Crack in gas tank

Get rid of that tank !------Or put a parachute on while out on your boat.

First the silicone probably isn't fuel safe.
Second your riding around with a BOMB in your bildge!!!
Replace asap.
Use NO drills of any kind or any power equipment.

In the late 80's a dealership in Glen Burnie, Md.
They took in a boat that had been rehabbed and was leaking gas.

They trusted their newest guy to repair.
He started to remove the carpet and flooring.

BOOM!!
The tank had been drained as much as possible yet in never really gets it all.
The vapors ignited when his portable drill was used.

Burns, 80% of his body.

Even static electricity canj cause a BOOM.

Water getting into the tank will be the least of your potential problems.

Awe come on guys need more info to make an accurate judgement. Mike, you got any pictures? How old is the tank, what caused the crack, and is it exposed to sun? JB Weld makes several products to repair plastic, I've used them with great success. I weld fuel tanks, when necessary precautions are taken, there is no risk. Only blew up one tank in all the years and I was still able to repair it anyway.....kinda scary, however. Have you ever used starting fluid to "catch a stubborn tire bead". Might be a video so you can see it in action, if not, I'm gonna make one next time.

No need to make a video....there are over a dozen on youtube
https://www.youtube.com/watch?v=_aejvCjVvWI

You can also use a rope and a dowel to make a temporary "Tourniquet" to expand the bead.

As to the cracked tank...we sometimes get careless with gasoline....I have visited a "Burn Unit" at a hospital and think about that every time I use gasoline. Gasoline burns are extremely painful and destroy the skin. The skin fights infection and when it is destroyed by burning, victims quickly die from infection. Gasoline is extremely dangerous and some people who work with it every day sometimes minimize the danger....that can be deadly mistake.

Great advice Bobby, thanks. Most certainly the dangers of petrol are often underestimated. Just yesterday as I was trying to start my 49 Chev truck the carburetor overflowing and spilled right down on the hot exhaust. Got lucky as I wasn't watching I was inside the truck, but when it continued to misfire, I shut it down. Previous owner had done a quick carb job......terrible work.