pointing ability - what affects it?

[fantasia7628]

Leach tension is achieved either by applying the kicker, or by mainsheet tension. If you need to ease the main to reduce heel, the you either do this by easing the mainsheet traveller (maintaing the sheet tension) or easing the mainsheet and applying kicker. On most yachts the easiest option is to ease the traveller; but it is essential that enough leach tension is applied. If you have leach telltales, then the top telltale (which is normally adjacent to the top batten) should just be stalling and the lower telltales streaming. In my experience it is the mainsail that determines pointing ability, aided by the slot from the genoa.

 

[jason -and the arguenauts]

Surely the argument should apply even more so to masthead rigs since the foresail area will be bigger than with a fractional of the same mast height.

 

[flaming]

Thats a thought. I only normally use the kicker to keep the boom down when running. But then how does what you suggest differ bfroim using the track to open the leach and the sheet to keep the tension you want?

Hugely simplifying a very complex topic, and working on "best assumptions" since I've never sailed a starlight 35, but...

Yes, sheet and traveller have the same effect as kicker, but sheet and traveller are preferable upwind until you're off the end of the traveller.

One of the things that gives you point is the leach of the mainsail. In a simplistic way, the straighter it is (sheet/kicker on hard) the higher you will point. However as with anything on a boat there is a tradeoff. Hardening the leach gives you point at the expense of power. So if there is a big sea running (likely as you seemed to have been well reefed) you will need to add twist (slackening the sheet/kicker) to give the power it needs to get over the waves. You should also set the jib car so that the profile of both leaches is as similar as possible for best results.
Hardening the leach also makes the boat more tricky to helm, as you make the groove upwind narrower, and the penalty for bad helming more exadurated.

However.... Yours is a masthead boat (right....?) so it's likely that the genoa has more importance. On mast head boats the forestay is normally tightened whilst sailing by using the backstay, are you set up to do this?

Given the sort of questions you're asking, a very, very good investment for you would be the North sails "trim" book. Which goes into great detail on all aspects of upwind and downwind trim.

 

[flaming]

Surely the argument should apply even more so to masthead rigs since the foresail area will be bigger than with a fractional of the same mast height.

Ah yes, but then there are mysterious "rig factors" and other things to take into account!

Rating optimisation is fascinating stuff, but I'd really rather race one design. It's just a shame that the dominant one design around here is the J109, which has possibly the most mis-matched hull and rig ever.

 

[dunedin]

If part reefed, this could be a big factor depending on method

If furler genoa, a few turns can give a very baggy shape unless there is a foam luff to absorb the bag. Our boat goes very well to windward - except previously when genoa reefed when it was hopeless. Changed to foam luff genoa and added thirsd mainsail reef point and transformed windward ability over 15 knots

The bit about race boats now having tall narrow jibs is heavily linked to specific rating rules such as IRC penalising larger genoas. In up to 15 knots our cruising 140% genoa is much faster to windward than the 105% blade jib, even though the latter is a much more expensive kevlar racing No 3

 

[lw395]

Flaming - what do you mean about leach tension on the main? We moved the mainsheet car up the track to get the boom along the centre line and adjusted the main sheet to get the leach tell tails flying.

That sounds oversheeted unless you have a very big genoa (which means the main is operating in deflected wind). The leach or bottom batten should be parallel to the centre line, not the boom. The bottom part of the main is over sheeted, the top is twisting off to get the tell-tales flying. Let the boom down a bit and more sheet/kicker. This is often a compromise, you will over sheet the very bottom of the sail for the best overall shape, but itsoundslike you could have been over doing it.

I accept Flaming's comments that modern boats designed for IRC don't have big genoa's but that's because the rating penalty is slightly bigger than the performance gain.
A Starlight is designed with a big genoa and should work well enough with it until it's too windy imho.

 

[jason -and the arguenauts]

Dont quite understand " The leach or bottom batten should be parallel to the centre line, not the boom." Did you mean to type foot instead of leach?

Anyway, the boat has a non standard 130% genoa with a foam luff and a loose footed main. Following my practice on the previous boat, I reefed the main to the first serious reef (it has a Cunningham type reef about 1 ft up) and took the genny in by one third. Clearly I overdid this in 18/20 kn because we went better as I let the genny out, but we still didnt point that well and speed through the water struggled to better 6.5kn..

Mind you we went like a scalded cat once we freed off a bit and left a Sigma 33 way behind in very short order, but by then it was too late.

Yes Flaming, we have a backstay adjuster - screw type with big handles - but I'm far from sure how to handle it.

I'm beginning to think that what I need is some lessons from a good racing skipper. I can't abide being useless at something.

 

[lw395]

Dont quite understand " The leach or bottom batten should be parallel to the centre line, not the boom." Did you mean to type foot instead of leach?



