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

backwinding with strong wind - max downhaul?
http://www.hobie.com/forums/viewtopic.php?f=37&t=8118
Page 1 of 2

Author:  Claus [ Mon Oct 15, 2007 12:07 am ]
Post subject:  backwinding with strong wind - max downhaul?

Hi all,

we have been out this weekend with quite strong winds (25 knots, gusts up to 30) and although we were able to control the boat, my impression was we were going slow. Especially in the gusts, when releasing a little bit of main sheet tension, the main sail would backwind, which is not very efficient. Also, I had to pinch quite a lot to hold the boat down. So the question is, how to prevent backwinding and be able to foot a little in these conditions ?

Of course, depowering is all. I already know one error we commited, we had the boards all the way down. Next time we'll raise them a bit. We had the downhaul (the lower part of the sail) about 1 inch above the black band, maybe we could have gone a little further? What is the max downhaul without ripping things apart?

Author:  BLR_0719 [ Mon Oct 15, 2007 2:13 pm ]
Post subject: 

In maxing out the downhaul I've always just taken the lines and given them nice hard tugs..no reason to strain yourself tightening up on downhaul. If you feel you're having to pinch a lot in heavy winds you can try maybe letting the traveler out just a bit. I don't know what everyones thoughts on letting the traveler out are but thats what I've generally done when the wind starts blowing real hard on the water.

As far as your backwinding problem, if you ease out the main try easing out the jib as well. I know one problem with backwinding can come from an oversheeted jib and undersheeted main.

Author:  abbman [ Mon Oct 15, 2007 2:37 pm ]
Post subject: 

Ok, I'm not a tiger sailor but I'd like to know. What is pinching?

Author:  BLR_0719 [ Mon Oct 15, 2007 2:54 pm ]
Post subject: 

the more you pinch, the closer you sail into the wind

Author:  abbman [ Mon Oct 15, 2007 6:26 pm ]
Post subject: 

Alright, that makes sense. Thanks.

Author:  Claus [ Mon Oct 15, 2007 10:21 pm ]
Post subject: 

BLR, the jib traveler was all the way open, and I also opened about 6-8 inches of main traveler. It was if the wind was entering from the wrong side on the main sail, the first 10 inches starting from the mast. The sail seen from above would be kind of a "S" shape. This only happened when we released main sheet tension in the gusts.

Author:  BLR_0719 [ Tue Oct 16, 2007 3:59 am ]
Post subject: 

Well to address the exact problem again it sounds like you're sailing slow upwind due to 1) bad air flow and 2) having to point very high to prevent from doing cartwheels across the water.

If you dumped your traveler a bit and were still having to sail real high to keep somewhat flat then it may just be that the boat was tuned more for light air (i.e. loose rig tension and minimal mast rake). As you said bringing up the dagger boards helps depower, how much it helps exactly I'm not sure. As far as accelerating out of gusts, if you're already pointing high and then having to head up in a gust, then yea you're not going to pick up much speed. If this was just a fluke day with heavy winds, I wouldn't worry too much about your tuning, just remember it for the next time you go out in high winds.

For your airflow problem, if you think your jib was positioned correctly, then maybe increase your outhaul...and if this is already maxed out then maybe increase the tension in your battens? Other than jib position, outhaul and batten tension, I'm not sure what else could take that bubble away

I must say that being inland and doing mostly lake sailing opportunities to sail in 25-30 knts are rare, so my experience in 25+ on the Tiger is fairly minimal. Although the times it has blown in that range I've experienced much of the same problems you're talking about as far pointing high and lack of acceleration out of gusts. Someone who is coastal may have some much better tips to address these problems

Author:  Hammond [ Thu Nov 01, 2007 6:49 pm ]
Post subject: 

You have several options, none of them great, but options none the less.

1) Uni-rig. The main may luff, but it will not be backwinded by the nonexistant main. You state that you have maxed out the jib traveler, but are still backwinding, there is no other full sail option.

2) Reef. You will have to modify your sail and take off the headboard to keep from damaging the mast as you sail, but this is the true best way to handle too much wind. It may be cheaper and easier to buy a smaller sail that will work. It will require the sheeting point to be equal to the full sail to keep from breaking stuff or requiring further modification to the boom and mainsheet. Also note, if you make the sail shorter than the spinnaker hoist point, you will not be properly supporting the mast (break it). With this much wind, you probably won't use the spinnaker anyway, but I wanted to point this out prior to breaking the mast.

3)Go get something to eat while waiting for the wind to back off a bit. Sometimes it is best not to leave the beach unless you have a safety crew (rescue) and lots of money to replace broken stuff.

