For gray water which we used everyday for cooking and showering, etc. The hoses stayed in and haven't leaked. Inside the ports on the side of the boat there is a ridge where the diameter is reduced, I just pressed the hoses in until they hit the ridge and they stayed. The type of hose I used kind of sticks to the port opening because it is kind of soft.
For the black water, we used the hose I mentioned, several (five I think) times and I just jammed it in tight. Twice I did it by myself with fingers crossed. The other times I held it in securely so no promises on how it will work for anyone else. So...your mileage may vary.
Rick