It's All About the Apparent Wind Tuesday 27 April 21

Big true wind values might sound impressive when guzzling beer with friends and we can set high “true wind” alarms on our fancy B&G Zeus3 chart plotter, but while underway an alarm for high (or even low) apparent wind would be more useful to us. Reason is that the loads on the rigging and the sails are a function of apparent wind. The pamphlet-like owner’s handbook that was included with our Seawind 1160 speaks briefly to reefing, and the numbers are basically: full main up to 20 knots apparent, reef#1 to 24 knots apparent, reef #2 to 28 knots apparent, and reef #3 for anything higher. Reef #3 is what we’d have set in a gale, unless things got so bad we needed to slow the boat down further and simply go with bare poles and maybe a bit of the jib. We don’t have a storm sail for this boat, just the standard sails for heavier conditions.

One of the delights of our Seawind 1160 is the screecher sail, which the book says is NOT a code zero, but most monohull folks tend to call it that. It’s a rather large, full cut headsail on a soft furler so it can be bricked, bagged and stowed in our big forward locker. The sail was an option when this boat was built, and part of the setup is the folding bowsprit that the tack of the sail attaches to. The soft furler has a continuous loop arrangement which makes rigging, deployment and retraction easy, but there is some technique involved to getting a nice furl with no baggy places towards the top. On our first passage from Ensenada down to Cabo San Lucas in Mexico, we tried to furl the screecher in rapidly rising wind and managed to blow out the tack attachment loop, turning a suddenly challenging situation into a royal mess. The sail ended up mostly in the water and it was good fun getting that all gathered up and bagged away.

The owner’s handbook suggests that the maximum apparent wind the screecher should be deployed in is 15 knots.  As well, Seawind suggests that when not in use, the screecher should be bagged up and stowed rather than remain furled and ready for deployment. Certainly in very windy conditions an unplanned deployment of the screecher would likely result in a lot of damage to the sail, and possibly some structural damage to the bowsprit and associated tackle. Furling while leading one of the sheets up the sail and other other down adds a good bit of insurance against the risk of an unplanned deployment.

The screecher seems to be happy somewhere around 70 to 130 degrees apparent wind, and reasonably flat seas. If it’s too lumpy the massive sail will breath and bang and convince you it’s about to explode. Maybe it is, and unless it’s only flexing occasionally, we don’t sail with it deployed. The real trick is to avoid overcooking the apparent wind speed for the screecher, and the best method for that is to use the wind steering mode on the B&G autopilot. We can set it to steer the boat to either true wind or apparent wind, and once sails are trimmed sailing to apparent wind makes for an almost carefree watch. Well, that is until squalls develop or a large wind shift occurs and suddenly we’re not going in the direction we’d hoped. Deep at sea that’s still not such a huge deal, but sailing amongst the atolls in the Tuamotus of French Polynesia, often one is pretty close to a boat eating reef, so subtle or large changes in boat heading often prompt a tack or jibe to remain clear of hard things.

It's the middle of the night and a squall just popped up on radar. With screecher furled away and full main sheeted in, I’ve just motored through the rain shower which, this time, contained no wind, but something in the area has sucked all the wind away. Suddenly the true wind is about 6 knots dead astern, and I’m making most of the apparent wind just by motoring through the airmass. Well, we’ve had some great days sailing and the forecast is for flakey winds the next few hours – perhaps they got that part right.


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