Just after some points of view on when to use these controls and how it effect performance/pointing in different wind strengths.
Thanks
Jonathan

Puller - this is used to stop the spinaker pole inverting a flexible mast, especially importantth carbon masts on a tight reach (avoid breaking it) => pull it on when even the pole is up, take it off on the beat.

Lowers - affects the lower bend characteristics of the mast, especially as resistance against kicker, i.e. the more kicker you have the more the mast will want to bend => a control for the beat. set up so they loosely hold the mast in line. Use them to straighten the mast, by tightening when sailing (straight mast for less wind / more power) loosen then to allow the mast to bend (heavy wind , less power). Get your crew to do the adjustment, the crew is in a better position to 'sight' up the mast when sailing to check the amount of bend. Warning, too much lower = inverted mast = (normally) very slow.

Thanks Alan
Would you use the puller in light winds when beating to counter any inversion below the hounds?
Jon

I don't think that is a good idea. You are likely to catch the jib when tacking, especially rolling. There should be no inversion upwind in light wind if your spreaders and shrouds are set up correctly. It seems to me that it is a good idea to keep your upwind/downwind rig setting routines consistent, for helm and crew.

Mike
We have the spreaders set at 40mm/15mm prebend as suggested in the tuning articles. We have Alverbanks sails, their tuning setup guide suggests 365mm length with 150mm sweepback (as do most tuning guides) which we have acheived. Still we have inversion below the hounds, with no tension on the lowers. The puller sorts this out, so beating with the puller in light conditions must be right. Unless the spreader setting is wrong which I will check again. 
We have an elastic pull back which easily retracts the puller before tacking.
I agree things need to be kept simple for the crew/helm routines. Being a helm I just want the best from the rig without the need to ask the crew to make any required adjustments. Selfish I know.
Thanks
Jon.

Perhaps you 'upright' position is infact forward of upright, I think that might cause inversion, but I haven't done geometry for years.

What boat is this on? Design and builder would be helpful.

The boat is a Winder mk 1. (8 years old this year)
Mast is Super spa.

Alan
Sighting up the mast on dry land. We can see an obvious inversion. I'm now thinking that the mast step could be wrong. Again something to check. What do you recon.
Jon

This doesn't sound right, though if you are setting up the mast without the sails up then the kicker will take out the inversion.  If it is the spreaders inverting the mast (I can't think what else will) then the inversion will be in a smooth curve from hounds to heel and if you set the mast up with the shrouds OUT of the spreader tips then the spreaders will be significantly in front of the shroud.  Most of the tuning guides I have seen suggest starting from the neutral position fore and aft.  The problem with Merlins is that the shroud base varies significantly from boat to boat and what you are after is a neutral position for your boat's particular geometry.  Consensus on mast step position seems still to be 5ft in old money from stem to aft face of mast (Chris Martin will correct me if wrong).  If that is right your spreaders are angled too far back.  Try changing it and see what happens - you can always change it back again.

Sorry should be spreaders angled too far forward, take them back more.

Andrew

As Alan says, worth checking that your mast is really upright.

Make sure boat is level, then tie a weight to the main halyard and use it as a plumb line. Theres an excellent article on mast rake on this forum which explains how to set this up.

If this all checks out, try raking the spreaders further aft (again as suggested elsewhere). It sounds as thought the shroud tension against the spreaders is not enough to counteract the forward pull of the forestay.

All the best, John

Use the stem and the transom as verticals to get the boat level - often people use the top of the centreboard case which is often not horizontal when boat is level.

Jon,

We had this problem on 3517 when we were using a deck stepped super spar ally and it drove me crackers!

The problem was the mast foot.  When mast was sitting on the step, the front corner of the mast foot tenon was touching the bottom of the mast step channel before the back corner, so as rig tension was applied the mast inverted until full length of the bottom of the tenon was incontact with the bottom of the mast step channel.

It became less of a problem as rake was applied.

The solution was to cut off the bottom of the mast foot tenon so that the mast foot was resting on the shoulders of the mast step fitting, with the tenon clear of the bottom of the mast step fitting.

Having done this the issue magically went away!

Good luck,

GGGGGGGG

Great responce 
Thanks to everyone for your advice and tips. 
Now need a nice calm day!
Jon.

