Yes, you have a serious problem to resolve! Fuel vapor is heavier than air
and will settle in the bilge causing a fire risk. There are numerous
sources of sparks around the engine that can ignite the vapors. From the
manufacturer there are things to reduce the amount of spark that is present.
If a automotive alternator or starter has been installed to replace the
original, they most likely don't have the spark protection covers.

There are other spark sources too.

Look for a break in the fuel filler hose or the tank vent hose, a break in
the tank, a break in the fuel line from the tank to the engine, a defective
fuel pump or a stuck carb float allowing fuel to flow out of the carb.

If it were mine, I'd find and correct the problem then let the boat set in
the sun until all hints of fuel is gone. I'd not even consider using the
boat until this is resolved.

Don Dando