I grew up in a place with 0.1knt of tide and wind that shifted once a week so cr*p in tricky tide but will give it a bash. I assume there are no shoals or anything that would affect the current in the channel

Head right off the line to pick up slacker tide or even back eddy off the headland and short tack up there until the channel. Then keep heading to the right and into the tide and try to cross the tide to the other side and come in to the with tide under me rather than coming from left and getting past the island in the lee of the shore. Reaches should be simpler with just crabbing enough to keep the track.

If nothing else it will give iGRF something to chew on

One thing I don't get, in the same sentence you say the tide is flooding in and they tried and failed to get the race off before it fully flooded. By 'fully flooded' do you mean 'high tide', or is 'fully flooded' max current? I guess the latter?

Also, no depth chart, so I'll assume there's no funky bathymetry or banks?

I'd start middle line. Against the tide (does it run that far down?) there will likely be sag, and if you are expecting the wind to go back left you don't want to be on the right of fleet. The shift is right phase so you'd want to sail starboard first if you are expecting it to go back left. 

I'd also go left up the beat to get in to the shore away from tide which is pretty much with the wind. There may also be a left shift with convergent wind on the left shore to add to the oscillation left you are expecting.

Coming in to the windward mark you'd experience a tidal lift in apparent wind too. You'd have to be careful not to over stand the windward mark though.

You'd want to get a good transit on the reach and crab down as the traditional fleet windward arc will be even more pronounced with the tide pushing people high. 

Not much to do on the bottom reach unless there is a tide line where the tide splits which you'd want to get the correct side of. 

Ultimately, only you were there, so you could say anything worked, and we'd have no recourse. 

No Graeme just busy working....but looking forward to hearing exactly how you think you won it.

So my strategy would have 3 parts.

1.  Take the 'free' southerly uptide gain behind the promontory immediately to the south of the start line.  I would want to be careful of any potential race on the headland.  I'd reckon that right would probably pay, depending on the exact shape of the land and the feel of the breeze.  Hopefully I'd have some shifts to help me get there efficiently.

2.  I think I'd then sail a short starboard leg until I reached the port layline.  This would come quite early because of the east going tide in the east side of the bay.  I'd be worried about what sort of tidal compression I'd experience around the island - if it's strong then I would have made the wrong call.

3.  For the rest of the race I'd make ground up tide when in less tidal flow, for example in the tidal lee of the island.  That is to say I'd emerge as far west as I could without overly compromising my speed.

If I thought there was going to be a significant increase in north going tide (a race) to the immediate west of the island then I would execute a different strategy.  I would sail a long port tack first and flick on to starboard when I got to the layline for the mark, or, depending exactly on my tacking angle, before that, in order to take advantage of the maximum flow in the main channel before being tidally sheltered behind the southernmost headlands.  But I'd still look to flick back on starboard and approach from uptide - remembering that this is predicated on a strong race off the island.

Sorry - I don't understand what you mean. If you're sailing out into the tide you are also going backwards with the tide relative to the wind so the 8-10knts you talk about would be 3-4knts slower (or whatever the tide was). If you're moving backwards relative to the wind I also can't see how the board got more air under the nose to help it lift either. I spent many years on boards and have not long bought a big ol' raceboard again, so sailing a board v a dinghy is not completely alien to me.

Explain again please? Perhaps it was just plain old windier over there which isn't the same as some magic tide trick

I don't see that there is a uptide gain south of the line, the way iGRF has shown it, the tide just runs straight into that arm of the harbour. Even still, you'd have to sail a header off the line on port to get there. When you do get there it will be a headed shore (divergent breeze) anyway. 

If there was a strong eddy you may gain, but all that effort to get over that way would be swept away when you hit the tide coming in northerly and north easterly. That tide would also give you another apparent header. 

Originally posted by sargesail 2.  I think I'd then sail a short starboard leg until I reached the port layline.

Coming up to the port layline late would feel pretty awful. Yes, the tide would be on your transom, but it would also be giving you a header. 

Originally posted by sargesail  This would come quite early because of the east going tide in the east side of the bay.

Damn straight there. 

You'd also imagine the boats coming out of the headland on port would get a tidal lift, of course as they went further right they'd know they'd have to come back in the corresponding header (I just think he tacking angle out of the headland on port would be better). 

But the above scenario is just the tide changing the apparent wind. I want you to explain how changing mode in tide can lead to a better VMG.

