Start with the exact boat, then describe how the sail will be used. Those two inputs give meaning to every role, dimension and handling choice that follows.
Select the boat in SurgeSails
Choose the correct Boat Model, year and rig where they are known. Add the Boat Name and confirm LOA. A matched boat record gives the configurator and sailmaker a starting point for the rig.
If the boat has a non-standard rig, an added bowsprit or a modified halyard exit, identify it in Note. The database is a starting point; it cannot see modifications made to an individual boat.
Define the usage
The system records Usage, but the useful design input is more specific:
- the wind range in which the sail should work;
- whether the priority is reaching, running or a broad general-purpose range;
- how many people normally sail the boat;
- whether it is one cruising sail or part of a racing inventory.
Describe those points in Note. They determine the recommended A-role, cloth weight, fullness and handling system.
Confirm that the boat can set it
A gennaker needs a fixed tack point forward of the forestay, normally on a bowsprit or at the stemhead, a suitable spinnaker halyard and sheet leads far enough aft.
Where the boat record is incomplete, send photographs of:
- the bowsprit or stemhead from the side and above;
- the masthead and halyard exit;
- the sheet leads on both sides;
- the boat from the side, showing the overall deck arrangement.
Tack height, sprit projection and the way the tack line is led affect the sail. If the sprit or its fitting has not been checked for flying-sail loads, that is a rigging question to resolve before ordering.
Next: choose the sail’s job
For one cruising gennaker, the normal recommendation is an A2. Read A1-A5 Sail Roles before confirming whether the sail has a more specialised job.