A speedboat drive made with SLS parts

Luca Dalbosco is just 16 years old but as a diligent tinkerer he already uses 3D printing for his models. Within a few weeks he has built a fully functional speedboat drive from SLS (“Selective Laser Sintering”) parts and is successfully navigating Swiss waters with it. In the interview he tells us how he went about it.

Fascinated by 3D printing

Computer science enthusiast Luca Dalbosco from Davos is passionate about 3D printing and technology. He is currently in his 10th high school year. Since the 7th year he has been taking part in a gifted education program, and the school administration has even provided him with an in-house FDM 3D printer. Inspired by an internet video, in which a remote-controlled model ship was additively manufactured, he was captivated by the idea of a self-built speedboat.

16-year-old Luca Dalbosco (high school student) with his finished speed boat and the lake of Davos in the background.

SLS for the jet drive

Due to a lack of knowledge of air flow, Luca was unable to design all the parts himself – he found the basis for the jet propulsion system on the internet. He proceeded to print most of the boat in FDM. However, this 3D printing method does not offer the necessary stability for the jet propulsion so another solution had to be found. Some time back Luca had the opportunity to visit the Sintratec Experience Center in Brugg (Switzerland), where he was introduced to the Selective Laser Sintering (SLS) process. With this impression in mind, he approached the 3D manufacturer with his drive parts to have them laser sintered in stable PA12 material on the Sintratec S2 system. Sintratec was happy to support Luca in this endeavor and sponsored the required parts.

After receiving the SLS components, the high school student was able to complete his speedboat and test his sophisticated drive on the water.

SLS jet drive components made out of stable PA12 material.

The speedboat drive and its mechanism

The electric motor drives the jet propulsion system, which consists of a tube (also called a stator). A rotor (or runner) is placed inside the stator. “The rotor sucks in the water through a hole in the boat’s hull through an intake, accelerates and spins it backwards via the tube”, the high school student reports. The water jet is not only accelerated by the rotor, but also receives the rotation from it. To prevent the boat from spinning at the rear, small walls are built into the tube (behind the rotor) that cancel out the rotation.

Luca adds: “At the rear end of the tube, the water jet is further compressed by halving the diameter of the tube from 40 to 20mm.” This allows for an increased acceleration. The complete jet drive with stator, rotor, nozzle and reverse bucket was printed with SLS parts from Sintratec.

Close-up of the SLS jet drive.

Steering and braking – no problem

To be able to steer the boat sideways, a movable nozzle is required that directs the water jet to port or starboard. Luca designed the boat in such a way “that the water jet can not only be directed backwards, but also under the hull towards the bow”. This is done via the so-called reverse bucket, which is folded over the nozzle from above. Braking is also possible from full speed, because the impeller continues to rotate at unchanged speed. Ergo: a practically immediate standstill of the speedboat.

Accelerating the SLS jet drive.

Braking the SLS jet drive.

Future plans in 3D printing

All in all, the project was successful and Luca Dalbosco found the cooperation with Sintratec very pleasant: “I find it very praiseworthy that Sintratec supports students in their project work so generously and with such dedication.” What the student particularly likes about the SLS printing process is, “that the powder offers a support structure that does not consume any material and can be removed from confined spaces – easier than support structures in FDM printing, for example.”

In addition, the student would like to incorporate the topic of 3D printing into his final high school thesis. Sintratec wishes Luca every success in this endeavor and much continued enjoyment in the world of 3D printing!

Luca’s SLS jet drive speedboat races into the sunset.

“What fascinates me about 3D printing is that you can save a lot of material in contrast to fabrication processes such as CNC milling. Because of the enormous freedom of form there are almost infinite possibilities with 3D printing and especially Selective Laser Sintering.”

Luca Dalbosco
High school student and 3D printing enthusiast