How do you gauge your speed

There is no doubt, the faster you go the further in you will have to trim in the sheet to maintain the same course.

The proof of this is shown in this extreme:

Go barrelling down the front of a wave on a run. As soon as you exceed the actual wind speed, your sail will billow in.

(If you’d like a video of this, watch the trailer for Bass Straight Laser.)

The apparent wind direction does move forward. If you were to maintain your trim regardless of speed increase, the weather tail would drop and the leeward tail would jump around.

However, to reach the “sweet spot” for maximum power for the new apparent wind, you will be pointing higher as well a trimming the sheet.

This is a different set of conditions to the first rule of tell tails which is made under normal windward beating conditions in a boat that will not plane to windward - such as the laser.

The degree of height gained may not be very much. The phrase “pointing higher” gives the impression of a huge gain to windward. This is not always the case and depends entirely on wind speed and wave conditions and the point of sail. Should the speed drop off, as it eventually will, you return to the old rule of sail balance and tell tails. Fast sailing in a laser is constantly shifting between displacement and planing theory. The desired effect, obviously, is to stay planing as long as possible.


All this is not to be confused with pinching in gusty conditions.

When you pinch, you are creating a backwind effect in up to the first third of your sail. This depowers the sail in the gust allowing you maintain trim and balance and gain height at the cost of losing a bit of speed and power.

Alternately you could - perhaps there are large waves - heel, bear away and lose height while gaining speed and power and then regain balance and trim. It becomes a tactical decision.

During pinching you make the choice to point higher to depower the sail using the rudder. It is not the apparent wind that has made you point higher. The apparent wind direction has stayed the same, though it has increased. If there is a shift, this also should not be confused with apparent wind change – it is actual wind direction that has changed.

During pinching your power has reduced, whereas in the case of boat speed moving the apparent wind forward, your power has remained the same.

These things become clear under real life conditions. You will have to be planing and paying attention to experience it in a laser. The effect is far more apparent in a multihull or fast boat like a skiff, 470, or Contender. As with most things, they are far easier to do and experience than to stop and think about them and be able to write them down later with accuracy.

It is more important to be able to sail balanced and win the race, or enjoy yourself and not capsize, than be able to explain how you did it.
 
Hey Victor -

I had the same problem remembering - then a buddy told me to think about it this way -

If you are in a car and you slam on the gas, does the wind feel more in your face?

Same thing in a boat - you speed up, the wind is in your face.

Or this "HPBL" - meaning Head up in the Puff, Bear off in the Lull. I actually wrote that on the booms of all the kids I worked with - Course, none of them are going to the Olypics, so maybe it is a bad idea;-)

Matt
 
Yeh, I mean it was clear when i looked at this:
true-apparent-wind-2_small.gif

as the boat speed increases, the blue (apparent wind) comes moves to the left, so the little boat (hehe nice pic) heads at a lower angle to the true wind. Right? For some reason when I ignored what this thing told me when i posted that.
 
Yeh, I mean it was clear when i looked at this:
true-apparent-wind-2_small.gif

as the boat speed increases, the blue (apparent wind) comes moves to the left, so the little boat (hehe nice pic) heads at a lower angle to the true wind. Right? For some reason when I ignored what this thing told me when i posted that.

i did say it moved to the left... though i accidentally wrote "comes moves" hehe same thing
 
so correct me if im wrong. faster you go, the closer the "aperent wind" gets to "true wind", also allowing you to point higher.
 
very confusing indeed...

so faster you go the further away "aparent wind" is from "true wind". thus not allowing you to point as high.
 
Exactly. It is confusing. Sorry merrily. I should never had brought it up. It's a confusing concept... I'm not even ready for it.
 
Summary: this is all you need to know from this thread




Or this "HPBL" - meaning Head up in the Puff, Bear off in the Lull. I actually wrote that on the booms of all the kids I worked with

Matt


might what to also figure out the BASIC'S of how to read telltales

KISS: Keep It Simple Stupid
 
The faster you go, the further forward the apparent wind becomes when compared to the actual wind direction.

e.g.

If the wind was blowing in your right ear at a stop, as you accelerate, the wind now blows in your right eye.
The actual wind direction has not changed. The apparent wind direction has changed, moving forward.
Again: If the wind is blowing steady Easterly and you accelerate to the North, the apparent wind moves forward to ENE.

