Second Genoa?

[Rossynant]

Surely new sail will make improvement, but this discussion so far omits some aerodynamic explanation.
As the boat "will luff up uncontrollably and come to a halt in irons" - to original question - may be she turns just because of high heel angle, this is common in modern design as hull shape is not balanced. Only thing to do is to reduce aerodynamic (heeling) force, which is not the same as reducing sail area Fuller sail gives more force, and rolled up genoa becomes fuller, thus may still produce too much force... so still more reefing is necessary, but there is a limit beyond which the sail is ineffective. Only way out is to change for flat sail, and cut like yankee or such, or set lower down.

Another aspect - small boat cannot point so high in strong winds, but for bigger angle also the sail should be set on bigger angle. It's often forgot that this angle cannot be changed on usual genoa, as sheet is led from deck edge and will not be moved outboard; the angle is always the same. So easing sheet only makes the genoa fuller and still "sheeted to much in" On small (short) sail this is less of a problem, genoa is long. There was a reason times ago to have working jib on boom. This was always set at angle proper to the wind, also on a reach, with much better result and no need for spinnakers. Still a lot speaks for this.

So best way to cope in hard weather to windward is to have flat, heavier sail for change. The hard way. Maybe on internal stay, cutter style, with a working sail set lower; may also be on roller.

 

[Greenheart]

Sorry I haven't read this thread very closely, I may be repeating, or completely off-subject...

...has anybody, having enjoyed the advantages and accepted the deficiencies of a roller-genoa for many years, ever gone back to the labour-intensive non-roller headsail, and then concluded that the performance/pointing advantage made the extra effort worthwhile?

I suppose the yacht has to have a fairly pure performance element in hull/deck design, to reward putting such a demanding rig on top. I'm curious how great the benefit is, always to have a choice of headsails and the option to set a perfect foretriangle in any wind force.

I wonder if yacht designers, on finishing a new yacht's projected performance figures, groan as they mentally subtract the performance-finesse which is certain never to be experienced by the vast majority of owners, who'll prefer the equivalent of automatic gears.

 

[dunedin]

My approach to this would be No2 sized roller genoa (new with all the bits), Detachable forestay to take a large 150% light weight genoa, and a no3/blade and a storm jib all on piston hanks. Use the roller for a quick sail in most conditions but if you have a longish passage and the roller genoa is not quite right use one of the other sails as appropriate.

Good luck with it.

Seems like a huge amount of hassle compared to a quality cut furling sail with a good foam luff. Fit on once per season and no foredeck work thereafter - and we are very performance oriented, always sail upwind rather than motor, so don't believe we lose much efficiency.
Sure with a full crew of 8 prepared to lug sails around, plus a set of Kevlar jobs of each size that would be even faster - but lots of effort. Note the Open 60 round the world racers now use only furler sails now - and they don't seem to be slow.

 

[johnphilip]

Please explain

Now, can I get on my new soapbox? If you want to have a genoa that works when partly furled, get rid of the sacrificial strip. Even with foam at the luff, it is the extra material of the strip that makes the centre baggy. It only takes minutes to fit a cover when you reach your destination.
Allan

Perhaps I am being dense but I cannot understand how the material of the UV strip makes the rolled sail baggy. I have not noticed this argument before on discussions on the virtues of covers over UV strips.

 

[johnalison]

I was puzzled too. I think bagginess occurs when the sail starts to stretch with age or in higher winds. I haven't noticed much difference in my laminate jib since fitting a strip. I still have a sleeve for it but haven't used it much lately because of the bother and because the friction was scuffing the leech of the sail a bit. Maybe a better made one would have helped.

 

[Allan]

Perhaps I am being dense but I cannot understand how the material of the UV strip makes the rolled sail baggy. I have not noticed this argument before on discussions on the virtues of covers over UV strips.

Right! This is no a good time as I'm well p1ssed.
As you reef the normal genoa with a sacrificial strip the strip .............. sorry too p1sedd!
Think about the thickness of the material, I might be be back when sober.
Allan

 

[Rossynant]

...has anybody, having enjoyed the advantages and accepted the deficiencies of a roller-genoa for many years, ever gone back to the labour-intensive non-roller headsail, and then concluded that the performance/pointing advantage made the extra effort worthwhile?

