Interesting subject I have found different brands different rollers and different people all get different coverage per Sq Meter .And the second coat takes less than the first .
I tint the first coat darker so it makes it easier to see the coverage on the second coat then on the third coat you can pick up where u may have missed when the paint drys
Most paint manufactures suggest 400 sq ft per gallon of hard bottom paint at the recommended film thickness.
A boat your size should take about 1.5 gallons per coat. I think there is a tendency to put it on a little heavier than the recommended film thickness.
Use a short nap roller to avoid putting it on too thick.
Both Pettit and Interlux have paint quantity calculators on their websites.