Vessel Controls

Sail Controls

Typical Mainsail

A typical mainsail (which includes our mainsail and mizzen main) will have the following controls: halyard, cunningham, outhaul, reef lines, sheet, traveller, and boom vang.

Halyard

The mainsail halyard is critical in the raising, lowering, and reefing of the sail.

Length The length of the halyard shall be at minimum twice the mainsail hoist (P) to accommodate a full drop of the mainsail. Additional length is provided to reach any line handling equipment such as rope clutches and winches.

Design Tension

Two-to-One Halyards A two-to-one halyard can dramatically reduce the compression loads within the mast column by halfing the tension in the bitter end of the halyard. The halyard is made fast to the aft end of the crane, led through a block or frictionless ring mounted in the sail's headboard, returned upward to the top of the mast over a sheave and then back down to the deck. In this configuration, the line tension is half that of the one-to-one halyard thus reducing the compression loading on the rig and loading on halyard components (sheaves, turning blocks, and the line itself).

The cost of this reduced tension is a doubling of the required action to adjust the halyard. Whereas a traditional halyard would yield 1-ft hoist for 1-ft trim, the two-to-one halyard will only yield 0.5-ft. This will be particularly important for sizing captive-reel drums. Note that this doubling of length is only applicable to the actionable travel and is not necessary for the additional length required to reach line handling equipment.

Typical Staysail

A typical staysail (which includes our jib and staysail) will have the following controls:

• Furling
• Windward / leeward sheets
• Halyard

We'll note here that the ASV Angelina will have a fixed halyard since dousing of the staysails would require hands on deck which, by definition, an autonomous sailing vessel shall not have.