A spinnaker or chute is a large (usually bright coloured) sail flown in front of the jib when on a downwind course. When you are on a downwind course your apparent wind decreases. If you want speed, you have to add sail area to make up for the diminishing wind.
Sidenote: Apparent versus true wind. True wind is the wind speed and direction you feel when standing still on a dock or when your boat is anchored. Apparent wind is a combination of true wind and the wind you create when moving. The wind indicators on your boat show the apparent wind.
Not all boats need a spinnaker, nor do all sailors want them. Chutes (named after the parachute they look like) are racing sails and require special gear and very careful handling. On a nice flat sea with a steady breeze flying a chute makes your boat fly and is great fun. When the sea gets a bit rough or the breeze picks up the beauty becomes the beast and you’ve got a huge amount of nylon (often wet) to manhandle. Spinnakers are temperamental and need serious muscle. One of the reasons it is so fussy to fly is that it has no supporting stay or spar, it’s connected to the boat only at 3 points, the head, tack and clew. Without perfect sail trim this humongous piece of nylon will flip flop and collapse. (Meaning you can’t set this and leave it while you fix a sundowner. Cruisers beware!)
The terminology of a spinnaker is tricky because it changes depending on which tack you’re on. When you gybe, the guy becomes the sheet and the sheet becomes the guy, the tack becomes the clew and the clew becomes the tack. Confused yet? [When you’re flying a spinnaker, you always gybe because you’re always sailing downwind. Remember, tacking is upwind and gybing is downwind.]
It takes a while to get used to, but when you get it right and the chute fills and the boat perks up and charges along, it’s magic. That’s when you know that the crew is working as one unit. And if the chute is full, they are one happy unit indeed.
The spinnaker is controlled by its sheet, guy and topping lift. The sheet is the primary control, keeping the sail full and drawing. The guy controls the fore-and-aft position of the pole, which should be kept perpendicular to the wind. The topping lift (balanced by the downhaul) raises and lowers the pole, which should be held close to horizontal and adjusted so the sail’s tack is at the same height as its clew.
A well-trimmed spinnaker will ride high and ahead of the boat, with an evenly rounded shape. The spinnaker’s size and power give it a great effect of steering. Sheeted in too tight, it may cause excessive weather helm, which in high winds can overwhelm the rudder, leading to a broach (and uncontrolled rounding up into the wind). If the sheet is eased too far out or the pole brought too far back, the sail develops a sideways force that can heel the boat to windward in a gust or cause rhythmic rolling from side to side. This is know as a “death roll.”
So what happens if you broach? Check it out.
30 knots of wind, death rolls, the boat rounded very suddenly and the pole hit the water. Broach. Not good.
Just for the record, WE didn’t broach, this pole belonged to our neighbours on Kats Paw II, a C&C 30. Spinnakers in 30 knots of wind may not always be a good idea.