Shifting Through The Sail Trim Gears

[Don Guillette]

If you ever drove a stick stick shift car did you ever downshift? Of course you did and the reason was the driving situation changed and you wanted to keep your momentum. If you were driving up the Baker grade going from LA to Vegas would you wait until the engine lugged before you shifted? Probably not.

On the water, the direction and speed of the wind can change every 5 minutes. Do most cruisers adjust their sails during these changes? Probably not and that's OK but maybe they would like to know the procedure in the event they find themselves in a puff situation where the snacks and drinks have just fallen all over the place and now they have to make a sail trim adjustment.

There are two ways to react to a large and sustained puff of wind. The first way is to wait until the puff hits and the boat heels over and then madly dash around to make your sail trim adjustments on the main and jib. To bring the boat back on its feet you could drop the traveler and ease out the main and jib. Actually, just dropping the traveler might correct the situation. Using the Baker grade analogy, your engine just lugged and you reacted to the situation.

Most of us can see the puff coming just as we can see the hill or grade in the distance. Next time you see a puff coming do these 5 easy things - tighten your boom vang, tighten your cunningham (if you have one) or the halyard, ease the traveler down and ease out the main and jib just a bit. When the puff hits your boat should stay on its feet. After the puff passes move the controls back to their original position. 3 out of 5 of those changes merely involve adjusting the angle of attack.

 

[RichH]

C'mon guys ....'bump' this thread.
Shifting gears is for safety as well as performance.

Here's a way to shift gears solely by use of the tell tales.

From the "Sailing San Francisco" website: www.sfsailing.com/cgi-bin/articles/trim/trimchapter7.cfm
Using Jib Telltales to Advantage

One valuable tool for upwind performance is genoa telltales. Genoa telltales serve as a trim guide and as a steering guide. Once the trimmer has set the sail to proper shape the driver can fine tune his course to suit the boat's needs. There is more to it than simply keeping the telltales streaming. Fig. 3.


Fig. 3 - Once you are sailing in the groove with the telltales flowing you can fine tune as follows:
Fig. 4 - Sail with telltales flowing to maintain full speed and pointing.
Fig. 5 - Push down against the outside telltales for extra power and acceleration.
Fig. 6 - For extra pointing in smooth water let the telltales lift occassionally.
Fig. 7 - When overpowered feather up and let the telltales luff to help depower.
Fig. 8 - Gentry Tufts are a series of short telltales which can help more narrowly define the steering groove.

 

[LuzSD]

so much good information, I struggle with the descriptions ( like reading instructions in French, which I know a little tiny bit!) but if I go really slowly and visualize each step it makes sense and I am learning. Thank you for the incredible amount of knowledge shared so freely! So much to learn and so little time!

 

[Alan]

There is a lot to learn but take heart the learning curve is really steep. After you get into it you'll suddenly have an epiphany and the light will go one nice and bright and everything will fall into place. From there on its a matter of refining and practice. The learning always continues but correct responses come faster, kind of like second nature.
Then you may even think about becoming a competitive racer. I know, dirty word, but it really can become addictive, really!

 

[RichH]

I'll offer the initial gear-shift with a question:

Does one need a 'powered-up' (first gear) shape or a 'flattened-down' (high gear) shape for sailing in LIGHT WINDS ???

If you dont know about sail 'shape' (that YOU control/adjust after you put a sail up) we can back off and start with that ........

 

[Alan]

There's a fine distinction here. In ULTRA- LIGHT winds of up to 3 knots true the sails need to be in the power-down mode. This means flattening the sails to allow the air flow to remain attached to the cloth as long as possible along the width of the foil. A flatter surface will accommodate a much longer surface attachment than a powered-up high draft one will. As the breeze begins to build the gears are progressively shiftedback to the powered-up scheme again. In effect the full range of adjustment starts with a fully flat sail in the lightest of air. Then the shape is adjusted progressively toward a full up power shape with a building breeze. As the breeze continues to build the shape is then progressively moved back toward a flatter shape again to help depower or power-down the increased breeze to minimize increased heel and helm while maintaining good boat speed.

 

[RichH]

Alan - your are 110% correct .... and how does one accomplish such flattening for such ultra-light conditions?

.... Hint: it isnt just the outhaul on the main nor the fairlead car on a jib is it !!!???

