aluminium watertank corrosion?

  • February 16, 2018 19:27
    Message # 5741328

    we have this white,slimy stuff wich turns into white granulate when dry,coming out of our watertank (guess its aluminium oxide because of corrosion?)

    unfiltered the water looks milky,with a filter its fine,but the filter clogs after a few days.

    is there any way to get rid of it?

    also any advice on where to cut inspection/cleaning holes or installing new tanks (ronco or blather) would be highly appreciated!

    thank you and sorry for the english;)


    ps: we are the ones that bought steve yoders w28

  • February 17, 2018 12:38
    Reply # 5741919 on 5741328

    Welcome to the forum. 

    It sounds like there is something in your water that is other than aluminum oxide.  The water should not appear milky.  I'd suggest you drain the tank completely, refill it with treated water and repeat.  Also make sure you drain the water lines, pumps and filter.

    When you refill the tank add some chlorine to kill whatever might be/is growing in the tank and lines.  Let the chlorinated water sit in the tank and lines for a day or so before you drain it.  You may need to repeat this a couple times.  Leave the filter out when you are draining the chlorinated water, no need to plug up fliters with water you are not going to use.

    As I recall Steve had a issue with slime growing in the waterlines several years ago.  I recall suggesting he change the lines.  He did so and the issue was solved.  I'd suspect with the boat having been sitting in warm weather for some time that the slime issue may have returned.

    Accessing the actual tank is best accomplished from under the center outboard settee seat.  There is a 1/2" plywood bottom to the undersettee lockers.  If you carefully cut and remove the plywood locker bottoms you will expose the top of the water tank.

    Kevin  W28 #58

  • February 19, 2018 19:43
    Reply # 5745947 on 5741328

    i filled a glass with that milky water from the tank and added chlorine and let it sat overnight.

    the chlorine didnt eat it,the white stuff sank to the bottom and when i stired it up the water turned milky again.

    so i still believe its aluminium oxide as a result of the corrosion.

    i`m thinking of cutting the whole center settee open to have access to the tank and make a inspection hole to see how bad its inside.

    does anybody know if i can get a new plastic tank (or 2smaller ones) in there with only this limited access?


  • February 21, 2018 21:36
    Reply # 5859971 on 5741328

    so....i started the project today and cut the center settee open to fit a plastic inspection is heavily corroded inside,big chunks of aluminium oxide on the baffels etc.on some spots there`s almost no aluminium left.would be a matter of time til it would start leaking.i think i will order a custom made flexible watertank from,cut the whole space under the center settee open and fit it in.

    does anybody have the exact dimensions of the w28 watertank?

    will add a photostory soon!


  • February 22, 2018 01:41
    Reply # 5870722 on 5741328

    greetings chris

    the design water tank dimensions for the W28 are in the construction manual on page 6-D-2.

    i measured the length of mine and it is 3" shorter than the design length. i can't vouch for other measurements because they are not accessible..

    i assume you have read steve yoder's post titled, "those pesky W28 water tanks."

    there have been other posts over the years, one that comes to mind was by a guy named eric.  he posted pictures of the start of the process but nothing since.. biiiiiig job !

    my tank leaks from holes in its upper surface, because of fasteners into and through the plywood that covers the tank. consequently i don't keep it fully filled. 

    the inside of my tank is probably not quite as bad as yours, but does have tiny flakes of white stuff floating around. i don't think the flakes are aluminum oxide, but rather some sort of aluminum salt. my tank is set up to collect rainwater off the deck, so it would certainly contain unknown contaminants.   i patched a small leak on the lower edge with epoxy putty about eight years ago. my tank had a hole drilled in it low down, a little aft of the ice box.  a nipple was fastened in place, so i can stick a hose on it and flush the thing out, getting some circulation between there and the fill pipe and visa versa..

    now this may be a silly idea, but i have considered removing the tank by cutting a hole in the hull from the outside, rather than tear up the inside of the boat.  the chunk of hull could be removed in one piece and then glassed back in place similar to a huge hull repair. before attempting this, i would certainly get some technical advice form some experts and proceed from there.  

    it would be nice if you could post some progress reports along the way.

    boating is fun


  • February 22, 2018 19:41
    Reply # 5873415 on 5741328

    heres how i built the inspection hole:

    (everything was done in aprox. 4h being on anker with the inverter,a dremel multimaster,a small 12v hacksaw and a 12v drill)

    -cut the sette open with the multimaster

    -cut the aluminiumtank with the hacksaw

    -inserted the inspection hole

    -built a wooden lip to fit the settee bottom back in place

    it`s corroded so bad inside:(

    i emailed for a custom made flexible watertank.

    the plan is to cut the tank the size of the settee and remove the two baffles.

    the old tank will work as a cage for the flexible tank.

    will keep you guys posted with the progress!


    Last modified: February 22, 2018 21:14 | Anonymous member
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