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#04 - Rig Blueprint

SAILING TIP #04   -  Rig Blueprint


How many RC yachts are out there sailing with the best sails and equipment but the very basics of rig set-up have never been checked thoroughly.  We will look at a few steps to ensure that the rig is standing centred in the boat.  It is imperative that the top of the mast be in the centre of the boat to start with so the same performance can be achieved on each tack.


With rig out of boat.


a)  Remove headsail from mast and spreaders from shrouds if possible.  Lay one shroud against the mast, pull tight (not too tight that the mast bends) and mark at the front centre of the mast at the bend in the bottom of the rigging screw.  Repeat the procedure for other shroud but use a different coloured pen for each side.  Mark the outside of the bend in the s/s rod protruding from the rigging screw.  A small length of masking tape at the front of the mast will make it easier to mark at where the two rigging screws terminate.  Record the difference between the two and equalise both by lengthening one rigging screw and tightening the other until they are the same length.


With rig in boat.


b)   Check where the top of the mast is in the boat by running a tape measure from the top of the mast down to where the shroud attaches to the eyebolt on deck or gunwale and record these measurements each side.   Some boats may be symmetrical but most would be asymmetrical so some allowance would need to be given here if the deck/gunwale shape is slightly different on each side.

c)   Check that the mast shoe, or the fitting that the mast heel fits into if stepped on the cockpit or deck, is in the centre of the boat.  If mast is keel stepped,  measure from side of mast out to shroud on each side.  Take the measurement from as low on the mast/shroud as possible.  Record the measurements.

d)   Measure the length of spreaders from side of mast out to where the shroud sits in the spreader on both sides.  Record the measurement and equalise if required.

e)   Check that backstay crane is centred fore and aft.  Looking down from top of mast confirm that it is pointing down the centre line of boat.

f)   Check spreader angle.  Lay boat on side and looking down from the top of mast eye the outer end of spreader with some point on deck.  Check both sides to see if the angles are the same.

g)   As a back-up check for spreader angle put a small mark on the backstay at the same height as the spreaders.  From this point on backstay measure to shroud where it sits in the spreader. Repeat measurement on other side.  Record measurement.

h)   Lastly re-take measurement from mast head to deck as per ‘b’ above.  All things being equal they should be within a couple of millimetres of each other. This exercise will get the mast centred and from here mast bend and rake adjustments can be carried out with the confidence the mast is as it should be athwartships.



Recommended to use nyloc nut (part # 031b) when  using the 3mm dia. rigging screw in place of the standard hex nut.  Once the rig is centred it’s important that any adjustment made to the rigging screw be the same for each side.  The nyloc nut will not move without the use of hand tools so if rigging screws have to be eased to rig the boat the rigging screw barrel can be rotated up tight against the nyloc nut, duplicating the correct shroud lengths.  If shroud adjustment is required put a small mark on the nyloc nut using permanent ink, hold the eye of the rigging screw with pliers, rotate the nyloc nut with spanner (clockwise to lengthen, anticlockwise to shorten) noting if it’s a half, one or whatever rotation so this can be duplicated with the other rigging screw.


Good Racing.