Waypoints and Sailboats

[jleaworthy]

Thanks Jimi, I've worked it out properly this time!

Leaving Nab at about HW Dover in order to miss the worst of the tides off Normandy you get the strongest tidal stream of three and a half knots during the ninth hour of your crossing. For the twelve hours, the tidal offsets mean that you travel an extra 6.3 M by following the track over the ground - just over 10% or an extra hour and a half - just about double my guestimate. Sorry.

John

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[tome]

I also have an elderly autopilot so can't link it to GPS. However, I still use waypoints when going to windward, ignoring the track but watching the bearing to waypoint to assess when to tack.

Last Sunday we were tacking back up the Solent in a SE'ly. I noted the best heading on both tacks and was able to steer a long tack through the submarine barrier on starboard once the bearing to go came down below 80 degrees and then put in another tack whilst watching the bearing to West Pole (the next waypoint).

Not wanting to end up in Bembridge, I put in couple of tacks and came round onto starboard again once the W Pole came down below 80. As often happens the wind veered S'ly into Chichester but this method works well for me when I'm feeling lazy.

I wasn't at my best Sunday, thanks to the hospitality of a great bunch from KPMG who had chartered a Benetteau for the weekend (rafted alongside) and into who's company my wife and I fell at the Folly. The Folly was great by the way!

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[MainlySteam]

Is this a fair assessment of responses so far with respect to waypoints when sailing:

1. Hardly anyone uses GPS waypoints for autopilot to steer to.

2. All use GPS for position fixing, with many using GPS for bearing and distance to waypoint determination, and some use crosstrack error as well for course correction.

I have to say I am surprised, but relieved, about point 1, which was the main part of my question - it is quite a revelation to me, at least.

Thanks everyone for your feedback, it is much appreciated.

John

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[vyv_cox]

I am a dedicated chartplotter user. I enter waypoints for just about every trip I do, even on home waters where I know every step of the way by heart. With my older plotter I mostly called up existing routes but maybe modified slightly with memory waypoints. With the new unit the addition of waypoints is so easy and fast that I find I am using stored ones less and less, just entering new ones as required. However, I have never linked the autopilot to the plotter. IMHO this is a very motor-boat type activity, as like many other sailing responders to this thread, I very often go nowhere near the waypoint when sailing. In fact, I play a little game with it, trying to guess/calculate the angle-off at which it will jump to the next waypoint.

The cross-track error adjustment, as someone else has said, is so much easier to visualise on screen, although in the past I used to use pencil on chart for the same purpose. I find the "motorway" display on plotters to be of limited use because it gives little idea of scale. Looking at my COG, or track as Garmin have re-named it, and comparing with the pre-set route, gives a far better idea of necessary corrections for tide and other factors.

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