78 H30 Water Tank Replacement

[MikeHoncho]

Well, it looks like the 3M 5200 patch work on my aluminum 40 gallon freshwater tank has either failed or (more than likely) there is another leak. I'm wanting to replace the tank and interested in experience in doing so. It appears the easiest will be either cutting the top out of the tank and installing a bladder bag or cutting the whole tank our and doing the same. I have experience with bladder ballast bags and feel these will be the best option, I think. The pressure water system is not used for drinking/cooking. Its used for non-pottable uses.

My tank was filled and my flow meter shows about 20 gallons used but now its empty without the pump running/cycling.

 

[Roland5048]

My h30 is a '77 and I've had thoughts about how I would replace the water tank if I needed to. I think your idea of cutting the top off and installing a bladder is probably the best idea I've come across. The sides of the tank would act as support for the bladder instead of just having it lie there with no support. The glass lay-up in some places seem to have been hastily put up with lots of rough edges that would lay to waste a bladder unless much smoothing was done and some other means of support were installed. I'd say, don't reinvent the wheel. Plumb in a bladder and be done with it. BTW, thanks for that suggestion.

 

[ggrizzard]

I had a similar problem, but...
My 79H30C tank was only about thirty gallons. It rested in the port settee base which had easy
access by cutting the top off, carefully. In 2008 I installed a Moeller poly-razz-matazz tank,
(I don't know the exact pollmer used). I think it is 32 gallons and It will last longer than I or the next owner will.
I use it for all needs and I've found no taste or leaking issues. You can spec the location of inlet, outlet and vent fittings to suit your particular plumbing set up.

 

[MikeHoncho]

I had a similar problem, but...
My 79H30C tank was only about thirty gallons. It rested in the port settee base which had easy
access by cutting the top off, carefully. In 2008 I installed a Moeller poly-razz-matazz tank,
(I don't know the exact pollmer used). I think it is 32 gallons and It will last longer than I or the next owner will.
I use it for all needs and I've found no taste or leaking issues. You can spec the location of inlet, outlet and vent fittings to suit your particular plumbing set up.

My port settee has two hatch covers that would require the top of the structure to be cut out to get a new solid tank in. I can get a bladder bag for wakeboard boats for a couple hundred bucks and they tend to have three ports, fill, empty and vent. I have 4 of them in my wakeboard boat that total about 2200 lbs fully loaded. They are really sturdy and I’ve had no issues with the bags only with my poor plumbing attempts

 

[Peggie Hall HeadMistress]

Bladder tanks are ok for water holding, but a good quality tank of that size will cost as much or more than a top quality rigid tank, plus bladder tanks must be secured to prevent chafing that results in leaks. I'd replace the tank with a rigid plastic tank.
Ronco Plastics Ronco Plastics marine Tanks is your best source.They make TOP quality thick-walled water and waste tanks for a very reasonable price and have more than 400 shapes and sizes, over 100 of which are non-rectangular, and they install fittings in the sizes and locations specified by the customer when they make the tank. There are retailers who sell Ronco tanks, but Ronco sells direct for a much lower price...and they're great to work with.

When looking at drawings it's important to know that there is no top or bottom until the fittings go in, and YOU decide where they go. So rotate, flip in any orientation to find the tank that fit your space.

--Peggie

 

[MikeHoncho]

I don't disagree with what you are saying but I can get a ballast bladder bag with fittings for under $300. These bags are built to support the water stored within them inside of unprotected storage lockers. I have 4 in my wakeboard boat that have been in place for 6 years with no issues. Never say never but having the bag in the existing, confined tank really minimizes the chafe potential. Placing it within the existing tank after cleaning it out while not having to cut the top off the settee is a huge plus as well as having the ability to inspect as needed.

 

[ggrizzard]

Placing it within the existing tank after cleaning it out

You may find that cutting the aluminum tank through the access hatch opening is a more painful process than cutting 1/4 in fiberglass around the perimeter of the seattee top.
YMMV!
BTW, after reading Peggie's post, I remembered that the tank I installed is from Ronco Plastics.
I bought it on her recommendation all those years ago!

 

[MikeHoncho]

Good news. The tank didn’t leak out. A screen was clogged leaking to a he inline shutoff solenoid I installed. I put a Shurflo strainer in between it and the solenoid. Problem solved until it isn’t again.

 

[Cary mcD]

Aluminum tanks, be it in ANY moored boat, particularly around/in saltwater, will 'corrode' from the outside. As the tank slowly assumes the 'cold' temperature of 'night' or 'the water'... they then become the 'sink' for condensation in the mornings. They 'drip,' turning humidity into liquid... and as water dripping upon the tanks runs down to the bottom most point it can access... THAT'S where the 'salts' will be washed to, and where the corrosion will form. Put a 'zinc' (wedge) on the tank at a reasonable point... maybe at this 'bottom' corner? GOOD IDEA!