Here some thoughts, they are in conformity with the advice given by John, which is very good. I would, however, like to comment on the rig weight and section thickness he mentions, see below.

Having the mainsail reefed and the mainsheet well tensioned will reduce mast pumping, but it is advisable to keep the inner forestay set up to resist the mainsail headboard load on the mast.

Generally the recommendation is to have the runners and inner forestay installed and ready for use, but they can be kept stowed when not required.

The runners can be taken forward to the shroud chainplates and attached to eyes there. To prevent them from chafing on the spreaders either install hooks on the spreaders for deflecting the runners, or put a sleeve of a soft material around them at spreader height.

The inner forestay can be led down along the mast and around a half moon near the deck to a small tensioning tackle aft of the mast.

The runners and inner forestay are used to stabilize and control the mast in high winds and big waves. It is not necessary to use them if the mast is stiff enough in relation to its height and the stability of the yacht, but then the mast will pump a lot, and the bend can not be controlled in the same way.

The stiffness of the Swan 411 mast is sufficient without runners so they are not really necessary in moderate conditions, except when a sail is carried on the inner forestay, then they are needed for tensioning the stay.

Similarly the inner forestay is not needed except when reefed and/or the runners are used. The recommendation is to set up the stay to prevent the mast from inverting, this can otherwise happen if the mainsail headboard and/or runners are pulling aft too hard.

When taking the runner tail to a winch do not use a winch handle, remove the slack just by pulling on the tail. Only when a sail is carried on the inner forestay it is appropriate to tension some more with a winch handle.

When the inner forestay and runners are not in use set up the mast with some pre-bend, thereby preventing the mast from pumping in moderate conditions.

Pre-bend is induced by moving the mast shoe some distance aft, and tensioning the backstay a bit. A suitable amount of bend is 100 to 150 mm (4 to 6 inches) measured halfway up the mast, depending on mainsail cut - check with the sailmaker.

In strong winds with full backstay tension the bend should be about twice that amount, and the mast shoe position should be adjusted to suit this.

Is there a hydraulic tensioner on the backstay, if so what make and size?

Referring to the rig weight I am sure that the units have been mixed up, it is not kgs but 750 lbs, meaning 340 kgs which is in conformity with other 411 rigs. The wall thickness is 3/16 inch or 4.8 mm which can easily be verified through a halyard exit.

Kind regards

Lars