After being caught out on the water with winds gusting 15 to 20 knots and having difficulty furling the sail I came up with the following solution.
I have been testing it for about a month and so far is working well. The long term problem of rust seems to be the main disadvantage so I am trying to source stainless or plastic bearings. I spray the bearings with Innox and this has minimised the problem.
The parts needed are
-grooved thrust bearing sized for a tight fit on mast
-small roller bearing sized to fit snugly inside mast tube. It needs to be slightly bigger than mast diameter but still able to fit in mast tube. I could only find a bearing the same size so I used heatshrink to increase the diameter slightly.
1- Remove plastic plug from end of mast
2- Drill a hole about 38cm from bottom of mast big enough to insert a line through. I used 3mm spectra line and tied a knot so it wouldnâ€™t come through
3- Fix a cleat to the mast below the sail and shorten the sail bungee. The sail is now attached to the mast instead of the boat.
(The plastic clip is for retaining the bearings when not in the mast tube)
4- Fit small bearing to end of mast, making sure it spins freely. I used a plastic shock cord button which was the right diameter to fit tightly inside mast. Tap a small hole in mast for grub screw to hold it in place. A stainless bolt attaches the bearing to the button and a nut as a spacer between bearing and button allows it to spin.
5- Fit the thrust bearing to the mast so that the bottom of the mast is now just above the bottom of the mast tube. In my case it is 20cm from the end. The bearing I got was a press fit for the top washer and a looser fit on the bearing retainer and bottom washer. The thrust bearing is now taking all the weight of the mast, transferring it to the top of mast tube and allowing it to spin.
The bottom bearing prevents the mast end hitting the side of the mast tube.
6- Mount a cleat for the furling line so the line runs freely in the gap between the pedals.
I use a plastic clip to ensure the thrust bearing doesnâ€™t come apart when out of mast tube.
I now have true roller furling and can easily adjust how much sail I have out when the conditions get tough.