Port and starboard water tank balance

Malabarista

Malabarista

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Hello again
After an epic sanding, grinding and flowcoating (PW) experience i hope never to have to repeat on my six water tank chambers i am confused about the plumbing. Each tank ( Port and Starboard) is furnished with a breather and a single outlet. The Port tank has a filler. The only filling connection between the two is achieved by ( i assume) the water pressure in the Port tank coming out of the outlet in the Starboard tank when i open the gate valve connecting the two tanks. The outlet on both tanks is around 15mm. Seems a bit small to equalise when filling. Am i missing something obvious?
Should there be, say, a 25-30mm pipe between the two with a gate valve to enable water to rapidly equalise?
Apologies if this has been covered i only did a quick search
Dave
 
I think a small bore connection is quite OK as it minimises transfer of water if the boat is rolling in any swell. As long as both tanks can be filled and the water used I see no problem. A better system would however be to have separate fillers for each tank and separate outlets so that you can choose which tank you are using and which is kept in reserve. I have two tall but fairly narrow 300 litre tanks under the forward bunks each side of the boat centreline and it makes little difference to trim if one is full and the other empty.
 
Malabarista said:
Hello again
After an epic sanding, grinding and flowcoating (PW) experience i hope never to have to repeat on my six water tank chambers i am confused about the plumbing. Each tank ( Port and Starboard) is furnished with a breather and a single outlet. The Port tank has a filler. The only filling connection between the two is achieved by ( i assume) the water pressure in the Port tank coming out of the outlet in the Starboard tank when i open the gate valve connecting the two tanks. The outlet on both tanks is around 15mm. Seems a bit small to equalise when filling. Am i missing something obvious?
Should there be, say, a 25-30mm pipe between the two with a gate valve to enable water to rapidly equalise?
Apologies if this has been covered i only did a quick search
Dave
Click to expand...

15mm is mebby a bit small, but not by much. Consider the diameter of the hose you use to fill with.. 15mm ish? and how long it is. Then remember that only half the water from the hose needs to go through thr equalisation connection, you wont be filling 1 tank then the other.
 
Ok thanks guys. I will go and worry about something important. ?…neoprene gaskets for sealing the inspection hatches…that will do…single sheet or CT1 the mitres…?
 
Norman_E said:
I think a small bore connection is quite OK as it minimises transfer of water if the boat is rolling in any swell. As long as both tanks can be filled and the water used I see no problem. A better system would however be to have separate fillers for each tank and separate outlets so that you can choose which tank you are using and which is kept in reserve. I have two tall but fairly narrow 300 litre tanks under the forward bunks each side of the boat centreline and it makes little difference to trim if one is full and the other empty.
Click to expand...

I have twin port and starboard tanks, and like the OP have only one filler. Each tank has an isolating valve, and the connection to the pressure pump is taken from the cross connection pipe. Since I would never dream of sailing with both tanks open, there is no way that water can move between tanks unless I want it to. The cross connection pipe will be 19mm.
 
Malabarista said:
Hello again
The only filling connection between the two is achieved by ( i assume) the water pressure in the Port tank coming out of the outlet in the Starboard tank when i open the gate valve connecting the two tanks. The outlet on both tanks is around 15mm. Seems a bit small to equalise when filling. Am i missing something obvious?
Should there be, say, a 25-30mm pipe between the two with a gate valve to enable water to rapidly equalise?
Apologies if this has been covered i only did a quick search
Dave
Click to expand...

We have basically the same set up, but it is the starboard tank that has the filler. The pipe between the two tanks is 1" diameter and has two gate valves with an unequal T piece in between, which goes to the water pump. With both valves open you equalise the water in the tanks, with only one valve open water is taken from that tank. With 500l in each tank it is important to equalise from time to time!
 
Thanks Peeps
Great advice as always. I shall be on it as soon as i can sneak off work and get back to the boat again. Such a great forum. Thanks
 
Lon nan Gruagach said:
15mm is mebby a bit small, but not by much. Consider the diameter of the hose you use to fill with.. 15mm ish? and how long it is. Then remember that only half the water from the hose needs to go through thr equalisation connection, you wont be filling 1 tank then the other.
Click to expand...

Maybe he's thinking of transferring it just before every tack. Don't have to worry about the racing rules when cruising. :)
 
Thanks for the help guys. Due to a wifely intervention ( she is ever so clever) rather than copying the previous set up with the water tanks ( we discovered a branch from the filler to the stbd tank) we are now having a separate filler for each tank. This means that the ever so long branched pipe which wriggled around the boat in an alarming manner has been consigned to the skip and I’m about to cut a hole in the cockpit coaming. Oh dear I’m getting scared…
 
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