I did a bottom job on my IP 380 using Trinidad SR hard paint in 2015. After 2 years in Florida waters it still looks good. I sanded off many coats of old paint using an electric 6" orbital sander. I did not sand to the gel coat but did remove 90% of the old paint. Where I did sand through, I applied 3 coats of Pettit high build barrier primer.
I applied 2 coats Trinidad SR and it took 2 gallons.
Pettit has a calculator.
www.pettitpaint.com/paint_calculator.asp
Using this calculator I thought I would have needed 3 gallons, (called for 1.3 gallons per coat) I applied using a small diameter foam roller and mixed the paint using a electric drill and mixing paddle. News says Trinidad SR may be available with the biocide Irgarol. See the article Bottom Paint Update in the April 2017 issue of Practical Sailor.