Which is best VMG...
- Thread starter weinie
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That would really depend on the boat BUT easing the main would flog the heck out it which would get expensive
From a racing standpoint are you covering your lead OR in the back ?
From a racing standpoint are you covering your lead OR in the back ?
In a general case 'neither', as to win or be consistently at the head of the pack you have to be going in the 'right' direction at the highest speed possible.
In a generalized case when electing not to reef, its usually much better to 'flatten' by more halyard (and cunningham) and outhaul control/tension ... to slightly 'open' the leach and reduce the amount of draft, etc.
Ditto too with the jib/genoa - by 'opening' the leech on the jib/genoa by slight rearward repositioning of the jib fairlead car - to open up the 'slot-distance' between the jib and main.
Pinching slows speed and drops vmg; easing the main drops speed and results in the boat 'footing off' for more distance to travel.
With SHAPE control, you still have 'options' such as slightly pinching up in the slower winds and footing off during the higher portions ... sailing a smooth "S" curve, instead of 'straight-lining' each leg which is usually always slower.
Your helm pressure when the boat is at maximum heel is your best indicator of what's to be corrected as for shape and trim, not the amount of heeling.
In a generalized case when electing not to reef, its usually much better to 'flatten' by more halyard (and cunningham) and outhaul control/tension ... to slightly 'open' the leach and reduce the amount of draft, etc.
Ditto too with the jib/genoa - by 'opening' the leech on the jib/genoa by slight rearward repositioning of the jib fairlead car - to open up the 'slot-distance' between the jib and main.
Pinching slows speed and drops vmg; easing the main drops speed and results in the boat 'footing off' for more distance to travel.
With SHAPE control, you still have 'options' such as slightly pinching up in the slower winds and footing off during the higher portions ... sailing a smooth "S" curve, instead of 'straight-lining' each leg which is usually always slower.
Your helm pressure when the boat is at maximum heel is your best indicator of what's to be corrected as for shape and trim, not the amount of heeling.
the best VMG is the higher one. It is on your wind instrument as a optional readout if you have the GPS connected to it.
Bottom line, try both and see what happens, if the VMG goes down you are trimming in the wrong direction.
With that said, all boats are different and you did not give us much to go on. what is the sea state? What is the wind speed? Do you have trained crew or are you single handing it? Is the hull clean or not? Which tack are you on and does that make a difference on your boat? (on mine the port tack is the racing tack for some unknown reason)
If you don't have a VMG indicator then remember the sine of a small angle is equal to the angle (in radians)(56 degrees/radian BTW) so if you bear off :
bear off angle new distance to cover
1 1.02 you can't measure this
3 1.05 or this
5 1.09 ok, close to 10% so this is getting significant
10 1.17 clearly going to have to account for this or greater amount of course change.
So keep it below 6ish degrees and do the Alfred E. Newman thing. Take it above 6 and you need to retrim or start forcing the other guys to take a longer route too. ;-)
Bottom line, try both and see what happens, if the VMG goes down you are trimming in the wrong direction.
With that said, all boats are different and you did not give us much to go on. what is the sea state? What is the wind speed? Do you have trained crew or are you single handing it? Is the hull clean or not? Which tack are you on and does that make a difference on your boat? (on mine the port tack is the racing tack for some unknown reason)
If you don't have a VMG indicator then remember the sine of a small angle is equal to the angle (in radians)(56 degrees/radian BTW) so if you bear off :
bear off angle new distance to cover
1 1.02 you can't measure this
3 1.05 or this
5 1.09 ok, close to 10% so this is getting significant
10 1.17 clearly going to have to account for this or greater amount of course change.
So keep it below 6ish degrees and do the Alfred E. Newman thing. Take it above 6 and you need to retrim or start forcing the other guys to take a longer route too. ;-)
Dang Phil's space remover
bear off angle ---- new distance to cover
1--------------------------- 1.02 you can't measure this
3 -------------------------- 1.05 or this
5 -------------------------- 1.09 ok, close to 10% so this is getting significant
10------------------------- 1.17 clearly going to have to account for this or greater amount of course change.
bear off angle ---- new distance to cover
1--------------------------- 1.02 you can't measure this
3 -------------------------- 1.05 or this
5 -------------------------- 1.09 ok, close to 10% so this is getting significant
10------------------------- 1.17 clearly going to have to account for this or greater amount of course change.
Some good info here in just a few replies!
As someone who has never raced or has even been on board a boat during a race, I was just wondering if there was a preference to lean one way or the other in this type of situation.
Just some background about this particular scenario:
I was attempting to out sail the boat next to me, as we were both close-hauled and on the same tack.
Wind was blowing about 15-20, relatively flat conditions. As I said only about 15 minutes or so before I headed back home on a broad reach so I felt it wasn't necessary to reef and then unreef.
I am in my catalina 27 with 150% genoa - single handed - hull is clean.