Exactly - so I'm not worried about the header!

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?

Looking at the vectors (3.5 knot tide, 9 knot true wind) this would feel like a 10-20 degree lift (assuming tide was slack or against on the north shore (far left of the beat). 

The component of the tide which is running in to the wind obviously increases the apparent wind strength for both port and starboard boats; however, the cross tide component would lift the port boats (and head equally the starboard). 

Basically, as the boats on the right come out from the head land, back toward the middle, they would feel the breeze increase as the tide gets on their stern, but also get a header. 

Originally posted by iGRF So this is actually what happened. Blue arrives at island before red tacks to cross channel.

OK - so talk me through the curved laylines.  Why does blue gradually get lifted on port?

Why does red gradually get headed?

And where can I get one of these windsurfers which point so high that the tacking angle looks like 40 degrees?

Getting pushing north east is pushing you in to and accross the wind. You will feel an apparent increase in wind and apparent backing (lift on port).

Do you mean heading west running tide. The only place the tide is running west is at the start?

Yes - I know that.  But what I'm getting at is that blue still has to make to the south into a north or north-west going tide.  Even if the diagram is not as drawn and the east going flood starts further west (unlikely) then it still starts as a north-easterly flow and turns east as you get east.  So going south before you are in north going flow is always a gain (other things being equal - which they're not!).

In the scenario you describe, I think you made the right choice. But those three point above make no sense. 

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. 

I think iGRF has drawn the lines a bit wrong. The way he's shown it both tacks are lifted in to the windward mark, which is impossible. 

As I said in another post  the right would look okay, until they came out from the shore. They would get a lift on port from the incoming tide, but when you're the furthest boat right on the course, the last thing you want is a lift on port! They, would have to get out of that right hand side at the top of the beat by sailing on starboard. Starboard tack will be feel an apparent header. 

Also, I wouldn't see going right as that much of a gain at the start either (unless there is a big back eddy which isn't shown). The tidal stream will be diverging in the middle as it splits (divergent) to two channels so the north bank probably won't see strong adverse tide, especially mid way up the beat. 

Then on top of that, iGRF does say the wind was in the right phase at the start, so you'd have to sail a ten degree header to get to that right shore. 

But, in the boat, you can't feel that. the boat can't 'feel' that. All the energy comes from the sheer between air and water. Those two things, nothing else. Whether it's just the air that's moving (lake) or air and water (sea) it is still just the sheer between the two.  

Also, you'd still not explained the 3rd point of tide hitting the foils etc etc. 

I feel your pain in terms of the interaction with the coaches.....

But I also put it to you that the lead you established that day was due to the lift off the northern cliffs, and not some inexplicable tidal magic?

Ahhh Mozzy - I've been here with GRF before.  I can't wait to see what he comes up with this time.  I've been waiting to hear about the wonder race that would prove his theory for years.  And there it was.....and I see nothing in it that remotely proves his theory.  In fact the decisive factor appears to have had nothing to do with the tide at all....

So either I'm still as dumb as I used to be for letting him troll me again....or I'm not the dumb one....

OK so blue, once on port, gets an increasing shove to the east from the tide, which has a greater east going component as she heads south.

What about red?  I'm not sure I understand how they stayed out of the tide.  Surely they crossed the main flow on starboard.  And what they experienced on the west coast they should also experience on the east?

So, simple tidal question. In the scenario above, which end of the line is favoured and by how many degrees (upwind start)?  

Maybe you're accounting for the inevitable pile up at the committee boat; but I didn't actually say there were any other boats, just simply which end was favoured. 

I just wanted to show that when the race officer sets this perfect line, the sailors will feel an apparent (and very real for them) bias of almost 10 degrees.  If you want to lead this race from the start, you need to be at the starboard end. 

What's also interesting, is the above information is pretty much redundant to sailors on the water. The bias will be apparent to them. Whatever technique they use to assess bias (crudely sticking the boat in irons or sailing the line on each tack and subtracting your tacking angles) will tell them the starboard end is favoured. 

The only person likely to be fooled by this is the race officer. Measuring his line against true wind, for boats sailing in apparent he will be unaware of the 10 degree starboard bias. He may even get cranky and go in to black flags when the resultant pile ups and general recalls ensue. 

A smart race officer will set a true wind port bias to account. He will also offset the windward right, to account for the apparent right shift and the fleet being swept right as they progress up the beat. Offsetting the windward will off course offset the run as well, so it's a balancing act. 

