setting?

Amac: Balance the helm of the boat.

John: Yep it is critical. I am not sure I have found the best setting – more testing required! In lighter air I find I suffer downwind if I have too much rake. I am keen to test with a lot more rake as per Amac when it is windy. My mast rake was really a best guess that I came to in the limited time I had.

Scott: Maybe it is critical. I don’t know. We haven’t tested enough to work out where is best. I just modify it within a 50mm or so range depending on conditions.

Si: Is it critical? Well it varies a lot amongst the top guys. The boat should not have any lee helm (bearing away) so drop the mast back until the thing sails straight or points up a bit.

Any other tips?

Amac: Sail hard, go left.

John: Get fit. Sailing a Moth well is tough on the fitness – the harder you hike and work the quicker you will go. Get every system working perfectly, maybe I am fussy but I just hate having ropes the wrong length or controls that are hard to use – the boats are hard enough, try and make it easy for yourself! The other thing is when you train try and be focussed on achieving something – there is a great temptation in the Moth to just cruise around because just foiling on a reach at 1.5 x wind-speed is a beautiful thing… But if you want to improve get a training partner, share info, race each other hard and try and get the most out of any time on the water.

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