... anyone can jump in.

 

[LuzSD]

There is a lot to learn but take heart the learning curve is really steep. After you get into it you'll suddenly have an epiphany and the light will go one nice and bright and everything will fall into place. From there on its a matter of refining and practice. The learning always continues but correct responses come faster, kind of like second nature.
Then you may even think about becoming a competitive racer. I know, dirty word, but it really can become addictive, really!

Actually Alan we do race, mostly we crew on another boat and we are pretty competitive. I know alot by instinct and get it right a fair amount of time, it is when I try to read things like this that I have to really slow down and visualize .... that is when names of things and direction all come into play and it is hardest for me then. Since I crew, I many times am told exactly what to do and that's great but I would also like to think it through and learn by doing, making errors and learning from them. I really do like competing in racing (normallly not that competitive) and EVERYTHING that racing one the ocean entails. So, I think I already have fallen into the addictive catagory but very happy to be there. I need to get better at vocabulary and understanding the more detailed parts like angles etc. but I guess I am still in the "trying to make it second nature " stages.

So don't mind me hanging on the edges here, I am learning every day by all that I read in posts like these!

 

[LuzSD]

Alan - your are 110% correct .... and how does one accomplish such flattening for such ultra-light conditions?

.... Hint: it isnt just the outhaul on the main nor the fairlead car on a jib is it !!!???

... anyone can jump in.

Is it that you bring the main up as high as possible so it is flatter and tighter? (maybe tighter is not a racing term, sorry)

 

[HEINZIR]

Increase Cunningham/halyard tension?

 

[Don Guillette]

LuzSD: Here's how sail trim works. First of all, it is not nuclear reasearch that goes on forever. It is like riding a bike - once you learn how to ride there isn't much more to it. Secondly, none of the experience guys on this forum were born with sail trim knowledge - they acquired it. Some acquired it easily and others, like me, learned it the hard way.

Here's the deal - there are only 4 things ALL and I mean ALL the sail trim controls for the main and jib are adjusting and they are DRAFT DEPTH, DRAFT POSITION, TWIST and ANGLE OF ATTACK. Once you understand those 4 element you're half way home. Next, you need to know which sail trim controls for the main and jib are used to adjust each of those 4 element and which way do you push or pull the controls to get the result you desire. Lastly, you need to know the setting for each control for each point of sail and wind condition. That was pretty easy wasn't it?? Actually, you could figure it out for yourself or you could save yourself some time and buy my book and chart as I've already done the work for you.

Here's the final test - when you know WHY you are making a sail trim adjustment you're home otherwise you're just guessing. During the 3rd hour of my "on the water" seminars participants can look at the sail trim of any boat near them and recommend the adjustment needed to obtain 100% efficiency and can explain to me WHY they recommending that adjustment. I love it when that happens as I've done my job.

 

[jimmyb]

Halyard, cunnigham, outhaul, and boomvang, tension them all. Im really new to sailing so be kind. Also if so equiped maybe less tension on the back stay adjuster? Im guessing this would stand the mast up and flatten the sail more. Jeez I hope I dont make and *ss of myself. Seems that woud be it. A traveler adjustment wouldnt do anything to flatten correct? Just angle of attack?

jimmyb

 

[jimmyb]

While we are at it one question please. I have a line running through the luff of my jib tied of to the tack cringle. Is this a tensioning tool or is just a structural part of the sail. If it is used for shaping how and when woudl it be used? Generally speaking.

thanks jimmyb

 

[jimmyb]

Oops. Think I got the backstay adjstment backwards. Tighten to flatten.?

 

[Alan]

jimmyb, good try you got most of it right. The one you got wrong was the backstay adjuster. Applying the backstay bends the mast back. Bending the mast back 'flattens' the sail not the other way round.

 

[RichH]

Here's where Im going with this: 'light' winds dont have much 'energy', and because of the low velocity and low energy the air doesnt like to 'turn corners' and can easily 'separate' from the sail.

Intuitively, but wrongly, most sailors will tend to 'power-up' (big draft or 'low gear' shape) a sail in 'light' winds ... and the usual outcome is the sails will be 'separating' instead of have 'attached flow'. Obviously if one doesnt have a full set of tell tales, one will never ever be able to detect the invisible 'separation'; tales will 'droop' on the leeward side, etc. if you do develop a separation stall.

