Now that we are officially boat owners and we have a boat at a marina, we spent a Saturday a few weeks ago at the dock doing an inventory of the items on board AND swimming off the back of the boat like other folks in the marina. We had a great day and learned more about our boat.
The very next morning, while surfing my usual nautical sites, I read a post about the dangers of marinas and electrocutions! At marinas that provide shore supplied power to boats, there is a real risk of electrical current running in and around the marina in the water. The issue is that not all boats do a good job of keeping their current only in/on their boat and many boat owners don't know they are leaking electricity. Meanwhile, the marina power supply posts continue to happily pump out as much current as is being requested.
There are ways to check to see if there is electrical current in the water (basically, attaching one lead of a a voltohm meter to the power supply post and the other in the water looking to see if there is current).
There have been a number of deaths attributed to this risk, including a 9 year old boy of a boating safety instructor.
One would imagine, with the conductive properties of salt water, that the risk is even greater in a salt water marina.
The advice I read about this issue is, if you are in the water at a marina and you feel a tingle, back away slowly (don't turn and bolt, that will disturb the current flow and could potentially make it worse). The best advice, of course, is to simply not swim in a marina. We will no longer do this.
Remember, you may feel good about your boat, but who knows about the other boats? Simply don't swim in a marina.