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STH 1 Prototype - first RC model

First project of the RC model from the SOUTH series. It is 40 cm yacht designed for the engineering classes. The model was desiged in Fusion 360. Electronic is made on Arduino base.

5/8/20241 min read

The first prototype of a remotely controlled sailing yacht that we ever built using a 3D printer.

The idea was born during our engineering degree project. The aim was to create fully 3D-printable design and to develop the electronic hardware responsible for steering. To the author's surprise, the yacht not only did not sink, but also responded to commands from the remote controller.

The deisgn of course was very crude: the hull was unbalanced and there was no real optimization. Nevertheless, the created STH 1 inspired us to continue the SOUTH series and to draw lessons from each itteration.

STH 1 had no active control of the jib the clew of the front sail was fixed to the mast with a few centimeters of excess line, allowing it to move freely as the boat changed tacks.

The rudder was connected to the servo via a toothed belt, which ensured a proper response to joystick input. However, this solution required additional parts, so it was abandoned in later projects.

The mainsheet control was implemented using a servo with the lever supplied in the kit. This was the simplest solution, but in introduced nonlinearity in the sheeting-in and sheeting-out process. That is why it was replaced with a "winch" - style solution in subsequent designs.

STH 1 also featured a rudder located behind the stern, which in newer projects was replaced by a rudder trunk flush with the deck.

The last major problem with STH 1 was significant leeway, due to the lack of a proper daggerboard-type keel and ballast. The ballast was mounted at the end of a keel shaped from an ellipse that turned into a circle, which guaranteed strength but offered no resistance to leeway whatsoever