Here is one possiblity:
New England Aquarium Dive Club - About Our Club - Who We Are
The NEADC often does club dives at Ft. Whetherill or at Beavertail.
And another possibility:
ScubaBoard - New England Lobsta Divahs
Plenty of RI divers in this forum and good info on local sites.
Or, you could send me a PM when you get your dates nailed down. I've done some diving there this winter but have never gone in the warm months.