You cannot point higher than your boat is designed to go just because you are going fast,

i.e. breaking the rules of sailing theory. At some point you will reach head to wind, regardless of how fast you're going.

but you are pointing higher when compared to the course you were sailing at the slower speed

and when compared to the actual wind

and when compared to any other boat that is not going as fast as you, on the same course as you.

This is why fast is good while racing. :D

You are not pointing higher by your own choice, but because you must use a higher course to keep your sails trimmed correctly, because your speed has changed the apparent wind.

Your sails use only apparent wind from the time you start moving. Actual wind direction is just a point to measure from.

As you slow down the apparent wind moves back towards the actual wind direction.

Slow is not good when racing. Avoid it at all costs.

Unless an obstruction is approaching fast, and your apparent speed towards the obstruction is increasing, then I recommend you use all the slowness you can find to avoid the hitting the obstruction with a high apparent speed.


If this has not increased you confusion, I will be very disappointed.
 
Chainsaw that somehow doesnt seem right but as a relative novice I may be missing something. Surely the highest you can theoretically point to absolute wind is when moving relatively slowly when actual and apparent wind are fairly close. Say the highest my boat can point is 45deg (to apparent wind). As soon as I start to move forward at 45deg the apparent wind moves forward (away from actual wind) so i have to bear away to avoid the dead zone (which also shifted forwards). So now I'm going faster, still at 45deg to apparent wind but now at 50deg to actual wind so even though I'm going faster it's at a more oblique angle so I may not actually make any more progress to windward even though I'm going faster. I am not sure if the optimum tradeoff between increasing angle away from wind direction and resultant increase in absolute speed can be calculated but isn't it possible that the optimum angle for absolute speed might turn out to be different to the optimum angle for progress to windward so maximum progress to windward might be achieved at an angle other than that which gives maximum absolute speed?
However I may be failing to take into account a possible change in the angular size of the dead zone with increasing speed? Does this zone shrink when speed increases? The above manouevring is assuming that all this is done with sails fulling sheeted so we are only using directional change to keep the sails full sheeting. If you take the apparent wind argument to its logical conclusion - the fastest I can possibly go might be on a screaming reach somewhere approaching 90deg to actual wind but at that point I may be making very little progress to windward?
 
so i have to bear away to avoid the dead zone (which also shifted forwards).

Have you changed the point of sail by bearing away though?

If you are planing close hauled, you are making gains to windward. If you bear away to a reach, you are not making as much gain but your speed increases. If you want to slow down while on that reach, you’d move to a broad reach that would in its extreme either make you luff (easing the mainsheet without bearing away) or you would have to bear away and go lower, for your point of sail.

If you’re in a laser, you won’t be planing to windward, so will make best gains to windward at maximum displacement speed. You will be pointing higher to some extent, but not as much as the angle between points of sail. As mentioned earlier, the phrase “pointing higher” gives the impression of tremendous gains rather than the reality which may be measurable, but not startling.


isn't it possible that the optimum angle for absolute speed might turn out to be different to the optimum angle for progress to windward so maximum progress to windward might be achieved at an angle other than that which gives maximum absolute speed?

Yes, I think this is what is highlighted above. Perhaps we could further complicate the “ifs and buts” of these “rules” by adding:

"So faster means pointing higher...within the point of sail"

If the apparent wind has moved forward, it’s moved forward on both tacks. (obviously)

Once you tack, would you not be covering less ground, and faster, over the same course as at a slower speed? (ruling out the possible changes that happen in real life such as wind shifts etc)

the fastest I can possibly go might be on a screaming reach somewhere approaching 90deg to actual wind but at that point I may be making very little progress to windward?

This is the same problem you have at slow speed. How fast to sail to gain optimum speed and make the highest gains to windward.


However I may be failing to take into account a possible change in the angular size of the dead zone with increasing speed? Does this zone shrink when speed increases?

Off the top of my head, I don’t know. :rolleyes:

If it stays the same but only moves forward, it would have the same effect as being smaller when traveling to a fixed point to windward on any given tack.

If a boat comes off the plane as it tacks, then the apparent wind suddenly moves back toward actual wind direction. Then under acceleration the AW moves forward again, until you reach the balance between speed and height again. It would seem like the deadzone had reduced under those conditions, but it may have only moved.

