To anyone who interested to use Landable Spawn points in his terrain.
I have used them in Kadesh - they are actually deports - that was spessially build and placed at water.
it includes 4 objects:
lake - void - non collidable - testure should be half transparent (very important)
entry - tower - alt of 10-30 feets - view point for tower
entry - hangar - alt of 10-30 feets - view point for hangar
entry - boat entry point - to spawn boat.
all this will make field (deport) that will be landable for boats and will be visible like lake.
if anyone needs original file of group I have used
mail me and I'll send you back the original file and half transparent texture (if you need) .