Rusting propane tanks

OK, I think this is a new subject. I can't find any discussion on it previously.

Our 2014 R27 has the swim step propane locker. Unfortunately, the propane tanks had quite a bit of rust already developed when we bought the boat after it had only 6 months on the water. During the 2015 season I sprayed the inside of the locker down after each use of the boat to minimize the corrosion. I have now pulled the propane tanks out and am looking at my options for reducing the rust.

I was hoping to replace the tanks with aluminum ones but it appears the 5lb tank is not available in aluminum. There also is not a fiberglass tank that will fit that I can find. If anyone knows of a source for a 5lb aluminum or fiberglass tank that will fit in the propane locker let me know.

I really like the swim step locker arrangement and don't want to change that. Unfortunately because the swimstep picks up quite a bit of water spray and the locker is not sealed (for venting reasons) the locker promotes corrosion to the extreme. Flushing it with fresh water after each use should make a difference but since our tanks were already rusted I'm not sure how much the flushing is helping.

I'm currently trying to clean the existing tanks up and repaint them but I'm not sure it is worth it as it may only last one season. Anyone else have any ideas short of painting or buying new tanks each season? (No, I don't think you can exchange this size of tank at the regular tank exchanges, if that is what you are thinking!)
Curt

Good morning Curt,
We have seen your beautiful boat mored on our way to Coopville several times.
We have had the same experience that you have had with our propane tanks.
I sanded ours down to bare metel (bottom half) at the begenning of the summer, primed them with rustoleum & then applied three coats of black paint,
The rust has started to rear it's ugley head again?
My research has unfortunately revealed the same as yours!
Maby someone smarter than you & I has figured this out?
Mike & Barbara Harbin
M/V Elan
Cutwater 26 2012

I had the same problem with a steel propane tank. I sanded the lower 1/3rd of the tank and used a product called
Galvcon which comes in a spray can. Gave it three coats and followed up with white paint.
This lasted about three years so well worth some elbow grease.
JIm

There are a few different coatings you could use, but to do a really good job would require substantial prep effort; you would have to purge the tank, remove the valve assembly, and sand everything to bright shiny metal (or have someone sandblast).

Galvanizing paint: I have seen some steel tanks painted with cold galvanizing paint. If the prep is done well, this will substantially reduce or eliminate rusting. It's not very attractive, but it is functional.

Epoxy-based paints: applied properly, these coatings are really tough. If you chip the coating the tank will still start rusting, but a couple coats of epoxy paint, properly applied with primer, will last quite a while. Downside is that good epoxy paint is pretty expensive.

I have no experience with this , but what if you went to one of the places that spray truck beds, it is like a rubber spray, should encapsulate the tank , you would just need to do bottom 1/2.
Just an idea

Thanks all. All great ideas.

In our case the rust affects more than the lower half of the tank. Unfortunately the whole thing needs to be done. I like the idea of galvanizing and epoxy paint. I think the only way to get the tanks fully sanded to bare metal is to sand blast them due to the tight spaces around the handle and base rings.

I'm not sure how much sandblasting would cost but given a new tank only costs $50 I'm thinking getting new tanks every couple years and lots of fresh water flushing may be the best solution.

Curt

I was as going to make your same last recommendation. To make the existing tanks last a little longer than one more season, you could just spray cold galvanized paint over (and color coat if desired) any rust areas that already showed up (or show up later) until you replace them a few years down the road. The galvanizing will be eaten away before additional rust continues. Cold galvanizing NEW tanks (right on top of the original paint) would help stave off the corrosion process also. But in the end, you really don't want to spend more money repairing tanks than periodically replacing, since anything you do will ultimately be temporary.

I'd vote for a quick grind with a wire brush head, coat with Tremclad primer or galvanized paint, and quick top spray of that rubberized rocker panel paint. Might even last till tank is due for replacement. Doesn't have to be pretty, it just needs to seal the tank against the moisture. I just did the rocker panels and lower inside doors on my 2002 Ford truck and it looks to be up to the challenge.