However, if it does get smaller, through some aerodynamic rule...lol... I’ll look it up and tell you tomorrow.
 
this is getting to ridiculously complex, even for me, can we hijack to deciding if the bow eye should be made out of carbon fiber? need to get all that weight off the bow!

If you vote me to the Laser NA board, I promise it will happen!
 
I'm not sure if this is valid or not but if we say that the limiting angle of the dead zone (relative to APPARENT wind) stays the same size for regardless of speed. If we also look at the case where all manouevring is done fully sheeted in. As I sail forward closely hauled on the limiting angle and pick up speed the apparent wind shifts forward and so the dead zone limiting angle shifts to leeward so i am forced to bear away to stay outside the dead zone. Granted I may now be going faster so my progress to windward may be the same (or slightly better or slightly worse - I don't know) but I had to physically bear away from the original closely hauled angle due to the forward shift in apparent wind (and the consequent leeward shift of the deadzone limiting sailing angle) caused directly by my increased speed.
This forward shift of apparent wind and consequent leeward shift of limiting sailing angle happens in opposite directions for opposite tacks so I can't help but feel that the effective total angle of the deadzone (relative to ABSOLUTE wind) might actually increase as your speed increases?
 
As I sail forward closely hauled on the limiting angle and pick up speed the apparent wind shifts forward and so the dead zone limiting angle shifts to leeward so i am forced to bear away to stay outside the dead zone.

If the AW moves forward, then the deadzone limiting angle has moved to windward, not to leeward.

As long as you don't change the point of sail, then I can't see how the limiting angle would become greater with increased speed.

(This is what I was I was going to find out about, but you're welcome to beat me too it... whether the deadzone limiting angle reduces, moves forward or stays the same.

I''m looking for answers... I'm looking I'm looking ...give me time man!

lol :D
 
this is getting to ridiculously complex, even for me, can we hijack to deciding if the bow eye should be made out of carbon fiber? need to get all that weight off the bow!

If you vote me to the Laser NA board, I promise it will happen!

If the apparent weight of the bow eye is 120g, dry, how much will it weigh made out of carbon fibre, wet, at planing speeds if the apparent wind has moved forward by 5 degrees?

Your nomination hinges on the answer. You have 1 minute. Starting...

...NOW
 
well, lets see if I can confuse everyone a little more...

My limited knowledge tells me:

When you go faster, the AW moves forward. To maintain optimum polars you have to bear away. Your polars don't change... ever. The dead zone is still what it always was, if you don't make a correction, you are now pinching. Think of it like a wind shift, because that is what it is, the usable wind has now shifted forward. You always sail to the AW, not the TW. I really don't care what the TW is.

This is my experience in racing the big boats. It may not apply here...

Now, notice I never mentioned speed, just polars. So, the real question is:

Can a laser pinch a little, while planing, and still maintain optimum VMG?

My vote is no. Physics is Physics, and wind moving over an aerodynamic surface behaves in the same way fast or slow. The only difference is the force. If you move the angle of attack of the airfoil in relation to the direction of the wind it reacts the same at all speeds (assuming some laminar flow, and not is a stall situation for those pilots out there)

Another magical question:

Can you trim the sail (change the airfoil) in a way to take advantage of the new wind angle? Does moving the draft back or forward help with the angle of attack change?

I think the only way to really know the answer to all of these questions is to fully rig a laser with instruments and go sailing...
 
When you go faster, the AW moves forward. To maintain optimum polars you have to bear away.

This is the part I don't get at all. Why would you bear away when the wind moves forward? You'd want to follow the wind up. Seems totally backward to me. Seems to me there's two issues here, also. Do you want to use the apparent wind to point better or to go faster? That's a tactical decision.

I remember that DrLaser had a great article on this topic, including the Polars. Does anyone still have it? I tried the archives but couldn't get them to work or find the article that I needed. If anyone has the article, please e-mail it to me. (don't post it here due to copyright considerations)

janet @ laserforum dot org
 
I am sailing with the wind at 45 degrees to the sail...

If I go faster the wind is now 35 degrees to the sail...

I have to bear off a bit to get back to 45 degrees to the sail...

