John is correct - a 6-1/2 foot draft suggests that a grounding is very likely somewhere on the ICW.
The “authorized” project depth (MLW, or at low tide) of the AICW is:
~ 12 ft from Norfolk, Virginia to Ft. Pierce, Florida
~ 10 feet from Ft. Pierce to Miami, Florida
However, shoaling and silting have reduced controlling depths, in many (changing) locations to as little as five feet (or less), and other underwater obstructions further complicate safe navigation.
Notwithstanding the likelihood of grounding (somewhere on the ICW) with a 6.5 draft, such groundings are not usually ruinous, and should not altogether preclude a safe & enjoyable transit from Nofolk to Miami.
See the Atlantic Intracoastal Waterway Association website:
Atlantic Intracoastal Waterway (AIWW)
and
ICW Channel Conditions:
This report only lists areas less than 8 feet in depth at mean low water.
ICW Channel Conditions