How do I adjust mast rake and rig tension on a Rasmus 35?
I'm setting up the rig on my Hallberg-Rassy Rasmus 35 and want to check the mast rake and shroud tension. How should I measure the rake, which turnbuckles should I adjust first, and how tight should the rig be?
Answer
Set your Rasmus 35's mainmast straight athwartships with modest aft rake, then tension the cap shrouds evenly and adjust the lowers to keep the mast in column. Set rake through the forestay's effective length, use the backstay to control forestay tension, and check the result under sail rather than judging tightness by feel alone.
Inspect the rig and supports
Rasmus 35s have had decades of repairs and replacement spars. Identify your mast, wire sizes, spreader arrangement and any alterations before choosing settings. On a ketch, tune the mainmast first, then the mizzen, assessing each mast separately.
Inspect the mast heel and step, the supporting structure below, chainplates, terminals and turnbuckles. Look for deck movement, cracking, rust streaks and broken wire strands, especially where wire enters a swaged terminal. Tightening the rig against a moving support will not give a reliable setting.
Support the mast with suitable temporary stays before disconnecting any standing rigging. Clean and lubricate turnbuckle threads with an appropriate rigging lubricant. Check adequate thread engagement at both ends and make sure the toggles articulate freely. There is no useful universal turnbuckle torque: measure wire tension instead.
Measure and set mast rake
Measure afloat in sheltered water with normal cruising loads aboard. Clear heavy equipment from the ends and check the boat's fore-and-aft trim. A stern-heavy boat can make the mast appear to have more rake than it has.
- Ease excessive backstay and lower-shroud tension while keeping the mast securely stayed.
- Hang a weight from the main halyard, suspended just above the gooseneck. Dampen its movement in a bucket of water if necessary.
- Measure the horizontal distance between the halyard and the aft face of the mast at gooseneck height. Record the halyard's exit position so subsequent measurements are comparable.
- Adjust the forestay's effective length to set modest aft rake, then take up the backstay slack and remeasure.
Lengthening the forestay generally allows more aft rake; shortening it brings the mast forward. A furling system may conceal the forestay adjuster and require partial dismantling. Follow its instructions.
Do not use Hallberg-Rassy 352 settings as Rasmus 35 specifications. Neither a 50 mm toggle extension nor another boat's rake measurement transfers directly. Without an existing tuning record, roughly 100 to 150 mm aft at gooseneck height is a provisional starting measurement, not a verified factory target. Refine it by checking the boat's balance under sail.