Yawing and Its Impact on Anchor Holding Power
As wind strength increases, the windage of the yacht largely determines the tension on the anchor rode. This tension will be similar whether using a large or small anchor—assuming the anchor is appropriately sized for the yacht. If the tension surpasses the ultimate holding capacity of an undersized anchor, dragging will occur. However, with a sensibly sized anchor recommended by the manufacturer, dragging is highly unlikely.
For example, a well-designed 15kg anchor, such as the Spade or Viking models, can generate an impressive holding power of approximately 2,000kg in clean sand seabeds. In reality, most boats will never experience rode tension approaching this limit. An 8mm G30 chain begins to stretch at around 1,500kg tension, which is typically far beyond what the anchor force will reach.
For further context, tests on a 45-foot production yacht (like a Bavaria) show roughly 650kg of rode tension at winds of 35 knots—substantially below the 2,000kg holding power of a good modern 15kg anchor. While wind gusts of 35 knots or more are rare during anchoring, they do occur. Still, there is no practical need to oversize your anchor beyond manufacturer recommendations. Oversizing may cause handling difficulties or other self-inflicted issues.
Research indicates that deeply set anchors resist yawing forces much better than shallow set ones. Interestingly, larger anchors can be harder to set deeply and thus may be more prone to dragging during yawing. Yawing is not limited to yacht design; it is influenced by external conditions, including veering winds caused by geographic features or gaps in surrounding terrain.
A useful analogy is the yawing motion of an aircraft landing in strong winds—its movement shows how wind direction can vary, just as wind shifts affect boats at anchor. Understanding how yawing impacts anchor holding is critical for safe and secure anchoring.
Source: Practical Sailor
https://www.practical-sailor.com/sails-rigging-deckgear/yawing-and-anchor-holding
"If your boat is yawing less than 30 degrees, don’t worry about it. When yawing approaches 60 degrees in a breeze, which seems to be the average of interviewed boat owners in windy conditions, rode tension increases by 30-60 percent, anchor holding is decreased by 0-55 percent, and your safety factor is reduced by 20-64 percent, depending on bottom, rode, and anchor type. If you can reduce yawing to less than 30 degrees with a riding sail, bridle, or other adjustments, that’s like doubling the size of your anchor. If the boat is yawing 120 degrees—not that unusual among boats with rope rode—rode tension is increased by 100 to 200 percent, the anchor holding capacity is reduced by 20 to 85 percent, and your safety factor is reduced by 72 to 92 percent, which coincides with the failures we have repeatedly observed. It’s impractical to carry an anchor large enough to hold such an unruly boat in all conditions, so you really need to do something about it".
In severe weather, use a bridle.
https://www.youtube.com/watch?v=3wLrcT3oSZg