Is it 3581 "Prologue"?

If so i remember Mike Anslow having a new heel fitting put on, and i'm sure we decided that the people who did it put it on back to front. The super spar resin heels do taper slightly fore to aft, and this would coincide with the issue Graham is describing on 3517.

GGGGG is right as usual. I had a similar problem with a very early Super Spar carbon mast fitted with an aluminium foot plug. When transferred from 3466 to a Winder Mk 1 3586 the tenon didn't fit the Winder supplied deck fitting. Extensive filing to make the straight tenon into a curved base had a good effect. Later the aluminium foot plug rotted away due to carbon chemistry and it was replaced after a Super Spars recall and (free) supply of a new plastic moulding. No more problems.

It is indeed Prologue. We have owned her since November. We noticed that in wind strengths between 3-9 knots pointing goes and power is lost. One of our top helms at Fishers Green pointed out that the mast was inverted below the hounds being a solo sailer he took one look and corrected it by applying the puller. I said that we only put the puller on during reach/running. Being new to the Merlin I thought well maybe he could be right. Now thanks for mentioning the possibility of a reversed deck step. I will have a good look again. This may explain why a small wooden block was inserted infront of the tenon.(I was wondering what that piece was there for). Maybe it has moved from its rightful position!.
Thanks Again.
Jon

Point for Andrew M.
"Consensus seems to be 5ft from stem to aft mast"
Is this the 2740mm mentioned as being from aft mast (allowing for sail track) to transom)in an earlier post, and this was critical? Doesn't it vary from design to design, and also depend on where the centreboard is placed? Any info welcome.

The small wooden block, to which you refer, was quite common on the early raking rigs.  It was put in front of the tenon to stop it jumping out of the mast step when you applied maximum rake. It may not be necessary with modern mast steps but be careful before getting rid of it.

The mast step measurements i took were fairly consistant among Ian Holt designed boats. I think the measurement was 53 inches from the jib tack. This applied across Winder, Turner and Chipstow built boats.

The boat at Midland that was significantly differant was Thin Ice, and i believe Smoked Salmon is the same. Jules will probably remember what the measurement was.

I consider it a bonus if I can remember where my glasses are when I wake up in the morning so you are expecting a bit much of me, Chris.

I seem to remember that the mast position was 75mm different.  Trouble is I can't remember which way... (I think it was longer than on a Winder which would make it 56 inches)

Jules

Update.
Found out today that we had zero'ed previously with the puller on and been sailing without any prebend. I can hear you all gasping in horror. (we are learning so bare with me). Once retuned she felt great and pointed well. Although we still found a slight inversion as we spied up the mast. My question now is 'Do we need to sort out this slight inversion or is this not worth bothering about' also we see on the various pictures that the mast step shows 4 holes beyond the forward screw. Should the mast step butt up to forward or aft screw. (we think aft). This maybe where the wooden block previously mentioned was installed.
Any feedback would be much appriciated to move us from the back end of the fleet.
Jon.

Jon, I am no expert, but I would be tempted to err on the uninverted side if possible, ie with more prebend. Any kind of inversion doesnt sound quite right to me; it would make it harder to set the main right (mains tend to be cut for straight or slightly prebent masts and create extra strain downwind, meining more reliance on the puller.

Cant really comment on mast foot position - mine is fixed so I have no choice in the matter, but I would say if you have more weather helm than you need, you probably need to come a little aft.

Sounds as though you are nearly there though. I would be tempted to get out and see how you fare against other boats before doing anything too radical.

Cheers, John

Sorry John; to much weather helm put mast FORWARD!

You are right. Sorry Jon.... but I think I am right about the inversion......

and if not, I am planning to go to Rutland this year and will shut up until then.....

Thanks for your reply John. Our solo expert thought mast forward to correct the remaining slight inversion. Does anyone know the measurement between the front of the mast and jib tack on a winder mk 1. Sorry if this is repeated on other threads.
Jon

Should be 53 inches if i remember rightly.

Unless you've moved it it will be right. Prologue was the boat i took the Winder measurement from.

Just to check Chris: 53 inches from Jib tack to the front of the mast foot, or to the front of the mast foot step?

Front

Of what?

sorry!

the front bolt in the step.