Confusion over symmetrical spinnaker trim

[bdh198]

I’m fairly new to racing so I apologise if my queries seem a bit basic, but I've recently been trying to get a better understanding of how a symmetrical spinnaker should be flown to get maximum performance from it.

Now I've read a few spinnaker trimming guides and watched a few clips on youtube, but I seem to be coming across contradictory information. I would therefore be extremely grateful for any wise words or clarification from any of the very experienced sailors and racers here.

1. On a reach, should the spinnaker pole be brought forward or aft in light or heavy air?

I understand that the spinnaker pole determines the angle of attack of the luff. Ideally you want the luff to be at right angles to the wind, and this is often achieved by ensuring the pole is at right angles to the wind. Now one source I've read states that in light airs the pole should actually be brought aft a little bit because the luff won’t be square on the pole (i.e. the pole is now position at less than 90 degrees to the wind). In heavy air the opposite should be done – the pole should be brought forward beyond 90 degrees to ensure the luff remains at 90 degrees.

However, another source states that on a reach in light airs the pole should be taken forward a few degrees to make the sail fuller. In heavier airs, the pole should be brought aft to help flatten the sail and de-power it.

2. On a reach in light airs should the outboard end of the pole (and thereby the tack) be lifted or lowered?

I understand that the height of the pole determines the position of the maximum draft of the sail (similar to a cunningham on the main). Several sources seem to suggest that in light airs the pole should be lowered as this increases luff tension and brings the draft forward creating a fuller shape and thereby more lift. In heavier airs the pole should be raised thereby moving the draft back.

However, another source (with an ex America's Cup racer, so one would assume he knows a thing or two) suggests that by lowering the tack in heavy air the draft is moved forward and 'de-powers the sail' and in light airs by moving the tack up the draft moves aft creating a more powerful sail.

3. Running before the wind (dead downwind) in heavy air should you raise the clews so that the leeches are flatter and the sail starts to spill more wind, or lower the clews so the leeches are tensioned, a greater curve and the sail therefore has less projected area to the wind, and the sail is more stable? And what should you be doing in light airs?

Any words of clarification greatly appreciated!

 

[savageseadog]

I can only comment based on my own experiences:

1) Generally pole further aft as you go further downwind. The issue in heavy weather is rolling which can be avoided by not going too far downwind and putting the pole further forward.

2) In light airs I generally point up more to increase the apparent wind, I lower the pole as well as taking it further forward.

3) Definitely don't raise the pole in heavy weather downwind., obviously more power if you do but you will potentially roll.

Avoid dead downwind most times.

 

[mrming]

I'm not going to comment on the theories above, but here's what I know from my own experience:

Tight reaching:

Light airs:
Pole just off the forestay. Judge the pole height by getting the luff breaking in the middle of the sail. Tweaker off on the sheet, creating twist and not choking the leech.

Medium airs:
Pole just off the forestay. Judge the pole height by getting the luff breaking in the middle (pole will need to come down more than above). Tweaker on the sheet, powering up the kite (ease it a bit if overpowered).

Heavy airs:
Pole just off the forestay. Pole down - treat the luff like a jib and try to get it much straighter than usual. Tweaker off on the sheet to depower the top off the leech. Time to "snake". Helm comes down in the gusts and trimmer eases to keep the boat on her toes. Helm steals back height in the lulls with the trimmer coming back in on the sheet. Good communication is the key with someone on deck calling the gusts and helm and trimmer constantly talking.

Broad reaching / running:

Light to medium airs:
Keep the corners level. If the clew rises, raise the pole to raise the tack. Likewise if the clew drops, drop the pole. Tweaker off on the sheet. Don't be tempted to square the pole back too much when broad reaching, read the sail rather than looking at the angle of the boom / apparent wind.

Heavy airs:
Time to de-power. As the boat starts to roll pull the tweaker on the sheet to close the leech at the top. Helm needs to steer to keep the boat under the rig. Next, oversheet to flatten the sail. Next, lower the pole to de-power even more. If you're not on a dead run you can also pull the pole back more that normal to flatten the sail further.

Hope this helps.