If pinching was faster you'd do it all the time, and it would become the normal course. So, by pinching, I take it to mean a higher and slower course which produces an overall slower VMG. 

The only time pinching for a mark is quicker than sailing your normal (fastest) course is if the gain from not having to double tack outweighs the gain of sailing you faster normal VMG angle. 

Basically, if you are on a layline with a weather tide and are struggling to make the mark, then you have understood. It is no different to underlaying a mark on a lake. So the decision making process is the same. 

How much will I loose by pinching (slower VMG mode) versus how much will I loose by double tacking. 

If you are far out from the mark, a two tacks is usually better. You will have plenty of time to complete the tacks (and could even do them on a little shift, or to get out of dirty air) and pinching from a long way out will mean sailing an inefficient mode for a long time. 

If you are very close to the mark, a double tack in such a short distance will usually be worse than just pinching "or 'shooting the mark". You'll also be on sticky ground rules wise if within 3 boat lengths. 

A classic  mistake, and it gets worse in big fleets is trying to pinch to lay a mark you have underlain from far out. You see it often in junior fleets in the very situation you describe. The sailors would do better if they accepted they had understood and sailed their normal mode and complete the extra tacks. 

Usually it is better in a fleet scenario to complete the first tack early, then you're not sat in the procession of pinching boats getting dirty air as well. 

If you are not in a fleet (or clear ahead ) I would do the extra tacks nearer the mark to make judging the true layline easier. 

I can draw out the vectors, but it will require knowing the speed penalty for pinching versus normal mode and the speed penalty of tacking; both will be class specific.  

Tell me this, if pinching is faster VMG than the normal mode, why do you ever sail the normal mode? If that high mode was best, then surely it would become your normal mode, because you'd always want the best VMG?

Makes no sense. And you see it in fleets all the time; if I just squeeze the bow up a bit further I'll make this mark. And they rack up from 100ms out. Then finally a boat doesn't make it, they've not left enough time to tack out, or even gybe out and the pile up starts. 

You're faster angle is your fastest angle. The only time I'd sail a slower mode is to avoid a late double tack. In a reasonably good tacking boat I'd never sail a pinching mode for more than 10-15 seconds. 

Same goes for gybing in to a leeward mark. Sometime I will sail low and slow for the last 10-15 seconds to avoid the dreaded double-gybe drop. Any longer than that and I'll just sail my fastest mode as I always would; because it's faster!  

Got that, and correction accepted 

Just seen this. So your answer to over standing the windward mark is to start further left? 

How would starting on the left possibly make calling the layline easier? 

The answer to that may be, that if you start port end you won't be first to the layline, so you can use the leading boats to judge when you should tack. Not going to win many races that way though!

I agree, you'd have to be weary of being swept past the starboard lay. If the race officer laid the course to true wind the beat would be feel offset and you'd have to spend more time on starboard than port. But starting on the left doesn't help you judge either of those factors any better.

The fact is, when a boat starting at the starboard end and a boat starting at port cross, the starboard boat will be clear ahead. 

Say the line was 100m. With a bias of 9.46 degrees the committee boat end starters would be 16m 'upwind' of the pin end starters. 

The conveyor belt analogy is correct. All boats will be lifted the same amount on starboard, and headed the same on port (from the true wind). If the conveyor belt keeps on moving at the same speed, nothing changes and the boat will finish the beat with same 16m difference they started it.

Take the same scenario as I've posted already (9 knots true wind, 1.5 knot cross tide at the start, line set square to the true wind).  The line is 100m long (so I've already told you the bias in meters). Boat A starts at the CB, Boat B at the pin. 

Both boats are perfectly matched in angle and speed. There are no shifts in the true wind. 

Both boats sail on starboard tack, as they progress the tide slackens to 0.1 knots then B tacks. When they cross which boat is ahead and by how far?

 

I'm sorry to spoil the earlier comments about how the line was laid, but any RO worth the title takes his wind readings from a 'free floating' boat and not one that is moored. At the OK's a fortnight okay, sailed over the highest springs of the year, we delayed final position whilst taking wind readings when drifting. Once we anchored the Committee Boat the course looked 'orrible and skewed - but as soon as the boats came out to start sailing and you could see them close hauled on both tacks, the beat looked spot on.

