Water ballast

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Alexis
Chief Steward
Posts: 91
Joined: Tue Feb 06, 2018 3:45 pm
Sailboat: MacGregor 26X
Location: SK, Canada

Water ballast

Post by Alexis » Wed May 22, 2019 11:32 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?

Alexis
Chief Steward
Posts: 91
Joined: Tue Feb 06, 2018 3:45 pm
Sailboat: MacGregor 26X
Location: SK, Canada

Re: Water ballast

Post by Alexis » Wed May 22, 2019 2:11 pm

The more I am thinking about that water level in the ballast setting at the top of the vent hole, the more I believe is has to do with the weight distribution bow VS aft. The water in the ballast was maybe flowing from the bow ballast compartment to the aft compartment.

So, my issue might not be the boat being too heavy, but too heavy in the companionway area and too light in the bow. So maybe the ballast counldn't fill completely because of a bubble being stuck in the bow section of the ballast (which would explain why Macgregor moved the vent to the bow in more recent productions...)

I will try to move some gears around and see what the effect is on the ballast water level...

Is my reasoning making any sense?

Baha
First Officer
Posts: 236
Joined: Wed Oct 15, 2014 4:58 am
Sailboat: MacGregor 26M
Location: UK

Re: Water ballast

Post by Baha » Thu May 23, 2019 3:42 am

Alex,

It is important to have a full ballast before raising sails. Having said that, mine is usually 1-2" below the top of the ballast tank. I have always believed that if I can touch it with my pinkie, all is well. Some folks here have rigged a mod which acts as a ballast level indicator. I am sure you can search for that.

Hope this helps!

Alexis
Chief Steward
Posts: 91
Joined: Tue Feb 06, 2018 3:45 pm
Sailboat: MacGregor 26X
Location: SK, Canada

Re: Water ballast

Post by Alexis » Thu May 23, 2019 10:47 am

Hi Baha,

Yes you are right, but in my case I was wondering if I had too much water rather than not enough! :)

Here is the thing: the ballast is made of a bow compartment and a stern compartment, which are connected by the starboard and port elongated "pipe"-shaped tanks. In a 1996 26X the vent is located just beside the valve, under the companionway step.

I filled the ballast while the stern was heavier than the bow, which resulted in some air being trapped in the bow compartment... In short the boat was stern-heavy and the water in the ballast just went where it is supposed to go: on the lowest section at the stern, which in the process trapped some air in the bow.

I will go back to the boat this Saturday and will move some gears around to adjust the weight balance and to check the effect on the level of water in the ballast.

I am certainly re-discovering what many Mac owners knew from years, but the weight distribution is important on a 26X especially if it doesn't have a ballast vent at the V-berth. It is important to bring some weight on the bow so the bow compartment fills first, without trapping air. I also have the feeling that the boat will sail better. In conclusion: on a 26X you want to use the storage under the V-berth for all your heavier items!

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Chinook
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Location: LeavenworthWA 2002 26x, Suzuki DF60A

Re: Water ballast

Post by Chinook » Thu May 23, 2019 9:18 pm

You should take a look at the water line stripe on the hull, when you're at the dock. It should tell you whether your trim needs adjusting. I agree on the need for weight toward the bow, especially if you're trying to run at full throttle. That bow weight helps the bow to come down at speed. I installed a triangular bladder tank, which holds about 20 gallons, under the Vee berth. This gives me the extra weight forward which I want.

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Tomfoolery
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Re: Water ballast

Post by Tomfoolery » Fri May 24, 2019 11:17 am

Except that on later :macx: boats, if you don’t move some of the heavy stuff back after trailering and let the ballast fill without paying attention, you can get just a bit too much water at the vent. Or out the vent, I should say. Something you only do once. :|

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Chinook
Admiral
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Location: LeavenworthWA 2002 26x, Suzuki DF60A

Re: Water ballast

Post by Chinook » Fri May 24, 2019 6:59 pm

I first learned about the effect of weight on the water ballast system the evening before we set out on our first Gulf Stream crossing to the Bahamas. We were headed for the Abacos, and the night before departure, I pulled the air vent plug and pulled up the "T" handle on the ballast drain valve. After allowing enough time for the tank to fill, I went forward to put the plug back in. I was startled to see that the water level in the little basin where the plug goes, was nearly to the top. I put the plug in and closed the ballast valve, and went out to see where my water line was. It was a couple inches lower than usual, a sure indicator that we were well provisioned for a 2 month cruise to the Bahamas. We had a great deal more weight in provisions and gear than usual. Next morning this added ballast manifested itself in another way, cutting our maximum speed under power by several knots. Weight does matter.

Alexis
Chief Steward
Posts: 91
Joined: Tue Feb 06, 2018 3:45 pm
Sailboat: MacGregor 26X
Location: SK, Canada

Re: Water ballast

Post by Alexis » Mon May 27, 2019 11:13 am

Chinook wrote:
Thu May 23, 2019 9:18 pm
You should take a look at the water line stripe on the hull, when you're at the dock. It should tell you whether your trim needs adjusting. I agree on the need for weight toward the bow, especially if you're trying to run at full throttle. That bow weight helps the bow to come down at speed. I installed a triangular bladder tank, which holds about 20 gallons, under the Vee berth. This gives me the extra weight forward which I want.
Hi Chinook, I moved around some weight this Saturday (mainly the water provision, which is in my case a small crate full of bottles) and noticed that the water at the vent went back to normal. I had my first sail and also preferred the feeling of the boat balanced that way.

I checked the water line on the hull, which seems right, but I am now wondering if when the whole family is in the cockpit, if the boat appears to be bow up and stern down - I need to work my style here... ;)

Alexis
Chief Steward
Posts: 91
Joined: Tue Feb 06, 2018 3:45 pm
Sailboat: MacGregor 26X
Location: SK, Canada

Re: Water ballast

Post by Alexis » Mon May 27, 2019 11:22 am

Tomfoolery wrote:
Fri May 24, 2019 11:17 am
Except that on later :macx: boats, if you don’t move some of the heavy stuff back after trailering and let the ballast fill without paying attention, you can get just a bit too much water at the vent. Or out the vent, I should say. Something you only do once. :|
That would be a mistake you do only once! I never though much about the vent location but I can see the impact is tremendous: with the vent at the bow you have a better solution to fill the ballast... and to sink your boat if you don't monitor the process!

Ballast operations should never be lost of sight anyway...

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