Paul is right! I'm not by any stretch a Civil War expert, but, I would assume the Hunley would have been primarily off the coasts of Virginia, the Carolinas, Georgia and East Florida. The Atlantic coast is typically a darker, dirtier blue gray color than off the Gulf coast which can be as light colored as aquamarine blue. Sometimes in modeling, we have to leave our preconceived notions that water is transparent behind. When you are swimming in it, it is transparent and glossy. With model ships, the scale effect is from the air as you are viewing it as you would in real life from above as in a plane. Considering that, hardly any water is transparent from the air except perhaps swimming pools and very shallow rivers and canals and some coastlines very near the beach. In the Atlantic, fairly near the coast, the first photo above would likely resemble the water surrounding the Hunley, possibly even more calm than that.
Even deep rivers such as the Mississippi, Missouri, Ohio and Columbia are not transparent from the air and they are not glossy. Most bodies of water are only the color of the sky being reflected off the surface of the water. The texture and turbulence is determined by the wind. I have seen clear resins used to a nice effect, but never when the ship model is in the water and will be viewed from above the surface. I've seen it most effectively used when under the surface with a sunken ship or a U-boat that is under water and things such as that.
I rarely get into these discussions because there are so many ways to create illusions in modeling. Modeling is an art, not a science. As sure as i tell you that the Cell-u-clay and oils are the only way, or even the best way, some clever, imaginative somebody will come along and prove me wrong. What I love about modeling is that the rules can always be broken using imagination and/or creativity. Nothing is ever etched in stone!