Without ‘the thing’ in place I can achieve the required pre-bend. (The front of the mast is hard to forward of the slot it sits in.)
Now you know why we insert removable chocks in light winds. They allow us to put some tension on the rig without bending the mast (much).
But, I cannot get the pivot pin in – it fouls the rear edge of the hole in the mast . The mast foot pin needs to move backwards by 2-3mm, but there’s no more movement to aft available.
If you can’t move the pin further aft, perhaps you need to reposition the mast step? BTW, the mast step pin is a course adjustment, a penny (or two) between the pin and the mast foot can be used for fine tuning. If you decide to re-position the mast step, check if the mast hole lines up with the tabernacle holes vertically. If not you could put a small plastic riser below the mast step. I have used some Formica for this.
Is it a total no-no to make the kingpost hole a bit bigger?
That is indeed a big NO-NO
The holes in the mast and in the tabernacle, with the mast pin inserted, limit the amount of play and ensures we all have the same amount to play with. It is one of the things a measurer looks at while scrutinizing a boat before a major racing event. Basically the mast pin seems to have no function (it just rattles around) but it is used as a means to limit the amount of mast trim.
Note: a test has shown that a woody in capable hands runs significantly better when the entire mast is moved back an inch or so. But at the same time the boat becomes much harder to handle by a less experienced sailor. Anyway, the discussion is moot because the rules simply don’t allow it. The hole rules have two purposes, to make it a safe boat and to create a level playground.
(I’m wondering if another type of adjustment can make that unnecessary, however. At present the rake is at its maximum — 7190mm. If I decrease the rake I think I will possibly achieve two favourable outcomes: pulling the mast backwards a) from the front of its slot b) towards the hole in the kingpost)
BTW, your new side chocks look exactly like the ones I had on my old boat, a MK2. Ply is perfect and may turn out more durable then plastics. Remember that there is a lot of force and friction going on while sailing. The mast is not static but moves all the time. You may find that plastics are either too soft or too brittle to last. Maybe POM is strong enough?
I simply varnished the ply chocks. If you rather have plastic, paint those ply chocks with yellow polyester paint…..