Advantages:
better / easier trim and set possibilities, especially with regards to
'flattening', etc. .... In constrast to a 'shelf foot' main which is
limited by the friction of the sail slugs.

A loose footed sail will not have a bolt rope (three strand dacron rope
inside a sleeve) on the foot section ... therefore will be more
dimensionally stable with respect to long term shape .... boltropes
need periodically to be 'eased' / adjusted / lengthened by a sailmaker,
etc. A loose footed mainsail has a 'taped' foot more dimensionally
stable but cannot be adjusted when the dimensions 'stretch' or 'go'.

Cheaper to build.

Disadvantages:
Needs a 'good' / convenient outhaul control ... because you will use it
a lot because you 'can'.

In article , prodigal1
wrote:

Looking for opinions about these as we're about to replace the canvas on
our 40 year old sloop. Advantages? Disadvantages?