The sails of a Class 40 explained by the engineer who designed them

After a week of being “stragglers,” with an Atlantic Ocean that did everything it could to scramble the Route du Rhum 2022 competitors, for the Class 40s, with less than 2,000 miles to go, there seems to be a glimpse of light at the end of the tunnel. And the light of course is none other than the entry of the trade winds, which become apparent when the virtual halfway mark has now been passed. Perhaps, using a bit of imagination, the smell of the air is starting to change, the wind is getting warmer and changing consistency, but the skippers’ heads still cannot go toward land, not at least if a good result is to be brought home.

Tradewinds signify the final farewell to the upwind and entry into the carrying gaits. Now, in addition to the skippers’ strategy, boat speed will be decisive. Sails will still play a key role, and it was about them that we spoke with Aerospace engineer Michele Malandra, designer for North Sails Italy, who edited for the Class 40 Allagrande Pirelli by Ambrogio Beccaria the design service, which is the study of various sail plan options to be adapted to Allagrande’s hull (a somewhat different job as you will read compared to the design of the single sail n.d.r.). Before we read the Engineer’s words and find out how the sails of Beccaria’s boat came to be, let’s look at what our people are doing in the Ocean.

Route du Rhum – What the Italians are doing

Our spotlight is always on the Class 40s, where Ambrogio Beccaria now occupies fifth position and Alberto Bona on IBSA Group is in seventh. Andrea Fornaro, on the other hand, after a technical stop in the Azores for a keel check that showed some problems, restarted and is sailing close to 15th position.

Beccaria and Bona are in the lead group, among the boats that will potentially go for the podium, clear of the breakaway of Yoann Richomme in the lead who does not seem intent on leaving any openings for his opponents.

Beccaria in the last 24 hours seems to have been less effective than usual, probably the autopilot that can no longer work in “wind mode” but only compass starts to weigh on Allagrande’s pace, although the physically toughest part of the race for the skipper seems behind him. He dropped back to the rear of the frontrunners Alberto Bona, who instead tried to keep a very high pace in the last 24 hours to stay hooked to the front of the race. However, both remain in the running for an important result and have cards to play for this second part of the journey.

Route du Rhum – How the sails of a Class 40 are made.

After Pietro Luciani‘s commentary on sail configuration, and Tommaso Stella’s on the halyards and rigging of a Class 40 the floor was passed to another super technician, Engineer Malandra of North S ails who studied various sail plan options for Allagrande Pirelli.

We asked him how many sails a Class 40 has and how a designer can “play” with the sail plan to seek maximum hull performance. And of course we also talked about the sails for carrying swells that will be indispensable now in the trade winds.

Design freedom on Class 40 sails

“There is a lot of design freedom on the sail plan,” Michele explained. “The big stakes are two: the maximum summed area of mainsail and jib, which has a limit, and the ban on using carbon. The first limitation actually leaves a lot of room, because it is possible to variously distribute the surfaces between mainsail and jib. In the case of Ambrose, I was in charge of doing aerodynamic studies of different sail plan configurations (we call them design services), especially regarding the distribution of the mainsail-jib surface. With our software we can do very precise simulations on various types of planes, and also simulate how the boat reacts to adjustments. The design of the profiles of the individual sails then was done by our French colleagues, who have a huge backgroung in these classes.

Doing an aerodynamic study also means, for example, deciding at what height to put the sail attachments and thus the halyard exits in the mast, another option on which the Class 40 regulations leave room for designers to move.

At this stage of study, it is crucial to figure out the best sail plan based on the keel designed by the designers, Gianluca Guelfi and Fabio D’Angeli in the case of Allagrande Pirelli.

“The sail plan alone doesn’t go anywhere,” Malandra points out. “My job is to make the right fit between what’s above with what’s below. We did simulations on what each type of sail plan would entail for the boat by analyzing the forces and moments produced, and we passed these analyses to the designer who evaluated them based on the characteristics of the submerged part of the boat. For example, with the same sail shape, we evaluated what the best rake angles (mast tilt on the fore-aft axis) were.

There is a limit to the boom travel to the stern, whose trope must be 80 cm inside the stern limit. When we were moving the sail plan back and forth in the simulations we had to deal with this limitation, and figure out how much area to move to the head of the mainsail when we went back with the mast. Moving the mast back you have to decide whether you want to keep a given area of mainsail and thus stretch it vertically, or decrease its area and add to the Solent. In practice, it is ultimately a compromise choice between the aerodynamic part and the immersed component. Having thought of a boat with the trim very much aft the mainsail area had to deal with that 80 cm limit.

What materials are the sails of a Class 40 made of and how many are on board?

“We made an aramid mainsail with 3 coats, a solent/J1 on garrocci with a vertical reefing also made of aramid, J2 same material, but rollable with vertical battens, and then the turret/J3. To these sails were added two Code 0 Helix polyester , one for masthead and one fractional, one for light air and one for wind. And then we made three asymmetrics, one on each halyard height, A2-A4-A6. For load-bearing gaits, therefore, the inventory is very rich. Compared to a crew gennaker, however, these are somewhat different sails for soloists: solo gennakers can also sail at tighter angles than intended to possibly limit sail changes. And in general that of making “tolerant” changes between sails is also done with upwind sails.

Instead, Allagrande Pirelli is the only Class 40 in the fleet with a steerable bowsprit, an option that could have opened up some unconventional choices. “There was a lot of space opening up because of the steerable bowsprit at the design level. We could definitely have made “rounder” sails to try to aim for more pronounced angles at the leeward. However, it meant making a sail that was too specific and unsuitable for solo sailing where a sail has to be able to work effectively even if used a little outside its angle ranges.” Designer and Aerospace Engineer’s Word.

Mauro Giuffrè