Sail trim question - Please

[Paulfireblade]

So firstly I should explain I have limited experience, I have never sailed dinghy's and and have only been sailing for two years. The first 18 months on RYA courses and training weekends where sail trim is mentioned but the priority is safety as it should be so I have done most of my learning on sail trim since buying my boat 8 months ago.

So I went out on the East coast on Friday, the forecast was gusts up to 24 knots with a WNW wind so no lee shore to worry about and the the swell was not too bad so we sailed south with the tide and the wind behind us I just put the genoa out and after about three hours we turned for home and we were now on a close reach but maintaining around 6 knots so I just left the Genoa up. When the wind gusted it also seemed to veer and the top quarter of the Genoa would luff, (I am assuming this was due to wind sheer at the top of the mast) but the remaining three quarters of the Genoa was working well with tell tales both sides moving nicely and speed remained about 6 knots. I had the Genoa car well back and good tension on the Genoa sheet. When the gust eased the luffing on the top quarter stopped.

I was concerned about vibration on the mast and wear on the top quarter of the Genoa.

My questions:

1.Should I have wound in the Genoa which would also have reduced the working sail area lower down to prevent the luffing at the top of the Genoa during gusts or is it acceptable for a small amount of the sail to luff with the majority working?

2. Never tried winding in a Genoa while powered up, is it even possible or do you have to de-power Genoa and lose speed to reef it?

I was only 1.5 nm from the port when this started to happen but I would interested in your thoughts for next time.

Apologies for my novice question.

Many thanks Paul

 

[roaringgirl]

You don't mention the boat type, but I'd be pleased with 6kts close-hauled

The genoa on our boat is enormous (170%+). She goes faster upwind with quite a lot of it rolled away in anything over 15kts.

When reefing upwind, we let the sheet out first so the sail is flapping, haul on the reefing line; then re-set the sail.

For the perfect headsail trim, you may need to play with the leech line and move the sheet cars (forward to stop the head of the sail from luffing)

 

[[3889]]

It's quite unusual for a luffing genoa to induce rig vibration. Do you mean luffing at the front edge of the sail or a fluttering leach along the back edge? If the latter then move the car forward to increase leach tension and/or tighten the leach line in the genny but not so much that the leach hooks. If the sail is stretched from age then this may not work but it is not a mission critical problem. You should definitely not attempt to reef a genoa under load.

 

[neil_s]

First of all - you get a brownie point for giving it a go! You're right, vibration due to a flogging sail is not good for the rig - or the sail. I sympathise - it's easy to just unfurl the genoa, but a more balanced sail plan would be better. Mainsail with a reef and 100% working jib would be a lot easier to control. You could certainly winch in the sheets for beating to windward if necessary. Might be even fun for 1.5 miles!

 

[Paulfireblade]

You don't mention the boat type, but I'd be pleased with 6kts close-hauled

The genoa on our boat is enormous (170%+). She goes faster upwind with quite a lot of it rolled away in anything over 15kts.

When reefing upwind, we let the sheet out first so the sail is flapping, haul on the reefing line; then re-set the sail.

For the perfect headsail trim, you may need to play with the leech line and move the sheet cars (forward to stop the head of the sail from luffing)

Pretty sure Genoa is 135% on a Jeanneau SO 34.2. Not the fastest in a light wind and I did have 0.7 - 1.0 knot of tide but briefly saw 6.5 knots a few times.

 

[Paulfireblade]

It's quite unusual for a luffing genoa to induce rig vibration. Do you mean luffing at the front edge of the sail or a fluttering leach along the back edge? If the latter then move the car forward to increase leach tension and/or tighten the leach line in the genny but not so much that the leach hooks. If the sail is stretched from age then this may not work but it is not a mission critical problem. You should definitely not attempt to reef a genoa under load.

