Ball Valves are quick and easy to operate
If you have your boat out of the water, and, you have the time and money, I believe that one should attempt to replace the gate valves. Gate valves take many turns to open and close, which means it takes time to operate, and because of how the valve is designed and operates, the gate valve may break in some position that can prevent the valve disc from closing when you want it to.Ball valves are very easy to operate, typically only taking a quarter turn to go from one position to the other. The handle of the valve will tell you immediately if the valve is open or closed. A gate valve will not tell you anything by looking at it. To be sure, one must lay hands on the handwheel and attempt to turn. There is a problem with this in that you may tighten the valve up and drive the disc into the valve seat and damage the valve/disc.A ball valve can be closed immediately if you need to and if you don't break the handle by being a little to aggressive with the handle,A ball valve is also easy to operate.Gate valves get cranky (no pun intended) as they age.Get rid of gate valves if you can when your boat is out of the water.