Edit - as savageseadog says above you may also want to head up a little when running in bigger breeze to help avoid the rolls of death.

 

[bdh198]

Thanks Savageseadog and mrming, those comments are very useful.

I suppose the best way to understand what is going on is to get out there and practice with a bit of trial and error. The problem with not having my own race boat is that most racing skippers aren't that keen on 'trial and error' when the race is underway!

 

[Foolish Muse]

I'll offer one contradiction to mrming, but only for Singlehanded sailors using an autopilot: in heavy air you want to make sure the sheet is eased enough that the chute collapses if the boat rounds up even a little. A tight sheet will cause the boat to round up much quicker. With a lose sheet the skipper has to sit and watch nervously every time the luff folds over on itself, but if he trims the sheet then he's just driving the boat into a broach. This is a very different approach to a crewed boat where the helmsman can steer to avoid any broach. Unfortunately an autopilot does not watch the spinnaker luff.

 

[lpdsn]

I’m fairly new to racing so I apologise if my queries seem a bit basic, but I've recently been trying to get a better understanding of how a symmetrical spinnaker should be flown to get maximum performance from it.

The most comprehensive book I've come across is the North Sails one "Trim"

Are you trimming the sheet or the guy on the boat you're racing on? That'll just maybe help focus the answers a bit.

 

[bdh198]

The most comprehensive book I've come across is the North Sails one "Trim"

Are you trimming the sheet or the guy on the boat you're racing on? That'll just maybe help focus the answers a bit.

I've recently been trimming the guy and was actually doing so over the weekend at the Taittinger Regatta (racing a First 40). In that position I'm getting a lot of feedback from the sheet trimmer who can feel the pressure in the sails and seems to be in a better position to know how the sail should be trimmed. However, I'm keen to do a bit of sheet trimming myself and I want to get a better understanding of how a properly flown spinnaker should look and feel. I'll have a look out for the North Sails book.

 

[lw395]

I've recently been trimming the guy and was actually doing so over the weekend at the Taittinger Regatta (racing a First 40). In that position I'm getting a lot of feedback from the sheet trimmer who can feel the pressure in the sails and seems to be in a better position to know how the sail should be trimmed. However, I'm keen to do a bit of sheet trimming myself and I want to get a better understanding of how a properly flown spinnaker should look and feel. I'll have a look out for the North Sails book.

Generally, unless the helm, sheet person and guy person work incredibly well together, I'd tend to set the guy and let the helm and sheet person drive the boat around that setting. As circumstances develop, the sheet person and/or helm will call for the pole forwards or back.
For instance, I will want the pole back if I'm trying to work low, or forwards if I'm about to luff up.
There is a balance between having the pole in the right place for where I'm steering right now, and where I intend to steer next.
So, until you can read the helm's mind, it's possible to over-think it.
Waving the pole around makes life hard for the sheet person if you are not in sync, talk to them, suggest moving the pole and do it when they are ready for it, don't make them work around you.
The best way to really get an understanding of spinnakers is with a two man boat, maybe 3. The most important spinnaker control is the tiller or wheel. If you can get some time steering with a kite up it's very worthwhile.

Basically though, there are two key postions. Just off the forestay for a close reach and the running position.
The running postion can be 90 degrees in light airs on some boats, or a lot further forward. It depends on the length of the pole vs the size of the kite, as well as the wind strength.
If you are neither running nor close reaching, pole at right angles to the apparent wind won't be badly wrong as a starting point, but the sheet person is always right, except when the helm is.

 

[mrming]

Good advice by lw395 above - it's rare for the guy trimmer to be actively adjusting unless the crew have sailed together a lot.

Incidentally, when you do get to sheet trimming, the best mantra I was taught was "if in doubt, let it out". Keep the luff constantly on the edge of curling and never take your eye off it for a second.

You'll learn to spot when the pole needs to go back or forward, and lw395's advice to keep an eye on the apparent wind until you learn to fine tune is spot on.

 

[flaming]

Good advice by lw395 above - it's rare for the guy trimmer to be actively adjusting unless the crew have sailed together a lot.

