Re: [Amel Yacht Owners] Slowing down in increasing winds


SV Perigee
 

Christian, Ian, Bill (K), Kent, Danny,

Firstly, belated thanks to you for all your input.  The delay in my reply is due, in part, to the fact that I was putting it all into practice.  Two legs, St Maarten to Antigua, and then Antigua to Martinique.

We are currently spending time in AMEL CENTRAL, MQ, for programmed repairs and maintenance.

We encountered boisterous conditions for both legs, no sustained down-wind sailing, mostly beam reaches and on-the-nose.  Winds to 28 sustained (apparent), with gusts to 35 in squalls.

The summary for the sail-trim: no need to slow down using anything but reefing up to 45 knots AWS.  I have not yet experienced anything above 45 knots, so trailing warps, chains, tyres, or the JSD will wait for another time or rather, hopefully, not!

Did do a little going downwind, and the wing-on-wing-on-wing works great out to 155º apparent, winds up to 25 knots, moderate seas.  The genoa fully out on the ‘correct’ side, dragging us downwind; the main being set on the windward side to balance, and strongly prevented; the mizzen following the genoa (and still prevented, of course).

For beam reaches and upwind, the amount of sail was set to obtain an average angle of heel of 15º - on the basis of my understanding that this amount of heel delivers the longest LWL (and hence STW).  Sails were trimmed for maximum boat-speed. This worked well, easily exceeding 8 knots STW in anything above 20 knots apparent wind speed.  When the wind picked up and there was a need to reef, sail was reduced as required to achieve a 15º angle of heel.  This kept the ride comfortable and fast, and the first mate happy.

We were at times pointing into the seas.  As Danny wrote, and I can confirm, that our SMs will quite willingly go “wave hopping” at 8 knots.  All that awful crashing and banging, quite unsettling.

So, from these short inter-island hops across and into brisk winds and confused seas, another rule-of-thumb:  slow down when the seas are “short and sharp”, especially when the wind is forward of the beam.

What is “short and sharp”?  My observation is that, when we are sailing upwind in winds of greater than 20 knots, and carrying best sail for that magical (mythical) 15º angle-of-heel, PERIGEE considers the seas to be ‘short and sharp’ whenever the period (in seconds) is less than the height (in feet).

How much to slow down? Can’t really say, but whatever it takes to avoid PERIGEE trying to launch herself heaven-wards through or over the waves.  I guess it depends somewhat on the direction of the seas. I also tried bearing off, but when the wind and wave-trains are not aligned, this might not work.  And in any case it then becomes the usual trade-off between VMG to WPT/Destination.  I didn’t get esoteric enough to look into the detail of the leeway trade-off when pointing up, but did get the feel that when heading anything closer than ~45º (apparent) to the wind, the boat slowed down whilst leeway increased, so we drifted sideways; so, the better option was to go faster at 50º off the apparent wind.  Danny mentioned that the wide keel (or, maybe it’s low aspect ratio, depth/fore-aft chord ), makes the keel stall quite readily.  I’m not sure how this all works, so I would definitely be interested to hear what others know, or think, is the case here.  What is that magic figure for ‘on the wind’?

BTW, we have happily and comfortably endured squalls (beam-reaching with all three sails up and heavily, but not deeply, reefed and trimmed as per above, 15º heel) with gusts to 45 knots (apparent), with only a moderate increase in heel.  Biggest sustained conditions experienced thus far: 6-7m seas in 35-42kt sustained winds, beam-reaching - only moderately reefed, as I hadn’t yet learnt about 15º heel and the SM design LWL etc at that stage, so looking back I was really quite over-powered, but it was still a very comfortable (and controllable) ride.

On a closing note, one interesting event was a ‘crash-gybe’ one night, whilst reaching in a squall.  This was to avoid crossing traffic (sail boat, but with no sails, or normal nav lights) which was sighted almost too late due to reduced visibility in the squall, combined with heads-down on the radar due to squall avoidance.  No damage done, as we were in standard offshore mode which is, even when on-the-wind, to have the main set with double preventers (one each port & starboard), and the sheet+preventer combination on the mizzen trimmed to minimise movement of the boom.  The genoa was reefed to the forward shrouds; this is now our SoP for upwind work in squally conditions at night. Never thought I’d NEED to use this arrangement, which was intended to minimise the consequences of an unintentional gybe (perhaps an A/P disconnect whilst below - I guess it happens).  But when I needed to put the helm down, powered up at going at 8 knots, with less than 3 boat-lengths to loud crunching noises, it worked a treat.  I must admit it did feel a little strange, and a bit disorienting, as I’d not tried a power gybe and then heave-to at night before.

The other vessel was not showing normal nav lights, only an anchor light - there was no response to horn or spot-light, even coming close on the second pass.  So, it seems possible that the other vessel was un-manned.  There was one vessel reported missing we later heard, having drifted off the shelf of an upwind island a day or so previously.  This was even with two anchors set.  The vessel signature on radar was obscured in heavy rain, and the anchor light blended rather nicely into the background island lights until almost too late.  No moon.  We could see the ghostly shape of the hull (no sails) only once we got close enough for the reflection of our nav lights - now, that really is too close, I can assure you.  It is my opinion that, in the absence of avoiding action, we would have T-boned this guy at 8 knots.  Gotta keep those eyes up and out of the cockpit.

And why is it that these things seem to happen between 2 and 4am, when the skipper is off-watch and asleep below.  Anyway . . .

... fair winds,

David
SV Perigee
On Dock #4, le Marin,
Martinique

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