You got a sweet deal on that.
I've done a lot of research on painting aluminum and Chassis Saver and POR-15 are some of the strongest, most abrasion resistant paints you can buy. They both have a silver paint color option. Chassis Saver is significantly cheaper. Both of these paints are near impossible to get off your skin and start to cure as soon as they are exposed to air/moisture--instead of opening the can, poke two holes at opposite ends of the lid, pour the amount needed in a tray, then cover the holes with silicone tape. Make sure you are protecting your skin, eyes, mucous membranes, mouth if using these products.
If the old boat is rusted significantly, you can just paint these directly without primer/etching/sanding. If there is original paint intact people recommend sanding and etching first. These two products do not bind as well to clean bare metal.
Good advice in this video
Abrasion/chip resistance shown in this video
With any paint, the results will depend greatly on the prep quality
Chassis Saver Instructions:
GENERAL SURFACE PREP: If dirt, grease or oils are present,
clean surfaces using a quality commercial water base
degreaser. For heavy build-up of grease, oil or road tar,
scrape or wire brush excess material prior to degreasing.
Allow surfaces to dry thoroughly.
RUSTED SURFACES: Remove loose rust and scale using a
stiff wire brush, by grinding, or hand tool cleaning. Remove
all loose, peeling or bubbling paint. NOTE: Chassis
Saver works best over rust. Do not over remove rust.
Chassis Saver needs to �bite� into a rough, rusty or well
scratched surfaces for proper adhesion. Use of �rust converter�
products should be avoided as they may affect
bonding of Chassis Saver to metal.
BARE, SMOOTH METAL: Clean, smooth or new metal surfaces
must be roughened prior to coating. Sandblasting is
recommended but manual sanding with 60 or 80 grit sandpaper
is also acceptable. When blasting, provide a medium
to coarse profile for optimum adhesion. Avoid the use of
glass, plastic or walnut shell blast media as they leave surfaces
too smooth.
ALUMINUM: Chassis Saver does not adhere well to bare
aluminum. Prime with a quality 2K epoxy primer or 2K self
etching primer. Do not use 1K self etch primers. It is advisable
to do a test area first to check adhesion.