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Shoreham Open 1


Grafham Grand Prix 2

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Mainsail M-10T

The full radial M-10T all purpose mainsail is developed to compliment all mast sections, it is manufactured from Dimension Polyant ODL06.

Mainsail standard features:

  • Class insignia
  • Sail numbers
  • Epoxy battens
  • Leech tell tales
  • Leech line
  • Long roll bag

For prices and more information contact our 505 Experts or your

Mainsail M-103DL

The 3DL M-10 all purpose mainsail is developed to compliment all mast sections, it is manufactured from Carbon Kevlar 680M.

Mainsail standard features:

  • Class insignia
  • Sail numbers
  • Epoxy battens
  • Leech tell tales
  • Leech line
  • Long roll bag

For prices and more information contact our 505 Experts or your

Jib (N-6R)

Developed from the successful J-2 design, the N-6R is an all round performer designed for the variable conditions usually experienced during a European regatta. It can be sheeted hard to match the pointing ability of the flatter designs yet with a shallow sheeting angle flattens and twists nicely in a breeze allowing the boat to be driven fast upwind. It provides a rounded easy to steer entry and bi-radial panel layout, which helps to control the position of the designed shape and form the main part of its success. It is manufactured from Dimension Polyant 208sq HTP+.

Jib standard features:

  • Epoxy battens
  • Large vision window
  • Flutter patches
  • Leech tell tales
  • Trim tell tales
  • Long roll bag
For prices and more information contact our 505 Experts or your

Spinnaker (XK-3)

The bi-radial XK-3 has been successfully developed primarily for light to moderate conditions and performs very well downwind in all conditions and up to 18kts on reaches, for all crew weights. It has been engineered in the same way as the V-8 with radial clews and narrow cross cut panels to ensure a smooth shape. It is manufactured from Dynakote 75.

Spinnaker standard features:

  • Sail numbers
  • Sail bag
  • Stock colours
For prices and more information contact our 505 Experts or your


This tuning guide has been put together by Ethan Bixby from North Sails in North America, who is the designer of our newest 505 sails.

The calibration scheme below does not reuse existing numbering schemes. We have tried to develop a calibration scheme that supports the following:


  • Uses reference points common to all builder's 505s, forward tack and aft tack 505s, etc.
  • Uses zero as the neutral, or basis datum setting.
  • Uses negative numbers for LESS of a control and uses positive numbers for MORE of a control. If that is not clear, the light air settings are on the negative side of the datum and the positive numbers are heavier air settings, finally forward is negative, aft is positive.

Mast Step

Measure from the back of the mast along the top of the CB cap, aft, over transom, to the aft most point of the hull (it may be slightly aft of the transom). Ignore the rudder fittings. The mast should be stepped as close to 10' 0" as you can get it and still get the right low bend at max. rake and not hit the partners. Don't worry if the step extrusion in the boat keeps you about 1/2" or an inch forward of this point.
Note: The aft end of the hull is where the class rule measurements are taken, not the actual face of the transom. This value is more reproducable across different hulls.


With no jib hoisted, connect a tape measure to the end of the jib halyard. Hoist and cleat the halyard to the point where the "O" on the tape measure starts at the top of the the "gooseneck band" on the mast, with reasonable tension applied. On a boat with an integral wire in the luff of the jib, you can use the topping lift as long as it is very close to the jib halyard/headstay intersection with the mast.

Take the jib halyard (or topping lift) forward and measure from the end of the halyard (at the same tension) to the top of the rail at the bow. This is the top forward part of the boat, regardless of where the headstay is.

Adjust the forestay/jib halyard and shrouds until a measurement of 3 '4" is obtained. The shrouds should not be excessively tight, but snug. Mark that setting on the forestay tackle in the boat, where you can see it. This is the datum rake number, mark it in the boat as "0". Measuring aft this should be 25'8".

For future reference record the distance from the eye to the fork pin to some reproduceable point on the boat. On a Waterat I use the bearing point of the jib tack fitting to the headstay fork/eye junction, and on my boat the distance is 5.5" as an example. Mark that setting as "0".

