Anchor Chain Length for Bahamas

[nial]

Towards the end of this year I hope to take my Flicka from Florida to the Bahamas. I need to get an all chain rode but want to get the shortest length that will do the job. 100 ft. of 1/4" grade 40 weighs 75 lbs and my anchor is another 25 lbs. so I'd like to keep it under 150 ft. if that's good enough. I'll get whatever is necessary to be safe but I don't know what anchoring conditions will be like so could use some advice. Thanks.