T3D 1.1 B2 - River Editor - need confirmation on Segment Length (possible bug)

On the River Editor, is segment length meant to do what it says "Divide the river lengthwise into segments of this length in meters". For some reason I have one visible gap where under water is not shown between an insertion point, however when applying a segment length to 200 for example, fills in this gap showing the underwater effect, but moving the player beyond this length of 200 shows a gap again, even when insertion points are further away. Is this length based on the overall river length or just a segment as it states?