Fin Trunk / Fin & Rudder alignment
I’ve heard from some folks concerned about the loose fit of the fin in its’ trunk as they struggle to assure that the rudder is in perfect alignment with the fin.
The generous clearance of the fin in the trunk is just to insure that the fin will never get stuck and will be easy to install or remove. The trunk with its’ 1/4” opening could accommodate a 3/16” thick fin as well, but 1/8” is all Emma really needs. The resulting play is not a problem in any way. When she is on one tack, the fin will lie to one side, and on the other tack, to the other side.
Contrary to what some may say, precise alignment of the fin to rudder is NOT an issue. If the fin trunk is fitted to the bulkheads as shown on the plans, and the rudder post is reasonably close to vertical, all will be fine.
Just before launching, eyeball the rudder and use the trim adjustment on the transmitter to center the rudder position. The boat will travel a course according to the fin, and you, the ever vigilant helmsman, will use the rudder (steering) to make changes or adjustments to that course.