What kind of craft will you be using? How safe do you want to be? Going out in the ocean in a 16 ft rowboat has a different safety
margin than in a 60 ft Oyster
20 miles in a 40 ft sailboat is about 2 to 3 gallons of fuel
on a calm day. Doesn't seem like much fuel.
Did you go online and check where the bank of the Gulf Stream
starts? Did you check the route
on your marine
chart for sufficient depth
. Did you check the marine weather
report for wind
and waves? Did you check the route
length wrt to average boat speed to estimate time in route?
Do you have sufficient safety gear
onboard in case of an unexpected weather
IMHO these are some of the basic steps that you would need to know how to do before heading out in the Atlantic Ocean
and executing even just a day passage