How do I adjust the mast rake and rig tension on a Hallberg-Rassy 40?
I'm setting up the rig on my 2008 Hallberg-Rassy 40 and have been told to aim for 600 mm of mast rake measured along the boom. Mine measures nearer 750 mm: should I shorten the forestay, and how tight should the shrouds be?
Answer
Set your Hallberg-Rassy 40's mast rake from the Seldén drawing for its actual rig, then centre the mast, tension the shrouds evenly and check the result under sail. Around 600 mm aft at boom height has been suggested for a 2008 HR40, but neither 600 mm nor 750 mm is a verified factory setting without the drawing and a matching measurement method.
Identify the rig and measure rake
The HR40 has noticeable aft rake by design. Do not straighten the mast just because it looks more inclined than neighbouring boats. Identify the mast serial number and obtain the matching Seldén rig drawing through Hallberg-Rassy or a Seldén dealer. Furling arrangements, replacement spars and previous alterations can change the correct setup.
Before adjusting anything, inspect chainplates, rigging screws, clevis pins, spreader roots and accessible wire terminals. Stop if you find cracked fittings, broken strands or seized threads. Extra tension will not cure them.
Measure afloat in sheltered water, with normal cruising trim and little wind:
- Ease the mainsheet and kicker, and support the boom independently so its weight does not distort the measurement.
- Hang a weight from the main halyard, clear of the boom. Lowering the weight into a bucket of water helps damp its swing.
- Measure horizontally from a defined point on the mast's aft face to the hanging line at boom height. Record the exact height and reference point.
- Repeat the measurement once the boat settles, with the backstay at a recorded setting you can reproduce.
A halyard exit behind the mast centreline adds an offset. Fore-and-aft boat trim also changes the apparent rake, so a 150 mm difference between two owners' measurements does not necessarily mean the forestay needs changing.
Set rake and shroud tension
The forestay's effective length normally sets rake. Shortening it brings the masthead forward; lengthening it allows more aft rake. The backstay chiefly controls stay tension and mast bend. It cannot replace a forestay-length adjustment.
On a furling forestay, the adjustment may sit beneath the drum or require work specified in the furler manual. Maintain the manufacturer's minimum thread engagement and articulation at both ends. Secure the mast with a suitable, independently attached halyard before disturbing a forestay connection. Never disconnect loaded standing rigging.
Once rake is set, hoist a steel tape on a suitable halyard and compare distances to matching port and starboard chainplate pins. Adjust the cap shrouds until the measurements agree, then sight up the mast track for sideways bends.