How do you gauge your speed

Discussion in 'Laser Talk' started by Skygod1, Jun 8, 2007.

  1. Chainsaw

    Chainsaw Brmmm Brmmm

    Likes Received:
    0
    Trophy Points:
    0
    As long as your tails are placed well for your sail and the draught of the sail is within a range of efficiency this is generally what happens:

    If the leeward tail is stable(ish), and the windward tail flicks around, you bear away or sheet in.

    If the windward tail is stable(ish) and the leeward tail flicks around you come up or sheet out.

    However, there are situations where the choice is one side or the other. In which case I recommend you chose the leeward side to keep stable.

    As wind velocity increases, the likelihood of you consciously having the time to think about what the tails are doing reduces dramatically. Sail trim becomes a balancing act ("of feel") between weather helm and boat trim. The only quick indicator you have to avoid capsize is the leech tail, which will give you a rough idea of how far away stall/overpowering is. However, once you master the feel of the boat under heavy conditions, even those become defunct.
     
  2. Chainsaw

    Chainsaw Brmmm Brmmm

    Likes Received:
    0
    Trophy Points:
    0
    What happens in real life, at speed, is that you come up momentarily to get the leeward tail stable, perhaps trimming in the sheet, then as the power comes on you can return to your course, perhaps easing the sheet and bearing away.

    How much you come up or bear away may be a lot (rudder use) or very little (kinetics body weight use).
     
  3. viktor188924

    viktor188924 New Member

    Likes Received:
    0
    Trophy Points:
    0
    Right, if you feel that you've lost speed, or 'stalled out' like in a plane, you bear off a little bit. In light wind, using 'kinesthetics' just lean your body weight out a bit. Once you get speed, you can go up again by leaning in. Try this (it really helped me understand how body weight works): try sailing without using your rudder! use the extra legnth of line that hangs from your traveller to tie the tiller so that it stays in the middle of the boat. It's important not to use too much rudder in light wind but I kind of got off track here.
    The first animation is of a boat heading too far up into the wind. you can see the windward telltale flickering. This means you have to bear off. Just like chainsaw said.
    Another thing important to speed: keeping the boat flat. In any condition, you have to keep the boat flat!
     
  4. Skygod1

    Skygod1 Member

    Likes Received:
    0
    Trophy Points:
    6
    Its all becoming clearer to me now.
     
  5. viktor188924

    viktor188924 New Member

    Likes Received:
    0
    Trophy Points:
    0
    If you want to get all technical, this works because of 'apparent wind.' The faster you go, the higher you can point to the wind ultimately making you travel less distance...
     
  6. Mawill

    Mawill New Member

    Likes Received:
    1
    Trophy Points:
    0
    Hello,

    I think that we have this backwards - Let assume you have a constant true wind (this being the wind you feel standing still). As your boat speed increases, the boat wind increases (as though you were in a car speeding up). As this happens, your Apparent Wind - the wind you sail by (which is a combination of the True Wind and the Boat Wind will move FORWARD - which means you have to either bear off or trim the main in order to maintain efficiency.

    So I think as you speed up you will have to bear off until everything comes back into balance. This is why you have to sail a very curvy course upwind. Head up as the gust hits (True wind increase) and then as you realize the benefits of the gust you have to Bear back off in order to keep the sails full. Same concept with waves (swells)

    I think I have that right?

    Matt
     
  7. Deimos

    Deimos Member

    Likes Received:
    12
    Trophy Points:
    18
    I don't follow why - can you explain why this happens.


    Ian
     
  8. Mawill

    Mawill New Member

    Likes Received:
    1
    Trophy Points:
    0
  9. Mawill

    Mawill New Member

    Likes Received:
    1
    Trophy Points:
    0
  10. Deimos

    Deimos Member

    Likes Received:
    12
    Trophy Points:
    18
    I thought it was the other way round as well. However, there seems no ambiguity or typos in the post and it clearly states "the faster you go the higher you can point to the wind" (due to the apparent wind). If people have more experience than me I am happy for them to explain stuff to me - only way one learns in life (hence my asking for an explanation).


    Ian
     
  11. Skygod1

    Skygod1 Member

    Likes Received:
    0
    Trophy Points:
    6
    The way I understand it is that the optimal trim position of the sail changes with forward motion.
     
  12. viktor188924

    viktor188924 New Member

    Likes Received:
    0
    Trophy Points:
    0
    Yes I did write it backwards. My dad has tried to explain it to me but I guess I still don't get it. My apologies! Ahhh
     
  13. Chainsaw

    Chainsaw Brmmm Brmmm

    Likes Received:
    0
    Trophy Points:
    0
    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.
     
  14. Mawill

    Mawill New Member

    Likes Received:
    1
    Trophy Points:
    0
    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
     
  15. viktor188924

    viktor188924 New Member

    Likes Received:
    0
    Trophy Points:
    0
    Yeh, I mean it was clear when i looked at this:
    [​IMG]
    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.
     
  16. Skygod1

    Skygod1 Member

    Likes Received:
    0
    Trophy Points:
    6
    Shouldnt the blue line move to the left instead of stay constant?
     
  17. viktor188924

    viktor188924 New Member

    Likes Received:
    0
    Trophy Points:
    0
    i did say it moved to the left... though i accidentally wrote "comes moves" hehe same thing
     
  18. onetwoMeny

    onetwoMeny New Member

    Likes Received:
    0
    Trophy Points:
    0
    so correct me if im wrong. faster you go, the closer the "aperent wind" gets to "true wind", also allowing you to point higher.
     
  19. viktor188924

    viktor188924 New Member

    Likes Received:
    0
    Trophy Points:
    0
    no it moves away from the true wind so point lower. i got it mixed up in my first post.
     
  20. Merrily

    Merrily Administrator Staff Member

    Likes Received:
    14
    Trophy Points:
    38
    This is a very confusing thread.
     

Share This Page