its ± 34.6 mph.
30 knots = 34.52 mph
If you meant nautical miles, then 30. Nautical Miles (per hour) and knots are basicly the same thing. the only difference is knots is based over seas soley due to raising and lowering tide levels (make it less accurate than physical distance) mile however is the distance of the ground. this is why most boats and all military have to recheck there voyage distance before setting sail as the tide may add or remove distance on them.
1 knot means 1 nautical mile per hour. The nautical mile used to be 6080 ft but it is now defined as exactly 1852 meters which makes it 6076 ft. The ratio to a normal mile is 1.1508, so 30 knots = 34.52 mph
30 kph = 16.2 knots.
29.92 mph
105 knots is 120.832 mph
35 knots is 40.2773 mph
441 knots = 507.5 mph
382 knots = 439.6 mph
22 knots = 25.3171479 mph
17 knots = 19.56 mph
8 knots is about 9.2 mph.
26 knots is approximately equal to 30 miles per hour.
308 knots equates to 354.44 mph
100 knots is 115.078 mph