You can specify both the sailing and motoring performance for the vessel. If the vessel is set to only sail, then the motoring performance is optional (and will be ignored.) If the vessel is set to only motor, the sailing performance is optional (and will be ignored.)

Sailing performance.

This menu allows you to select one of the imported polar diagram files for the vessels sailing performance. While the available sailing polar catalog contains many sample polars, only those which have been imported are available from this menu.

If you have a polar diagram file you would like to import, there is a menu item which allows this.

If you want to browse through the collection of sailing polars in the system, there is a menu item to open the Polar Diagram Manager which is where the sailing polar collection is located.

Note that vessels may share the same sailing polar file. You can think of each sailing polar as an object, which more than one vessel can reference, much as multiple drivers can share the same car. If you modify (edit) the sailing polar, all of the vessels using it will be affected.

Sailing speed scale (A).

(This setting is enabled through the application preferences.)

This setting allows you to apply a scale factor to the performance diagram. For example, if you race a vessel harder than you cruise with it, you can reflect this difference by applying different scale factors.

If this setting is disabled, then a speed scale of 100% is used.

Normally, the vessel speed is calculated using the performance (polar) diagram given the true wind speed and angle where the vessel is located during the isochrone calculation. If you have a speed scale specified, the polar diagram speed is multiplied by the scale provided.

For example, if the polar diagram determined that a vessel would sail at 6 knots for a given wind speed and angle, and the speed scale has been set to 80%, the solver will use a speed of 4.8 knots (as 4.8 is 80% of 6.)

Note that while multiple vessels may share the same polar diagram object, each vessel can specify its own speed scale. This would allow, for example, for you to create multiple vessels, each sharing the same polar, with different speed scales applied. This would let you compare the effect, on a route, of pushing the boat harder or backing off.

Night speed scale.

The system considers night as being the time between sunset and sunrise, calculated at the vessel location.

If you generally slow down at night, you can provide the scale factor here. This can help model the reefing at night principle which many cruisers follow.

If this setting is disabled, then the sailing speed scale is used at night.

Motoring performance.

If your vessel is not a pure sailing boat, you need to provide its motoring performance. The menu allows you to choose from the motoring performance polars created, as well as create a new one, or open the Polar Diagram Manager.

Each motoring performance object can be shared by more than one vessel, in the same manner as how sailing polars can be shared.

Motoring speed scale (A).

(This setting is enabled through the application preferences.)

This setting is analogous to the sailing polar scale. The speed calculated by the system for a given true wind speed and direction is scaled by the given amount.

Multiple vessels may share the same motoring polar, but each has its own independent speed scale.