Tuesday, July 23, 2013

Cruising (Asymmetrical) Spinnakers


Sailing with my cruising (asymmetrical)  spinnaker is great on light breeze days when I am sailing downwind for several miles.  When I had the cruising chute made, I specified that I wanted a full 180% spinnaker with the foot of the sail modified to give the asymmetrical shape - - that is to add a partial panel to the bottom of the sail to extend the tack corner down – rather than cut the leach of the sail up.  My way actually makes the sail larger rather than smaller than a “normal” spinnaker.  This is perfect for light breeze days with winds between 5 and 10 knots.  As the wind gets up to more than 10 knots, this asymmetrical spinnaker is too much sail though.  And, the boat quickly can become overpowered…… this can lead to a broach…
Spinnaker broaches – even with a cruising spinnaker – are scary and no fun at all.  Double that if you are single handing your sailboat.
Broach = most typically happens when a boat is on a broad reach with spinnaker set and there is an overpowering weather helm.[1] This may be due to excessive heeling, swell that causes the rudder to be partially lifted out of the water, or because the stem digs into a wave causing a strong lateral force. The boat will come quickly across the wind with too much sail set. It can also happen on a close reach where it is typically precipitated by sudden waves.[2] With an inattentive helmsman it can be a consequence of a gybe, which can be a dangerous manoeuvre even when performed under controlled circumstances. When it happens unexpectedly and the helm isn't corrected, the heading of the boat may veer into the wind causing a broach.

 



The worst broach I have experienced on Snickerdoodle happened one day when I was single handing.  At the marina, the wind seemed to be in the 5 to 10 knot range out of the SW.  So, I decided to sail to Whiskey Rock (about 8 nm to the NE).  It seemed a perfect day for a spinnaker broad reach with the cruising chute.  So, I rigged everything up and motored out of the marina.  I raised the mainsail and then changed course to the SE on a broad reach – with the Navico tiller pilot steering the boat.
Up on the foredeck, I raised the cruising spinnaker in its “Chute Scoop” sock, made sure everything was all set, and raised the sock to deploy the spinnaker.  The wind was light as I was in the lee of Leiberg Point.  Back in the cockpit, I could see that the wind was quite a bit stronger coming out of Idlewild Bay (from SW to NE).  “This is going to be great,” I thought, seeing that there were many white caps marching across my bow about 500 meters ahead.



As I came out from behind the lee of Leiberg Point, the first 20 to 25 knot gust hit the sails… AND heeled Snickerdoodle over until there was water washing against the portside main cabin windows.  Can you spell decks awash?  Snickerdoodle rounded up with the spinnaker still in the water and then righted herself as wind pressure moved forward to the point where both sails were luffing.  “Oh boy,” I thought.  “This will be a fast reach to Whiskey Rock… and I fell off to a broad reach.  The second strong gust hit the sails at just about the same time.  Snickerdoodle was knocked down so far that the sheet and tack adjuster line were both under water.  In fact, the whole portside coaming was under water and water was freely flowing over the coaming and into the cockpit.  “Hmmm, this isn’t good,” I thought as I noticed there were no hatch-boards in the companionway.  “If we tip much more, water will begin to flood the main cabin.”
Luckily, Snickerdoodle again rounded up head to wind and righted herself.  “Time to douse that spinnaker,” I decided.  And I cautiously went forward and pulled the downhaul line on the Chute Scoop - - - and successfully doused the spinnaker.  It was a terrific – and fast – sail to Whiskey Rock under mainsail alone.
Here are a couple options for if you get caught with the cruising spinnaker up and wind building to uncomfortable strength.  First, you can douse and lower the spinnaker completely.  Another option might be to partially douse the spinnaker by hauling the downhaul line part way down.  I saw a friend of mine sailing this way a couple weeks ago.  It looked pretty neat.
So, don’t be afraid to sail with your asymmetrical spinnaker.  But make sure that you are in fairly light breezes until you get used to that big, powerful sail.  Enjoy




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