I just bought an older wenonah ultralight sundowner that was painted many years ago with autobody paint. That paint held up well, actually. But it's ugly and I want to repaint it. After sanding, what product would you all recommend?

I'll also be sanding and varnishing the wooden gunwales. I think it'll end up beautiful.

Why re-paint it? Some might argue that depending on the condition of the hull you should roll & tip some epoxy and/or varnish (or both) on it.

You will want to buy a topside marine paint and a primer that is compatible with the paint. Topside paint is just that, marine paint designed for use on a boat where it is not submerged for weeks at a time.

Here is but one example.
Topside paint

For your gunwales you can use either linseed oil such as Watco oil available everywhere. I prefer oil as it has a more natural finish and brings out the beauty of the wood. Or you can use spar varnish which is made for outside use.

That black canoe doesn’t look all that pretty as is is now.
Tom

I like to paint canoes. I have been doing it for years. It spruces them up. It provides UV protection. It covers up repairs, fading, and everything else.

You can use fancy epoxy paint, fancy marine enamel, oil based porch paint and even gloss or semi-gloss latex house paint. I have used all of them. Recently I tried Rustoleum oil based marine enamel and like it a lot on a dark green OT Canadienne in kevlar. The boat looks new.

I've painted a couple of canoes and presently have a 12' motorboat painting project going.

There are two choices:
1) You can use a two-pack paint system, which is more expensive, more toxic, but much easier to apply, requires less sanding, and will last longer and have better gloss. These involve a primer and topcoat, each of which comes in two separate cans that have to be mixed in the proper ratio right before application.
2) You can use a one-part alkyd or urethane paint, which is cheaper and more straightforward, but you'll have to sand after every coat and it won't last as long.

Awlgrip and Perfection are examples of two-pack paint systems from different vendors.

One-part paints, you can use porch floor paint from Menards or you can use a marine paint like Brightside. Costs are similar and results are similar with the marine products being a little easier to apply and a little more expensive.

With two-pack paints you have to apply the topcoat outside or in a very well ventilated area (garage with the garage door open e.g.) and use a half-face respirator and gloves, because they have isocyanates in them which can lead to serious allergic reactions with the effects being cumulative over all the times you work with these products.

The other drawback of two-pack paints is that they use a solvent system that will react badly with any existing one-part paints already on the substrate. If as you say the canoe was previously painted with auto-body paint it was probably a two part paint so you'll be fine with a light sanding, but there's no good way to tell for sure. Some people see if acetone will soften or dissolve the paint, if it is two-pack it won't.