Hobie Forums
http://www.hobie.com/au/en/forums/

upwind angle of AI?
http://www.hobie.com/au/en/forums/viewtopic.php?f=71&t=24429		 Page 1 of 2
Author:  TJ [ Tue May 11, 2010 5:12 pm ]
Post subject:  upwind angle of AI?
My boat is not here yet - hopefully not more than another weak, and I am wondering about how many degrees off the wind the boat can sail and maintain some performance. My current boat will sail up to 45 or 50 degrees, but not well. It starts to drop in performance inside of 70 or 75 degrees. Given that the AI seems to sail faster on the other points of sail than my current boat, I would be happy if it could maintain speed at 70 or 75 degrees off the wind.

It's a bit confusing, reading some of the comments, because some talk about how well it points, but there seems to be more comments about it not pointing so well. I understand that it may not come around so well. I have sailed a couple of kayaks, including a Chesapeake Light and a Hobie Revolution and the poor tacking wasn't a big deal - just peddle some or put a paddle in the water. I'm more interested in being able to make some upwind headway. I also know that, by adding some peddle strokes, you can sail higher - even my sloop points higher if I add some electric or gas power, but what about if you just want to plug the peddle slot up and sail the whole way?

Thanks, Ted
Author:  chrisj [ Tue May 11, 2010 6:55 pm ]
Post subject:  Re: upwind angle of AI?
Hi Ted,
I've found that, with the drive out, the AI performs creditably at 45-50 to the wind, although obviously not as fast as at 70-75 degrees. With the drive in it points very high. Here's a recent track log of mine, travelling straight into the wind and using the Mirage Drive for assistance. As you can see, the AI was pointing at 16 degrees with the sail not luffing and the wind definitely providing assistance.
Image
As to coming around with the drive out, the AI is not good. In light wind, it is possible to let it get caught in irons, then backwind the sail to force it around, but in moderate winds, I have not been able to achieve this.
I get howled down whenever I say this, but, with the drive out, I have found it consistently easier and faster to bear away and come around 270 degrees through a tight gybe to change to the opposite tack. I know this is heresy in a normal boat, but the AI has a very tight turning circle, plus no boom to whack you on the head as you gybe.
Author:  TJ [ Tue May 11, 2010 7:17 pm ]
Post subject:  Re: upwind angle of AI?
Wow, that's very impressive Chris. That will be very handy in tight areas and when wanting to get to an upwind local faster. In my Chesapeake Light kayak. I kept a short canoe paddle handy and used it to help bring the boat through the wind. It was no bother. She had the small Hobie sail on it, an even smaller jib on it and two home made amas. It wasn't a very good sailor with that rig - topped out at about 5 knots and was a battle when the wind piped up. Looking forward to giving the AI a try. This weekend will be an eight mile paddle, in an old white water kayak, down Juniper Creek in Ocala National Forest, unless the AI get here before then.

Thanks for the info, Ted
Author:  KayakingBob [ Tue May 11, 2010 8:50 pm ]
Post subject:  Re: upwind angle of AI?
Great answer Chris.

Just to add my 2 cents to it, the angle to the wind varies with the wind strength and at about 30mph or so you can no longer make headway into the wind. (But boy does to fly on a beam reach then)

Enjoy your new boat TJ
Author:  chrisj [ Tue May 11, 2010 10:51 pm ]
Post subject:  Re: upwind angle of AI?
reconlon wrote:
Just to add my 2 cents to it, the angle to the wind varies with the wind strength and at about 30mph or so you can no longer make headway into the wind. (But boy does to fly on a beam reach then)

Bob's absolutely right there. That track log was recorded in 5-10 knot wind.
Author:  JollyGreen [ Tue May 11, 2010 11:02 pm ]
Post subject:  Re: upwind angle of AI?
Image

This is about the performance I get on any given day. As long as the wind is about 10mph or greater. Worst I've been in is I would guess about low 20s. I did not have a problem with upwind performance, but I could see how 30mph would be bad!

Wind is usually NE in Hawaii, on my upwind tack I was keeping as close to the wind as I could while maintaining optimal speed. This is also with the drive in and peddles held up against the hull.