D

And there are too many that aren't worth the title....the number of times I see an RO with a compass and a bit of string at anchor.  As I moaned about it at the weekend one of the group commented that a friend of his used tidal stream data in a computer to work out where his marks should be....and that's fine.  But all too often you end up with a WM where the string was pointing!

Used to love Ken Falcon as RO - would jump in a RIB and then 'borrow' a boat to get a feel for conditions.

Did you up hook routinely between races to test that your feel for the tidal apparent was still in date?

You got me! I've edited to starboard. Both boats start on starboard and sail on starboard until the tide slackens and B tacks. 

Sam - as soon as the line was closed we were off....Of course, taking readings from a moored boat works fine on a pond....

D

Sounds like you did an excellent job at the event you ran though. 

When I'm race officer at my club I just guess the course by eye. As long as they can cross the line it's all fair; everyone has the same opportunity to choose the correct end. 

Once I did lay a finish mark that dried out... oops, I did get a fair bit of stick for that. But there is no rule that the course has to be on the water!

I doubt anyone takes floating wind readings for club racing, for instance, and lots of club will be working off fixed lines anyway!

Spot on! A would have a one meter lead and B would have to avoid. 

I remember Raceboards Open Meetings at Morecambe many years ago, I got there early one year and helped set the course marks with the aid of a wheelbarrow (and, incidentally, collect them the same way after the event)  happy days......

This conveyor belt theory. Why is it assumed all boats drift downtide at the speed of the current?  Isn't that like assuming all boats can run downwind at windspeed?

All boats do drift down tide at the speed of the current. Unless you're sailing them through the water. In which case they will move in a direction over land which is the sum of those two vectors (the tide and the sailing).

Trust me, when the wind drops to nothing, and the tide is flushing out the harbour, all the boats, 49er to oppie, all drift out the harbour with equal hopelessness! 

Boats aren't rigidly attached to the water, the water flows past and hydrodynamic forces are imparted.  I can't see why they should be the same regardless of the type of boat, in which case I can't see why they drift off at the same (current) speed. Therefore, if not all boats slip at 1.5kts in the example above, the winning tactics might not always be the same?

But the wind resistance is just the gaseous fluid motion bit of the vector.

In a flat calm the rate of drift is the same.  Seen it in the Cherbourg Race couple of years ago.  Heaps of different boats drifting together.  Possibly you could have assessed that the much heavier ones had momentum and took longer to start drifting the other way when the tide turned.

Or that might have been the beer we were drinking for breakfast..... 

A2Z; ask yourself this. When it's a flat calm on the lake, do the boats move through the water? The boats aren't rigidly attached to the water on a lake, but if they are becalmed they don't move. You don't see water flows past and hydrodynamic forces moving boat through the water on a lake do you? 

So if you accept all boats becalmed on a lake sit still,  then why would they move through water when becalmed in a current? If there is no force to propel the boat through the water they will sit still, apparently attached to the water and from the shore the boat will appear to move with the tide. 

Now, add in wind. All boats are still affected just the same by tide (this is where iGRF is wrong about boards being more or less effected by being lighter or having less hull in the water or whatever). The tidal vector is the same for all boats. 

Now; when boats move faster, their vector through the water will be greater but crucially tidal vector remains the same. So it's more accurate to say: "all boats fast or slow are affected the same by current over time, however faster boats which cover more ground in a set time are less affected by current over a set distance". 

Some boats may move faster through the water, but not because they are 'cutting through the tide better', but simply because they are cutting through the water better. They are just a faster boat. 

Now, this is where things do get interesting, if you're still following me. We race around marks which are fixed to the ground. If all boats raced against the tide for 60 minutes all boats would experience 60 minutes of tide, regardless of how fast they are: simple. If there was 1 knot of tide, all boats, no matter how fast or slow, will be moved 1 nautical mile by the tide in those 60 minutes.  

However, we don't race for set times, we race over set distances fixed to the land. Faster boats spend less time going around the course, so spend less time being affected by the tide. 

This phenomena is called the 'tidal gate'. If you go from a favourable tide to an unfavourable tide the time between boats on the water will reduce. The opposite is true is you go from unfavourable to favourable.  You will notice this most when beating against the tide. The lead boats round the windward mark and accelerate away stretching out a large lead over the water. When they head up round the leeward mark, the pack appear to catch them back up as the leader hits the unfavourable tide.

