> In calm conditions wouldn't the joint of the bridle and chain often be sitting on the bottom?
It's a rule
of thumb rather than an ironclad essential.
= greater load on bridle attachment points because of the angles involved.
Longer bridle = more likelihood of it grounding in shallow anchorages
in light conditions.
You don't want the bridle on the bottom, but you also don't want high loads pulling the bows inwards. If you anticipate high anchor
loadings then the bridle legs should be at least
the width of the hulls. If it's a lunch hook in a shallow bay with only a few knots of wind
, you can snub the bridle up so that the angle off the bows is only about 45° rather than the 60° that 1:1 will give you.