Todd2 and Pleeson,

We are thinking alike. I just got done spraying them down with cold galvanizing and plan to put a more durable top coat on tomorrow. I then plan to toss these tanks when they get too far gone and coat new ones before installing next time.

Curt

If you've already painted with cold galvanizing, then this is too late for you, but it may be good advice for someone else; A product called Ospho, is phosphoric acid, which chemically converts ferrous oxide (rust) into ferrous phosphate (primer). It brushes on easily, then rinses off after 20 to 30 minutes. After that, apply a top quality paint and it should last a while. Naval Jelly will also work, but it's a gel so doesn't flow into the cracks and crevices as well as Ospho. Both are acidic, so wear gloves and eye protection.

Red Raven":8ydp58my said:

... the 5lb tank ...

Click to expand...

Is the propane tank only 5 lbs? With normal use for cooking, how long does it last?

Ron

To be clear, I agree to do it "right" all the corrosion should be removed by some means or another (power wire brush, sandblast, inhibited acid, or a phosphatizing treatment, etc). BUT, if you are just trying to limp along long enough till the expiration date, cold galvanizing (the thicker the better, since its a sacrificial anode) will slow the corrosion process much longer than just paint. Top coats will slow it down too (and look better if that's what you're after). It all depends on how much, time, effort, and money it's worth to you to keep the corrosion away from a used tank vs. a brand new one. Everyone made valid suggestions here.

BradOwens, or anyone who might know -- likely places to find and buy Ospho?

Gini

I got mine at West Marine.

Checking on line, I see it is also available at Ace Hardware.

I had the same question, Ron. I think that Red Raven means 5 gallons, which would be 20 lbs. Propane weighs approx. 4 lbs/gallon.

Ron and Sam,

The propane tanks that fit in the propane locker on our R27 are 5lb tanks (1.25 gallons). The 20lb tank size (standard barbecue size) is much larger and will not fit. The 20lb tanks are available in aluminum which would be my preferred option for dealing with the saltwater corrosion. Alas, the 5 lb tank is not available in aluminum and thus the rust problem.

Curt

We had and have same issue. I went the ospho / rustoleum route but this only lasted about 2 seasons. The base ring around the tank has taken the brunt of the rust activity and now has swelled enough such that it will not fit back into the tank holder nor will the propane locker close properly.

I have managed to get the tanks to fit but by design this is a very tight fit and upon further investigation it appears that drainage of the locker leaves a lot to be desired. Such that the propane tanks feet are most always wet ( fresh or salt ). I don't think the design is up par as compared to the rest of the boat.

Bingo you now have a chronic issue. I have been considering some sort of bucket like device to set tanks in to minimize / prevent water intrusion however due to the tight design criteria this would require base modifications but may solve the long term issue.

Nate

The 5lb tanks last the whole season for us. We use the boat for a mixture of day trips, weekend trips, and longer week long trips. The propane is used for both the range and the barbecue. We probably used propane around a couple dozen times total and it lasted all season. The tank for the range was nearly empty at the end of the season. The barbecue tank was more than half full.

I like the swim grid propane locker solution because it allows us to use the space under the stern cockpit seat for storage. I also think it is inherently safer as it has natural ventilation and the propane can't get down in the bilge (from around the tanks anyway). It also has a place for or gas can for the dinghy which also is a much safer place to keep gasoline than anywhere else on the boat. The trade off of course us that the swim grid is wet and thus the problem with rust. Sealing the area from the possibility of water incursion would defeat the safety feature of the locker that doesn't trap propane.

While the rust is a minor challenge, I still prefer this overall solution to the alternatives. I think it is a good design given the trade offs but would be even better if aluminum (or stainless!) tanks of that size were available. Also, buying new tanks every several years is minimal cost compared to the other costs of maintaining a boat like this.

Thanks everyone for the great ideas!

Curt

My R27 has 13# tanks. The cost of aluminum tanks is around $150 each. I would rather spray paint them every year until they are no good and buy new ones. It would take about 9 years to recoup that money. Just my opinion.