On my boat, the "pressurized" raw water feed to the Tides dripless shaft seal
is tapped from that circuit right at the water line level.
The exhaust ports
are higher, by about an inch.
The path from this raw water inlet / outlet to the exhaust port is about a foot up / down, along a convoluted path.
There is not a risk to hydrolock from this water path.
Also, there is not a sinking risk if this small diameter hose became loose. The water flow is small. Any one of my three automatic bilge
pumps would have no problem staying well ahead of this flow. Sometimes they do stay ahead when I intentionally drop the hose to perform service