Can't agree with that. We don't let our guy trimmer cleat the guy. It must be ready to be eased forward to help the trimmer out in a big collapse. Basically if the curl goes more than a foot or so the guy should go forward until the kite is full again then come back to "base".

In terms of trimming and where the pole should be....

The basic rule of thumb of 90 degrees to the windex is pretty good. Pole should go forward and down if you need to depower, and up to power it up in medium breezes. Try not to bring it back past 90 degrees though. Conversely it often needs to go down in the very light.

 

[lw395]

Can't agree with that. We don't let our guy trimmer cleat the guy. It must be ready to be eased forward to help the trimmer out in a big collapse. Basically if the curl goes more than a foot or so the guy should go forward until the kite is full again then come back to "base".

In terms of trimming and where the pole should be....

The basic rule of thumb of 90 degrees to the windex is pretty good. Pole should go forward and down if you need to depower, and up to power it up in medium breezes. Try not to bring it back past 90 degrees though. Conversely it often needs to go down in the very light.

Fair enough on a well-crewed boat, you can expect the guy trimmer to know what the others want. If my guy trimmer is openly inexperienced enough to be asking questions on here, I'd rather he was just ready to move it forwards when asked, rather than letting it forwards as I bear way on the wave, so between us we over correct. Communication between trimmers and helm is generally a good thing. Asking what they want pre-race shouldn't hurt. (Not 2 minutes before the start!) Ease the pole forward when there's more than a foot of curl is a good yardstick, I may borrow that....

 

[mrming]

Can't agree with that. We don't let our guy trimmer cleat the guy. It must be ready to be eased forward to help the trimmer out in a big collapse. Basically if the curl goes more than a foot or so the guy should go forward until the kite is full again then come back to "base".

By "actively adjusting" I meant doing so without a cue from either the trimmer or the helm. If we're lucky enough to have a dedicated guy trimmer we certainly don't let them sit there with it cleated while they drink tea and eat a nice piece of Battenberg.

A few times a year I sail with a group where we've all raced together for 15 years plus. In that crew everything happens telepathically and you may well get an ease on the guy to prevent a collapse before you even ask for it. Luxury that!

 

[lpdsn]

I've recently been trimming the guy and was actually doing so over the weekend at the Taittinger Regatta (racing a First 40). In that position I'm getting a lot of feedback from the sheet trimmer who can feel the pressure in the sails and seems to be in a better position to know how the sail should be trimmed. However, I'm keen to do a bit of sheet trimming myself and I want to get a better understanding of how a properly flown spinnaker should look and feel. I'll have a look out for the North Sails book.

It would be good to learn to trim the guy well then worry about sheet trim later. Two basic points:

It's the sheet trimmers sail so he/she is in charge, but there isn't time to tell you when to make minor changes. Listen out for what they have to say though.

As Flaming says, if you want the best out of the boat you need to actively trim the guy.

You start off by trying to keep the pole about 90 deg to the wind. You can tell from the shape of the luff whether you've got it too far forward or aft. It either seems to be stretching away from the pole or is blossoming to windward - it'll soon become obvious - chat to the experienced trimmer on board to get feedback.

You should adjust as the boat comes up or bears away and as it accelerates or decelarates. So if you feel the boat accelerating down a wave ease the pole forward and as she slows bring it back.

Next you need to be alert to what the driver and sheet trimmer are doing and saying. If they are talking about coming up for a bit more power in the sail or bearing off to use the power, trim at the same time as they do.

If you've a collapse it usually helps to get the pole forward as the driver bears off to help re-fill the kite. Some boats of course just blame the sheet trimmer and never learn (and if the sheet trimmer starts playing safe you'll be slow).

If tight reaching keep the pole off the forestay. Anticipate gusts which might cause the pole to bang the forestay (good for neither) as the guy stretches under load - even dyneema stretches a bit.

Watch the downhaul - whether you're adjusting it or not - just in case there's a SNAFU.

Pole height issues are usually obvious from the way the luff starts to curl (keeping just a bit of curl is sheet trimmers responsibility) but you can chat if you see an issue.

Lot's more to getting it spot on, but that should be a start and you can learn from there.