In 2016 I called the factory for bottom paint recommendation. Ronnie Gonzales told me the factory uses SeaHawk AF33 as Curt also stated. If you have had good service from the paint that was applied I would stick to it. It is better to over coat (in like kind products). I just repainted my C26 for the first time.
I painted the bottom in 2016 with 3 barrier coats and 2 anti fouling ( Pettit Vivid). The barrier coats are optional and only done at first bottom paint application or after a soda blast. I used 1 gallon of paint for two coats of paint.I would estimate a minimum of 1.5 gallons for the R31. The Vivid is applied very thin for a smooth finish. I believe this would be true with the AF33. I use a 3/16 Nap foam roller that is solvent resistant. 9" for major areas, 3" for prop tunnel, transom, and strakes. 1" for thruster tunnel and all the small hard to get area's and a 1.5" brush. I recommend using a paint thinner that the paint manufacture specifies for the bottom paint you are using. I thin a quart at a time.It will roll on smoother and easier if thinned. Hull preparation is key to longevity of the paint and reduces build-up of old pant. After the bottom is pressure washed thoroughly and dried I sand the complete bottom using a orbital DA sander. 80 grit paper, scuffing the bottom to get good paint adhesion. After a complete sanding I wash the bottom with soap and water lightly to remove any sanding dust. let dry, apply the first coat. Paint hard to get areas first then strakes, complete using the 9" roller. I give 24 hour dry time before second coat. All water line areas to chine I will three coat them.
The sanding process is a messy job. I did it in a storage building with boats very close by. To eliminate bottom paint dust which gets everywhere when sanding I set up a inexpensive vac system.
Inexpensive sander with hose attachment very light but it did a good job scuffing the bottom I used 80 grit paper
https://www.boschtools.com/us/en/boscht ... k-29195-p/
I mounted this on a 5 gallon pail with a lid. I attached my wet vac to the cyclone. The 5 gallon pail was 1/4 full of dust after sanding the bottom. There was little carry over dust to the wet vac bag filter. The fine dust will damage wet vac motor bearings similar to dry wall dust.
https://www.amazon.com/gp/product/B07XL ... UTF8&psc=1
This hose attached to the cyclone and to the sander. I wore a mask and
https://www.amazon.com/gp/product/B00OB ... UTF8&psc=1. The white coveralls. The dust on the suit ,the ground and boats around me was minimal to nothing. I had $120.00 invested in the setup and it was well worth it.
I paint all metal hardware that is in the water. Thru hulls, thruster housings, rudder, trim tabs, swim platform support brackets, keel shoe. All are primed with metal primer as a barrier coat and then painted with anti fouling. If you paint the engine, generator and air unit thru hulls make sure that there is no build-up of paint that can obstruct the water flow the pick-ups are marginal at best so any reduction in flow area may reduce cooling.
Good Luck with your haul out.
