Blogpost #2 2022 - PoliTO sailing TEAM

Ongoing work towards the Foiling SuMoth Challenge 2022

We have finally finished the design part of the project and now we are watching our moth coming alive. The team is very committed to the project and is working with perseverance and commitment so that the project will be completed as soon as possible. For the electronic flight control system, we designed the servo motor and its location, a feasibility study for all the possible weight and their best positioning, and also had to discuss how to connect the cables and the sensors.
Once we came up with a clear idea regarding these previous steps, we made an interface between the mechanical control system and the new electronic one.

To complete it we’ll have to define the mechanisms and all the regulations.
Furthermore we could compute a fem analysis even though we’re not sure about it yet. We are planning to test it directly on water with our Mach 2 where our athletes are training for the competition.


Overall description and hints on the design

The idea behind our project is to have a reliable moth were the sailor can feel confident and have the mind on the race; in order to guarantee it we have paid particular attention to the fly control because we want to have stable flight.

  • Another focus point the team had was to ensure that the boat wouldn’t have structural problems since we do not want the performance of the boat to be affected by breakages.
  • The name choice: the boat name is always a special decision; when you name it you truly realize that all the work done previously is coming to life.
    Our new moth has the name of a particular animal that lives near the sea but it’s not a fish; it can fly over the waves, exactly as we hope our moth will do.That’s why we decided to name it SULA.
  • Wings bars: in order to be more sustainable and upcycle more materials, we decided to re-use old windsurf mast  as tubes for our wings’ bar.

Achieved milestones

Finally, after having completed the design phase, we moved on to the construction phase and started the main bulk of our work. The first step was the production of the hull and deck moulds. For these our main objective was to limit the amount of material used, consequently reducing waste and our environmental impact to a minimum. The moulds were made by joining many small components in expanded polyurethane foam, each milled separately then assembled. This allowed us to greatly reduce the hours spent using the milling machine, meaning thus that our energy consumption drastically decreased.

Once the preparation phase was concluded, we proceeded with the lamination of both the hull and deck during the same week with no hitches. In addition to the major work done on the hull and deck, the team has proceeded to finalize the last parameters regarding the foils, in order to complete the production of the moulds (necessary for the production of the foils themselves) and to begin lamination. We have also done a structural test for the foils since last year we had problems with the intersection between the vertical and the horizontal part and the results are promising.

Readiness to competition, what does the team need to complete before the Challenge

We still have lot of work to do before Sula can fly over the water surface, but we will manage to complete it for the competition. We hope that the moth will be ready to fly at the end of May so that the sailor can train and finish the rig for the competition.

We still have to close deck and hull, build the structure for the mast base and the wings bars, make the tramps, place the flight control system, wrap the hull and place all the blocks on the deck. In the next week we will start milling the foil moulds, but we still have to finish and define the design of the gantry and the rudder attachment.

Sustainable choices applied

In order to minimise the impact of manufacturing, we have paid lot of attention to the production of the hull and deck  moulds.

Our first step was choosing the material to be used; our choice was expanded polyurethane foam with density 120 Kh per cubic meter, since using denser foams would have affected excessively our SM$ budget. Aware of the heavy cost of this material and the difficult processing that would result, the initial idea of a mould milled from a single block was discarded and it was opted for a division into five blocks in turn divided into several slabs that are then glued together. Thanks to this method we were able to save about 50% of the initially estimated material volume to significantly lower the machine hours and make the assembly and milling operations much more agile.

A line of thought similar to that adopted for the hull was applied to the deck mould.

This mould is divided into two different parts then subsequently glued together. The stern part, which is characterised by an almost linear geometry with minimal curvature, is composed of 8 plywood ribs  arranged vertically. To make the surface of the mould on which we have than laminated, a 4mm plywood sheet has been used, duly cut and fixed in place with nails.

The bow has a more complex geometry due to the presence of the bowsprit and the end of the flange; for this reason it was decided to mill it entirely from a single 10cm thick plate of expanded polyurethane foam advanced by the processing of the mould of the hull. The two parts were then aligned thanks to the use of the central band and were glued together.


During these months we also participated in many events like the SEATEC and COMPOTEC in Carrara; the A&T in Turin; and thanks to another team of our university, we had the great opportunity to host a workshop about sustainability at the annual conference 22.

But our commitments are not over yet, in fact we plan to attend the JEC in Paris and also the SALONE NAUTICO in Venice, where we will have the honour to expose one of our boats and tell our story, in order to make ourselves, this incredible university universe, and the foiling one known a little bit more.

We are full of events and projects and we couldn’t be happier about it.