Sail Trim

[Island Time 1,246]

Late last week, Booboo came and looked at my RF headsail on Island Time. Its getting on, and has done a lot of miles. It is a laminate sail, and is badly creased in the leech - like a hook, but 1st one way then another. Now, I thought laminates were good because they don't stretch and loose their shape, but apparently they shrink! Anyway, he took the sail away as he says they can improve it, so that is good.

However, while there, he commented that the halyard was small (6mm spectra), and he likes to have a knuckle in the front of the sail caused by halyard tension. I'm sure he's right - he knows way more than I do about this.

This is what I had thought - slacker luff, draft aft, finer entry, better pointing but more accurate helming required, and not so much power. Better to weather in flat seas.

Tighter luff, draft fwd, rounder entry, better power, less accurate helming needed, better in waves.

I generally used this sail with quite low tension on the luff, as a luff crease was easy to generate and I like to point well. I thought that a luff crease would cause flow separation? Yes, I know that the crease will dissipate as the wind increases, but it's a RF headsail, and will get rolled up a bit then as well.

Am I just old fashioned? What are your thoughts?

I'm sure Booboo will help set it up better when he brings it back!!

[Black Panther 1,599]

While we're at it, my headsail is laminate but on hanks. It takes shitloads of halyard tension to get rid of the scallops between the hanks, enough that I feel the luff is too tight - maybe that isn't the case?

[tuffyluffy 76]

A bit of a generalisation on my behalf, but I thought all RF headsails were crap and compromised performance one way or the other, therefore anyone with them isn’t too fussed about sail shape.

[Battleship 100]

Are you sure it's 6mm spectra IT? if so that sure is tiny for your boat.

[Island Time 1,246]

Yep, its 6mm spectra. I thought the breaking strain on that is 1800 odd KG - is that right KM? Heaps strong enough?

It's on an Alado furler - no swivel at the top, Sail either fixed at top of foil, or halyard comes back down foil to the drum. Halyard Tension is via an old laser kicker block with jammer....

 

TuffyLuffy, I realize I do a different type of sailing to many of you serious races, but are you saying the Vendee Globe sailors, for example, are not interested in performance? I do a lot of short or single handed miles - yes there are downsides to RF, but I would not be without it. It does not mean I don't want to have the best sail shapes that I can......

[Guest]

Are you sure it's 6mm spectra IT? if so that sure is tiny for your boat.

Strength wise it's fine but from the hand handling and jammer angle it's small. But if it's cleated off on the foil then it should be fine..... if it gets Booboos approval with the shape thing in mind.

 

Probably closer to 1300kg (800 if knotted) when in use like that IT but agree that's more then it'll seeing right now. From IT's description the 'cleating off' doesn't use hands or std jammers so all good.

 

Interesting Boo says they like to use the halyard to shape. If the halyard has to be there why the hell not use it. I love good multitasking like that.

[tuffyluffy 76]

 

TuffyLuffy, I realize I do a different type of sailing to many of you serious races, but are you saying the Vendee Globe sailors, for example, are not interested in performance? I do a lot of short or single handed miles - yes there are downsides to RF, but I would not be without it. It does not mean I don't want to have the best sail shapes that I can......

 

IT, I’ve never used RF so im speaking from a position of ignorance, and I don’t take my keelboat racing seriously at all, well, not on my boat anyway.

 

Regarding the VG guys, I haven’t paid much attention but from what I’ve seen, they predominantly use them for downhill/reaching, and never partly unfurled?

 

I can definitely see the benefits of RF for a gennnaker/code type sail where its either fully furled or unfurled. But rolling up the luff on a upwind sail to reduce sail area just cant be good for sail shape. If I look at my number 1 headsail, then imagine 3-5 metres of it rolled up on the forestay, its not going to be pretty – a blue tarp from Mitre 10 would look better. I’m not knocking RF, and I “get it” when short-handed, but having a good sail shape on a partially furled headsail seems like a contradiction. At best you’ll get a 4/10 for shape compared to a decent number 2, 3 or 4.

