Given the interest in the previous painting tutorial, I figured I could also share the traditional hellenic way for trireme basing. I will merely copy-paste from an ancient carved stone text by Thestikolos of Rhodes that I have in my library, which explains everything.
"For this method you will need the following stuff: the Vallejo product called Water Texture (there are several iterations, but you want the Mediterranean of course), a spatula, a common kitchen sponge and a painted base.
Painting the base with a base color is the first step. You can already experiment here a lot, because the color you choose for the base will have a great influence on the final result. See below the three test bases painted, respectively, with a very light blue, a medium blue and a dark Prussian blue. All three are made with the same Water Texture!
Personally I like using Vallejo Medium blue because it's deep enough to look like open sea, but not too dark.
When the base color is dry, use the spatula to generously cover the base with Water Texture. Use wide, regular, horizontal strokes. The texture feels like very dense paint and it's easy to apply. Cover the whole base and do not let areas without product. Don't worry about being precise, and don't worry about the colour - it looks very different when fresh.
Immediately after applying the Water Texture, you want to "sponge" it. This will give it a wavy look when dry. Simply press the sponge gently on the base: just press it on it vertically, without swishing the sponge around.
After that, apply the ships directly on it. No glue necessary: it is sticky when it's fresh. Now you want to leave it alone for the night, to make sure the Water Texture is properly dry before painting.
The next day you will finish. First, apply a thin line of very light blue, starting from the prow and going down all along the hulls, to do the water moved by the ships. Do not be precise, actually use the tip of the brush and just follow suit the hulls. It will automatically conform to the texture of the waves. Use a very light blue so it contrasts nicely with the wine-dark sea. Let the brush spend all the paint from prow to stern, so that it is more charged at the prow.
When this is dry, you can add the white for the wave crest, directly over the light blue. Even here, just use the tip of the brush vertically over the base and let it move along the hull until it is almost without color at the stern.
Even for this, do not worry about being precise, covering completely the light blue or not. Actually, on the contrary, let the brush tip flow naturally.
Make sure to tip the point of the brush vertically a little bit behind the ships, to paint a proper wake. Do 3 wakes - left and right oarage and hull. Remember that these are probably going at some 7 knots so do not exaggerate!
Finally, do not forget to sacrifice a goat to Athena to thank her for the support".