Fantasy Galleon

[Midgardsormr]

The trouble is that it's got a very pronounced contrast between bright and dark, which makes the tiling obvious. You might be able to disguise that with an additional texture of a different size blended into it... Perhaps a clouds render out of Gimp would do the trick. Try adding another sheet filled with the attached texture, and give it a transparency effect to taste; 15% is where I'd start. The texture is 700 X 700, so it shouldn't line up with the existing water, and should therefore break up the obvious repetition (I hope).