An ocean-going barge is 50.0 m long and 20.0 m wide and has a mass of 145 metric ton. will the barge clear a reef 1.50 m below the surface of the water?

Since its mass is 145 metric tons, the barge must displace 145 metric tons of water
in order to float. 145 metric tons= 145,000 kilograms.  Use the rough-but-close rule
of thumb that 1 liter of water has 1 kilogram of mass. So the barge displaces 145,000
liters, which is also 145 cubic meters of water.

(Length) x (width) x (depth of the part under water) = 145 cubic meters

Draft of the barge (depth under water) = 145 / (50 x 20) = 145/70 = 2.07 meters.

No, it will not clear the reef 1.5 meters below the surface.  Either the barge will shave off the top 0.57 meter of the reef, or else the reef will do serious damage to the barge. In any case, there will be a situation.