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Rotostay fs4 Roller Reefing

The Rotostay fs4 furling gear is fairly simple, consisting of a furling drum mounted on a spindle assembly at the lower end, an aluminium foil extrusion revolving round the forestay and a cap casting with a bush at the top end.

These notes assume that the gear has been lowered, and this is best done by lowering the mast.

Undo the three dome head nuts – the top flange of the drum can then be separated. (This may be difficult if there is significant corrosion around the bolts). You then have access to the bottom forestay terminal – use a spanner on the flat and undo the locknut, then unscrew the fairlead/spindle assembly. The drum is held onto the spindle with a star-lock washer, but can be removed with care, using a pair of small screwdrivers to gently ease up the tabs on the washer. Check the play of the drum on the spindle – it doesn’t need to be a super-accurate fit, but if it’s really sloppy the bushes will need replacing. All the bushes (bearings) are plastic of some sort – possibly nylon – with the top bush in particular being prone to wear and UV degradation.

You will probably find that the three countersunk machine screws are seized solid in the drum, in which case you have to make the decision on whether to leave them in place or remove them. If you decide to remove them you will undoubtedly destroy them in the process -a process that will involve heat, penetrating oil, swearing and finally drilling them out when you realise the first three don’t work. If you do decide to drill them out, be careful to centre the drill accurately, use a low speed drill and start with 4mm. If the drill wanders it will either break or veer off into the softer aluminium. Speaking from experience, don’t start unless you have access to a well equipped workshop with at least a pillar drill.

Furling drum and spindle – click to view a larger image

The upper flange of the drum is welded to the lower section of the foil. The foil sections are joined with machined aluminium sleeves, and (because the sleeves are not stainless) there shouldn’t be too much corrosion. The usual problem with the joints is that the pop-rivets have become loose. Drill them out – use a large (say 8mm) drill to drill off the heads, and drift the rest of the rivet out. The sections can then be separated.

At the top end, a cast aluminium cap (complete with U-bolt for the halyard block) is an interference fit on the foil. It can be tapped off using a small block of wood to prevent damage to the foil. The forestay terminal will fit through the end cap bush. Note the forestay bush – this is effectively the upper bearing on which the foil revolves. Being fairly small it is likely to be worn significantly. It is designed to sit on top of the foil section – the flange should be slightly bigger in diameter than the inside ‘diameter’ of the foil extrusion. When assembled, this bush will rotate inside the end cap bush, rather than around the forestay itself.

Arrangement at the top end of the furler – click to view large image

The furling drum (lower section) mounted on the fairlead/spindle assembly, showing the starlock washer ready to be pushed onto the spindle.

Refurbishing and reconditioning

Much will depend on the facilities you have available. If you have access to a pillar drill and a centre lathe you will be able to completely overhaul everything. Failing that, you may have to find a local machine shop willing to turn up new bushes. You will definitely need to use the services of a rigging company to make up a new forestay.

The forestay is 4mm stainless, plastic coated.Use the old forestay as a pattern to get the correct length and to match the fittings. It is very important that the new terminals fit the fairlead/spindle assembly, and that the forestay bush is threaded on to the forestay the right way round before the top terminal is swaged on.

With all the aluminium components dismantled they can be cleaned and de-greased using caustic soda. Add the caustic soda crystals to some very hot water. Use an old brush to clean all the components, and rinse immediately in more hot water. Don’t leave them to soak – you may come back to find very little of your furling gear left! A minute or so is enough. Use rubber gloves and goggles, and dispose of the used caustic soda sensibly.

With everything dry, give the aluminium components a coat of etch primer (nasty stuff – read the warnings on the can and follow them). I used an aerosol can (see below) and did this outside with a mask on. I followed this with a few coats of alloy wheel spray paint, which was a very close match to the original anodised finish.

New bushes can be turned from either Vesconite (as shown in the photos) or some other sort of suitable plastic (I believe acetal is ok, but nylon isn’t as it swells when wet). All the bushes simply tap into place, provided they are turned to the correct dimensions. If you aren’t able to make them, or get them made for you, Rotostay are able to supply some components as spares.

Re-assembly is straightforward. Duralac (a barium chromate paste) should be used, especially on the stainless bolts holding the drum together. Use monel pop rivets, again with Duralac, to fix the foil sections together. Thread the forestay down from the top end, assemble the lower terminal onto the drum spindle, and then fit the spar end cap (making sure you line the U-bolt up with the luff groove so it locks in place).

Materials and components:

Rotostay – http://www.rotostay.co.uk, tel: +44 (0)2392 583633

Note: Update Jan 2012. Rotostay don’t seem to be around any more, but a Gosport company, XW Rigging, can supply spares and technical advice. Their contact details are:

Further update April 2012. Contact Mark Flew at Flew Sails, based at Wicor Marine, Porchester.

Vesconite – http://www.vesconite.com, tel: UK office 0800 731 97 45

Zinc chromate spray and Duralac paste – Airworld – sales@airworlduk.com

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