News Design differences in sails for shorthanded/autopilot boats versus fully crewed boats

17 Oct 2013

By Richard Bouzaid – Head of Design, Doyle Sails NZ

The first thing you look at when designing any sails, regardless of the type of boat they are for, is the type of racing that they will be doing and the budget for the sails as this will dictate the inventory. Depending on the size of the boat, features that are important for shorthanded sailing are primarily weight, handleability and flexibility. Doing sail changes shorthanded is a major operation so we design sails to be easy to handle and to cover a bigger wind range and angle so they need to be changed less often.

A jib or a mainsail for shorthanded boats will usually be designed to be a little more all-purpose and with reaching in mind, so they are not just upwind-focused like a typical mainsail/jib for a fully crewed boat. To achieve this, these sails will be designed with more twist, and often small geometry changes, so they can be used more effectively when sailing on angles other than upwind. Hugo Boss is a great example of this compared to an IRC boat – none of her sails are designed as pure upwind sails because upwind sails are more tweaky to trim adjustment when reaching, and when you are sailing shorthanded you can’t constantly be trimming.

Hugo Boss MED2

For yachts being sailed shorthanded, durability of sails is really important as the sails will typically see much harder time than the sails of a fully crewed yacht. Any sails on a shorthanded boat will flap more when being changed than in a fully crewed scenario as it takes a lot longer to implement the change and it is often done late. To counteract this we look at the structure of the sail to make it more durable. This might mean the sail needing more weight, a different balance between highly durable fibres and low stretch fibres, but this is justified as the sail needs to be able to handle more abuse than a sail of a fully crewed yacht. If/when you get caught out with the wrong sails in higher wind speeds the sail will flap an awful lot during the process of getting it down.

In certain types of sail, such as downwind sails, you’ll see a lot more difference in the design of sails for shorthanded boats. For example flying sails (gennakers and the like) that require constant trimming aren’t usually a very good option if you are sailing shorthanded. Instead we tend to design sails that fly straighter in the luff, with rounder entries. This gives a wider steering groove so that the sail won’t collapse and flap and will generate high driving forces. Sails for shorthanded yachts typically need a bigger angle and windspeed range than fully crewed boats, as again sail changes are tiring and costly performance wise as they are time-consuming. In general shorthanded downwind sails are more reaching oriented than VMG running oriented because autopilots typically handle steering a boat better when the rudder has some load, compared to when the boat is sailed at deeper angles and the auto pilot has to work hard to keep up.

It’s also typical in shorthanded sailing that you would use furling sails more often, such as furling systems for semi-flying gennakers and jibs. This gives the sailor more options and more flexibility for getting sails away without getting into too much trouble from having too big a sail up, so you tend to be able to push on with larger sails and higher performance longer. For example the Open 60 yachts all have headsails and flat gennakers on furlers and their only big running gennaker on a snuffer sock, which they tend to drop much earlier than would be the case fully crewed.

In general the smaller the boat the more the inventory for shorthanded and fully crewed yachts will be similar as the changes are manageable. By the time you get to a 40ft boat you will be starting to think more about how to minimise sail changes for a shorthanded boat and to get more range out of each sail code. When it gets to the 60fter range everything should be on furling systems as it is too difficult to make any changes without them.

To summarise the key differences between the sails for shorthanded and fully crewed yachts are:

- Sails will be designed to have a bigger range to minimise the number of sail changes needed.
- Sails will be designed to be more durable and handle more abuse as sail manoeuvres take longer.
- The number of sails in the inventory will be minimised to keep sail changes to a minimum, while giving up as little performance as possible. This means the sails need to be capable of being used through a wider windspeed and wind angle range.
- Sails will be designed for a wider steering groove, which typically means they’ve got rounder entries at the front so they won’t collapse or luff as easily. This is primarily for the ease of auto-pilots to help with boat tracking.

 

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