Monday, April 2, 2012

Tide Trumps All

Part of our sailing area is in a dredged channel which is considerably deeper than the surrounding water. When the RC includes this area in the course, I have learned to repeat to myself before starting that the tide trumps any other consideration in how to sail the course. Or if I forget to remember this basic truth, the sight of many sterns soon reminds me. Hopefully the RC will have mentioned the tidal flow at the brief, but in any case the first thing I do in going out to the course is look at the channel markers to see which way and how much they are leaning. 

The channel and tidal stream are both parallel to the direction of the prevailing wind and so on the beats and runs it is especially important to get things right. This means simply to avoid the channel and head for shallow water when you go against the tide and stay in the middle when you go with it. That magic carpet has little regard for the wind and it disdains headers and lifts as passing whims.

But the beats and runs are fairly straightforward in terms of tidal strategy and the real fun is around the marks. Obviously you have to compensate for the flow as you aim for the mark, but you must also remember to take the stream into account as you round the mark, since if you tack or gybe there will be some slower movement in the middle with the tide eagerly waiting to pounce. And, if there is congestion at the mark, you can be sure someone has misjudged things and will be trying tack or gybe in a panic.

And finally, the downstream side of any obstacle – particularly larger ones – will have some weird stuff going on as the tidal stream curls around and gets choppy and confused. Probably the toughest area I have encountered in our area is a large buoy that is in the shadow of wind turbulence from a highway bridge that I am convinced has a very nasty troll living under it – which must explain the alternating bands of prevailing wind, dead calm and 90ยบ shifts. When the tide is streaming past that buoy and the troll is playing games, it gets interesting.

1 comment:

  1. Congratulations on taking on dinghy sailing when you are old enough to retire. Looking forward to hearing more.


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