| Re: Help me understand down wind on the tornado
[Re: ckuang]
#153080 08/21/08 08:19 AM 08/21/08 08:19 AM |
Joined: Aug 2004 Posts: 145 Cheshire, UK Simon
member
|
member
Joined: Aug 2004
Posts: 145 Cheshire, UK | I'm surprised no-one has chimed in on this one - perhaps they're celebrating or commiserating...
I'n no expert, but I try to keep the main trimmed downwind. John Pearce put it best for me: "the sails don't know they're going downwind" - so trim them! Having said that, the spinni is the main engine, but the mainsail makes a difference too, especially if you're trying to lift the hull.
Yes, the main is acting as a backstay - but it doesn't have to be tight like the shouds - just don't let it go. And if you do, grab it quick!
Simon Shadow 067 | | | Re: Help me understand down wind on the tornado
[Re: Simon]
#153082 08/21/08 08:31 AM 08/21/08 08:31 AM |
Joined: Feb 2004 Posts: 3,528 Looking for a Job, I got credi... scooby_simon Hull Flying, Snow Sliding.... |
Hull Flying, Snow Sliding....
Carpal Tunnel
Joined: Feb 2004
Posts: 3,528 Looking for a Job, I got credi... | I always play the main down wind when sailing 2 up with the kite. Gusts come, shifts come and the flow over the mainsail changes. Easing the main also effects the shape of the kite as the top of the mast moves and so moves the head of the kite.
So, to an extent (depends on how strong your mast is) you can play the mainsail to keep the telltails flying. Let everything out and the mast might break so take some care.
If I had a spare hand I would play the mainsail down wind single handed on the F16. I will sometimes change it downwind if I am not on the wire or when I gybe.
F16 - GBR 553 - SOLD I also talk sport here | | | Re: Help me understand down wind on the tornado
[Re: ckuang]
#153087 08/21/08 12:17 PM 08/21/08 12:17 PM |
Joined: May 2003 Posts: 4,451 West coast of Norway Rolf_Nilsen
Carpal Tunnel
|
Carpal Tunnel
Joined: May 2003
Posts: 4,451 West coast of Norway | Sorry ckuang, I dont have a number for you. On the T we set the mainsail so the telltales streamed and went from there. Often that was with the traveller out 10cm and some sheet. More than one armlength of sheet released from that setting was more than what we wanted to try. I have seen some of the alu wingmasts really bend forward with the sheet released completely but that is neither fast nor safe. I dont have any advice but watching the mastbend and dont do anything scary. I dont have a F16 yet. I have sailed tornados until last fall, then we began building some F16s. We hoped to launch this summer, but alas. Now we aim for next summer. We have a building blog here: http://woodastic.blogspot.com/I have been hanging around the F16 guys for a very long time, but have not taken the jump until now. Our masts will be Tornado sections cut down to size. | | | Re: Help me understand down wind on the tornado
[Re: ckuang]
#153088 08/21/08 12:55 PM 08/21/08 12:55 PM |
Joined: Feb 2004 Posts: 3,528 Looking for a Job, I got credi... scooby_simon Hull Flying, Snow Sliding.... |
Hull Flying, Snow Sliding....
Carpal Tunnel
Joined: Feb 2004
Posts: 3,528 Looking for a Job, I got credi... | hey Rolf, on your f16, are u using an ahpc section? what is too much? sorry i know it sounds like a funny question, i'm hoping to find the approximate limit without having to actually experience it, i f you know what i mean I would say, unless your mast builder says otherwise, an "armfull" is the most you should let go unless you can afford some desctructive testing. I would define an armfull the distance holding the sheet whith your fist touching your chest to fully extended, so maybe 2 feet or so.
F16 - GBR 553 - SOLD I also talk sport here | | | Re: Help me understand down wind on the tornado
[Re: Rolf_Nilsen]
#153094 08/22/08 08:21 AM 08/22/08 08:21 AM |
Joined: Feb 2004 Posts: 3,528 Looking for a Job, I got credi... scooby_simon Hull Flying, Snow Sliding.... |
Hull Flying, Snow Sliding....
