I feel a resurgence in wingsail ideas , maybe mostly from my quarter, but I am certainly interested in how the BMWO ideas would translate in RC multi’s,
I lifted the interview below from another site as I thought it answered alot of questions for me…maybe you to!, enjoy!!.
Dirk de Ridder, the man who operates BMW Oracle Racing’s solid wing, tells us his secrets
Friday February 12th 2010, Author: James Boyd, Location: Spain
Dirk de Ridder holds considerable responsibility for BMW Oracle Racing’s result in this 33rd America’s Cup. While on normal softsail boats trimming the rig is the responsibility of a small troupe of trimmers, grinders, etc with the solid wing sail all these responsibilities fall on his shoulders, via just a piece of rope to operate the traveller (there is no mainsheet) and a rebuilt garage door remote control to drive the wingsail’s other hydraulically-operated functions.
As a sailor De Ridder has done the rounds. Nephew of the Checkmate Peter de Ridder, rather than the Mean Machine one, our man has done three Volvos on board Merit Cup, then winning with fellow BMW Oracle crewman John Kostecki on illbruck and then with Paul Cayard on Pirates of the Caribbean. He previously spent two years with BMW Oracle just before he left to join Pirates. He did a Star campaign with Roy Heiner in 2000. And to confuse the ‘de Ridder’ issue further in between all this he was a regular part of the Mean Machine crew with the ‘other’ Peter de Ridder. “It is a bit complicated,” he admits.
From his job doing traveller with BMW Oracle before he went to Pirates, when he returned to the American challenger under the new Coutts regime, his job on board the trimaran initially with the softsail rig was mainsail trim. Even this was very different to the mainsheet trimmer’s role on a monohull he says: “The traveller - you move it a little bit, but the problem is that we cant the rig so far to weather [up to 15deg] that all the load is on the leeward traveller, not the weather traveller - so you had to pull the traveller to leeward, rather than ease it. So we always ended up sailing more on the mainsheet than the traveller. It took some getting used to.”
In addition, with such a phenomenal apparent wind machine that the black and white trimaran is, the apparent wind, even when technically downwind in any sort of breeze is never more than 30degs aft of where it is upwind. De Ridder gives the example of their genniker, the shape of which he says is flatter even than an overlapping genoa on a keelboat. So the traveller would never get dumped far.
Another less obvious responsibility of the mainsheet trimmer with their softsail rig was that of managing the loadings of the boat. "When you do the mainsail, most of the loads going into the boat come from the main sheet, so that has all disappeared now [with the solid wing] because we don’t have any mainsheet load.” From more than 20 tonnes, de Ridder says that with the solid wing sheet loads rarely hit 3 tonnes. They have gone from operating the mainsheet from a top of the range primary with a 7:1 purchase, to a 2:1 on the equivalent of a pit winch. Meanwhile the responsibility for the overseeing loadings has now shifted to navigator Matteo Plazzi, who presses the buttons that operate the rig rake and rig cant hydraulics.
For someone with such a long background trimming conventional rigs, the move to the solid wing was a far from natural one, admits de Ridder. To help them get used to it, the team acquired Ben Hall’s solid wingsail A-Class cat and travelled up to Toronto on several occasions to sail Fred Eaton’s C-Class cats.
“When it first got introduced to us, it was very much all the boffins saying it was ‘perfect’,” recounts de Ridder. “Then they show you a very simple presentation of the size of it compared to say the mainsail. And you go ‘that’s bullshit - there’s no way…’ [the area of the solid wing is 50% of the softsail rig’supwind sail area]. Then you go sailing on the A-Class and the C-Class and you start going ‘that’s pretty impressive’. Then we got it in San Diego and once you get your head around it and you start believing in it, it is very impressive.”
The biggest problem de Ridder says he has found with both the softsail as well as the solid wing is simply their towering height - the solid wing is 68.5m high, almost exactly twice the LOA - and the huge wind shear than can occur between deck level and masthead. “You can have two knots on the water and 12 knots on the top. It is the same with Alinghi as us – you see pictures where it is a glass-off, but you are flying a hull, because there’s still seven or eight knots at the top of the wing. That is a beautiful thing, but it is hard with the wing - you have to have really good sensors to measure that. If you don’t have those, it makes it pretty hard.”
The solid wing also seems to defy all he has learned as a mainsail trimmer. “Especially the bottom camber is something you have to really get used to and get it explained by the experts why it has to be like that, because it doesn’t look right. If you are used to looking at a sail, it is the opposite - you have a huge amount of camber in the bottom flap and that angle goes up as it gets windier, because you twist more. So you can’t look at it like a sail.”
De Ridder reckons he has got to the stage where he could trim the wing visually, but he almost never does. “The best piece of advice I got – because we have MANY experts – was form Mick Kermarec and he said ‘just put it to the target camber, close your eyes and the sail the boat like you were doing mainsheet.’ So just trim it with the traveller and the twist controls and just do what you normally do with a keelboat with the rudder angle and boat speed.”
Having developed their targets for different wind speeds and angles during their training session with the solid wing sail while they were in San Diego, de Ridder says that Kermarec’s advice proved right: "Keep the hull out, minimise rudder angle [to reduce drag] and just sail to boat speed and then the wind angle will come on its own and its been pretty accurate actually.
“On the softsail you always look up to make sure it looks right. With this, unless a cable breaks you don’t really look up. The bottom camber doesn’t change that much and if the rake is right you just go back to how you would normally sail a boat.”