Noise Reduction in Cycles Water

I rendered this image at 1000 passes

As you can see there is quite a bit of noise in the water below the ship. Having read Brecht’s article on Noise reduction, I can imagine where this comes from. I have however no clear idea what I can do to improve the result.
I use the sky shader for the overall illumination and an additional plane to simulate my sun. This plane is quite a distance away from the model and has a high intensity (~1000). I checked ‘No caustics’ to avoid fireflys.
As the water surface is relatively calm I might be able to reduce the light bounces as the water is the only reflective material and for the most part does not reflect on itself.

Try increasing the Clamp… eg: 0.1 - 0.5
Render > Integrator > Clamp

I tried a bit with fiddling the settings. All Renders are 200 passes:

That’s the original render only with 200 passes and no clamp

Clamp setting of 0.1. As you can see the image looses contrast. I think I would have to increase the strength of the light source. But would that not also increase the introduced noise?

Clamp setting of 0.5. This one has more noise than the previous one, but about half as much as the original. Also the color saturation is much better here.

Just render more samples. A scene can potentially take many thousand samples to fully converge. Clamp is intended to reduce fireflies, not noise in general, and it’s a rather crude hack anyway.