The numbers are for clarification, I am not saying what the proper angle to sail a laser is.

understanding pointing versus speed is what makes good sailors into great sailors.

this is how I understand it:
(the small blue lines are your boat)
 

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Quit showing me the diagram. I don't get the diagram. Your explanation still doesn't make sense to me. Our speed increases as we settle into the tack and the apparent wind moves forward, closer to the bow. It's like you've gotten a wind shift up. Why don't you head up? Don't tell me because the true wind is still back there, the apparent wind is driving the boat, ain't it?
 
Also, what do you think, people? Should we ask Bradley to split this thread? It's gotten away from gauging your speed.
 
From the link that I suggested earlier, an RYA dinghy instructor (British certified instructor) says that you can either head up OR bear away when the apparent wind shifts forward, and the boat will accelerate. There are also some hints for gauging your speed. See below:


"On a windy day, the Laser will plane if you point a little below a close-hauled course and hike like mad. in reality you go from displacement, to bow out of the water to planing; with noticable performance improvements at each stage. Watching videos of Lasers training you can clearly see three stages in the displacement to planing transition.

My suggested explanation is:

1) Boat accelerates and overtakes its bow wave ("official" planing definition) - bow lifts out of water.
2) As boat accelerates apparent wind shifts forward (heads) so sails depower.
3) Sailor trims in/bears away and suddenly accelerates.

Things to look for at the transition are:

1) The bow wave out each side leaves the sides of the boat much further back.
2) Wind shifts forwards.
3) Boat accelerates.
4) If you are hiking you can probably see the bow lift if you are sitting forward.
5) Transom wake turbulence decreases.
6) You are moving faster than another Laser.
7) The rest is instinct...

In reality, what you should be focusing on is not "Am I planing, if so, how fast am I going?..." but more like:

"How do I get this boat to go even faster?"

In terms of performance, knowing if you are planing or not does not really improve your race results.

One thing to note is that if your laser is going more than 5kts, then it has to be planing! You can plane and still not go that fast. The trick is to make the transition from slow planing to damn fast planing because anyone can get the flat aft section of the Laser to plane..."
__________________
Will Richards
RYA Dinghy/Race Instructor
www.saildisc.co.uk
 
look at the diagram again.. I added to it. I added a boat, and the dead zones in a few different places.

In the middle of the diagram is a boat on the red wind line at 45 degrees to the wind, and a boat on the blue wind line at 45 degrees to the wind. they are pointing very different directions.

On the right side of the diagram the boats are pointing in the same direction, as the wind comes forward (boat on the blue line), if no changes are made, it comes into the dead zone.


If the wind shifts up (coming more from the bow), and you head up (more into the wind) you are now head to wind.
 
Y'all are very kind to stick with explaining this. I've had an epiphany and I get it now. Bear away. The apparent wind has shifted and you just shift your boat to keep at the same angle to it. I got confused by "being headed" and "heading up," I think. Sorry Tannerz, the diagram still didn't help, but how cool is it that you can change it in a previous post!
 
I feel left out right now... I think I might be the only laser sailor left on earth not with a post on this thread!

I'd like to state that I'm also an RYA Dinghy/Racing instructor, and for what its worth, having those qualifications doesnt mean we always know what we're on about!! You know what they say.... "those that cant do, teach" lol.

I've owned 6 lasers, and dont think I've ever had one planing upwind. That said, I did borrow one from a friend and on one beat it absolutely flew, just breaking a plane from the leeward corner of the transom, for short periods, between sets of waves.
I've tried everything I can think of to get mine to do it, and it just doesnt happen! :(

On the subject of apparent wind and pointing higher....
As the boat speeds up, the apparent wind moves forward, as in a heading shift, essentially forcing you to sail lower. you bear away, and your speed increases further, and it starts over again!
----------
Food for thought...
Then of course you get the extra leeway, which changes the angle of attack for the centreboard, which then starts to generate more lift to windward, which effectively creates a lifting shift!! help! way out of my depth here!
Back to reality...
----------
In a high performance skiff, like a 49er or RS800, the apparent wind shifts far enough that you often cant lay up to the mark on a broad reach, so the top guys will sometimes stall the kite (sheeted in until the boat stops) and then sail slowly using the true wind to get up to the mark. In these same boats, the difference in speed downwind means that twin wired boats can often sail faster and lower on the runs than the boats with only one guy on trapeze, due to the increased power, and hence apparent wind!!
 

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