Friday, June 3, 2011

Project: Remove the daytank

I'm not sure when it was installed. It doesn't look like a factory job tho.  And yet, it is difficult to see how it could have been gotten in there without the removal of the floor timber.  And how would you do that?

We are talking about our daytank.  It is a 40 gallon steel tank, obviously  designed for some other purpose and adapted to serve here.  Unfortunately, the adaptation process was inadequate.  The tank leaks from an inaccessible fitting on the bottom - we've never used it.

So, out it will come.

But that is far easier said than done...  The first step was to un-plumb it from the fuel system - I got that done last Monday.  Next, the four 1/4" thick stainless straps  needed to be removed - I got all but one of the big lag bolts holding them down out - I need bigger tools for the last one.  The picture shows the tank - a kind of grey-green color; the tan square in the bottom of the image is the front part of the generator.

And finally, I started to cut away at the tank.  See, there is no way the 19" tall tank will fit thru that 18" tall space between the floor timber and the generator.  And even if the measurements were reversed, it still wouldn't fit because it would have to go thru on a diagonal, and there is no way that can happen.

Now there are some logistics involved here.  Cutting the tank is a noisy, difficult operation.  It is wedged in there with little clearance for multiple fuel plumbing runs, the exhaust plumbing for the generator, the cooling water for the generator and the heat pump, and finally, lots of heavy cables connecting the batteries.  (I am really going to appreciate the room we will recover when it is out.)  Getting the sawzall into a position where it can bear on the task without cutting something else is difficult.  All of this says that I should think about the logistics in order to make the fewest cuts possible.

I have decided to take off the top half of the tank.  This will make it possible to pass the remaining bottom half between the floor timber and the generator.  But I cannot do this in a single cut because I can't get at the outside of the tank with the sawzall - I must make the cuts from the *inside* of the tank.  The last thing I got accomplished on Monday was the removal of perhaps the first quarter or so of the tank top half - the picture shows this.

Next Monday:  lots more cutting...


Ken said...

Very basic question here ... what is a daytank? A tank big enough for a single days fuel? A tank only to be used in the daytime because, like the 18 hour bra, it disappears at night? Inquiring minds want to know!

Chuck said...

A day tank is usually a small 3 - 8 gallon tank located above the engine, which will gravity feed the engine even if the fuel pump fails. Your 40 gallon tank counts more as an additional tank due to the addition of the genset. It appears to be monel from the picture. I would bet that they removed that cross member when they installed the genset and tank as well as all of the other filters and plumbing you have there. Monel tanks were considered the best at the time and had a price tag to match. One of your POs spent upwards of $30k for what I see there.

bob said...

Hi Chuck -

You could be right about the material choice for the tank - there wasn't a trace of rust on it, and it was heavier that I would have expected for stainless.

I believe that it was installed when the original generator was replaced - that required cutting one of the floor timbers (not visible in any of the pictures) - the alternative would have been to remove virtually the entire interior of the boat. I believe that the tank was dropped into the opening ans slid forward to the position you see, and then the new generator was installed.

I can tell you that the tank was not new when installed here. The installation was sloppy and the tank was mounted sideways - that is the dip tube ran from stbd to port instead of from top to bottom. It clearly was adapted to this service.


chuck said...

The natural dull grey with the green patina was the give away. See what says about dissimilar metals used with Monel. A galvanized pipe plug or other fittings in the bottom would fail eventually. It might have been 10 - 20 years old when they installed it. FYI the scrap value is pretty high because of the nickel content. Take it to Pacific Iron on 4th Ave S after you get it cut up.

They will call it "cupronickel" rather than Monel.

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