Our example is a Westerly Centaur built in the 1970s, typically the mast control lines were lead to mast mounted winches and cleats which involved going up on deck to make adjustments.

The mast base organiser location is such that the lines exiting the mast have the best deflection to the deck organisers mounted on the coachroof, the first image shows the ideal location and angle. The mast base area to be drilled into is solid fibreglass and quite thick so no issues with strength here, you do need access underneath so the headlining will need to be peeled back. Drill out the holes to 6mm and introduce a suitable sealant onto the countersunk M6 machine screws and into the holes. It is a good idea to add a barrier cream such as Duralac onto the screw heads where they contact the anodised aluminium base. Underneath you can use large penny washers or make up a wooden or metal backing plate to spread the loading on the bolts. Use M6 nyloc nuts to secure and cut off the excess bolt length with a dremmel cutter or similar to get as flush a finish as possible for when the headlining is replaced.

Attach the correct sized double tang blocks ( Size 3 on the Centaur part# 03 090) to the swivel posts using the plastic spacer washers provided for a snug fit then lead your control lines through.
The mast base organiser has a safe working load of 1540kg making it suitable for yachts up to 33ft (10m), another great product from Barton Marine!