Tactical 'Pop' Quiz

I'm confused. The article recommends sailing up the left side of the beat (which among other things means avoiding the stbd layline). GRF says he'd start on starboard tack (i.re. going left) - isn't that the same thing in principle -you're both avoiding going right, which with a necessarily flexible strategy in shifting winds is the most you can set in stone, isn't it?

Mountains, molehills?

Originally posted by Medway Maniac I'm confused. The article recommends sailing up the left side of the beat (which among other things means avoiding the stbd layline). GRF says he'd start on starboard tack (i.re. going left) - isn't that the same thing in principle -you're both avoiding going right, which with a necessarily flexible strategy in shifting winds is the most you can set in stone, isn't it? Mountains, molehills?

Er when are we going for that race again?

Not sure if I should write this, dont want to go giving a river man clues


The bit I took issue with was approaching the windward mark with
effectively the tide on your weather bow, by coming in from the left late.

Yes I'd go left, but it would be middle and left with as much time spent on
starboard as 'tempting' knocks would allow. but my final run would be on
starboard having understood enough for the tide to lift me the last bit.

Not banging in from the left with the risk of whisking by, tacking and
overstanding even further, if I wasn't ahead further putting myself at the
risk of early rounders being carried down on top of me or at the very least
adding wind shadow to the already eroded windspeed the tide was
dealing..

Clear enough now?

Well it's always a difficult one, and I've never seen a definitive calculation
written, but as a rule of thumb, lets say 8knots wind and 4 knots tide left
to right.

So your sail is being driven by 8 knots true and then whatever created
wind your particular craft is capable of which produced the apparent wind
your sailing on.

So basically going one way a percentage probably 50% of the tides speed
providing your bow gets a sufficient angle against it assists the 'created
element of the wind that produces the apparent wind and going the
opposite way, it degrades it. So the boat travels not only physically faster
through the water that is flowing say 10 knots of combined speed 8 from
the airspeed and two from the tide and 6 knots air speed the other way,
and because the created element of the wind is stronger one way it also
enables the boat to appear to point higher, whilst not being able to point
as high on the opposite tack. (I'm guessing at what level the speed of
current contributes, it would vary according to the precis angle it lifts the
foil at I guess 50% at 45 degrees no doubt some maths head could
elaborate.)

Anyway, maybe it's more noticeable for us on Boards (the displacement
speed type), but it's been my experience that it most certainly has a
similar effect on the boats I've sailed to date.

It needs sketches and angles to explain thoroughly, I'm available for
lecture tours (that's a joke, me lecturing dinghy sailors could you
imagine it ) Eric Twiname covered it I'm fairly sure in Start to Win..

Edited by G.R.F.

Arrrhhh, you see there's the confusion that's simple vector logic.  now if the tide and wind were equal all the way acroos the race course it wouldn't matter which way you went, cause assuming everybody hit the layline and went the same speed it would be irrelevant (you'd spend the same time on each tack regardless of the order you did them).  What I believe your saying is you need to be on the appropriate tack at the appropriate time to suit the variances in wind and tide across the course.

ie. minimise your time on the bad tack and maximise on good!

Absolutely.

Another layer to this should be that you need a good
reason NOT to do the longest tack first. In this case,
if the w/w mark is dead upwind (true wind) and the tide
is flowing l to r, then starboard becomes the long tack.
Doing your short tack first quickly narrows your options
and puts you into a corner.

But yes, if wind and tide are constant up the course,
you have to do both tacks and it doesn't matter which
order you do them in.

Of course, wind and tide are very rarely constant up the
whole length of the course!


Edit: Oh, I see! Tack'ho was replying to GRF, not me!
Yes, what he said.




Edited by Roy Race