Spinnaker Pole Height Question

[Ducati]

Can you tell me why and when we raise or lower the spinnaker pole?

Thanks

 

[Alan]

Raising the spinnaker pole raises the tack of the spinnaker and opens the luff or leading edge of the sail. Spinnakers are flown most efficiently with the leading edge just on the edge of stall. If the leading edge is breaking about 1/2 way up the luff the pole height is correct. If the break is occuring higher up the pole it too low pulling the leading edge too tight.

 

[Barnacle Bill]

Spinnaker trimming 101 suggests that you keep the corners of the spinnaker level when flying a kite with a pole. You can adjust the tack (corner of sail attached to the pole) by raising and lowering the outer end with the pole foreguy/downhaul and topping lift to keep the corners even or level. You also want to have the corner attached to the pole out as far as your pole allows. So, when you adjust the outboard end (for instance, raising it), you can then raise the inboard end which will push the forward end out further. The other rule of thumb is to keep the pole parallel with the water and square to the apparent wind. Of course there are modifications to this. In heavy air, fore example, the pole is usually eased forward (not square) by easing the after guy (the line attached to the pole side) and then the tweakers are pulled in (pulling the after guy and sheet down to the deck midships) on both sides to choke down the sail down for better control when the wind is heavy. That's my 2 cents

 

[RichH]

Raising the spinnaker pole raises the tack of the spinnaker and opens the luff or leading edge of the sail. Spinnakers are flown most efficiently with the leading edge just on the edge of stall. If the leading edge is breaking about 1/2 way up the luff the pole height is correct. If the break is occurring higher up the pole it too low pulling the leading edge too tight.

Alan is spot on ... especially about the 'breaking' ... or 'slight curling' of the luff. A spinnaker as he states is most efficient (and is most stable from collapse, etc.) when the luff is 'just beginning' its curl near the middle of the luff
.... if the curl occurs more above the 'middle' then pole is lowered;
if occurs lower down than the middle then the pole (tack) is raised.
Same thing, different wording.

But "when in doubt, first let it (sheet) out"

{BTW- The same is done with the tack line on an asymmetrical .... the tackline adjusts where the 'break' or 'curl' is happening and is adjusted the same way to get the sail to begin its break/curl in the middle.}

Keeping the pole horizontal keeps the tack/luff at the max. distance from the mast/mainsail for better airflow. ;-)

 

[Joe]

Adding to that........ the spinnaker pole height determines the full or flatness of the chute. If you lower the pole, (keeping it parallel to the deck, of course) it will tension the luff/leech and slack the foot, just like moving the jib car back on the head sail... the result of the slacking foot is the clews move towards each other giving the sail a fuller shape.

Conversely, raising the pole height relieves tension on the luff/leech. The clews rise up and move away from each other resulting in a flatter profile.

 

[shemandr]

To bring it back to the question: Which is the power up position and which is the power down position? "Up" and "down" may be confusing language but its the best I can do.
The answer isn't, in my opinion, intuitive - although its contained in Joe's post.

 

[RichH]

Just like any other sail - 'power' is principally attained by maximizing draft (versus the speedo) in contrast to power-down or a 'speed shape' which is a reduced draft (versus the speedo). The draft control of a spinnaker is the sheet ... followed by a tack height adjustment to insure that the spinn is 'breaking at the luff' in the correct middle section which governs 'stability' of the sail.

Additional 'depowering' can be obtained by lowering the pole (or tightening the tackline on an asym) which tightens the luff and opens (flattens) the leech ... and causes the luff to break lower down. Interestingly with any 'free flying' sail (spinn, drifter, tall boy, spinn staysail, jib NOT attached to a forestay, etc. if you adjust in any direction from the 'optimum' the sail becomes 'unstable' ... the further from optimum the more 'unstable'.

Power/Depower ... first gear/high gear: Same as with a jib - jibsheet/fairlead car; and, same with a mainsail - outhaul/vang or traveller

;-)