In my 20 years of crossing to Bimini, I have experienced all varieties of conditions. I always aim for a safe crossing but also for a fast & comfortable crossing as well. There is nothing better than crossing when the sea is flat as a lake. I've even seen a group of people crossing in jetskis (WITH AN ESCORT BOAT) during these conditions. However, I have also made a huge mistake in crossing in 4+ foot waves that messed up my boat, made passengers sick and extended the crossing by a full hour and a half.
The most treacherous part of getting to Bimini or the Bahamas is crossing the Florida Gulfstream, just beyond the reef. The most reliable tool I've found to tell me what the conditions are for the crossing is the free FishWeather Mobile App [ iOS Android WebApp ]. Like any weather forecast, it is accurate within the next 12 - 24 hours or so and the longer range forecast is constantly changing. It is critical to know the wave heights you will face when crossing the Gulfstream and the direction of those waves. Local TV weather forecast is never this detailed in marine forecast so don't just rely on the weatherman. Bimini Bay Resort has its own weather station device for very detailed weather conditions but it does not indicate marine waves or conditions.
As a general rule, I do not cross the Gulfstream when the waves exceed 2.5 feet if I am crossing with passengers, 3.5 feet if it's just me and seasoned mariners. 4 foot waves or greater for vessels smaller than 70 feet (except Sport Fishers that cut through waves with deep V hulls) makes for a very rough crossing. Wave heights on this app has on occasion been 1/2 to 1 foot (more or less) than the app indicates so if the heights indicated in the app are within this margin of your wave height tolerance, then its advisable to head out and check the actual conditions to see if they are tolerable to you and your passengers.
NOTE: The wave heights vary along the crossing when they are greater than 2 feet. Typically, you will see lower waves along the Florida coast and then suddenly taller waves beyond the reef that runs along the Florida where the ocean drops from 100 feet to more than 500 feet where the Gulfstream's warmer waters mostly flow all the way to Bermuda. When you approach the deep reef, you may find a change in wave height and wave direction which then persists for the rest of the crossing with occasional large swells that make your hull go bang. Then as you approach Bimini a few miles out (right about when you get cellphone signal) you may experience smoother conditions as the wave direction changes towards Bimini making for following seas. This is mostly noticeable when the waves are between 2 - 5 feet. Beyond that it's just rough...