New fresh water system advice

[SloopDogg]

Hello all,
I decided it was time to replace the sole of the main salon in my 1985 Tartan 40. This past weekend I went down and started ripping out the previously poorly repaired port side and the terribly deteriorated, rotten starboard side.

I bought the boat 2 years ago this month and have been tackling the deferred maintenance and shoddy repair work of the PO.

So, as I started getting the 1/2 inch T&H plywood layer up I noticed that it was glued to q 1/2 inch sub floor with epoxy and that sub floor layer is in rough shape. The sub floor layer goes under the settee fronts and is tabbed to the hull it seems. The settees are where tartan installed 2 48 cal aluminum tanks 32 years ago. I noticed moisture in the sub floor up against these settee fronts.

The condition of those tanks have been a concern for me and I suspected leaking this year. so now that I've git it all ripped apart and have easy access to removing the tanks, I want to replace them. I've also decided to replace all the water piping with a pex manifold and home runs to each fixture. I feel this will make for easy winterization as each fixture will have pretty easy disconnect points at both ends. I should be able to simply drain the whole boat, blow out the lines and not worry about antifreeze so much. this also allows me a shut off point for all fixtures.

I'm excited about the idea of having a fresh water system that would actually be safe to drink!

So now, what about the tanks? I'm considering several things;
1. pulling these testing and repairing (not worth it on such old tanks and there is some negative press on aluminum and drinking water from an aluminum container)
2. Have a poly or a stainless tank made from the original drawing which I have (seem really expensive!)
3. go with flexible fresh water holding tanks (40 to 50 gal models are under $500 each)

 

[Peggie Hall HeadMistress]

There's a 3rd choice: Ronco Plastics Ronco Plastics marine Tanks (no relation to the VegoMatic Ronco) makes TOP quality thick-walled water and waste tanks for a very reasonable price and has 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. They're also great to work with.

 

[SloopDogg]

Hi Peggie! thanks so much for the reply. I've sent to drawings for the original tank over to Rocna. They are researching their catalog to see what they can come up with. I've also contacted the original fabricator for a price on a stainless tank.

By the way, I followed all your advice on the whole sanitation system as my first project on this boat 2 off seasons ago, all new hoses, and two 1-1/8 inch vents, on opposite end of the tank top, to opposite sides of the hull, very far forward. the holding tank was very far forward so i was able to get away very little horizontal runs. No stinky head odor on our boat. I also scrubbed the heck out of the bilges, there really is no good reason to live with a stinky boat! Thanks for all you do for us boaters!

 

[FastOlson]

I agree that a rotomolded tank from Ronco (Great people to deal with!) is a great idea. OTOH, if you cannot find the shape and size that works for you, have a custom ss tank welded up. We did that many years ago for one of our boat's two tanks.
The new ss tank was done exactly to my plywood mockup with fittings to my spec. Due to having a baffle in it, there are two 6" clean out ports on top. We wipe the inside clean a couple times a year and our water is always drinkable. I found a welding shop that did "brewery grade" ss welding, and the workmanship is awesome. Shop around and ask around.... the best shops will charge about the same as the mediocre ones...

It is really worth it to have a drinking water system that you can use on your boat 'just like at home'.

Additionally, do Not use aluminum for drinking water tanks on your boat.

 

[David in Sandusky]

So what’s the problem with drinking water from an aluminum tank?

Research?

 

[Peggie Hall HeadMistress]

So what’s the problem with drinking water from an aluminum tank? Research?

Some research has found some evidence of a link between aluminum used for cooking etc and alzheimers. The jury is still out, but as almost always happens when there are reports of anything being good OR bad for us, there's a stampede to jump on that bandwagon. When it comes to avoiding aluminum cookware or water tanks, I can't fault anyone for choosing to be "better safe than sorry" whether that link is ever proven or not.

Fwiw, though...aluminum (least expensive) and stainless steel (most expensive) water tanks have an average lifespan of about 20 years...plastic (more expensive than aluminum, a LOT less expensive than steel) water tanks can outlive the boat.

 

[FastOlson]

So what’s the problem with drinking water from an aluminum tank?

Research?

It is not completely the fault of the metal, per se, but the corrosion from average city water chemicals, over time, worsens the corrosion. Basically the alum. corrodes and small grains/granules of a white-appearing oxide wander thru the water system.
I got about a table spoon of this stuff out of our former (OEM) hot water tank. It had an alum. inner tank and a painted steel outer shell. I replaced it before it could leak, due to lots of rust on that shell. Once the old tank was out on the dock, a little pile of oxide ran out of the hose connection when I laid it down on that side.
So drinking the water is probably not gonna hurt you, but the the oxide gets into your pump and check valve, and will add to the guck in the little screen at the end of the faucet. Might not be synonymous with "health food" either.

We changed to an all-SS tank many years ago. No more corrosion.

Having said that, there is one place that your boat should have an aluminum (5000 series) tank and that is for the diesel fuel.

 

[py26129]

I'll third Peggie's good advice re. Ronco. I installed one of their tanks when I replaced my holding tank and could not be happier.

Cheers

Matt

 

[Hayden Watson]

Have you ever thought of making your own plastic tank? All of the tanks on my Class A motor home ar made this way.
https://www.bing.com/videos/search?...57BCB3AE78496ECAB60157BCB3AE78496EC&FORM=VIRE
Tools

 

[Peggie Hall HeadMistress]

I viewed the vido...impressive! However, it didn't appear that he was welding PE...and the technique used doesn't seem to be what I've always been told is needed to weld PE...i.e it's necessary to simultaneously melt the edges of the seam while injecting new melted poly so that they meld together into a single mass. That's not what's happening in the video. Triple M Plastics uses polypropylene (PP) for their custom welded tanks because it's easier to cut and can be welded as it seems to be shown in the video.

I sent an email to Techspan asking them for more info...and I'll also give Triple M a call tomorrow. Meanwhile...I'm not knocking this idea, I just want to know a LOT more about what it can and can't do.

 

[Hayden Watson]

I learned to plastic weld when I was taking in an industrial arts Primary Education major in college. Basically any thermo-plastic can be welded with a hot-air welder. As with metal welding you need to have a compatible welding rod and proper temperature and speed. At 1:35 in the video they talk about temperature settings. At 2:08 they talk about rod selection. The rod must be the same formulation of plastic as the base plastic. They are using a contrasting color so that you can see the weld but in practice, most would use the same color. The first video in my pervious post shows making a tank by a custom fabricator and they use fancier production welding equipment but the process is the same.