We have lots of sharks in Hawaii, but seldom see them and there are less attacks as the sharks tend to stay deep and have a lot to eat. Most attacks occur in the boat by a shark upset after having his meal taken away and being pulled out of the water. The ones that live on the reefs are beneficial and are seldom a threat. It is the pelagic one's that are dangerous and responsible for most attacks. Tiger sharks are most apt to hit boggy boards head on as they look like turtles, especially when the surfers are wearing small feet and hand fins. Also short boarders occasionally get munched on as they are deeper out and often have limbs dangling in the water.
Florida is a very different situation as the shallow waters are over fished and sharks come in shallow to feed and breed. I would say that bull sharks would be the most dangerous as they can swim up rivers and attack. Next would be tiger sharks as they are unpredictable and will eat most anything. As a hammer head has small cat like teeth, they will do the least damage, and you and shark can be pulled back to shore if it does not let go.
A small spinner or black tip would most only be a problem if they were excited by what you stirred up with your scoop. I hunt in a shallow protected lagoon and usually have several large fish follow me while detecting to snatch what I stir up.
I have not heard of any detectorist being snipped by other than a small shark (most likely accidently). I suspect that the larger sharks would stay away as they sense electromagnetic fields and are sensitive to noise. If they were attracted to the sounds, you would hear of a large number of detectorists being hit by shark.
If you treasure hunt, where there are a lot of sharks, I would be extra cautious at sunrise and toward sunset and evening as that is when they mostly feed.
(Just kidding.)
