The answers are in this forum, many times over. Be sure to read over
http://fksa.org/showthread.php?t=2278
There is Tiki Beach, Neil Hutchinson's designated launch in south Ft. Lauderdale. More about that area at:
http://fksa.org/showthread.php?t=1981
Be sure to not come within 100 yards of the guarded beach and see Neil, Chris or someone at the concession stand to discuss restrictions before rigging and launching here.
Then there is a small area north of Dania Beach fishing pier. Do not ride closer than 100 yards from either John U. Lloyd Park to the North or the guarded beach to the south of the pier. You should give good leeway to the pier itself to avoid getting hooked by fisherman that may intentionally try to snag you.
Then there is Mead St. in Hollywood. This area is restricted on weekends during the season and on crowded holidays. Do not come within 100 yards of shore to the north or south of this narrow designated launch.
There are other smaller launch areas near Bakers Haulover Inlet and around 87th St. in Miami. The same rules apply, DO NOT come within 100 yards of shore in guarded areas.
There is still more info about these launches in the archives of the forum that can be found by running searches.