Both of those paint jobs are beautiful.
Can someone explain to me the roller and tip method of painting?
The roll and tip method is pretty easy, but also easy to screw up. There is a video on Interlux's web site somewhere showing the method.
The roller type is important. Do not under any circumstances use a roller from the hardware store, not even for the primer. Redtree makes a good roller cover. It's an extremely thin foam roller that's also epoxy proof. This roller will allow you to apply the correct amount of paint, which isn't much.
The brush is extremely important too. Most paint manufacturers recommend a badger hair or similar brush to tip the paint. One of these brushes will set you back about 25 bucks. I didn't like the finish I was getting with my badger hair brush, so I went shopping. I found a set of paint brushes in the oil painting section of the local hobby store (hobby lobby) right next to Mr. Happy trees. They were a cheap "chip" brush, but the bristles were a very fine, soft nylon. These brushes were awesome. Almost no brush marks immediately after tipping, and those marks laid down about 5 minutes later. The best part was that these brushes come in a 3 pack for 3 dollars. I only used the 3" brush, and threw all of them away after each uses. The thinner to clean them would cost more than another 3 pack.
The roll and tip process itself is best done with 2 people. I had 3 people on hand when I painted because I was able to use a rolling scaffold. My friend would roll, I would tip, and whoever else we could get would drive the scaffold.
One of the first tricks you have to perfect is getting exactly the right amount of paint on with the roller. Too little and the brush will drag and leave ugly "chatter" streaks. Too much and the paint will run, and I'm not talking very much too much.
Roll the paint on, being careful to get the right amount of paint on. Then follow immediately behind with a dry brush to knock the roller stipple down. The brush should glide smoothly on the surface. If it doesn't, you could have too little paint, or the paint may need to be thinned a little. The brush should be held at about a 45 degree angle and make vertical strokes from top to bottom. I masked off the bottom of the boat with heavy masking paper. At the bottom of each brush stroke I wiped the brush on the paper to remove excess paint. If I didn't, the paint would run under the rub rail. If you make a mistake, or have a run, or anything else, DON'T GO BACK AND FIX IT. Odds are you'll make your mistakes in the first coat or two, and you'll be sanding anyway. Even if you make a mistake in the final coat, don't fix it. It won't look that bad after it dries, and you won't see it with the boat in the slip.