I'm beginning to think that what I need is some lessons from a good racing skipper. I can't abide being useless at something.

What I meant was the aft portion of the mainsail, say the last foot or so, draw a horizontal line on it, that line should not (generally) be hooking up to windward, it should be in the region of parallel with the centre line of the boat. On a yacht there is always some twist, so think about say 1/5 up the sail, not too near the foot.

With huge genoas (ior not irc), the genoa backs the airflow all around the main, so the boom can be in farther.

Coaching is a good idea if you can find the right coach. But I would advise against getting a string of guest skippers to the detriment of your own hours on the helm. Sounds like it's perhaps a trimmer you need rather than a helm, but the two must work together.

I'm having a few boatspeed/handling issues myself, we are trying to get out for a good half hour before each race to practice and try things, then have a short 'tea break' and go racing. There are too many other things to worry about in the race, better to focus on one at a time separately.

 

[ianat182]

Pointing ability

No one seems to have mentioned it,but when you reefed the main how hard did you tension the main halyard,I'm betting that you aimed to get it as hard as you could and produce a flat sail. I've been down this route before and found that the main becomes de-powered .
The answer for me was to ease the main halyard so that there were just very small lateral creases at the luff. The difference was amazing, and when really on the wind the genoa slightly backwinding the main seemed to accelerate the air through the slot,and our speed from 5 to 6.5 kts. I never could understand why dinghy sailors had creases in their mainsail luffs, but now realise that the draft of the sail moves slightly aft and gives the power for speed upwind. Try it out, it may work for you.

ianat182

 

[bbg]

Following my practice on the previous boat, I reefed the main to the first serious reef (it has a Cunningham type reef about 1 ft up) ...

I'm beginning to think that what I need is some lessons from a good racing skipper. I can't abide being useless at something.

Cunningham is not a reef. It is a luff tension control. What you should do, typically, is hoist the main all the way to the top (on a racing boat there will be a black band around the mast to indicate the highest you are allowed to hoist - normally you can tension the halyard quite hard and still not go beyond the black band). As the wind strangthens it pushes the maximum draft of the sail aft. By tensioning the cunningham you tension the luff of the main and pull the draft back forward. It changes the shape of the sail, not the size.

As for taking lessons - if you can encourage someone with experience - doesn't have to be a skipper - to come out with you and make it clear you WANT to be coached / want to learn, you will pick up a lot very quickly. Even better, see if you can get one of the racier boats for a couple of races. I suspect you will pick up a lot about boat handling.

 

[Danny Jo]

What an excellent thread - lots of food for thought.

A factor that has been hinted at, perhaps, but not mentioned specifically in all this discussion about sail trim, is optimization of keel performance. I suspect that because you cannot trim the keel, some sailors forget about it, pinch like hell, and slide away to loo'ard. Fin keels need plenty of water flowing over them to provide you with lift to windward - this may mean not pointing as high to sail faster, but by greatly reducing leeway give you a higher track over ground (i.e. better VMG, velocity made good, to windward).

If you have a plotter, try putting in a waypoint 10 miles to windward, then sail to optimize your VMG.

 

[jason -and the arguenauts]

Seems to me that ianat182 and bbg are saying almost the opposite. one says slacken off the halyard , the other says use the cunningham to tighten it and move the draft forward.

any third party views on this issue?

 

[flaming]

Seems to me that ianat182 and bbg are saying almost the opposite. one says slacken off the halyard , the other says use the cunningham to tighten it and move the draft forward.

any third party views on this issue?

Completely depends on wind strength, how much sail you have out, whether or not your boat is headsail driven, etc, etc.

Certainly too much cunningham/halyard can be as bad as too little, but the rule of thumb is that they should be tightened as the wind increases.

 

[[10753]]

Not all Twin Keeled Yachts point badly

 

[dunedin]

Seems to me that ianat182 and bbg are saying almost the opposite. one says slacken off the halyard , the other says use the cunningham to tighten it and move the draft forward.

The effect of halyard tension/cunningham will be very similar on all boats. As the wind strength increases the deepest point of the sail curve moves back - towards the leach. Tensioning the front of the sail - via the halyard or the cunningham moves the fullness forward again.

What differs more is what is best for a particular boat. To get any sense of this is it important to
(a) make record of the settings and wind strength
(b) take photos of the sails - for this setting looking upwards from the boom

As a general rule the depest point of the sail should be between 40% and 55% back from the luff. The precise position depending upon the boat. But if much further back than this the sail just generates drag

 

[jason -and the arguenauts]

Found the answer - it's a bit embarrassing in truth. When I put the sails back on, I didnt close the clutch on the outhall so the main was loose footed - literally.

So I suppose the culprits in the first race were over reefing, outhall when not reefed, lack of backstay tension and mast bend so the sail was over full in the middle

Anyway, the next 2 races were a second and a first so I'm a happy bunny again.