Carpal Tunnel
Joined: Feb 2004
Posts: 3,528 Looking for a Job, I got credi... | It is complicated........
First consider letting out the kite and nothing else...
It flogs and you loose power but the whole rig becomes unstable. If you decelerate, the kite then starts to power up again (maybe).....
What happens if you oversheet the kite?
You loose power and so you may reduce heeling moment and thus prevent a capsise or pitchpole, but you then have tight sails and may be in trouble as the rig loads up as you might simple blow over sideways as the apparent wind moves aft as you slow down.
IMO, you need a mixture of the two.
Now, consider what happens when you free some mainsheet and do not change the kite. Letting some mainsail out you reduce heeling moment and drive (remember if you decelerate you may bring the sail back into the sweet spot and then power up again). BUT also what is happening at the top of the mast?.... Less sheet load means the mast tip moves forward (and maybe away from you). BUT the distance between the head and the tack of the kite has reduced and so the shape of the who kite has changed. This MAY also flatten the entry of the kite (most kites flatten as you ease tension in the luff).
Time on the water is key, but initially I would suggest dumping an arm full the kite until you get batter and can then combine oversheeting the kite with dumping small amounts of mainsail and then re-shet kite and mainsail and you will then also learn when you cannot over sheet the kite. It takes time to work it out.
F16 - GBR 553 - SOLD I also talk sport here | | | Re: Help me understand down wind on the tornado
[Re: Rolf_Nilsen]
#153096 08/22/08 10:19 AM 08/22/08 10:19 AM |
Joined: Feb 2004 Posts: 3,528 Looking for a Job, I got credi... scooby_simon Hull Flying, Snow Sliding.... |
Hull Flying, Snow Sliding....
Carpal Tunnel
Joined: Feb 2004
Posts: 3,528 Looking for a Job, I got credi... | For once we disagree Simon. I think an armful to be the max, but very soon you will want to begin easing just 10-20cm before sheeting in again. It is all about feel for the boat and the conditions. Anyway, key is to not accidentally adjust rudder angle while sheeting the main.
I dont know how much the mast moves while sheeting the main going downwind and how that changes the spi shape. Never been in a position to study that. Rolf, Are you talking about the main as in "an arm full"; if so I agree, I'd never suggest dumping the main in the gusts unless you want to buy a new mast... I agree that sailing down wind and playing the mainsheet, you MUST stear carefully at the same time. I think the T medal race action from the Games where it shows Bundy putting the mainsheet in his mouth so he can still steer with one hand while playing the mainsail is a classic demonstration of sailing down wind 2 up.
F16 - GBR 553 - SOLD I also talk sport here | | | Re: Help me understand down wind on the tornado
[Re: scooby_simon]
#153097 08/22/08 11:56 AM 08/22/08 11:56 AM |
Joined: Jul 2001 Posts: 1,200 Vancouver, BC Tornado
veteran
|
veteran
Joined: Jul 2001
Posts: 1,200 Vancouver, BC | [quote I think the T medal race action from the Games where it shows Bundy putting the mainsheet in his mouth so he can still steer with one hand while playing the mainsail is a classic demonstration of sailing down wind 2 up. [/quote] 'cept he was on the tramp...thus only 1 up ;-) From a post today over on the TornadoCat Yahoo forum from Oskar Johansson (Team CAN helmsman): ...Even though it was only 15 knots of breeze there was almost 2 knots of current going upwind which created steep waves. Everyone had to throttle back downwind, thus sail lower angle and play main much more frequently to power over waves. It felt more like 20-22 knots of breeze due to the rough sea state. Great sailing conditions....
Mike Dobbs Tornado CAN 99 "Full Tilt"
| | |
|
0 registered members (),
654
guests, and 156
spiders. | Key: Admin,
Global Mod,
Mod | | Forums26 Topics22,405 Posts267,056 Members8,150 | Most Online2,167 Dec 19th, 2022 | | |