All of your rake settings can be simply marked on the luff of the jib adjacent to the fork/eye junction. This is the best repeater and easy to see! Mark one inch increments at additonal inches, i.e. 1,2,3,4,5,6,7.

Note: that the forward rake measurement is much less sensitive to mast bend, shroud tension, hull rocker, and height of transom.

Mast Ram (Bend)

Set rake to 0 (3 '4" forward) or 25'8" (aft) with mast dead straight and the rig just snug.

Scale at Deck Level

With the mast straight as above, make a mark on both sides of the mast where it is closest to the partners. Mark this as "0". Measure imperial or metric postions from there, with negative numbers toward the bow and positive towards the stern.
This can be your only scale, or you can transfer numbers up to the ram for a wider scale and possibly better visability.

Note: a deck level measurement is reproduceable across all 505s, whereas measurements on the mast change with ram geometry.


Shroud Tension

 Rake Mast Ram
 Shroud Tension
(use Loos Gauge)
 Mark the
Shroud Tackle
 0 0 150lbs 0
 1 -15mm 150lbs 1
 2 -3mm 350lbs 2
 3 0 400lbs 3
 4 3mm 400lbs 4
 5 7mm 400lbs 5
 6 10mm 400lbs 6
 7 13mm 450lbs 7
Note: the goal of this is to have an approximate shroud tension to headstay relationship, and have it marked.

Jib Leads (Fore & Aft)

In light or no wind, with the mast rake set to "0" as above, and the ram set to "0" as above, sheet jib in hard. Sight down lead lines on the jib clew. Move jib cars fore or aft until the jib sheet is lined up with the more vertical line. That is the standard power setting. Mark that hole on the jib track as "0". Number holes with negative numbers forward from there, and positive numbers aft of that hole. The angled aft (slightly closer to the horizontal line) is for heavy air depowering when raked. In practice, you may not need to actually move the jib car for heavy air, as rake changes the lead angle for you. You may need to move the jib lead aft for light air, flat water.

Jib Lead Tension

With the jib still sheeted as above. Mark a spot on the jib sheet that is clear of the cleat and turning blocks. You will be calibrating the jib lead tension based on that mark, so mark the corresponding point on the seat tank as well.

Note: that we use the "normal" trim line on the jib as this allows us to reproduce fore-aft or up-down jib lead measurements across any jib sheeting system, long and short luff jibs, and forward tack and aft tack boats.


Roll the boat over on it's side. Pull board out and put it in the down position. Set the leading edge of the CB perpendicular to the bottom of boat at the centreboard trunk. Mark the head of the board (perhaps aft end of the head) level with the top of the CB cap. Mark this as "0". Mark increasing numbers in 1"intervals up the back end of the head. Mark "1,2,3,4,5,6,7,8". Also mark a position with the board as far down (raked forward) as possible.
Also measure from the top of the centreboard to the aft end of the hull on the centreline. With an HA board this number should be roughly (depends on rake and board depth) 122".

Note: we're open to suggestions on this. This measurement will result in different effects with different CB planforms. I think what we are really trying to measure is where the centre of area or pressure is fore and aft and below the hull.


Set the spreaders to 16.5" length (measured from the side of the mast to the shroud), and for 6.5" poke. For lighter teams, and in very light or very heavy air, increase sweep to 7". Lighter teams can also shorten spreaders to 16".

Note: that this measurement is from the shrould to the closest part of the mast, along the spreader. This measurement assumes that your spreaders are 124 inches above deck level (old US specs) AND assumes your shroud chainplates and mast step locations are the same as other boats. If any of spreader bracket height, mast step position and shroud chainplate location are different on your boat, these measurements will not result in the same effects we get.

We have a comprehensive measurement system to relate spreader height, hounds height, spreader details, and triangulation of the chainplates. Contact us for this as it is a much better tool to obtain the actual deflections and angles.

Good luck on the water!

Main Batten Set

Jib Batten Set

300mm (12") Sail Numbers & Letters

Please contact us or your local North Loft or Agent for prices and to make your order.

Contact the 505 Experts:
Tom Gillard
+44 (0)1329 443430 Work
Tim Rush
+44 7973 512645 Work
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