Sailing in tide..quiz.

Originally posted by mozzy ]You sail on the difference between air and water. Two things. Over the ground is only relevant in that as the tide is moving it makes the apparent wind different on water compared to land. Its not a separate for to true wind.  Your third point is crap. Leeway over foils is about 3-4 degrees. This doesn't change if you are in tide or not.

You only move because the water provides resistance to the wind.

That then enables created wind which also combines against the static resistance of the water to enable forward motion.

If the water moves away from the wind at the same pace, no forward movement of the boat will take place.

If the water were moving toward the wind at the same speed then the boat will move forward as if the wind speed were double.

I'm sorry but whoever told you all that doesn't entirely understand what is going on, where the Energy is coming from.

Three elements, not two.

Edited by iGRF - 02 Oct 17 at 10:24pm

Originally posted by sargesail Originally posted by iGRF So this is actually what happened. Blue arrives at island before red tacks to cross channel. So tell me why it wouldn't have been faster for blue to do a hybrid of the two: short tack like red and then do a starboard leg from the end of the headland until meeting the port layline drawn?

Pretty much what we'd been doing earlier in the week when the windward mark was sited just at the tip of that left arrow. The main reason to go left (as also pointed out by Mozzie, credit where it's due) was the likelihood there would be a better lift off the opposite cliffs, which would get the nose into the tide earlier than rounding the headland where the lift off the land petered out, quite why they didn't harden up to head out to sea I'll never know, they were not stupid, some were Hayling sailors so not tidal neophytes, but then again who knows what squads have to do when their coach is dictating the route.

I didn't win the race, I spent too long berating the coaching team who were moored at the island, about listening to lectures on tide and not arguing the point when I bother to drive down to weymouth at my own expense to try and help them, but then it's not in a paid professional coach's interest to have anyone around with superior tactical advice is it? Then I always was naive..

Edited by iGRF - 02 Oct 17 at 10:11pm

Originally posted by iGRF 1) Energy from the true wind drives the boat/board, this generates, then combines with 2)The created wind of the board boat moving OVER THE GROUND 3)The third force is the water which as a fluid also moving over the ground, like the wind can either combine with the wind to act in concert (the force is greater, the more angled the lower foil is (think sheeting it in)) or it can act against and reduce the energy from the true wind.

Edited by mozzy - 02 Oct 17 at 10:05pm

Originally posted by KazRob When you head back out from the shore the tide is heading NE-ish so you should get pushed that way and in a reduced wind strength.

No it wasn't a flier, it gets back to my explanation on the Gate start thread, we are using the energy from three sources instead of two.

1) Energy from the true wind drives the boat/board, this generates, then combines with
2)The created wind of the board boat moving OVER THE GROUND
3)The third force is the water which as a fluid also moving over the ground, like the wind can either combine with the wind to act in concert (the force is greater, the more angled the lower foil is (think sheeting it in)) or it can act against and reduce the energy from the true wind.

That's it really.

By harnessing an extra 4 knots on the centreboard, it combines with the 8 knots in the sail to drive the craft faster, the fact the water is also moving like a conveyor belt is irrelevant, what is important is the board/boat speed over the ground and relative to everyone else.

Edited by iGRF - 02 Oct 17 at 10:00pm