 

Personally, I'd rather hit the autopilot and spend 5-10 mins on the foredeck swapping out a sail than look a partially furled headsail.

[Island Time 1,246]

Indeed, diff between RF and RR!! When racing, downwind I use it as a RF, and Spin or Kite if poss. Sometimes (downwind) partly unfurled if too windy for the other sails. Performance downwind does not seem to be effected too badly. The sail (that booboo took) was specifically designed for RR, having a pocket at the luff of differing volume along it's length to help the sail hold shape when partly rolled up. It is, of course, a compomise.

To weather, rolling it up is bad! distinct drop off in pointing and boat speed - way better to change to number 2 etc...as you said.

 

When cruising, I put up with it - we still outpoint most cruisers by a fair bit... and, well, it's not a race!

 

So back to the original question - do you guys set up your headsails with a knuckle caused by halyard tension? Perhaps I did not understand Booboo correctly??

[Farrari 4]

IT I'm not 100% sure what BooBoo is referring to with a knuckle but I do apply a fair bit of halyard tension from time to time to adjust the headsail shape; far more tension than a laser kicker block could tolerate. This all can be done from the safety of the cockpit. I had a system on my old Tracker that sounds similar to what you have and I replaced it. There was no real way of applying enough tension and it required someone to go up to the bow usually at a time when it was dangerous to do so. It had 6mm spectra on it from memory.

 

It will be interesting to hear what BooBoo has to say.

[Island Time 1,246]

I presume he means a vertical crease just back from the luff due to halyard tension, but I could be wrong. I'm sure he'll catch up with this thread given time.

I reckon I could put a few hundred KG on that halyard if I wanted.... not enough??

[B00B00 310]

Ha, interesting topic.

By knuckle I don’t mean a crease up the luff just a nice draft forward shape. All the modern design sails are much more draft forward shape with a straighter or flatter exit. This is especially important on modern racing boat that have very tight sheeting angles (IE closer to the centreline). On more traditional boats with wide sheeting angles there is a limit to how draft forward you can design the sails because your angle of attack (the actual angle the wind hits the sail) ends up very wide. But you still want the draft to be pretty far forward. Fine entries are Ok in flat water with a good helmsman but only if the sheeting angle is pretty wide which in turn produces less power. So you were spot on with your points Matt. Effectively its all about the angle of attack if you want to sheet it closer (to the centreline) then you need more knuckle to keep the right angle of attack.

What I think might actually be happening with yours Matt is that with your small halyard its just stretching when its loaded then taking up in the lighter conditions causing the over tensioned halyard crease problem in the light airs. Like bungee cord as a halyard!

Forestay tension also makes a massive difference to the amount of depth in the front of the sail. Its the same as mast bend but in a negative sense not a positive(a straight forestay makes the sail flatter and a saggy forestay gives it more shape).

[Island Time 1,246]

Booboo, I thought you'd read this eventually! I did not think spectra stretched much? And, anyway, when I take the halyard off, the headsail is fixed at the top, and I adjust it (with the same block) at the bottom. When I do it that way, there is less than 1m of the spectra to stretch - so that should be minimal.... right?

 

Agreed about forestay tension - but on a rig like Island Time it's a compromise - twin spreaders (straight) with lowers and babystay. Masthead. No adjustable backstay. I normally tension it to about 20% using a Loos gauge, and leave it there - there is no provision for backstay adjustment while sailing, only the turnbuckles. That is partly the reason I can have the radar gimbled off the backstay...

 

Probably time the rig tensions are checked again anyway, so when I get that headsail back I'll go thru it all again.

 

Booboo, I just thought some others might get something out of this as well!

 

Matt

[Kestrahl 6]

While we're at it, my headsail is laminate but on hanks. It takes shitloads of halyard tension to get rid of the scallops between the hanks, enough that I feel the luff is too tight - maybe that isn't the case?

 

It could be a problem with the rope in the luff of the sail, the rope should a diameter relating to the size of the sail and seized at both ends. I've seen cases of to small luff rope, sailmaker forgot to seize or no luff rope at all.

