Selfsteering with trim-tab and horizontal vane - How I built it using 3D printed parts

A self-steering system built on a transom-mount rudder with a trim tab
The control is made with 3D printed parts, a speargun tube 30-26mm in carbon, and a pair of old Pathos carbon fins cut and glued together.
With light winds the vane is too small, so a new larger vane must be built, maybe in fiberglass or maybe with sail fabric on GRP rods... depends on what is available as leftover in the cellar and in the garage: the important is that the weight and the center of mass of the new vane is the same of the carbon vane.
This carbon vane has been tested in the past days leaving it mounted in the harbour with strong wind: the vane bends when reached the limit and guts hit it, effectively releasing excess power.
The trim tab itself has been built with a 360 degrees rotation and a fast engage-disengage system to allow it to be absolutely neutral during the maneuvers in the harbor, especially the reverse which is a source of disasters for most self-steering systems: this one, has a simple rope that is pulled to free the vane and released to engage it with the trim-tab
- The vane axis in inclined backways of 20 degrees.
- The trim tab is balanced with 20% of the chord forward to the axis
3D printing
- Material is PCTG @ 240 degrees, no fan
- 80 degrees heated plate
- 0.3mm layers to increase local heat and ensure proper bonding between layers.
- Filling 40%
- Thickness 6mm for top and bottom and 3mm for vertical walls