Use this sailing calculation for planning or education when the vessel, units, reference directions, environmental conditions, and assumptions are explicitly known.

Load (N)

Required number in N. Tension on the tail side that the winch must hold.

Power ratio

Required number. Mechanical advantage of the winch, handle length times gear teeth over drum circumference.

The cited overview of Sailing supplies background for the terminology and domain context used by this tool.^[1]

Compute the handle force needed to trim a load as the load divided by the winch power ratio. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Handle force (N)

Returned number in N. Force applied at the winch handle.

• Vessel design and loading, sea state, wind, current, tide datum, weather, chart accuracy, equipment, crew, and safety margins can make real conditions differ from a simplified result.
• Use finite inputs in the displayed units, preserve source measurements and assumptions, and independently verify consequential decisions.

Cross-check current charts, tide and weather services, instrument data, vessel manuals, and applicable navigation rules, and retain a conservative alternative plan.

• Winch Power Ratio Calculator

  Compute ideal winch mechanical advantage as the handle-to-drum radius ratio multiplied by the dimensionless gear ratio. Real handle force is higher because this ideal model excludes friction.

• Anchor Rode Length Calculator

  Compute the anchor rode length needed from water depth, freeboard, and scope ratio.

• Anchor Scope Ratio Calculator

  Compute the scope ratio from the deployed rode length and the total height to the bow chock.