Yes this is inconvenient aspect of TG's current renderer. The backface culling or clipping, whatever it is named, isn't that advanced yet so the renderer can't decide/predict really accurate where to render the water and where not. It is performed during rendertime.
A work-around which works for me is to create a new camera and raise this above your scene and make it face down 90 degrees to your render camera. Set it up so that the render camera and the edge/shoreline where you want your water to be are visible in the preview.
Go to your waterobject and set the translation coordinates the same as your rendercamera and decrease the radius of the waterobject. You can measure the desired radius roughly by using your mouse in the preview window.
You'll see that the default radius is way too big for your scene.
Set the radius just a little bit bigger than is necessary just to make sure it reaches the shoreline in the whole image.
Keep in mind that it is circular and that on the far left and right side of the image the waterplane could not be visible. It is then a matter of putting the translation coordinates of the water object a couple of hundred meters behind your camera and increase the radius of the waterplane.
You now have essentially created a much smaller waterplane which just fills your area of interest without having it to render throughout the horizon
If you need any help just PM me...since I'm dutch as well this wouldn't be too difficult
Martin