4) Have Matt Miller sail the boat for you so that you can enjoy the view as he super pitchpoles the boat :lol:

Author:  ncmbm [ Fri Nov 02, 2007 12:45 pm ]
Post subject: 

The backwind issue is a mast pre-bend issue. Check the pre-bend in your mast. Tiger tuning guide online will instruct. I sail an 18SX with Tiger main and experience the same backwind issue, before anyone says its the big 18 jib, I run a Tiger jib. I think proper bend in the mast will solve your problem.

Author:  flumpmaster [ Fri Nov 02, 2007 6:45 pm ]
Post subject: 

Some ideas for sailing upwind in 'Tiger weather' (25 knots and above):
  • Lot of mast rake. We have ours below the top gudgeon when measuring using the normal method.* We are virtually block to block on the mainsheet system when fully sheeted in (as tight as you can go with a 9:1 system).
  • More diamond wire tension. We run about 1 5/8" rake with the STX main and with the Diamond tension at 42 on the black Loos gauge (about maxed out) we get about 1 3/4" of prebend. We count quarter turns on the turnbuckle to make adjustments on the water. This will flatten out the main.
  • Tight standing rigging. We put a little grease on the mast ball so the mast will rotate nicely, then wind the rig tension up to 25 on the Loos gauge (we use stay masters on the side shrouds for finer adjustment). This is adding more preload to the mast as well as preventing it from flopping about in the waves that typically go with 25+ winds.
  • The stiffer battens in the top two positions
  • Jib downhaul nice and tight. We have a 2:1 cascaded to a 2:1 (4:1 total) and pull this about as tight as it will go when it is blowing hard.
  • Lots of main downhaul (cunnigham). If you have a cascade system then preload the cascade as hard as you can so that you don't bottom out the blocks. We downhaul with an 8:1 with 2:1 cascade (16:1 in all) until the bottom of the sail is into the black band - basically as hard as the crew can pull it.
  • Main sheet in as hard as possible unless a puff is hitting - then ease until the boat accelerates and work it back in while grabbing a little height. The crew works the main sheet on our boat as soon as we are double trapped.
  • If the boat seems still over powered then de power in this order:
  1. Under rotate the mast - we do this until the arm is pointing at the inside of the hull at the rear cross beam
  2. Drop the jib traveller if you seem to pinch too hard to keep the hull down.
  3. Drop the traveller just a few inches
  4. Raise the boards about 6"
  5. Drop the traveller some more (it has to be thermonuclear to do this).

* Normal method for measuring mast rake: Attach a shortish section of line to a trap wire that does not have a bungee attached. Swing the trap wire forward and hold it taught using the short line so that you have it stretched out to the clevis pin that holds the bridle wire to the hull tang.

Now holding the line at this place swing the trap towards the back of the hull and see where you make contact. Your full range is just infront of the rear deck port to somewhere below the top gudgeon.


Image

Chris.
Hobie Tiger 2273

Author:  Claus [ Mon Nov 05, 2007 3:57 am ]
Post subject: 

Thank you very much flumpmaster, your "total depowering guide" will result very useful for a lot of people I suppose!

Author:  joclo [ Thu Nov 29, 2007 10:20 pm ]
Post subject: 

I would also look at how much mast rotation you are using as a first step and prior to adjusting mast bend rake ect ect, have the rotator further to the back of the boat in heavy winds and forward in lighter winds.

Generally back of the center board 20+ and going forward 20- this flattens out the main in conjunction with the downhaul "pull it on hard".

We have consistent 20+ in AUS sailing inshore and offshore and have been learning the hard way.

Hope this helps

James

Author:  Claus [ Tue May 06, 2008 10:44 am ]
Post subject: 

Just wanted to get back to this post and say thank you again to all, especially flumpmaster. We have been out last weekend with 20+ knots and we really enjoyed our ride, the boat was well trimmed and we have been able to drive it with good speed. We only had problems sticking our nose in a lot of waves downwind, but this is another story.

Author:  The King [ Mon Jun 16, 2008 3:40 am ]
Post subject: 

Hi Claus

Good advice from everyone. I just want to add......

Use more down haul man!!! Send it hard!!!! Bugger the black line!!!! The eyelet on my mainsails will pull past the bottom of the silver sticker. The mast hates it, my warranty voids, the upper battens invert, the downhaul blocks and my crew squeak and grind in protest but the boat leaps out of the water and smokes.

Cheers

Scott

Author:  Claus [ Mon Jun 16, 2008 8:56 am ]
Post subject: 

King,

So how many inches from the "loose" downhaul position (i.e. no wrinkles) would that correspond to? In our case about 4 inches to max. downhaul. Maybe you have an older sail? We could not get our downhaul below the silver sticker, even with the incredible Hulk as a crew...

Page 1 of 2 All times are UTC - 8 hours [ DST ]
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/