 

I'm pretty happy with the Dacron furling cruising genoa i built for our Davo 35, when I'm bored one day i might take photos of the sail shape at various amounts of furl upwind and check it out on the computer. From looking at it a few times it hasn't been excessively deep and we have done a couple of races with it partially furled upwind and actually did pretty good. One of the keys is truckloads of forestay tension (backstay adjuster).

[Guest]

with the fosters type furlers keep in mind that as the forestay sags it'll actually ease the halyard

[Guest]

Late last week, Booboo came and looked at my RF headsail on Island Time. Its getting on, and has done a lot of miles. It is a laminate sail, and is badly creased in the leech - like a hook, but 1st one way then another. Now, I thought laminates were good because they don't stretch and loose their shape, but apparently they shrink! Anyway, he took the sail away as he says they can improve it, so that is good.

However, while there, he commented that the halyard was small (6mm spectra), and he likes to have a knuckle in the front of the sail caused by halyard tension. I'm sure he's right - he knows way more than I do about this.

This is what I had thought - slacker luff, draft aft, finer entry, better pointing but more accurate helming required, and not so much power. Better to weather in flat seas.

Tighter luff, draft fwd, rounder entry, better power, less accurate helming needed, better in waves.

I generally used this sail with quite low tension on the luff, as a luff crease was easy to generate and I like to point well. I thought that a luff crease would cause flow separation? Yes, I know that the crease will dissipate as the wind increases, but it's a RF headsail, and will get rolled up a bit then as well.

Am I just old fashioned? What are your thoughts?

I'm sure Booboo will help set it up better when he brings it back!!

 

 

Cruising boat.

 

Sail on a furler

 

Talks like he wants a racing sail.

 

Buy a sail from North's... leaders in racing sails

 

Probably want durability?

 

What a difficult customer!

 

Buy two. One cruise one race

[sow1ld 2]

In flat water lighter airs I sail with a loose haylard Draft aft so better pointing. I have a navtec hydraulic backstay and when I run Draft aft shape I put 2500-3000psi (that's lots) on the backstay to create a fine entry of the forstay too. Combined that allows us to have fantastic height but the groove is very narrow.

I put the backstay on first then set the haylard tension otherwise when u crank on the backstay it in turn tightens the luff tension which us undesirable for a Draft aft state.

Both my no1 (orginal 1976) & my no2 are fairly tired so naturally have Draft aft shape which is why I sail that way.

I figure if I put lots of haylard tension on to bring the Draft forwards that might just be the end of my sails!

My friend prefers more draft forwards so when he sails with us he puts lots of haylard on and leaves the backstay fairly loose. Last week we plotted the results in 8-10knots true. Speed wise there wasn't any real difference 6.5 6.7 knts either set up , but Draft aft configuration we hovered around 26-29 apparent wind angle. The other way we hovered 30-35awa.

We outboard sheet anything over 50awa.

Oh and where a stock cav36.

[Island Time 1,246]

Never said I wasn't difficult !

Still, no reason not to get the best from what you have

[Tim C 23]

Don't tell your Cat 1 inspector that you can't drop your furling genoa at sea. He won't be impressed. Sails lashed at the head have no place on a cruising boat. If it rips or the furling fails, you want to be able to get the sail down...

 

 

 

 

 

 

 

PS I am a YNZ safety inspector

[Island Time 1,246]

Tim, I don't have to take the halyard off. It's normally left on for ocean crossings, + I have steps up the rig, so its no big deal really....

[Guest]

Never said I wasn't difficult !

Still, no reason not to get the best from what you have

Totally agree.

 

For what it is worth

 

Looking at the fact a RF head sail is a compromise ( in terms of sail shape, durability, rollerbility..) and the fact that you will never get an "ultimate racing configuration" I would go with an sail that suits a Med to heayy air breeze. (Average breeze you sail in 80% of the time? Maybe?l

 

Thus the racing shape theory of "less Halyard tension" to get a finer entry light air sail is replaced with your sail maker theory. Especially if you are sheeting to a narrow angle.

 

Also the iron spinnaker replaces the light air Genoa on most cruisers... well thats my experience anyway.