Just wondering how to test for a leaking fuel tank. Sometimes I notice a slight fuel smell in the cuddly cabin of my boat after a trip back to the dock, other times I don't smell it. I'm hoping it's not a leaking fuel tank. I have never noticed any fuel in the bilge of the boat though.

check that the fuel tank vent hose hasn't come off and is venting inside the boat.

Also check the clamps on the fill hose. I was getting a strong fuel smell in my cabin of my Pantera.
It ended up being the clamps on the fill neck were very loose. Of course I found that out after pulling out the floor in the boat.

Just buy a "T" fitting to go in line at the vent tube. A cheap air pressure guage and your all set. Very LITTLE air! If it loses air obviously there is a leak. Soapy water around all areas you can get to. If it's not visible you are going to have to get way more involved.

a plugged tank vent will also force it to vent by pushing gas out the fuel hose till engine floods a little. or it could find a small vent leak up top like a hose fitting or fuel sender flange. gas is pretty fragrant. you don't need to be pumping it out with the bilge pump in order to smell gas. but if you see pretty rainbows when you turn on the bilge pump, you do have a problem...

I only smell it every now and then. And on my formula you can't see really any of the tank but the last maybe foot in the bilge..I'll have to check the clamps. But the problem is there is no real access from the bilge to the cabin. So how am I smelling it in the cabin?

Find the tank vent thru hull fitting. I had a wasp build a nest in mine and plugged it solid. The area around the tank is not sealed between under cockpit and under cuddy. A breeze can blow in cockpit and push fumes into cabin thru the floor.