Fluttering of the leach along back edge, fairly new sails but I may have been positioning Genoa cars incorrectly. Both you and Roaringirl have suggested moving car forward but when I looked up car positions on the internet I thought it said further forward wind move cars back and further behind wind is move cars forward.

Did I get that Ars@ about face oops.

As I was on a close reach I had pushed the cars towards the rear of the track.

 

[RJJ]

On a close reach, genoa only is typically not a great sail plan. You can't wind the sail all the way in as it will stall out (in the absence of the mainsail). You're pushed to sail close-hauled, or near close-hauled, if the wind should swing against you (a header); or to avoid an obstruction. Because your tacking angle is wide (probably 120 degrees+) it may be hard or impossible to tack throug waves should you need to.

A better sail plan is always some combination of main and jib. But in the interests of efficiency and laziness we all make compromises from time to time.

I wonder if the gusts were making you head up into the wind, even as little as 5 degrees, which of course would make the jib luff? You should get clear about whether what you're experiencing is related to being slightly over-powered, vs purely a matter of sail trim.

to your specific questions:
- most genoas are designed so the foot is close to the deck when close-hauled . This is efficient - when you're close-hauled - because the deck "end-plates" the sail, stopping the wasted energy of the wind slipping around the foot
- the implication is that as soon as you ease the genoa (see above), the head will twist off and tend to luff/flap. To some small extent, we all live with it for much of the time.
- to some extent you can counteract this by moving the genoa sheet lead forward and outboard (the other alternative is to sail with a higher-cut genoa which is less efficient close-hauled, but more effective on a close or beam reach; or you can sheet the sail tighter so the head doesn't flap so much, but then obviously the lower part of the sail is over sheeted which is slow and makes you lean over)
- reefing the genoa could make the situation worse because it's the same effect as moving the genoa/jib car back (when you should be moving it forwards). On many cruising boats you soon run out of travel on the car.
- I would only reluctantly furl the genoa under any load. I always bear away to a deep broad reach and ease the sail. On our 45 footer, if I get this right (careful not to gybe if the main's up) I can pull the furling line easily by hand up to 30 knots (the most I've tried). It takes seconds; you only need a few boat lengths sea-room.
- It's not a cardinal sin to winch in the furling line, but be very careful as the winch offers sufficient power to break the set-up in the event of some minor line snag. If pulling by hand, you'll notice the snag and sort it.

 

[Paulfireblade]

First of all - you get a brownie point for giving it a go! You're right, vibration due to a flogging sail is not good for the rig - or the sail. I sympathise - it's easy to just unfurl the genoa, but a more balanced sail plan would be better. Mainsail with a reef and 100% working jib would be a lot easier to control. You could certainly winch in the sheets for beating to windward if necessary. Might be even fun for 1.5 miles!

I have sailed in that sort of wind on the river so I thought next step coastal and with no Lee shore.

Point taken re Genoa, always reef main according to conditions but Genoa is generally unfurled all the way which is so easy to do. Good point.

 

[johnalison]

Problems with sail handling and maintaining a course are reasons why I seldom if ever sail on foresail only. A cruising boat will be able to make ground to windward under genoa alone but without a slot it is never as good as with two sails. You never know when conditions will change and you will need full performance and control. Whether a part-furled genoa performs adequately depends on the quality of the sail and its age. A foam luff can help a lot, and high-tech sails even more so that in cruising terms little may be lost. It is easy enough to unfurl a sail in any wind but furling in part or fully can be challenging. In high winds this may involve letting the sail flog, which is not good for the sail or the nerves. It is much easier and quicker to turn off the wind and put the sail into the shadow of a mainsail, given enough sea-room, and use of a winch should never be required. Most boats will be better balanced sailing under a part-furled jib and full or reefed main, which also has the advantage that jib sheet loads are much less.

