Marine vs RV fresh water tank

[PhilPB]

Hi all. I'm adding an additional freshwater tank and have been scouting around. Is there any discernable difference between an RV and Marine freshwater tank aside from price? Is it possibly the wall thickness? Outlets for the most part seem to be the same.

 

[SteveK]

Let me guess they are lighter weight material expected to sit on a flat surface not often available on a boat.

 

[PhilPB]

Let me guess they are lighter weight material expected to sit on a flat surface not often available on a boat.

The plan is to mount it on 3/4" marine ply flat surface between stringers.

 

[jgwinks]

I doubt there's any difference at all. The wall thickness should be in the specs, the thicker the better. The big difference in Marine tanks is they're made in odd shapes to fit in a boat where rv tanks are probably all rectangular. If rectangular fits, go for it.

 

[rslifkin]

I'd say if the wall thickness and tank size/shape is suitable, go ahead and use it. There's no reason it needs to be a marine specific tank if the specs say it's suitable for your needs.

 

[slowgoesit]

The only thing I'd add to the above, is try and avoid fittings/valves that stick straight out from a tank, making them susceptible to damage if something shifts up against it. A 90 deg fitting right out of a tank, keeping the associated lines/valves etc close to the tank is generally a good idea.

 

[Shrew]

The only difference I've ever seen is the selection of RV tanks tend to be wide, long and flat. Boats tend to be taller and narrower.

 

[Comodave]

The only place I buy plastic tanks is Ronko. They have hundreds of stock tanks and their walls are very thick. They will put fittings in the tanks where you specify.

 

[backinblue]

Hi all. I'm adding an additional freshwater tank and have been scouting around. Is there any discernable difference between an RV and Marine freshwater tank aside from price? Is it possibly the wall thickness? Outlets for the most part seem to be the same.

My guess is that the main difference is that marine version will be more $$$.

 

[Max1]

I bought a 22 gal RV freshwater tank to increase our freshwater capacity. I would have liked larger but the one I bought fit perfectly in the nook I had in the hold.
As far as I can tell, its not much different than the tank that is currently in the boat.
Just make sure you secure it properly. You dont want it to shift. I took this photo when I first put it into the compartment. I have since secured it firmly with wood straps secured to the platform.

 

[PhilPB]

My guess is that the main difference is that marine version will be more $$$.

Haha...that's a given!

 

[ranger58sb]

The only place I buy plastic tanks is Ronko. They have hundreds of stock tanks and their walls are very thick. They will put fittings in the tanks where you specify.

And they came make the fittings innies or outies, too.

-Chris

 

[rslifkin]

For tanks, if Ronco doesn't have a suitable shape, I've been happy with the tank I bought a few years ago from Trionic for a replacement holding tank. Basically the same rotomolded design, I think mine is 3/8" wall. There's a good bit of overlap between their catalogs, but the sizes and shapes available do differ slightly, so sometimes one supplier has a better fitting tank than the other.

 

[sean9c]

Depending on size you may have to think about baffles. I doubt that they're putting baffles in rv tanks

 

[rslifkin]

Depending on size you may have to think about baffles. I doubt that they're putting baffles in rv tanks

None of the rotomolded tanks have baffles, only tanks made by other processes can.

 

[psneeld]

RV need baffles too if the tank size demands it.

My 58 gal rotomolded fuel tanks had a baffle in them...it had a large round hole from top to bottom in the tank.

 

[sean9c]

Like what psneeld said. I've also seen them with various shaped lumps that stick into the inside.

None of the rotomolded tanks have baffles, only tanks made by other processes can.

 

[rslifkin]

I guess those holes and such count as sort of a baffle, but I've always figured they didn't block enough area across the width of the tank to have more than a limited effect. Certainly not as much effect as a typical flat plate baffle with holes top and bottom.

 

[Greg QS]

The rv tanks are lighter weight/ thinner walled. But much less expensive.

 

[psneeld]

I guess those holes and such count as sort of a baffle, but I've always figured they didn't block enough area across the width of the tank to have more than a limited effect. Certainly not as much effect as a typical flat plate baffle with holes top and bottom.

According to the tank specs, they are engineered baffles.

Baffles sometimes can over restrict flow.

As far as wall thickness that some seem concerned about, a lot can have to do with size and shape of tank.

Best to compare as close to apples to apples as you can from the tank specs. Of course a smaller fresh water tank doesn't have to be built too hefty... and worst case if not in a bad spot is some fresh water in the bilge.

 

[C lectric]

I used to RV and was checking out RV tanks while doing so.

RV and boats are quite different. The two tanks are usually of different materials.

In general RVs are a much stabler platform so the tanks are often vacuum formed of ABS in two pieces and then glued together. THat process thins the original sheet.

Boat tanks rotomoulded will have more consistent wall thickness as long as there is enough material put into the mould. They are also made of HDPE, a tougher material.

Boat can be subjected to rough water conditions which can cause liquids to slosh violently about causing almost punches from the inside. Those punches have been known to burst the tank.

Be very aware of wall thicknesses. Be aware of the material the tank is made of and HOW it is made.

I spent many years in the Plastic industry and although not expert have pickup enough knowledge generally to not expect an ABS tank to stand up to the same abuse as an HDPE tank.

Just my thoughts.

 

[psneeld]

I had a rotomoulded tank in my Class C and Fifth wheel as they were internal. One had an unusual shape, the other was just a large (60 or 80 gal) rectangular tank. The belly tank on my newer class A (external tank) is black and I would guess ABS.

I think many tanks are made exactly the same and some are sold as marine, some RV. Prices vary wildly for each category.

Funny..... but to me .....the side to side motion of my motorhomes when crossing uneven pavement like pulling out of a steep drive can be just as violent as the motion in my 40 foot trawler.

 

[C lectric]

Yes, but would that violent action carry on at that level once moving?

 

[psneeld]

Not sure what you are getting at.... I googled both marine tanks and RV tanks...a huge overlap in rotomoulded and even some listed for either.

If you find a rotomoulded tank of similar wall thickness and design as a marine one for a cheaper price....go for it...it is probably the same anyhow.

As far as motion goes, sure a boat may have sloshing going on for day, weeks even on a long trip. Does that lead to fatigue? I am not sure.... but just for a sudden, violent motion.... I wouldn't say my boat had them any more or less than my RVs.

 

[Comodave]

It is a guess but when we had our RV it never moved nearly as much as a boat in heavy seas.

 

[Shrew]

I had Ronco make me a custom tank about 10 years ago for a previous boat. I chose the location and size of all of the fittings.

 

[Comodave]

Yes, I have had Ronko make 3 or 4 tanks for me and they were great. Heavy wall thickness.