Originally Posted by tallswede
I have only one gate valve on my boat. It is on the engine coolant to the water heater coil. I use it to restrict flow through the heater coil. I feel this is not too severe a service for this valve due to the antifreeze solution in the cooling system. Other through hulls etc. should all be ball valves for quick reliable operation.
Gate valves aren't typically used for throttling as the gate is wedge shaped and when in the partially open the flow past will rattle the gate in the seats. On cheap small diameter valves (and big expensive ones too), this will often lead to the gate to stem connection wearing and the gate liberating itself from the stem. If the stem is in the vertical position, the gate drops and shuts off flow.
In your case, not a big deal. But a good reason not to use them "improperly" in a critical service.