5o5 worlds - Gate starts

There is the effect tide has on the wind you feel. But crucially you can only take advantage of this if the tide changes (either in strength or direction over time or across the course).

Edited by mozzy - 29 Sep 17 at 11:04pm

Originally posted by mozzy There is the effect tide has on the wind you feel. But crucially you can only take advantage of this if the tide changes (either in strength or direction over time or across the course). If you have a tide running across the wind it'll create what feels like a shift in the true wind away from the direction the tide is running in,  if you're on a boat (it's actually a shift in apparent, as even when you're not moving through the water, you're still moving). So, to give an example. If you had a 7 knot wind, with 2 knot cross tide (left to right) at the leeward mark, and 1 knot cross tide at the top mark, it would shift the wind felt by 16 degree at the bottom, but only 8 degree at the top. As you sail the beat you would feel a persistent left shift of 8 degrees. In which case, just like any persistent left shift, it would pay to go left.  But, the problem with iGRFs post is he doesn't say how the 3 knot cross tide changes across the course. If the 3 knot tide gets stronger toward the windward mark, it will pay to start late (go right). However, these are pretty extreme examples. Imagine the wind was 12 knots, and the tide 1 reducing to 0.5. That would be feel like a persistent wind shift of less than 3 degrees. Not sure I'd hit a corner for a three degree shift when it's flicking back and forth by 5-10 degrees...  But the people who believe you can just pinch a few degrees higher and get a magical extra lift are just mad.

As much as I enjoy joshing with you boys, I would dearly love to show you the facts of racing in tide.

So here are a few points to consider.

1) Tide generally is more important when the wind is light.

2) Tide is rarely constant across the entire course in the sort of inshore racing we enjoy, but even if it is constant, it always pays to use it to advantage early in the race, for the same reason that we tell folk not to make mistakes at the start and in the first few minutes of the race. Why? make a mistake at the start for one second and you lose 20 places in a 60 strong fleet, make the same mistake at the windward mark and you might just lose one place, so logic dictates for those first few hundred yards you are pedal to the metal.

Now, even though basic tactics are that we're racing for the buoys and shouldn't get involved in inter board/boat tactics, during the first half of the race you are permitted to position yourself as well as you can against the rest of the fleet for the inevitable line up on the lay line and that means going faster through the water than they are, even if the water itself is a uniform conveyor belt toward the mark.

And so, in light wind, if there is a couple more knots to be had over the water, which a favourable tide in one direction brings, then take it early.

3) Time and tide wait for no man, not only is tide never constant across an entire course, even offshore, the tide is ebbing or flowing and will increase and decrease in strength if not during the course of a race, certainly in the course of the morning or afternoon, so it could be increasing or decreasing and the early or late decision rests with that. Either way you need to know.

4)Tidal estuaries, tide is certainly not uniform in coastal estuary there will be inevitable channels of deeper faster flowing water, you can see it, learn to read the water, I accept you can't feel it in boats as well as we can on boards, but that doesn't mean it's not there to be used just as you use shifts and I'm sorry, but just inching high enough to get an unfavourable tide onto the bow as against the weather side, can make a difference, it happens here at home every week, where we have a bend in the tide and sometimes the weather mark lay line is inconveniently sited.

5) There are also times when pinching in tide is a disaster and sailing free is faster, typically on a starboard lay line approach, better come up under faster and approach on port knowing they'll all be stuffing to try and make the buoy. Also the opposite can be true if it's favourable, many a time I've taken ten places tacking early and letting the lee bow take me up whilst 'they' get forced to sail back down to the weather mark because of tidal overstand.

But it's not rocket science you just have to apply a little logic to your situation, once you know what's going on, which for the life of me I never understand why so few bother to find out.

I may be a bit flippant with throw away lines like the go early late thing back there for gate starts, but you have to accept, I've been sailing in tide for over forty years, from Whitby to Whitstable, from Hayling to Hartlepool, Exmouth to Eastbourne, Paignton to Pevensey, Dale to Deal and generally winning more often than not.

Give me a tidal situation and generally I'll give you a sailing solution, wind permitted, so go ahead troll me all you like, I just hope one day we meet on the water in a bit of tide with not a lot of wind...

Edited by iGRF - 01 Oct 17 at 1:01pm

In number 5, it is the tide taking you up, and you are able to pinch to get there because going more slowly but sailing a shorter distance is magnified by tidal effect, and the overstanding boats are possibly even fighting the tide now. The tide is simply moving the whole boat.

I'm trying to see a situation where the tide is against you on that final approach, rather than taking you sideways, and by pinching, you present the lee bow to the tide. You are then moving through the water, and the tide then presses on the bow to force it to windward. Nope, all I see is a boat pinching into the tide and slowing down, stopping and then even drifting backwards on the tide, whilst the boats who stood on before tacking onto starboard have enough speed to beat the tide. Maybe if you draw it?

To be fair everything iGRF said is true apart from the non sense apart pinching to get the tide on a favorable side of the bow...