46 CFR § 153.353 - High velocity vents.
The discharge point of a B/3 or 4m venting system must be located at least 3m (approx. 10 ft) above the weatherdeck or walkway if:
(a) The discharge is a vertical, unimpeded jet;
(b) The jet has a minimum exit velocity of 30 m/sec (approx. 98.4 ft/sec); and