6. Sail Trim

Even the best autopilot can be crippled by poor boat trim, and the Rudder and Deadband settings affect how accurately the boat holds the heading.

The boat must be balanced on all points of sail and in all wind conditions for proper autopilot operation.

This means that through the skipper’s selection of sails, trim and heading, the boat should tend to maintain a stable course without a significant amount of weather or lee helm. Reef and trim or head-off when wind and sea conditions increase. The Rudder control manually sets the rudder response for one consistent response, the autopilot will not automatically adjust for changing conditions. The CPT is not recommended for racing.

When sailing, the boat should maintain adequate speed for effective rudder control; it must make enough headway for steering to be effective. When wind and seas increase, and especially when running downwind, quick rudder response becomes important; lowering the Deadband and slightly raising the Rudder control helps with full keels, and increasing vessel speed or falling off will lessen the effect of following seas. Fin keels may benefit from lowering the Rudder setting due to increased speed and rudder efficiency.

Warning

Always be aware of the relative wind angle and keep the boat on a course to prevent an accidental gibe. If the boat is in danger of broaching, change heading or speed, reduce canvas, or put a competent helmsman at the wheel.

Because of the manual Rudder and Deadband controls, the CPT performs best when the boat is balanced for consistent steering needs. If the wheel needs to be turned very little while going down the face of a swell, but then turned wildly at the bottom or in gusts, the boat is not balanced for the conditions, and the pilot will not anticipate the constantly changing steering needs.

6.1. Boat Balance

A balanced boat has very little or no helm, either weather or lee. A boat that is trim and balanced does not round up to windward at every gust. A boat with a heavy weather helm is one that has been poorly trimmed or is carrying a poor selection of sails. The boat should be trimmed for consistent steering needs.

By spending time trimming the boat properly before engaging the CPT, you will place lower current demands on your boat’s electrical system, steer a straighter average course, and create less wear-and-tear on both your boat and your CPT. Practically any boat can be made to sail with a balanced helm for reasonable lengths of time. You should strive for this as closely as possible before engaging the CPT.

6.2. Beating

Do not carry too much sail area and do not over-sheet the sails. This will create weather helm, excessive heel and probably slow you down. If the boat has weather helm, ease the main sheet until the main is on the point of luffing or just luffing slightly. If the boat still has significant weather helm, take in a reef on the main or slide the traveler car to weather, while easing the sheet to put some twist in the main to allow the top of the sail to luff. In heavy weather conditions where one sail will suffice, sail under jib alone.

In gusting conditions some boats, particularly fin keel/spade rudder boats and others with too much canvas spread, will head up at every gust. The main should be sheeted loosely enough so that it luffs as soon as the boat heads up. With some boats the main should be left luffing slightly when on course. This will allow the jib to push the boat off, as drive from the main is lost. Maintain a course that will give the boat an adequate steady speed and effective rudder control. The goal is to balance the boat and eliminate the need to change the steering with every gust, to keep the steering needs consistent.

6.3. Running

If running downwind with twin poled-out jibs: The jibs should be sheeted a little looser than would be optimum so that if the boat tries to round up the leeward sail will spill air and the boat will return to course. If the main is carried, there should be a poled-out foresail on the opposite side. If conditions put the boat on the verge of broaching, the main should be dropped, or fall-off and change to a safer course. When it gets to surfing conditions, a competent helmsman should be in charge. Generally, at slow vessel speeds the rudder is less efficient and requires a higher Rudder setting; higher speeds require a lower setting. Get to know your vessel’s characteristics; there is usually an optimum vessel speed, course through seas, and amount of canvas that best balances the boat to meet the wind and sea conditions.

6.4. Reaching

Twin poled-out jibs or a main and a poled-out jib can be used up to 30° to 40° off a dead downwind course. (See the comments above on running.)

In high winds and particularly in gusting conditions, both sails must be sheeted looser than usual, or sail area reduced. THE MAIN SHEET MUST BE EASED! If the boat still wants to head up at every gust, put a twist in the main, reef it, or drop it.

Always rig a preventer to the boom when running or reaching in case of an accidental jibe.