The net tide is always unfavourable, if you finish roughly where you started. This is because when the tide is against you it will make the leg feel longer, and when it is with you it will make the leg shorter. So around the whole course, you'll spend more time in unfavourable tide. 

This is why HISC adjusts handicaps, as on any given day faster PY boats, over a set distance course, experience less tide (and tide is always net unfavourable) giving faster boats an advantage. However, as the tide is always different (either itself or compared to the wind) it means the magnitude of the advantage for faster boats speed is constantly changing. Therefore there can never can be one fixed PY. 

Also, slow boats aren't equally slow / fast on all legs. Some boats are better at reaching, or beating, or fetching. The PY would also need to account for which legs the tide was unfavourable, and how this matched against the boats strength on these legs. 

Complicated enough for you? 

I very nearly added the following to my previous post the decided it was stating the obvious :-

"And most boats will sail pretty effectively in 3 knots of wind"  

The start line scenario isn't wrong. I clearly showed it was true and backed it up withe maths. That you still argue otherwise or can't comprehend it is another thing. 

Yes, a tidal increase in wind can lift a board on to the plane. And it can and does an RS200 as well. 

What you fail to realise is that when the tide shifts the apparent wind it shifts it in one direction (which should be obvious, it can't lift both tacks, or head both tack). This will favour one tack or the other. When the tide increases the apparent wind it increases it does so for both tacks. 

So in the board race you described, where the current lifted you and increased the apparent wind allowing you to plane. That's fine. But, the increase in apparent would have also been enough for the board on starboard to plane. It's just that they would be on a header and you were on a lift. 

You need to work on your problem setting iGRF. There are so many things left out or wrong. 

Okay, so by triangle course you mean a course that start on a reach? 1st leg a broad reach, second leg a tight reach and third leg presumable a beat? 

Originally posted by iGRF   The advantageous cross tide assists on the 1st leg, but is disadvantageous on the 2nd.

Okay. I get this, that's fine. But really, the extent to which a boat has to crab across the tide to stay on the rhumb line is determined by:

Originally posted by iGRF   It is still a reach though but the wind is failing

So, you're saying the wind is dropping, but not so much as they have to start tacking to get over the tide and up to the mark. I think I understand that. But again, you don't say what the wind started out at, or what it drops to.  

Originally posted by iGRF   Boat A gybes and sails for the mark with the tide still on the weather side of the foils.

Sails for the mark... so ambiguous. Do you mean points it bow at the mark? Most people in this situation would sail for the mark by taking a transit to show them where the rhumb line was and crab the tide. AS you can tell from my bullet point list above calculating the true heading needed is difficult, so just taking a transit and keeping the boat on it is a very practical way of solving the problem. 

Tide on the weather side of the foils? Ha. The tide is coming from the weather side of the boat, the foils, the rig and everything. It is a single factor, moving the whole boat in one direction as one. Meanwhile, the foils will experience flow in from the direction the boat is moving (through the water). In terms of flow on the foils where the tide is coming from makes no difference. The boat isn't moored to the bottom. 

Originally posted by iGRF   Boat B gybes higher and presents the bow directly into the tidal flow.

So, boat B sails higher, directly in to the tide. But, the tide is still slightly across the reach (although we don't know for sure as you haven't provided the information). If they only sail directly in to the tide, they will never reach the mark. (unless the mark is directly in to the tide as well... in which case boat B is doing the same as boat A, which is sailing directly to the mark as well).

There must be a second part to B's strategy. I.e. they sail directly in to the tide, then bear away later on the reach to cross tide and drop down to the mark. 

Sailing high then dropping low could be a good strategy in a failing breeze. You'll spend more time fighting the tide when you have breeze to do so, then can ferry glide down to the mark later on when the breeze dies... none of that is in your description of the strategy though. 

Originally posted by iGRF Who gets to the lee mark first?

Hilarious. Prove it. 

But, bear in mind whilst you're proving this, its also going against why you had that one decent beat and got the better of the 'squaddies'. For if it's true that tide lifts you on both tacks then both the starboard boats in you scenario and you on port would be lifted. So if this was the case, how did you get an advantage? 

Like I said iGRF, even a broken clock is right twice a day. It sounds more and more like you lucked out and experienced a tidal gain one day and beat some decent sailors. 

There are plenty of times in sailing when people adopt the best strategy for all the wrong reasons. It doesn't prove they know what they are talking about, or are good sailors. 

Watch from 10 minutes in... 