As the wind picked up, I began by bringing the traveler to windward and easing out the main sheet to open the leach to spill some wind while still trying to maintain a good angle of attack. The Halyard was already pretty tight, draft forward, and outhaul maxed out as tight as possible (not loose footed - so not too much control here).
Genoa is tightly sheeted in then back off a tad to minimize the wind from backwinding the main through the slot. Unfortunately, I do have some trouble finding the sweet spots for the genoa cars due to the size of the 150 sail... the cars were just forward of the winch at the time. Moving the cars too close to the winch makes using the winch difficult as the angle of the sheets becomes too great.
As the "pressure on the helm" picked up, I knew I was applying too much rudder and effectively putting the "brakes" on. Obviously the boat was not balanced so I had two options that I toyed with...pinching and letting the main out.
I was just wondering what the experts would do in this situation...if there was a preference... or maybe another tactic that I'm overlooking!
As someone who has never raced or has even been on board a boat during a race, I was just wondering if there was a preference to lean one way or the other in this type of situation.
Just some background about this particular scenario:
I was attempting to out sail the boat next to me, as we were both close-hauled and on the same tack.
Wind was blowing about 15-20, relatively flat conditions. As I said only about 15 minutes or so before I headed back home on a broad reach so I felt it wasn't necessary to reef and then unreef.
I am in my catalina 27 with 150% genoa - single handed - hull is clean.
As the wind picked up, I began by bringing the traveler to windward and easing out the main sheet to open the leach to spill some wind while still trying to maintain a good angle of attack. The Halyard was already pretty tight, draft forward, and outhaul maxed out as tight as possible (not loose footed - so not too much control here).
Genoa is tightly sheeted in then back off a tad to minimize the wind from backwinding the main through the slot. Unfortunately, I do have some trouble finding the sweet spots for the genoa cars due to the size of the 150 sail... the cars were just forward of the winch at the time. Moving the cars too close to the winch makes using the winch difficult as the angle of the sheets becomes too great.
As the "pressure on the helm" picked up, I knew I was applying too much rudder and effectively putting the "brakes" on. Obviously the boat was not balanced so I had two options that I toyed with...pinching and letting the main out.
I was just wondering what the experts would do in this situation...if there was a preference... or maybe another tactic that I'm overlooking!
ok, you did not need to "keep the power up" due to waves or a dirty bottom etc and already in a close hauled so you really don't have the option to pinch as that would not materially effect the distance you needed (close hauled to pinch is <6 degrees) to cover but it would drop the speed. I'd be bearing off to get a more favorable wind angle but not so much (<6 degrees) as to effect the distance I needed to cover. Then trim the jib and main for the angle and wind speed change in the normal routine. ie tighten up all the corners of the main to flatten it ( a cunningham is great for this BTW), slack the mainsheet and move the traveler up to maintain angle of attack but spill the wind up high with twist and move the jib sheet lead cars back a bit to dump the wind up high.
Remember, if your anchor beats his anchor across the finish line you win and just a little speed increase adds up over time. it is all about balancing the increased distance you need to cover and the speed you cover it at when going to windward. ie as you mentioned at the start VMG
Remember, if your anchor beats his anchor across the finish line you win and just a little speed increase adds up over time. it is all about balancing the increased distance you need to cover and the speed you cover it at when going to windward. ie as you mentioned at the start VMG
OK I think I understand what happened ......
As stated previously, 'helm pressure' (your chief 'complaint') is the key indicator and is caused by two reasons, possibly 3 reasons especially when beating in increasing windstrength:
(Assuming woven dacron sail cloth, less so with 'quality laminates' ....)
Possibilities
1. incorrect 'position of maximum draft position' in mainsail
2. boat is skidding to leeward (adverse side pressure on the rudder due to the 'skid')
3. increased wind strength changes the SHAPE of a woven dacron sails and increases 'stretch' in the rigging which affects jib/genoa shape.
..... a boat dragging its rudder or is 'skidding' is going to be slow, wont point well, and will carry excess heel.
When you note increased helm pressure due to heeling and are 'pointing' or are closehauled, firstly you have to or should immediately look at the stern wake (turbulence wake of the keel/rudder) to see if its coming off the stern at approx. no more than a ~4-5° angle. If you have a tiller just look at the tiller angle.
1. If the stern wake is less than ~4-5° offset, the boat is not skidding to leeward, and you can usually 'ease' helm pressure by increased main halyard tension (and/or cunningham tension) which shifts the point of where the maximum draft in the main occurs to 'more forward', and which also 'opens' the leech. If totally unable to relieve adverse helm pressure by change of sail shape (halyard/cunningham tension) then and only then begin to drop the traveller (but you will begin to lose some pointing ability in doing so). In all trim adjustments, the second from the top batten's aft end should be nearly parallel (as a goal) to the boat's centerline for 'best' pointing - most boats!!!
Watch carefully the shape of the mainsail leech you want the 'shape' of the leech so that all leech tell tales are streaming straight aft and that the leech shape allows the air flow to 'exit' ... straight back. If you apply too much mainsheet tension, the leech can 'hook up to weather' which causes the boat to heel over and slow down but can 'pinch' ... you want that leach shape to be flat and not pointing to 'windward'. In high winds its OK to let the leech 'point' a bit to leeward ('tripped leech') ... all controlled by mainsheet tension.
