How do I adjust mast rake and rig tension on a Hallberg-Rassy 37?
I want to check the rig tune on my Hallberg-Rassy 37 because the helm feels heavy going upwind and the leeward shrouds look slack. How should I measure the mast rake and set the rig tension without overloading anything?
Answer
On a Hallberg-Rassy 37, centre the mast athwartships, record the existing aft rake and measure shroud tension before making adjustments. Set rake through the forestay arrangement, tension the shrouds evenly to your rig's specification, then check under sail for a straight mast and light weather helm.
Check the rig first
Identify the mast section, standing-rigging specification and mainsail arrangement from the mast identification plate and boat documents. HR 37s commonly have Seldén spars, but replacement rigging and differences between conventional and in-mast furling arrangements mean turnbuckle measurements will not suit every boat.
Inspect chainplates, spreader roots and tips, wire terminals, turnbuckle threads and clevis pins. Cracked terminals, broken strands or a moving chainplate need attention before tuning. Extra tension will not cure them.
Work afloat in sheltered water with normal cruising stores aboard, representative tank levels and the boat upright. Keep the mast supported throughout. Never disconnect a loaded stay or shroud.
- Use a steel tape, a suitable rig-tension gauge, two correctly sized spanners and fresh split pins.
- Record wire diameters, exposed thread lengths and existing gauge readings.
- Check that turnbuckles retain the manufacturer's minimum thread engagement at both ends.
There is no useful universal turnbuckle torque because thread friction varies too much. Measure wire tension instead.
Centre the mast, measure rake
With the boom supported independently and the mainsail stowed, use the main halyard to compare distances to matching port and starboard chainplate pins. Apply the same halyard tension each time. Adjust the cap shrouds until the measurements match, then sight up the mast track for sideways bends.
To measure rake, hang a weight from the main halyard just above gooseneck height. In calm conditions, measure the horizontal distance between the halyard and a repeatable point on the mast. Record that point, as the halyard sheave position affects the reading.
Do not copy a rake measurement from another 37-footer. Start with the HR/Seldén setting for your mast. If it is unavailable, preserve the existing rake while correcting alignment and tension.
Lengthening the forestay generally increases aft rake; shortening it reduces rake. On a furling forestay, the adjustment may be concealed beneath the drum or require a different procedure. Check the furler instructions before moving anything. A backstay adjuster primarily controls loading, forestay sag and mast bend. It does not replace setting the forestay length.