We found it annoying that the rotating mast on our 26M would not turn freely leading to sudden rotation and shock loading on the rigging when it suddenly rotated after sufficient wind power had filled the sail. To address this we have fitted a ball bearing thrust bearing to the mast base to replace the rather crude stack of greased washers used in the original.

The bearing used was a high quality stainless ball race from SKF that fits the UNC bolt that is fitted to hold the mast base parts together. This bolt has a captive nut so can’t be readily changed to a metric size. We used a 12 x 26 x 9mm SKF thrust bearing (part number 51101 SKF - £11.55 online from bearingstation.co.uk) but used only the lower grooved bearing thrust washer with the captive ball bearings in their holder whilst running the ball race against the flat base of the mast instead of the upper grooved thrust washer provided. Why? – because the original stack of washers gave a 6mm gap and the full thrust bearing is 9mm thick - if we had used both the supplied grooved thrust washers with the bearing race it would have lifted the mast by about 3-4 mm which would have increased the rigging tension. So by leaving out the top race we kept the gap between the two parts of the mast base the same as original. If you have screw rigging screws this may not be an issue but we use the original stay plates and don’t have any adjustment on the forestay so didn’t want to alter the rigging tension or mast angle. Whilst rigging screws offer a more sensitive adjustment than stay plates they can’t be so readily kept at the same place year after year when the mast is lifted and lowered multiple times and Mac 26’s don’t normally have any adjustment on the fore stay if they are fitted with the standard furler. So if like us you want to keep the rigging the same you need to measure the gap before fitting the new bearing and keep it the same.

The upshot of this simple cheap modification is a mast that now rotates very freely even in the lightest of breezes as soon as the boom moves across and is totally silent.

Mike Clarke - TARKA Mac 26M