My 3870 Water Tank Replacement-gctid804530

[kev_rm]

And so it begins. Will post as I go along here.

I cut a couple of access holes to see the condition of the tank, in the hopes maybe some epoxy would get me another year or so... the first compartment looked pretty good and made me hopeful.... the second compartment showed many holes in the baffle and very bad pitting along seams, so she's coming out.

[Cool_Beans]

Following along for the ride and an idea of what I'll be getting myself into before I have to do mine. . .which didn't leak until AFTER the boat was paid for inch: Weeping drip I might be able to patch from the underside and buy some time, but for now I can live with the gallon a day drip :dry:

Good luck, and takes lots of pictures!

[floatyerboat]

Good Luck to you on this project. I just replaced the water tank on my 88 3218. Once the tank came out I noticed that the spot welds for the baffles to the tank eventually worked their way loose after years of water sloshing back moving the baffles back and forth. If the tank manufacturer would have also tacked the baffles to the sides of the tank it might have held. Like taking a piece of solid wire and working it back and forth until it snaps.

[Guest]

Good luck on your project. I just had mine opened up. It was too far gone. I put it back and am building a tank for under the forward berth. I will wait till fall to tear out and replace original. Too short of a season on Lake Superior to tear into that now. I will post some pics this weekend. My new tanks in the bow will hold almost as much water as original tank. One will hold 48 gallons and one will hold 29. I am going to leave the new tanks and just valve off the separate tanks. Will see. Should help keep the bow down.

[kev_rm]

"zrziemski" post=804541 wrote:
Good luck on your project. I just had mine opened up. It was too far gone. I put it back and am building a tank for under the forward berth. I will wait till fall to tear out and replace original. Too short of a season on Lake Superior to tear into that now. I will post some pics this weekend. My new tanks in the bow will hold almost as much water as original tank. One will hold 48 gallons and one will hold 29. I am going to leave the new tanks and just valve off the separate tanks. Will see. Should help keep the bow down.

I thought about just doing the berth tank for a long while yesterday after realizing how big of a project this was going to be.... my problem is my next trip is a long one and I need to get back near stock capacity or I'll be spending a lot of dollars and time refilling. What pains me is I think a decent sprayable coating that's food grade would give me a few more years at least out of this tank but based on the research I've done, I do not believe such a thing exists..

[RDOIII]

I don't envy anyone undertaking this job.

I replaced mine two seasons ago

I decided to expand the water capacity by utilizing all the space to the top of the galley floor

While a lot of work - months of weekends - the result is i have 140 gallons now - and it all stays in the tanks until I use it!!

The reworking of the floor was a potential concern as it eliminated the step down prior to the master stateroom - but the revised floor levels work just fine

Some photos hopefully are attached - while you will not likely attempt this it may help with visualizing your project

RDOIII


Attached files

[kev_rm]

OK so subfloor is out and head hoses off... ready to start cutting tank. I did most of this so far just with an oscillating saw. For the tank I was hoping to use power shears but I can't find any that are able to do this thick of metal so I'm going to cut the top of the tank with a saws-all and the bottom where its close to the hull with reciprocating saw. We'll see if the first piece comes out ok then will be confident I can remove rest without pulling the walls down....

[aspen1880]

I'm following along too. What's the game-plan? I'm guessing that you'll cutup the original and

the idea is to remove it completely via that galley floor opening (which will be the only

floor destruction). I figure that you are gonna install multiple custom poly tanks that are side by side?

[RDOIII]

"kev_rm" post=804722 wrote:
OK so subfloor is out and head hoses off... ready to start cutting tank. I did most of this so far just with an oscillating saw. For the tank I was hoping to use power shears but I can't find any that are able to do this thick of metal so I'm going to cut the top of the tank with a saws-all and the bottom where its close to the hull with reciprocating saw. We'll see if the first piece comes out ok then will be confident I can remove rest without pulling the walls down....

Noted thought on using reciprocating saw - Like jig saw I assume.

This will not work as in will cut through the base that the tank is sitting on - almost made this mistake myself

Used hand grinder to cut the tank on the bottom (as well as elsewhere) and you can then control the depth of the cut

See my photos for view of the floor under the tank

[kev_rm]

Correction to above - Oscillating saw for the bottom part of the tank. Just as good of depth control as a grinder and a heck of a lot less mess. Blades are pricey tho.

As far as Game plan? probably two poly tanks. I thought about bladder but they have a fixed 2d shape that is essentially just as limiting as a poly tank. I'll know more after I take measurements.

Got the first section out. You can see the seams are corroded on the outside, and I can shine light through the baffles... Probably weeping for a long time.. but haven't seen the portion where the major recent leak is.. yet.

[kev_rm]

Second half came out with no additional cutting, that seriously just made my day!

Found the leak, too - spot weld on baffle port side of forward baffle. epoxy theoretically would have kept me going for a while, there is no way I would have found this leak without taking the tank out anyway..

[kev_rm]

Would appreciate any thoughts on tank selection. I believe the slot I have is ~72"L x 17"W x 10"H with an overall width of 36" between the stringers

best option I found after a quick search was Plastic Mart 33gallon Two of these would be a tight fit width wize.

(the interconnect fittings would have to be on aft ends.)

Looked again at bladders, could not find any that would get me more capacity in that space than the lesser of the two above..

Edit: this one looks good too: Dimensions: 67L x 14W x 10H

[floatyerboat]

One visible broken spot weld and probably many more on the verge of going south on you soon. I cleaned the inside of the tank at the baffle and notice on mine a few spots that were ready to snap or that did snap. You did the right thing.

[kev_rm]

Tanks ordered today from Ronco... ~$600 total including freight to east coast (from California)

[kev_rm]

Its like christmas in may. Heading to the boat hopefully thursday to begin install. Hope they fit

[img ]http://imgur.com/HFVK99K.jpg[/img]