Some boats belonging to "ocean wanderers" I know have cutter arrangement, two stays, two sails. Both on rollers...

 

[PeterWright]

Effect of Sacrificial strip

Modern roller furling genoas have some rope or foam padding in the centre part of the luff, so that each roll takes a bit more cloth out of the middle of the sail than the foot and leech, The effect of this is to flatten the sail as you roll up. If you look closely at the padding, you will notice it is tapered - wider in the middle of the luff.

A sacrificial strip will behave just like padding at the foot and leech, causing the sail to become fuller as you roll up - the opposite of what you want. You will end up with a very deep draft in the middle of the sail causing a large entry angle even when sheeted hard. Hence the boat won't point. Even if you have no sacrificial strip, the leech and foot still have more cloth in them so you will suffer this to some extent.

A well designed luff pad will compensate for the effect of the extra cloth (including the sacrificial strip) up to a certain point. I don't believe any sailmaker can make a 150% genoa which sets well as a storm jib.

On our Moody (I=15.77m, J= 5.03m) the 140% genny sets well when rolled up to the third mark, which is 1.5m back from the luff. Beyond that it starts to lose shape.

I find sacrificial strips much less hassle than a sock, so I'm overjoyed with the advent of the padded luff to the sailmaker's toolbox.

 

[Greenheart]

On our Moody (I=15.77m, J= 5.03m) the 140% genny sets well when rolled up to the third mark, which is 1.5m back from the luff. Beyond that it starts to lose shape.

That's pretty damned impressive! Who's the sailmaker?

 

[johnphilip]

Modern roller furling genoas have some rope or foam padding in the centre part of the luff, so that each roll takes a bit more cloth out of the middle of the sail than the foot and leech, The effect of this is to flatten the sail as you roll up. If you look closely at the padding, you will notice it is tapered - wider in the middle of the luff.

A sacrificial strip will behave just like padding at the foot and leech, causing the sail to become fuller as you roll up - the opposite of what you want. You will end up with a very deep draft in the middle of the sail causing a large entry angle even when sheeted hard. Hence the boat won't point. Even if you have no sacrificial strip, the leech and foot still have more cloth in them so you will suffer this to some extent.

A well designed luff pad will compensate for the effect of the extra cloth (including the sacrificial strip) up to a certain point. I don't believe any sailmaker can make a 150% genoa which sets well as a storm jib.

.

I am not convinced there is any significant effect from this. As the sail is furled the rolls are not on top of each other as if the sail was rectangular but barely overlap. Therefore the additional thickness from the UV strip is negligable. I think that the cause of a baggy half set genoa is in having having a bit of shape in the full sail, this will become exaggerated as the sail furls. The distance around the arc of the full sail is greater than if flat so the "shape" becomes exaggerated.
This also explains why a blown out used sail sets much worse than a rolled new sail.
I have been disappointed with the set of a previous sail with luff padding, our new rag seems to roll pretty well without one but the sailmaker did say we might want to add the foam strip after a few seasons.

 

[PeterWright]

Hi Dan,

The sailmaker is John Parker of Parker & Kay at Suffolk Yacht Harbour, Levington. He also made the sails for my previous boat and they were still setting nicely when I sold her after 8 seasons of club racing and cruising. They are Dacron, not laminate but a special cloth to suit the tri radial construction (something to do with the balance between the weave and weft crimp/tension). Peter Kay, the other half of the business, is somewhere among the fleshpots of the Solent, if that's closer to you. They are now affiliated to the 1Sails group.

John's skills at sail designing and building are impressive, but you need to remember that wiith a J of 5m the foot of our genoa is around 7m long, so it is not unreasonable to roll up 1.5m of that.

Hi Johnphillip.

I agree that rolling a shaped sail without a pad will produce a belly anyway, but the sacrificial strip makes this effect worse. This does not rely on the strip overlapping in each turn of the roll (although it must do so to serve its purpose, and that just makes things worse) it is because the sail + sacrificial strip is about 20% thicker than sail alone. so the roll at the ends is fatter, pulling in more of the leech and luff than the belly of the sail. What you really want in a roller genoa is a flatter sail when rolled; this cannot be achieved without padding the centre of the luff. If your sail has no padding, it's either too flat when fully unfurled or has too much draft (and hence too large an entry angle) when reefed.

Peter