2. If stern wake is greater than 4-5° offset, immediately check the apparent 'sag' (to leeward) in the forestay wire. If the luff is now relocated towards leeward due to sail pressure stretching the forestay ... resulting in the 'sag' .... apply backstay tension until the luff shape is returned to the shape that the sailmaker cut into the sail. A sagging to leeward forestay will cause increased heeling, slow boat, and a boat that is skidding off to leeward (and with consequential radical drop in VMG). A boat that is skidding off to leeward will 'feel' like increased so-called weather helm .... the angle of the stern wake turbulence will tell you which is which - a skid or actual weather helm.
Again, here's how to set up correct 'forestay/backstay' tension to match the wind loading on the headsail to be sure that the forestay sag is MATCHING what the sailmaker cut into the luff shape in anticipation of 'normal' wire sag: http://www.ftp.tognews.com/GoogleFiles/Matching Luff Hollow.pdf
You can 'help' the backstay tension to affect 'best' jib luff shape by increasing the jib halyard pressure (& also forcing the Pt. of maximum draft more forward and which will also 'open' the leech and the 'slot distance') but you 'can' jam a furler (until you release the higher halyard pressure) in doing so.
2a. Once you lessen or correct the 'skid' (less than 4-5° of stern wake offset), then go back and attempt to re-balance the helm pressure by mainsail halyard/cunningham tension; and, if helm pressure remains greater than what you can easily control by your finger tips on the helm; then and only then begin to drop the traveller. For those of you who can, apply mast bend, now is the time to do so to help 'flatten down'. Do not go beyond LESS than 3-5° stern wake or 'rudder angle' or your keel will be unable to develop 'lift' to windward ... and your VMG will drop although your speed will 'seem' to vastly increase because the keel is no longer 'lifting' the boat to windward - the keel is no longer 'flying'. You cannot have noticeable 'weather helm' and expect to 'point well and at speed'. Halyard tension on dacron mainsails is fully explained in: http://forums.sbo.sailboatowners.com/showthread.php?t=120970 (post #1)
In all of the above, the goal is get ALL telltales streaming aft 'perfectly' ... all done by sail
'shaping'.
Woven dacron sails, especially plain vanilla dacron, will stretch severely with increased windloading ... to be successful especially with pointing in changing wind speeds you have to continually correct the shape of the sails to their OEM design shape ---- halyard, cunningham, outhaul.
Most woven dacron sails will 'max out' at 15-18 kts. of apparent wind ... beyond that windspeed the sails will become 'powered up' (slow but with greater heel !!!!) because of the undue stretch of the sail cloth and change of 'shape' due to increasing or changing wind speed .... and your job is return the sail to its design SHAPE ... halyard/cunningham for helm balance; outhaul to control the optimized amount of draft / amount of heel, balancing the amount of 'power' or 'speed'.
Tip for outhaul / draft adjustment (any wind speed): once set up for 'appropriate' helm balance, then adjust the outhaul tension versus the 'speedo' or set the amount of outhaul tension to get the maximum speed (speedo) out of the boat when beating .... this will 'automatically set' the correct amount of draft (power-speed ratio) vs. the height of the waves that you have to 'punch through'. Flat sails (speed shape or 'high gear' shape) for flat water (and 'light winds' and 'heavy winds'); well drafted sails (power shape or 'lower gear') for waves ... even when 'reefed'.
Other --- Flattening (speed shape or 'high gear' shape) will depower in the higher windranges; so if you do get stopped/slowed by an errant large wave/wake or when tacking when flying flattened sails you'll have to drop the traveller for when 'accelerating' back to top speed / vmg.
;-)
- Traveler to leewward, mainsheet tight, vang tight. You want that foil flat, and traveled out to leeward.
- You don't need a 150 Genoa in +15 knots. Furl to -100%.
Let's assume the halyard tension is maxed, the outhaul is maxed, the mast is bent, and the sails are flattened appropriately. Furthermore the bottom is cleanish, it's a fin keel, shoal draft boat (i.e. Catalina 27), the sails are dacron (I only know one guy who has laminate sails on a Catalina 27 - and he wins a lot), the sea state is consistent with a 18 kt. breeze on LI Sound, and get back to the OP question: Is it better to pinch or foot. My answer is foot. But when pushed upwind don't fight it and take the upwind distance.
wienie, I have a Starwind 27, which is very similar to your masthead rig. I added a backstay tensioner a few years ago and found out what a difference it makes. I assume your 150 genny is not roller reefed, as mine isn't either. As the wind picks up to 15 knots or more, it is imperative to tighten the forestay to take out the excess sag which you undoubtedly have as you feel the helm pressure increase. I tension the backstay and feel the helm pressure virtually disappear. Your quandary is then a moot point, and you'll be pointing higher without losing boat speed.
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