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#1 Thu 02nd Apr 2015 14:54:08

Kushka
Member
Registered: Thu 12th Mar 2015
Posts: 7

Water tanks

Can anyone tell me is th
ere a valve to control water flow to the tanks.
It takes a long time to fill them but short time till empty. Thanks.Ronnie.

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#2 Thu 02nd Apr 2015 16:25:11

twotails
Administrator
Registered: Thu 20th Nov 2014
Posts: 271

Re: Water tanks

Some 'dogs have a single filler point on the foredeck, others two.  To my knowledge, neither setup has any form of restriction, such as a valve, on the way to the tanks.  The actual run from the foredeck to the tanks is not too difficult to follow through the cupboards and under the saloon berths, so you should be able to see if there is a problem on the way, such as a distorted pipe.  As a last resort it would be possible to remove the supply pipe from the elbow above the tank and see if there is a blockage of some other sort on the way by running water through it.  A remote possibility is that the venting pipe from a tank is blocked and thus does not allow the water into the tank.  Again you would have to investigate the pipe run and see it you can blow down it.

On Twotails the tanks are linked with a section of pipe below the galley sink at each end of which there is an on/off valve.  Between the valves is the supply line to the galley foot pump.  This means you can select which tank to use (or both).  If you leave both open there is the possibility of water moving from one tank to the other when the boat is heeled under way.  In addition there is a separate outlet from the port tank to the focsle wash basin pump.  If you fill both tanks until they overflow into the cockpit, and you still run out of water relatively quickly, the only thing I can think of is that the vertical suction pipe within one of the tanks has broken off short.

I would be interested to know what you find!

John Lansdell.

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#3 Tue 04th Jul 2017 23:42:47

Marcus Hember
Administrator
Registered: Wed 22nd Mar 2017
Posts: 17

Re: Water tanks

A further couple of water tank questions from Black Dog....

Firstly, Black dog has an arrangement involving small transparent tubing connected to the top of the draw points from each tank; there is small bore piping, a glass jar, and some very small valves which, it appear, provide some sort of a water content meter in a tube adjacent to the forward side of the chart table.  Some components seem to be missing; can anyone provide a drawing or explanation as to how it is supposed to work? 

Secondly, the gas locker on the port side of BD has been modified and whoever fitted it cut off the overflow pipe from the port tank; now, when I fill to overflowing it runs into the bildge. I cannot locate the source of the overflow pipe, it seems to be forward of the Port fuel tank.  Any hints as to how I can get at it and extend / route it appropriately?

Thank you!

Marcus,

Black Dog.


Marcus Hember
Black Dog SD41

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#4 Sat 15th Jul 2017 10:54:57

Kittijay
Member
Registered: Fri 13th Mar 2015
Posts: 9

Re: Water tanks

Hi Marcus.  I thought I had discovered pretty well every square inch of my Seadog but the tank vent/overflow pipes, not sure.  Think I might have spotted the Stbd one when I had the base of the pilot berth up and was working on the battery isolator switches.  From memory think it was a separate small pipe outlet with plastic tube.   I've always wanted a keel water level gauge our tanks  of somesort.   I know there is a method of measuring height of water in a borehole by having a small tube running down to the bottom, connected to an air pressure guage at the top.  you pump air into the tube until you get max pressure and then use the the formula I foot of water in the borehole is equivalent to a pressure of 2.31 p.s.i.  to calculate the total height of water in the borehole.   But our tanks must be too shallow to use that method? Must have been a clever scientific bod who owned the boat before you.    All the best.  Martin Waterman.  Kittijay. Based Conyer, Swale, Thames estuary.

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#5 Wed 19th Jul 2017 23:47:51

Marcus Hember
Administrator
Registered: Wed 22nd Mar 2017
Posts: 17

Re: Water tanks

Hi Martin,

Right - I've sorted it and it actually works brilliantly.  I've drawn a very bad diagram (!) and it accords exactly with your suggestion except that rather than a pressure gauge it uses a manometer and the depth is exactly equal to the depth in the tank.  This small tube runs up the aft side of the bulkhead fwd of the chart table and works well as a gauge.  There is a small anonymous piece of brass tube sticking out from under the chart table into which one blows; when you hear a bubbling noise you are blowing a smidge too hard - ease back and measure the tank contents.  Beautifully simple!  Whoever did this also used some dye to make it easier to read.  Diagram is at the link:

Black Dog water Gauge diagram

I'm assuming that whoever installed this opened the tank extract tubes under each berth and drilled a hole, then inserted a small pipe which goes to the bottom of the tank (or relied on the uptake pipe which is the 'effective' fill anyway).

This pipe has a T - piece - one bit to blow into, the other of which goes into a small jam jar with a rubber bung, which is full of dyed water - the pipe goes into the top of this jar so it pressurises the air in the top of the jar.  There is a second pipe which goes to the bottom of the jar, so that as the pressure in the top of the jar increases, coloured water to the same pressure is pushed out of this pipe and to the indication.

Quite long winded for such a simple system!  My port tank has been disconnected I suspect by someone who did not know what they were looking at, so task this weekend is to re-instate it (well, it is on the list!)

Hope that is useful.

Marcus
Black Dog.

Last edited by Marcus Hember (Sun 05th Nov 2017 00:22:17)


Marcus Hember
Black Dog SD41

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#6 Fri 21st Jul 2017 22:25:10

Kittijay
Member
Registered: Fri 13th Mar 2015
Posts: 9

Re: Water tanks

Hi Marcus.   That is so brilliant.  Thanks very much for the very clear description.  I wonder if archemedes could have explained it better.  No chandler needed.   I have separate taps on the 'draw' pipes so should be able to plumb into them for the blow/jar tube.   As you say, adding the job to the never seeming to diminish list.  Martin.

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