Normal cruising cut sails typically will have a very-rounded luff shape, or 'entry'. Set up / raise a sail for 12-15 knots and the position of max draft will be at about 35-40% of cord length, and with a rounded 'entry' or luff shape, etc.; by halyard tension (see previous posts on 'how to properly raise a dacron sail", etc.).

Difference in 'raising' (from normal 10-15kts) a 'dacron' sail for LIGHT winds.
A dacron sail if set up with 'very little' luff tension will have a more FLAT luff entry shape (less potential for invisible separation stalls), but the draft then 'goes aft' because the amount of halyard tension governs where the draft is located (helm balance). Since FLAT shaped sails are 'best' for light winds, the outhaul is hard tensioned --- by watching the midcord tell tale: open until you get a separation stall, then bring in 'slightly' while watching the speedo for 'max.'. The sail will be draft aft because of the 'soft luff' tension; so, the way you then must compensate is by letting the boom, not the traveller, slightly fall off to leeward (increasing the angle of attack)- traveller usually set to the WINDWARD side so that the boom can also 'lift' and match the requirred 'twist'.
Light winds have the MOST 'gradient wind" - wind is faster at the mast head than closer to the water .... so therefore you also really have to be dead-on in matching the gradient wind with the correct amount of 'twist' - both for accelerating and for 'speed sailing'. All governed by watching the tell tales .... quite simple!!!!!

So, mindful of Don's DRAFT DEPTH, DRAFT POSITION, TWIST and ANGLE OF ATTACK, for 'light winds' and to prevent 'the deadly separation stalls' you have to set the sail with light halyard tension, compensate for the 'draft aft' shape by allowing the BOOM (not the traveller, with vang 'released') to drop to leeward, when going to FIRST GEAR. As the boat then builds speed and becomes faster, the increasing speed of the boat is *increasing the apparent wind* that the sail 'sees' .... and you can then start bringing the boom back towards the centerline ('high gear').

In the special case of light winds:
FLAT SAILS, FLAT ***LUFF*** shape, less DRAFT - to prevent separation stalls, LOTS of 'twist', OPEN the angle of attack and 'bear off' to 'accelerate' (low gear) to compensate for the 'draft aft' shape. (if you have the means, you can also 'close down the slot' between the main and jib (to divert 'more' wind to lee side of 'both' sails) - the tell tales and the speedo will tell you 'how much' to close.)
Then when up to speed (max. 'apparent' wind) then trim/shape 'normally'.
IF you dont accelerate (low gear to high gear), the apparent wind will NOT increase, ...... and youll soon have to switch to the iron genoa because 'light wind' SHAPE is different than when 'normal' - 10-15kts. Sailing, shaping, trimming (shifting through the 'gears' in light winds will be 'startling', and will keep you 'sailing' when others are 'motoring'.
If you do this 'right', you can very efficiently 'ghost along' when the water is unrippled and totally flat ... simply by MAKING your own apparent wind.

There are some 'tricks' to help accelerate when in 'light conditions' (but VERY illegal when racing): With the boat 'well' heeled over to leeward and needing to accelerate, 'pump' the mainsheet in and out !!!! - so that the boom moves or 'fans' between its far leeward to centerline position and cycling about once every 2 seconds, keep this up until about halfway to your 'target speed', then 'trim in' and GO ... as you have artificially increased boat speed (by the 'fanning'), which automatically increases 'apparent wind'. and once your apparent wind is max'd you can 'just keep on sailing'. If you tack, then begin again and accelerate through all the gears (and tricks).



;-)

 

[jimmyb]

Thanks for taking the time with us. I learned alot. Was very suprised to hear how the tensioning of halyard or lack there of affects the luff shape. Thought it woud be the opposite.
jimmyb

 

[sinnettc]

How much outhaul is enough?

I don't play the outhaul like I do my traveller, but I have learned enough here to understand its purpose and I use it depending on the wind conditions.What I'm still a bit confused about is how far I should be easing it when I want the main powered up. I've got a 9 foot boom so obviously I don't want to move it 3 feet, but are we talking 3 inches or 6 inches or what as the maximum range of play? How do I figure that out?

