Steve,
Oh OK, I've attached a picture of the worst bit - that is expected then?
Hmm, that's particularly bad, attached is what I get when using multipolygon (and my h v patch). As you can see, not bad at all. Zooming in and out doesn't make it change very much.
I took another look at the NZ maps on your suggestion and there are indeed a few artefacts there which look similar. Interesting. If there is no obvious reason, then reducing the number of sea polygons would be a good idea I suppose.
Perhaps, but when there is a lot of islands, you are always going to get a lot of sea polygons. That is one definite advantage of using generate-sea=polygons because then you only get one polygon per island and one sea polygon per-tile (obviously, these may be split if they are large). Mark
