Anchor Scope

Anchor scope compares how much rode is let out with the total vertical distance from the bow roller to the seabed. It matters because a longer line spreads the pulling force more horizontally, helping the anchor dig in instead of being lifted straight out. The formula works by using the actual suspension depth the rode must span, which is the water depth plus the boat’s freeboard above the waterline.

Use this when deciding how much chain or rope to deploy for anchoring in a given depth. It is also useful when checking whether your current scope is adequate for weather, bottom type, or the type of anchor system you are using.

• Using water depth alone and forgetting to add freeboard
• Mixing up scope ratio with anchor chain length in metres
• Writing the result as a simple number without stating it as a ratio