choosing the sails

When we were putting our new GP 26 together, we wanted to look for a sailmaker on the march, and we started and ended with Doyle. We really liked how they approached the program, so we thought putting a series of articles together outlining their sailmaking process. – Ed.

doyle gp 5SA: I’d like to start with a first article about the things that you guys did in terms of rig analysis, sail design, etc. that I thought were so impressive, and I think anybody looking for sails will find that compelling. I will rely on you guys to provide the substance of that article – tech, renderings, etc.

Doyle: Back in mid-2014 Sailing Anarchy’s editor Scot Tempesta approached Doyle Sails NZ about designing and building a sail inventory for his new Jim Donovan-designed GP 26. Were we up for the challenge? Damn straight we were.

At Doyle, working with the customer directly in the design stages and ensuring an end result that works for their boat is key. The sail design software that we use is highly advanced and allows us to accurately design sails on accurate boat models, and customize accordingly. Richard Bouzaid, Head of Design at Doyle Sails NZ, led the charge on the design process of the sail inventory for Scot’s GP 26 and he gives his insight into the process here:

This is the first GP 26 to carry a Doyle inventory and our initial steps were to work directly with Jim [Donovan] on how we could best tailor sails to the design. A lot of discussion between us, Jim and Scot took place around the existing GP 26 fleet, how they were being used and how Scot’s boat would be used by comparison. The end goal was to produce a configuration that would be practical for the sailing the boat would do; being based in San Diego the inventory would need to suit typically light winds.

Early on we decided on a square top mainsail. None of the other GP 26s has this type of sail and at this time the rig design is not configured for this type of sail – a job that will come after the launch, when running topmast backstays will be added. In addition, we also designed two headsails and two gennakers, which is a fairly simple and cost effective sail inventory. The plan is also to add a Code O later down the line, once the boat has been out sailing and we have a better idea of how she sails and see if the rig can handle this type of sail.

doyle gp 2Jim supplied our design team with a model of the hull and details of the mast tube section. We then modeled this in our software to establish a base tuning configuration that Scot could start with and to have a good idea of the rigging and sail trim adjustments that he should use through wind ranges.

This will allow Scot and his crew to get straight into sailing at high efficiency, with defined rig adjustments for different wind speeds, and to set the sails to suit all conditions. As the yacht has the ability to do a lot with the mast, this insight into accurate tunings should prove a real advantage. While we would not undertake this detail for all of the sails we design and manufacture, this level of tuning detail is a good exercise to demonstrate the kinds of information that our very advanced design software can provide when required, and much of this information is transferable to other projects of similar style.

doyle gp 1After undertaking our initial analysis, modelling the rig and creating the rig tuning and sail trim tables, we then optimized the sails to match these rig setups. This is where we do adjustments to the luff curves to match the mast bend and forestay sag to get the best match to the mast/forestay and we can see the effect through the mastbend/forestay sag range on the sail and gauge the relative performance differences.

This is the same sort of thing that can be achieved with hours of sailing, and tweaking luff curves on the sails, but before the boat actually sails and before the sails are built. All of this analysis is done with the structure that we are intending to build the sail from, and through this process we can establish if the sail structure is working as we want it to, and within the structural safety limits, and make any necessary adjustments.”

With design work complete it was over the floor for the sails to be built in the dedicated Stratis plant and 7,000 sqm Doyle loft. Next, we’ll see how the things look!