Carbon Mast Rigging Guide

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The settings on this guide are based on settings used by experienced Blaze sailors for the Hartly sail, we recommend these as the "basic setup" from which you should then tune to suit your own sailing style and weight. The North sail requires a slightly tighter lower tension, as the sail suits a stiffer mast. 

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Mast Foot Position

The forward face of the mast to the forestay U-Bolt - 1072mm

 

Spreader Length

From sidewall of the mast to the shroud - 380mm

 

Spreader Defection

The distance between the mast track and a straight edge connecting the outer ends of spreaders - 180mm. 

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Spreader Deflection is measured by putting a straight edge from shroud to shroud and then measuring from the mast to this edge.

 

Mast Pre-Bend

Measured at the Spreader - 10mm to 20mm

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To measure the mast pre-bend, put the rig tension on with the sail down. Take the end of the main halyard and pull it tight to the gooseneck. This creates a straight line with the Halyard from the mast crane to the gooseneck. The mast bend is then the amount of forward bend in the middle of the mast. If you can, measure the distance from the halyard to the mast track to determine the mast bend.  

 

Mast Rake 

Mast to the bottom of the transom - 7020mm to 7060mm

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To calibrate your tape measure, ensure the tape measure is pulled to the top of the mast. Measure to the deck, next to the mast foot with the tape measure and ensure you get a reading of 6512mm. Adjust how the tape measure is pulled to the top if you do not get this reading. Once you get a reading of 6512mm at the deck, take the tape measure the transom and measure to the bottom edge, either side of the rudder post. 7020mm for a more depowered rig. 7060mm for a more powerful rig.  

 

Rig Tension

Measured on shroud around the same height as the superspars sticker on the mast - 100kg (220lbs)

 

Lowers Tension

Tension the forestay. Set lower to allow 40mm - 50mm movement sideways at the midpoint of lower.

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The softer the lowers, the more mast bend and depowered the sail will be.  However, too loose and the Vang won't work effectively. Too tight, and the sail will not have enough luff curve. 

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Download the carbon rig guide here. 

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Aluminium Mast Tuning Guide

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The settings on this guide are based on settings used by experienced Blaze sailors for the Hartly sail, we recommend these as the "basic setup" from which you should then tune to suit your own sailing style and weight.

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Mast Foot Position

The forward face of the mast to the forestay U-Bolt - 1072mm

 

Spreader Length

From sidewall of the mast to the shroud - 380mm

 

Spreader Defection

The distance between the mast track and a straight edge connecting the outer ends of spreaders - 140mm. 

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Spreader Deflection is measured by putting a straight edge from shroud to shroud and then measuring from the mast to this edge.

 

Mast Pre-Bend

Measured at the Spreader - 10mm to 20mm

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To measure the mast pre-bend, put the rig tension on with the sail down. Take the end of the main halyard and pull it tight to the gooseneck. This creates a straight line with the Halyard from the mast crane to the gooseneck. The mast bend is then the amount of forward bend in the middle of the mast. If you can, measure the distance from the halyard to the mast track to determine the mast bend.  

 

Mast Rake 

Mast to the bottom of the transom - 7020mm to 7060mm

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To calibrate your tape measure, ensure the tape measure is pulled to the top of the mast. Measure to the deck, next to the mast foot with the tape measure and ensure you get a reading of 6512mm. Adjust how the tape measure is pulled to the top if you do not get this reading. Once you get a reading of 6512mm at the deck, take the tape measure the transom and measure to the bottom edge, either side of the rudder post. 7020mm for a more depowered rig. 7060mm for a more powerful rig.  

 

Rig Tension

Measured on shroud around the same height as the superspars sticker on the mast - 100kg (220lbs)

 

Lowers Tension

Tension the forestay. Set lower to allow 90mm - 100mm movement sideways at the midpoint of lower.

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The softer the lowers, the more mast bend and depowered the sail will be.  However, too loose and the Vang won't work effectively. Too tight, and the sail will not have enough luff curve. 

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Download the aluminium mast tuning guide here. 

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Further Tuning Guidance 

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Below are some further tuning tips from the old website forum archives. Please note, some of the following details may differ from the above tuning guides.  However, most are still relevant to the aluminium mast and North sail.  

 

Blaze Set-up Guide - M7 Rig.