 

[RichH]

While we are at it one question please. I have a line running through the luff of my jib tied of to the tack cringle. Is this a tensioning tool or is just a structural part of the sail. If it is used for shaping how and when woudl it be used? Generally speaking.

thanks jimmyb

Jimmyb ---
If I remember your particular rig correctly, your jib doesnt 'attach' to the forestay with piston snaps, hanks, etc. to the forestay, nor does the luff fit into a foil. If it does attach there may be a few 'fabric tabs' that connect to the forestay with 'snap buttons'.

The boat has a standing 'forestay' but the jib has either a 'wire/cable' or a small very strong 'high-tech line' inside a sleeve at the jib luff .... and there is a cringle at near the tack of the sail and is located 'right behind' the 'sleeve' for the luff 'wire' or 'line'. When you raise this jib, you first connect the tack of the sail to a bow fitting, then connect a THIMBLE EYE (connected to the 'wire' , etc. on the jib ———to the halyard ..... is this correct????

If so, This a common (to the midwest and Great Lakes) 'running forestay system' ... that cringle near the tack controls WHERE the point of maximum draft in the jib is adjusted - pulling tension on the cringle puts tension on the SLEEVE but not the 'wire'. Am I still correct???
But first, this is how such a sail is 'raised' so that everyithing 'works' well:
1. Attach the tack of the sail to the deck fitting,
2. attach the halyard to the THIMBLE, then
3. pull the halyard 'for alll you can put into it - the halyard SHOULD be BAR TIGHT ......
4. THEN 'slack' the standing forestay until its 'floppy' !!!!!!!!!!!!
When sailing, the entire forestay load is carried entirely by the twisted WIRE or super strong line that is INSIDE the sleeve at the luff !!!!!!
5. Then how you tension the luff, for the days wind/wave conditions, is to apply tension between the 'cringle' and the deck fitting ---- almost totallly slack for 'light winds' and for 'blammo' conditions you pull the cringle almost all the way to the deck fitting !!!!! ....
6. When finished sailing, for removing the jib, .... you FIRST re-tension the 'standing forestay' back to 'normal', drop and disconnect the jib, etc. --- the job of the 'forestay' is only to hold up the mast when NOT sailing !!!!!!

Such a jib is cut to be flown on a VERY TIGHT wire or 'rope' (inside that sleeve) ... and your rig (fractional rig) when overpowered, and with a tight backstay, will 'automatically' bend the the top of the mast and automatically 'flatten' the upper panels of the mainsail --- but the wire/rope inside that sleeve on the jib has to be almost BAR tight to do this.
Only when sailing 'downwind' and for long periods - slack the jib halyard ( leave the 'standing forestay 'floppy' - or 're-tension it'.

Is this 'close' to what you have??
Its a VERY good system and is used on the ultra-fast iinland lake SCOWS ( ... up to 38ft. long scows), etc. and is quite common on racing boats designed on and around the Great Lake and the Midwest. With added 'complexity' such a system is used to 'rake the mast on-the-fly' (!!!!!!) and simultaneously adjust the tension in the 'forestay'/jib-luff'-wire.

 

[RichH]

I don't play the outhaul like I do my traveller, but I have learned enough here to understand its purpose and I use it depending on the wind conditions.What I'm still a bit confused about is how far I should be easing it when I want the main powered up. I've got a 9 foot boom so obviously I don't want to move it 3 feet, but are we talking 3 inches or 6 inches or what as the maximum range of play? How do I figure that out?

A fairly bombproof way of correctly setting outhaul tensionamount of draft):

Once you get the boat initially set up (sail shaping) then 'trim optimization' in accordance with what the tell tales are telling you (and Don's - DRAFT DEPTH, DRAFT POSITION, TWIST and ANGLE OF ATTACK); Disregarding the amount of heel, then watch the speedo as you tighten/ease the outhaul ... the max. speedo value (and tell tales) vs. in/out on the outhaul will tell you the correct amount of draft for the 'present wind/wave conditions' .... any adjustment on 'either side' of 'perfect' (amount of draft) will SLOW the boat ... in those condiiions less than when you purposely 'de-power for survival'.
For 'major' changes in outhaul tension you may have to go back and make correction in shape/trim necessary to get the tales flying correctly ... and then 'repeat' the outhaul adjustment.
;-)