Boats sit still on a becalmed lake because there are no aerodynamic or hydrodynamic forces to move them.  However, if the water is moving due to a current, there are hydrodynamic forces in play. Each boat will then accelerate until they achieve a steady velocity (in the direction of the current) and with a magnitude such that the drag of the boat moving through the water is equal to the force of the water (current) on the boat. This requires that the boat speed must be less than current speed, because if the boat moved at the speed of the current there would be no hydrodynamic force. The boat would have to slow down until such time as the hydrodynamic force equalled the drag again. This is true even ignoring aero drag.  So I maintain that boats drift downtide at a speed less than the current. This doesn't alter the basis of the argument that a shift in apparent wind occurs, but the size of that shift might not be as big as expected.  

What are these 'hydrodynamic forces' you talk of? if the boat is stationary in the water (albeit moving in relation to the land)?

Originally posted by A2Z Each boat will then accelerate until they achieve a steady velocity (in the direction of the current) and with a magnitude such that the drag of the boat moving through the water is equal to the force of the water (current) on the boat. .

The interesting question is "would that apparent wind be sufficient to allow a boat to make progress against the tide?" (I think no but I could be wrong) 

Pretty similar planing speed to the 49er I used to sail. Not only would getting in tide take you to the mark 3 knots quicker, but you would be sailing in 8 knots breeze. 8 knots was enough for you to plane so you would see a significant increase in boat speed through the water. 29er was the same, but you needed more like 10-12 knots. 

Interestingly, for moths, if it is wind against tide, they are better sailing against more tide downwind. The increase in boat speed from the additional apparent more than outweighs the additional distance they have to sail through the water. Only works for boats which have VMG greater the wind though. 

Your anchor scenario is exactly my point.  Here you have hydrodynamic forces acting on the hull and tension in the anchor cable is holding it still.  Cut the cable, the hydrodynamic force now accelerates the boat until the drag of the hull equals the hydrodynamic force. At this point the boat moves at constant velocity, but the magnitude of that velocity surely depends on how draggy the hull is.
 

No it doesn't. 

The hydrodynamic drag will affect the acceleration....the change in velocity.  

Given 2 boats of different profile both end up accelerating......and as they approach the speed of the current the flow past the hull tends to zero....so that the hydrodynamic drag tends to zero so that the difference in hydrodynamic drag tends to be even smaller than that.....

A 'fascinating' race during that very high pressure week in June.....drifting up and down the Solent with the same piece of flotsam alongside us.

The point is, shortly after coming off the anchor, that force (the anchor) is no longer acting on he boat and it slows through the water to zero. Once it's off the anchor the only forces pushing the boat through the water is the sheer between wind and water. 

The tide doesn't move a boat through the water, because the tide is the water. So how fast a boat moves through the water does not depend on tide, but on how much power the sails have and how draggy the hull is, exactly the same as a lake. 

The point is, shortly after coming off the anchor, that force (the anchor) is no longer acting on he boat and it slows through the water to zero. Once it's off the anchor the only forces pushing the boat through the water is the sheer between wind and water. 

The tide doesn't move a boat through the water, because the tide is the water. So how fast a boat moves through the water does not depend on tide, but on how much power the sails have and how draggy the hull is, exactly the same as a lake. 

A low drag boat with efficient rig will go faster in a 3 knot tidally induced apparent wind than a high drag boat with inefficient rig. But the speed difference between the two boats will be same as in a 3 knot true wind with no current. 

The starboard boats get swept toward the layline, and they get the increase in breeze, however, the shift in wind is a header for them, which is why you won out coming in from the left. 

So you start a thread describing a situation where you get a tidal lift, and now, ten pages later your going to think of a method to disprove it ever happened. 

On the plus side the clear explanations of tidal effects are probably very helpful to people who don't already know this stuff, so it's probably worth it from that point of view!

I showed a situation where the wind was veered for sailors on the water compared to the true wind felt by the RO.

The video I posted showed how as the boats went from no tide (feeling true wind) to the current, where the tide backed the true wind, favouring boats which had created leverage of the left (just like a regular wind shift). 

I can't think of another way to frame effect tide has on apparent wind. 

This sort of tidal knowledge is useful. You will know that not only when you hit a cross current will it sweep you sideways toward a side of the course (and layline), but it will also shift the wind lifting you up toward the layline as well. 

Hopefully the thread has been useful for people and some have learnt a few things.