diff --git a/doc/ta4_doc.lua b/doc/ta4_doc.lua
index b2c5c43..b7e32c6 100644
--- a/doc/ta4_doc.lua
+++ b/doc/ta4_doc.lua
@@ -47,8 +47,8 @@ techage.register_category_page("ta4wt",
 		"a pillar by means of TA4 Pillar nodes (power cables have to be inside).@n"..
 		"Please note the following limitations:@n"..
 		"- pillar height between 10 and 19 m@n"..
-		"- can only be built offshore (the info tool indicates where a wind turbine can be built)@n"..
-		"- 14 m free space in all 4 directions (e.g. to the next wind turbine)@n"..
+		"- can only be built offshore (20 m in all 4 directions is water)@n"..
+		"- more than 14 m to the next wind turbine@n"..
 		"- the wind blows only between 5 and 9 o'clock and between 17 and 21 o'clock"), 
 	nil, 
 	{},
diff --git a/wind_turbine/rotor.lua b/wind_turbine/rotor.lua
index 46bd866..44b3efa 100644
--- a/wind_turbine/rotor.lua
+++ b/wind_turbine/rotor.lua
@@ -29,6 +29,8 @@ local power = techage.power
 
 local Rotors = {}
 
+local MAX_NUM_FOREIGN_NODES = 50
+
 local Face2Dir = {[0]=
 	{x=0,  y=0,  z=1},
 	{x=1,  y=0,  z=0},
@@ -48,6 +50,8 @@ end
 
 local function add_rotor(pos, mem, player_name)
 	mem.error = false
+	
+	-- Check for next wind turbine
 	local pos1 = {x=pos.x-14, y=pos.y-9, z=pos.z-14}
 	local pos2 = {x=pos.x+14, y=pos.y+10, z=pos.z+14}
 	local num = #minetest.find_nodes_in_area(pos1, pos2, {"techage:ta4_wind_turbine"})
@@ -61,8 +65,11 @@ local function add_rotor(pos, mem, player_name)
 		return
 	end
 	
-	local data = minetest.get_biome_data({x=pos.x, y=-1, z=pos.z})
-	if not techage.OceanIdTbl[data.biome] then
+	-- Check for water surface (occean)
+	pos1 = {x=pos.x-20, y=0, z=pos.z-20}
+	pos2 = {x=pos.x+20, y=1, z=pos.z+20}
+	local num = #minetest.find_nodes_in_area(pos1, pos2, {"default:water_source", "default:water_flowing", "ignore"})
+	if num < (41*41*2-MAX_NUM_FOREIGN_NODES) then
 		if player_name then
 			minetest.chat_send_player(player_name, S("[TA4 Wind Turbine]")..
 				" "..S("Wrong place for wind turbines!"))
@@ -91,6 +98,9 @@ local function add_rotor(pos, mem, player_name)
 		obj:set_rotation(yaw)
 		Rotors[hash] = obj
 	end
+	
+	local own_num = M(pos):get_string("node_number") or ""
+	M(pos):set_string("infotext", S("TA4 Wind Turbine").." "..own_num)
 end	
 
 local function start_rotor(pos, mem)