 

[Paulfireblade]

Lots of very sensible suggestions, thank you all so much. In my defence it is the first time I have sailed windward without the main up,

I will be better prepared next time and have the flippin genoa cars in the right direction

 

[roaringgirl]

I keep these 2 books on board:

"Sail Trim" by Peter Hahne
"RYA Sail Trim Handbook for Cruisers" by Rob Gibson

They are both well-thumbed.

 

[john_morris_uk]

Wind gust producing a luffing sail suggests to me that the OP might benefit from learning about ‘velocity headers’.

 

[roaringgirl]

If you're heading upwind, you can depower the headsail for reefing by just pointing a bit higher. Easy if you've got the main up too, as the main can point higher than the headsail. Depowering the main for reefing on a close reach can be done just by sailing on the headsail and releasing the mainsheet.

 

[Paulfireblade]

to your specific questions:
- reefing the genoa could make the situation worse because it's the same effect as moving the genoa/jib car back (when you should be moving it forwards). On many cruising boats you soon run out of travel on the car.

Thank you, for your detailed information and I have to say I had to read it twice to fully appreciate everything you have said. The Leech was simply too loose as I had moved the Genoa car backwards instead of forwards.

 

[Paulfireblade]

I keep these 2 books on board:

"Sail Trim" by Peter Hahne
"RYA Sail Trim Handbook for Cruisers" by Rob Gibson

They are both well-thumbed.

If you're heading upwind, you can depower the headsail for reefing by just pointing a bit higher. Easy if you've got the main up too, as the main can point higher than the headsail. Depowering the main for reefing on a close reach can be done just by sailing on the headsail and releasing the mainsheet.

Recommendation appreciated and I will order today. I knew about de-powering main from MOB practice but I didn’t realise about pointing higher to depower foresail while main still powered. Many thanks for explanation.

 

[Paulfireblade]

Problems with sail handling and maintaining a course are reasons why I seldom if ever sail on foresail only. A cruising boat will be able to make ground to windward under genoa alone but without a slot it is never as good as with two sails. You never know when conditions will change and you will need full performance and control. Whether a part-furled genoa performs adequately depends on the quality of the sail and its age. A foam luff can help a lot, and high-tech sails even more so that in cruising terms little may be lost. It is easy enough to unfurl a sail in any wind but furling in part or fully can be challenging. In high winds this may involve letting the sail flog, which is not good for the sail or the nerves. It is much easier and quicker to turn off the wind and put the sail into the shadow of a mainsail, given enough sea-room, and use of a winch should never be required. Most boats will be better balanced sailing under a part-furled jib and full or reefed main, which also has the advantage that jib sheet loads are much less.

Ironically I have never sailed upwind but now I actually appreciate the benefits of having both sails up thanks to everyone’s great help.

It was drummed in to me on Comp Crew to never use a winch on the furling line.

 

[Paulfireblade]

Thank you, everyone and some great explanations that have really helped to fill in the gaps of my understanding. Still so much to learn but such a great experience at the same time out on the sea making way with just the wind for power.

 

[oldbloke]

The reason you move the cars back in a breeze is to depower the sail by stretching and flattening the bottom of the sail providing drive with less drag and letting the top twist off, depowering it (and opening the slot if the main is up.
It sounds to me as if you, and the sail, did more or less the right thing. If the top was actually flogging then maybe ease the cars sl forwards till it stops . Overall it sounds like a nice successful day out .

 

[dunedin]

In my experience circa 50 % of cruising jibs / genoas on boats we pass going upwind are badly set, usually not sheeted tight enough and therefore fluttering high up out of sight of the helm sitting behind a wheel.
So it is great that the OP is taking an interest in these things - a bit of experimentation and will soon get the hang of things.

Going upwind in a breeze, luff up a bit to back wind the sail slightly to make winching the sail in easier, then fall back to the course.
And if safe to do so, once sailing put a harness on and nip up to the foredeck and take a few photos of the sail shape and the track settings, adjust as necessary then nip back up and take more photos. Can sail for decades and learn nothing sat behind the wheel.