Awesome news regarding the lack of rounding up into the
wind.
Did you experience any
weather helm? Which is what you feel pulling on your
wheel or tiller where the
boat is trying to turn you up wind under certain sail trimming conditions, which we referenced in earlier posts.
Or did the boat sail true without needing much countering
helm [downwind turning] to keep it from heading up?
It looks like you had adequate amount of "rail meat" available to ballast your boat if the wind came up and if need be just shift the kegs of
beer to port or starboard.
The image below is of a key way / slot, a key, and key seat which is a common method of providing for torque transfer between a levering object, [e.g, your tiller / rudder turning quadrant] and the shaft.
Hope you and your friends enjoy many grand days on the
water.