Water ballast
Posted: Wed May 22, 2019 9:32 am
Hello,
I finally could put our boat on the water this weekend! I brought her to the dock, and then filled the ballast. It was quite interesting while being in a quiet location, to see (and hear) the process of the water entering, as I usually do that on the lake. Because it took a few minutes, at a point in time I left the ballast filling itself and focused on other tasks on the boat. I got back to the open vent and noticed that the water was very visible an inch or so under the surface of the step. Then I was distracted for a few minutes and left the vent unattended. I walked to the bow, then to the stern.
When I came back to the step I noticed that the water was about a quarter of an inch under the top surface of the ballast, a few drops had even splashed around on the step. But it wasn’t raising any more.
My boat is a 1996 26X (the vent plug is under the step) and isn't usually loaded very much: small engine and gas, composting toilet, maybe 40 Lbs of water and provisions, a few gears around...
So, my (many!) interrogations are:
1. What is supposed to happen if a Mac is left unattended with the ballast valve open on calm water (I know this should never happen but I am just wondering, right?) I am guessing the ballast fills itself until the hull buoyancy compensates the ballast increase, then the filling process should stop. So a Mac with open ballast on calm water won’t sink. Am I correct?
2. I regularly check the ballast through the vent hole before sailing and I have noticed that the level of water seems to vary a lot. I had already seen the water as high as I describe it above so I don’t really worry about that (though obviously the boat seems to be at a drop away from sinking…)
- Could the apparent level of water in the ballast vary that much because of the balance of the boat at that exact moment?
- Could a pocket of air in the ballast (think “bubble”) artificially raise the amount of water in the ballast when checked at the air vent? For instance I wonder if some air trapped in the bow section could “push” the water at a higher level at the air vent under the step?
3. I am wondering if my boat is too heavy for some reason. How can I measure if she sits correctly in the water?
What do you guys think?
I finally could put our boat on the water this weekend! I brought her to the dock, and then filled the ballast. It was quite interesting while being in a quiet location, to see (and hear) the process of the water entering, as I usually do that on the lake. Because it took a few minutes, at a point in time I left the ballast filling itself and focused on other tasks on the boat. I got back to the open vent and noticed that the water was very visible an inch or so under the surface of the step. Then I was distracted for a few minutes and left the vent unattended. I walked to the bow, then to the stern.
When I came back to the step I noticed that the water was about a quarter of an inch under the top surface of the ballast, a few drops had even splashed around on the step. But it wasn’t raising any more.
My boat is a 1996 26X (the vent plug is under the step) and isn't usually loaded very much: small engine and gas, composting toilet, maybe 40 Lbs of water and provisions, a few gears around...
So, my (many!) interrogations are:
1. What is supposed to happen if a Mac is left unattended with the ballast valve open on calm water (I know this should never happen but I am just wondering, right?) I am guessing the ballast fills itself until the hull buoyancy compensates the ballast increase, then the filling process should stop. So a Mac with open ballast on calm water won’t sink. Am I correct?
2. I regularly check the ballast through the vent hole before sailing and I have noticed that the level of water seems to vary a lot. I had already seen the water as high as I describe it above so I don’t really worry about that (though obviously the boat seems to be at a drop away from sinking…)
- Could the apparent level of water in the ballast vary that much because of the balance of the boat at that exact moment?
- Could a pocket of air in the ballast (think “bubble”) artificially raise the amount of water in the ballast when checked at the air vent? For instance I wonder if some air trapped in the bow section could “push” the water at a higher level at the air vent under the step?
3. I am wondering if my boat is too heavy for some reason. How can I measure if she sits correctly in the water?
What do you guys think?