3:1 is fine for all chain rode for average / light conditions. As
always, more is usually better with wind, etc. Remember to count the
height of your anchor roller above the water in your calculations for
depth. Mine is 8' off the water. Make a real difference! As far as how
to anchor, usually do what everybody else in the anchorage is doing. If
they are Bahamian moored, you probably should to. If everybody is
single, stick with that. Hopefully everybody will swing together, and
if you anchor differently, there may be some "bumps in the night". Of
course, if everybody is stupid and anchoring wrong, get away from them
and do it right! :-)