As a general rule of thumb, the length of the rode (anchor line + chain) should be how many times the depth of water in which it will anchor?

The principle behind the length of the rode is rooted in ensuring proper anchoring and stability. A commonly accepted guideline is that the length of the rode — which includes both the anchor line (rope) and chain — should be between seven to ten times the depth of the water where the vessel is anchored. This ratio allows for adequate scope, which is essential for maintaining the anchor's grip on the seabed and providing enough slack to adjust for tidal changes and wave action.

Having a longer rode relative to the water depth creates a catenary effect, where the rode lies in a gentle curve rather than being pulled straight. This curvature helps absorb shocks from wind and waves, decreasing the risk of the anchor being pulled out of place. It also prevents excessive strain on the anchor and the vessel. When the rode is not long enough, the anchor might not set properly, or the vessel could drift if the conditions change.

The other options suggest either too short or too long of a rode, which could compromise the effectiveness of the anchor and the safety of the vessel. Therefore, adhering to the seven to ten times rule is highly recommended for reliable anchoring practices.