There are a couple of places. Most of the marinas cater to boats passing through and are expensive for long stays. Marlin Marina (242-393-7873,4) in the harbor is pretty cheap. It's just a bit east of the Paradise Island bridge and very close to a decent sized shopping center. It's pretty much a working marina that doesn't cater to short term rentals but will take longer term deals. Lundy, the dockmaster, is a great guy and also happens to be the Bahamas sloop champion in several classes. One of his boats, Silent Partner, is the boat to beat in the Bahamas. He could probably hook you up with someone to look after your boat. I was paying $400 a month for my 41 footer two years ago. I left my Pearson 30 there unattended for about 8 months each year for several years and had no problems. It is rather exposed, however, to the wakes and tides of the harbor. If you want to be near Nassau it's a pretty good deal if you don't mind a place that's kind of down and dirty.
Right now I'm keeping the boat in Coral Harbor, which is on the south side of the island and a bit out of the way. It's a well protected canal community, kind of like Ft. Lauderdale without the infrastructure. You pretty much need a car if you're going to do much on the island. There is a grocery store a short walk away and you could stay there for a while without wheels if you're not being a tourist. I'm behind a private home that is 'the marina that isn't a marina'. The owner, Nick Wardle (242-362-1574), keeps a close eye on the boats. He runs the engine and generator when I'm away and checks the boats regularly, including hurricane preparations as necessary. Nick runs the morning cruisers net and hosts the Thursday cruisers luncheon at the Green Parrot. Nick's a bit pricey but he is diligent and I feel that my boat is safe. His current rate for 40 to 50 feet is $500 per month plus electricity ($7 per day) and water (city water fill or washdown $5, Rain water $.40 per gallon).
I found another dock in the same area and spoke to the guy. I don't know rates or amenities but his e-mail is email@example.com
. His name is Caius St. George (242-362-0630).
That's Nassau. Bimini has several marinas but I have only passed through so I don't know about longer term deals. There are some other places where people have left boats in the Abacos but I have no personal knowledge of them. If I can get any other info please let me know.