Chopped from a previous article I've written...JH
Acrylic gel medium...Acrylic gel medium is available from any art supply store. I prefer the clear, but you can experiment with different colors. I prefer the Liquitex brand, it comes in a large toothpaste-like tube, and has the consistency of toothpaste. The method of application is the same whether you require a smooth surface or choppy, rough seas.
I start by painting the base an overall flat blue-green. I then glue the hull of the ship to the base, and build the model, using the base as working platform. This wworks out real well, as it prevents my handling of the ship itself, and eliminates my big fingers crushing the PE and getting fingerprints on the model. Once the model is completed, I touch up any areas on the base with the blue-green base. Depending upon the ship, I sometimes mask the side of the hull with blue low-tack masking tape, this prevents any gel medium from getting onto the hull. Squeeze a small amount of gel onto the base, and even it out, leaving enough gel to cover the base surface. Work the gel up to the hull of the ship, and around the bow. A little heat from a hair dryer will speed up the process, the gel will turn an opaque white, like half-dried white glue. At this point, go back and reapply gel to the areas you want to build up, bow waves, wakes, etc. Go after the gel again with the dryer until it turns opaque white. If you desire rough, choppy seas, stipple the gel with a flat paintbrush. If you get the gel on the hull of the model, it can be removed with a cotton swab and some rubbing alcohol. For heavier seas, you may have to go back and repeat the last few steps over until you get the desired results. Gel can be built up upon itself as many times as you require. With repeated applications of gel some dramatic effects can be achieved, such as bow waves and heavy seas.
Once the gel has dried and stippled to your liking, it’s time to start painting and drybrushing the water. Apply a thin coat of the blue-green base coat to the top of the gel, dry-brush a lighter blue on top of the base coat, then drybrush a blue-white or green-white (depending on which ocean you’re in) along the tops of the waves, the bow wave, along the hull, and in the wake. The amount of white you add is obviously proportional to the speed you ship is making. A lot of white along the hull and wake implies you ship is under way, while little or no white implies your ship is either at anchor or all-ahead-dead-slow... I recommend experimenting with this method and developing your own preferences. Once the gel is dried completely, drybrush the 'water' with clear gloss or Future Floor Wax to give you the shine effect.
The beauty of gel meduim is its ease of application, the ability to build up layers, and the lack of odor, heat, and its ability to take paint. It's is easy to use, mistakes are easily repaired, it dries rock-hard, isn’t sticky like resins, and is relatively inexpensive, with a single tube costing $10-$15. Once tube is enough to do anywhere from 5-8 1/700 ships with average size bases, depending on how crazy you decide to get with your waves, etc.