JG
Author:  chrisj [ Tue May 11, 2010 11:54 pm ]
Post subject:  Re: upwind angle of AI?
OK, applying a similar analysis, the angle between your port and starboard tacks varied between 92 and 108 degrees, so your angle to the wind varied between 46 and 54 degrees, which is probably the range within which we trade off pointing high and water speed. Given you weren't using the drive, that seems about right.
Image
Author:  KayakingBob [ Wed May 12, 2010 12:06 am ]
Post subject:  Re: upwind angle of AI?
Jollygreen,
If you keep the pedals together when sailing upwind (fins down) you may see at least a 5 degree higher angle pointing and more stability in gusts.
Author:  TJ [ Wed May 12, 2010 4:35 am ]
Post subject:  Re: upwind angle of AI?
That's better performance than I am used to in the Potter. It's good to know that this will be more than an out and back play thing like in the old wind surfing days.

Ted
Author:  JollyGreen [ Wed May 12, 2010 8:52 am ]
Post subject:  Re: upwind angle of AI?
Wow, you guys are fast and good! I wanted to do the plots like chrisj, but I just don't have the software or image editing tools. Thanks for the analysis. I'll also try sailing with the fins straight down, especially if it makes it point better. I'm happy with what it does now, but if I can make it a little better might as well do it.

JG
Author:  chrisj [ Wed May 12, 2010 12:42 pm ]
Post subject:  Re: upwind angle of AI?
Jolly, just for your interest, I did that with Deltacad, which is shareware. Demo version is fully functional and free. I also use Faststone for the screen captures, also shareware (free for the highlighted version)..
Author:  skua [ Wed May 12, 2010 4:44 pm ]
Post subject:  Re: upwind angle of AI?
JollyGreen, I think you do well with your tacking with dagger only. I am happy if I get that angle (I think I normally do something close to 55 degrees). I find that if I try to go higher, I loose too much speed. So I am among the guys that would say that the AI isn't pointing so high. But I almost always sail without pedals since I like the sailing experience / helm balance better without. But now I've heard you guys I will try it with pedals in and straight down, to see if I can get a better angle too (this is interesting also when sailing with my jib). Might make the AI gaining quicker into the wind (but not sure for it will be slower). Anyway, thanks for the tip, reconlon!
I also agree that the angle gets bigger in strong winds. It also seems to grow in very light winds; the dagger seems too small or short then. But most will pedal along then, anyway.

Chrisj, if I pedal-sail at angles that small into the wind, most part of my sail would be luffing (hope this is the correct word), I personally wouldn't consider that to be sailing I think. Wouldn't it be better / quicker then to furl the sail and pedal straight into the wind (or maybe even lower the mast)? Or do you feel you still get some power out of the sail?
Author:  chrisj [ Wed May 12, 2010 5:58 pm ]
Post subject:  Re: upwind angle of AI?
skua wrote:
Chrisj, if I pedal-sail at angles that small into the wind, most part of my sail would be luffing (hope this is the correct word), I personally wouldn't consider that to be sailing I think. Wouldn't it be better / quicker then to furl the sail and pedal straight into the wind (or maybe even lower the mast)? Or do you feel you still get some power out of the sail?

Hi skua,
I agree that there are times when it is better just to furl the sail and pedal straight upwind, but there are other times, usually in lighter winds when the sail and the pedalling seem to complement each other. I tighten the mainsheet, but not too much, then bear away until the sail just stops luffing, while maintaining a steady rhythm pedalling. If I have to bear away too much from my heading, I pedal through to the opposite tack. When I recorded that track log, I seemed to be making much better headway than two other AI's on the same heading. I was surprised myself when I analysed the log, that I was only 16 degrees off the wind. I think what is happening, is that in light winds, the pedalling generates a bit of extra virtual wind which lifts the boat above the threshold necessary to get some lift from the sail. I wouldn't call it sailing either, more like sail-assisted pedalling. Synergy is the English word. I'm sure there's a Dutch equivalent. Ah, here it is: "synergie" :wink:
Author:  okz00k [ Wed May 12, 2010 6:49 pm ]
Post subject:  Re: upwind angle of AI?
Here is an interesting comparison. The northerly track on the west side of Pittwater was into a 10-15 kt breeze. The lower half of the southerly track near the east shore was into 30 kts + with not much sail out.
Image
Author:  skua [ Thu May 13, 2010 2:34 am ]
Post subject:  Re: upwind angle of AI?
Hi Chrisj, thanks for the clarification. Although I normally prefer pure sailing, the possibility of making use of the pedal-sailing synergy as a great option. (synergie is the Dutch word for sure!) I never thought it might work at these tight angles. But it is a good way of making headway in very light conditions in either case!

okz00k, did you assist your sailing with pedaling? I guess you did at least in the 30kts-wind part?
Page 1 of 2 All times are UTC - 8 hours [ DST ]
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/