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Rake

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Attach a tape measure to your halyard and pull to the top of the mast. Now measure the distance to the bottom of the hull at one side or other of the rudder-post.  A  good starting point is to adjust the forestay to 7050mm (7 metres and 5 cm).  If you have an adjustable forestay this can be your 'central setting'. Make sure that at the extremes of adjustment you cannot rake your mast beyond  7020mm - it may simply fall down when you least expect it. Put knots etc in any rope system used to prevent you from exceeding the limits of 7020mm.

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The Blaze rig works best set up to be 'sloppy' it seems - therefore the spreaders work in a different manner to those found on 'tight' rig tension boats. The M7 'hangs' off the windward shroud and the spreader merely inhibits it inverting to windward towards the supporting shroud. From memory, my own are shorter than most at about 26 or 26cm and are relatively 'forward'. This allows the boom out further off-wind and when coupled with the sloppy rig - you can run deeper…

 

Kicker

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The thing to realise is that the rig is powerful and the mast a trifle too stiff, so the kicker DEPOWERS upwind in the Blaze close-hauled, this is because kicker (upwind) shunts the boom forward into the mast increasing bend which depowers the rig, so we do need to be able to use the kicker to DEPOWER - it pushes the lower mast forward when applied and this opens the leach near the top and flattens the sail lower down as well.

So it all works upwind so how do you drive it off-wind?

You also need to increase it off-wind to MAINTAIN the power and reduce sail twist.
Pull the kicker ON when off-wind (not what you might have been taught is it), this stops the boom going too far towards the sky but don't overdo it as you want the leach to fall forward on occasion so you can sail by the lee.

 

Mainsheet tension

 

If everything set up right will close the leach and increase power without shunting the boom forward - it just pulls down. Off-wind you have much less ability to use mainsheet tension to power up of course and the leach will drop away very easily - especially if you have a little kicker on. So you then have to put it on MORE, particularly if the sail is not getting linear flow over it as in dead running (i.e. drive through drag like a parachute)

 

Lowers

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with mast set up but without sail and boom in position these should also permit a fair amount of movement - measure at mid-point and set so that 5-6cm of sideways movement is possible. With some lowers supplied they are either too short or the adjusters are too short. Either way, you must change this fitting if needed to get this amount of slack..

 

Here is some info added by Myles Mence

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The settings I detail below have given me good pace against heavyweights at the
last two meetings - Warsash and the Nationals - when winds have at times been
well above 20 knots.

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On the scales in my shreddies I weigh 68kg.

Mast rake: 7m 70cm
Heel of mast to forestay fitting: 1045mm
Spreader length (inside of shroud to nearest point on mast): 305mm
Spreader deflection: 110mm
Rig tension: 69cm*
Lowers pretty slack (I haven't worked out a way of measuring their tension
yet!).

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*To measure rig tension: with a tape measure - measure from chainplate at deck
level 35cm up a shroud, mark with a piece of tape. Then with your tape measure,
measure from nearest point on mast just above gooseneck to the mark on the
shroud pulling the shroud away as hard as you can, rather like drawing a bow and
arrow. Record the measurement which will be in the region of 65 - 70cm. This is
your rig tension and you will find this method surprisingly accurate.

Some sailing technique notes for lightweights:

1. In lower winds you will need to increase rig tension to about 67cm or you
will not point. Ditto your lowers.Rig tension and lowers may not be adjusted whilst sailing

2. In strong winds you will not point as high as heavyweights and so don't try
to. Sail low and fast.

3. The prevailing authodoxy amongst the fleet is to sail with a very full foot.
On the wind in strong winds this creates too much power for the lightweight and
you will need to stretch the foot out - but not tight - a certain amount of flow
will help over waves.

Off the wind if you can reach the control blow the clew off, if not leave it
alone.

4. As the wind increases and on the wind lift the centreplate up about 15%, this
reduces excess lift and improves the balance of the boat (as increasing wind
moves the centre of effort aft in the rig).If it is blowing I lock my plate in
this position throughout the race and leave it alone.

5. Pull the cunningham on until you burst an eye and then pull it harder, this
will get the roach to feather away. Let it off downwind.

6. Kicker: in heavy weather and on the wind - masses. Progressively let it off
downwind as the course goes deeper. On the run let it off until the roach starts
to go forward, some twist is good.

Good racing!

Myles
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