Before you try to wetsand and buff it out, contact Petit to make sure their paint is compatible with that. I used interlux perfection, and if you wetsand and buff perfection, you will end up with a dull boat.
I didn't see any primer on the boat before you painted. I will be very surprised if Petit doesn't recommend using an epoxy primer first.
I was able to get a finish better than my neighbors spray job by using the roll and tip method. Preparation is key of course, and you may not want to put the effort into your paint job that I put into mine. Here's the play by play.
1) go over the boat with a fine tooth comb to find even the smallest ding or scratch and mark them with a pencil.
2) repair dings and scratches with epoxy filler. I used west epoxy thickened with microballoons. Sand filler with 80 grit on a flexible longboard.
3) repeat steps 1 and 2.
4) apply 1st coat of primer.
5) wet sand primer with 320 wet/dry. Use one of those handy squeegees for wetsanding (3M makes them) to find out when you have the area perfectly level, and all brush marks are gone.
6) repeat steps 1 and 2
7) Apply primer coats 2 and 3 and maybe even 4 as above until you cannot find the repaired areas to save your life.
8) Get a helper.
9) Apply 1st coat of paint. Thin the paint just enough so that the brush doesn't drag on the paint at all when tipping. It should be silky smooth, but don't over thin or it will run. One person should be rolling and the other tipping. Be very careful not to apply too much paint or it will run and you'll just waste the paint. If you don't apply enough, the brush will drag and leave ugly marks.
10) wet sand the boat with 600.
11) apply coats 2 and 3 and 4 as above, except don't sand the last coat.
If you want any hope of having a good looking paint job, you absolutely must wet sand the paint that's on your boat. Subsequent coats will not hide the brush marks in your paint.
When I painted my boat, I tried the high dollar badger paint brushes. I had the best luck with a very cheap nylon bristle brush I got at the local Hobby Lobby. The bristles were very fine and soft, and left only the lightest brush marks. Those brush marks laid down flat after about 5 minutes.