The quickest way to start a brawl is to walk into a bar full of sailors and yell:
Who believes that chain catenary improves anchor holding?The fight usually breaks into two opposing gangs: those who believe that having a lot of chain on the bottom increases holding, and those who have actually observed an all chain rode being pulled bar straight in strong winds who cry "bullshit". But the reality is much more nuanced, and understanding that can help us anchor more safely...and avoid bloody noses in bar brawls. Let's turn our attention to the former: how to use catenary to help us anchor, and when not to rely on it.
The Governing TheoryFirst off, a bit of theory. I'm sure most of us know this, but it's worth revisiting, because it's the basis of everything else I'm going to write about:
With almost all anchor types, both ultimate holding, and speed and reliability of setting, increase as the angle of pull, when measured against a horizontal line, decreases.(By the way, Danforth-type anchors, including the Fortress, are, as far as I know, the only exception to the rule. They set better if the stock is lifted off the bottom a bit.) Let's leave ultimate holding out of it for a bit (we will come back to it later) and focus on setting. There are three ways we can decrease the pull angle and thereby help our anchor to set:
- Increase the scope.
- Increase the catenary.
- A combination of both.
A Lesson LearnedAbout 20 years ago, we changed from a CQR to a SPADE anchor, both set on 7/16" (~ 11mm) G40 (high test) chain. The new anchor worked so well that we got a little slap happy about our anchoring technique:
- Drop anchor.
- Let the chain run to 5:1 scope before putting any load on it.
- Wait for the breeze to straighten the boat out.
- Back down hard to set.
- Have tea.