Spinnaker Pole Problems

[Colin Brown]

Hi I have started to race my Beneteau 21.7 with the spinnaker and have a problem with the spinny pole. The pole is clipped on the windward sheet, the guy, and the kite sets very well. Then for some reason the pole slides away from the kite and down the guy sheet between 300 and 600mm. The whole kite becomes unstable in medium to strong winds as the pole no longer locks the clew of the kite into a fix position. Any suggestions please on the likely cause? I have had 50 plus years of racing high performance dinghies and have never experienced this problem before.

 

[B27]

Are you using twinning lines/stranglers/barbers so that the guy is pulled down?
As in a dinghy. the guy wants to meet the gunwhale somewhere near the shrouds when the pole is at all forwards, maybe further back on a run.
Then the angle the guy makes at the pole pushes the pole forwards.

Bigger yachts will rig the pole with a foreguy, rather than a downhaul led to near the mast, the foreguy pulls the pole forwards as well as down.

 

[Colin Brown]

Hi I am using twinning lines/barber haulers, mounted on the deck and the shroud base. The pole wants to run aft away from the clews. I will try rigging the barbers further forward tp see if that helps. The boat has a block in the middle of the foredeck, for a forgery i would think but never used it. Very difficult to use when 2 up and sailing at Ullswater, as the wind is always all over the place here.
Any further advice/ suggestions very welcome

 

[Motor_Sailor]

Just checking you have a pole uphaul (topping lift) attached to a two legged bridle on the pole?

If the pole topping lift is set up hard so the pole is level, the outer pole end can’t drop down the guy as that is sloping down to your twinning block.

 

[B27]

For this to be happening, the line the guy wants to take must be pushing the pole end back.
Possible cures:
Pull the guy on more and ease the sheet
Get a longer pole. Or a smaller kite.
Pull the twinning lines on further or move them further forwards
Move the pole downhaul forwards along the deck.

Steer higher? Or more actively to keep the boat under the kite.

Raising the kite end of the pole might make the kite more stable.
As might pulling on a little twinning line on the sheet side.

It would help to know how the leach of the kite is inter-acting with the main.
If the leach is getting too close to the main then easing sheet and maybe pulling on the guy a bit.
If you're not on a dead run, it MAY pay to sheet the main in and ease the kicker some, to make the shape of the main more similar to the shape of the kite. This is a thing in asy dinghies I've sailed, but also conventional kites.

The problem may be a lot clearer viewed from lying on the foredeck or sailing another boat.

Sometimes kites get too old to set nicely in a breeze.

 

[Colin Brown]

Thank you all for your replies. Here are a few items I have noticed re the set up on other 21's
Twinning lines are on the shrouds, others are 600mm further forward, in line with the mast
My pole is 200mm shorter (at 2400mm) against ZSpars recommended 2600mm
There appears to be two different places on " others" masts to fix the pole to, About 500mm higher than my standard fitting
Going to give it a good once over this weekend and report
Further suggestions always welcome
Colin

 

[Laser310]

For what it's worth, some people, in some classes, think it's fast to fly the tack away from the pole end like that.

I have never been a big fan of the technique, but I do see that in some cases you can get the tack to fly a bit further outboard, while also being higher, than if the tack is snugged to the pole end.

I guess being further outboard might give more projected area, as long as whatever is gained by being further outboard isn't lost by also being higher.

anyway, i've seen very good sailors in an isaf international one design class do it

 

[Birdseye]

The only way that what you describe is happening Colin is if the pole is not under sufficient compression to hold it as far forwards as it can get so the weight of the pole is winning and its sliding down to a point where the compression does hold it. So the initial geometry is wrong suggesting as B27 has commented that you need a longer pole or to raise the end of the pole.

 

[Colin Brown]

Thanks to everyone who has kindly replied
I moved the twinning lines take off points forward by 500 mm and it seems to have solved the problem. Also moved the pole downhaul fixing at the mast forward by adding a short rope length of 75mm. These two changes were the fix
Thanks