The Mast Support is designed to be strapped between the mast and the aft crossbar. The arm and notch on the back supports the tiller crossbar (for the new style rudder castings). There is also some room around the mast and the crossbar to allow for some padding to be adhered to the part. The front of this is flat so that it can be printed laying on its face and not need any support.

This part is best printed with top, bottom, and walls set to be over 1mm thick. I prefer the grid infill set to about 15% and the option to 'connect infill lines' selected.

I printed mine out of PLA with top, bottom and walls set to 1.6mm thick. It's strong enough to support the +150 lbs loads that the mast and strap exert on it during trailering and setup/take-down.

The Mast Support is about 7"x10.5" and may not fit on smaller printers.