Water and Fuel Tank replacement

I’m repowering the boat and while the engine is out I’m going to replace the 35 year old SS water tanks that leak and the black iron fuel tanks while I have easy access to them. I’m thinking I want to go back with roto molded poly water tanks and aluminum fuel tanks. Would everyone say that would be the preferred choice of materials for the tanks?
Should I put inspection ports big enough to be able to clean the inside of the 75 gal. water tanks?
I understand Ronco and Miller are the most recommend suppliers for the poly water tanks. Who would you recommend to build the two 150 gal. Aluminum fuel tanks here on the east coast? Any other recommendations or things I should consider would be appreciated.

Don Sasser

I got ronco tanks last year - 6 of them.

They are great to work with, and not horribly expensive as long as you work off of their catalog (which has tons of options, and you get to customize where and what your fittings are).

Personally, I don't think cleanout ports are required for freshwater tanks, especially if they're poly (though I would say the opposite for fuel tanks). The freshwater tanks I replaced had no possible means for access and they lasted for 30 years (they ultimately corroded through from aluminum & chlorine reactions). We always fill the tanks through a shore water inlet which is plumbed through a filter. This means all the water that hits our tanks is filtered first which prevents any kind of sediment buildup.

As a side note, I remember looking at your boat when we were in the market - why the repower?

Yes to poly water tanks and aluminum fuel tanks. Nothing wrong with inspection ports on the poly as long as they're in the top. If you're going to add ports to the fuel tank, make sure you can clean past the baffles.

Ted

I just bought an off the shelf water tank from Ronco. They have a lot of tanks choices and were great to work with. Ask for Jr. I had a narrow hatch to deal with to get the tank below so it limited my options. The tank seems to be of good quality. It only took about tens days to get it. I used there website drawings and built mock up tanks from cheap thin plywood to find one I could work with.

I had a quote from SP Sheet Metal Co in Barnagat, NJ. I have not done anything about new fuel tanks yet but their quote looked reasonable. They will epoxy paint the tanks and have many other options available. On a 200+ gallon tank it would be only $325 to upgrade to .25” thick aluminum. They also use 5052 aluminum which is the preferred alloy so I am told.

We went with aluminum tanks when we replaced our fuel tanks. The tanks are NMMA certified using ABYC standards. RDS Fabrication in Perry Florida did the work. Not cheap and they’re busy but they did the job right. Ours were custom and not just a square box.

Custom Marine Fuel Tanks

Here’s a thread detailing the project:

http://www.trawlerforum.com/forums/s32/krogen-42-fuel-tank-replacement-28204.html

One could make a case for polly fuel tanks depending on the boats use.

With multiple individual tanks (say 50 gal each) only 2 would probably work fine for local or weekend use , the rest could be filled for a cruise , or for winter heat.

With a metal tank I would require some sort of sump to be built in,that can be easily serviced.

Most of the tank problems are from water in the tank, supporting fuel eating bugs.

If the water can only effect the sump , even with poor or infrequent maint the tank should stay cleaner.

If you can make poly fuel tanks fit they're great, I've had aluminum fail after less than ten years and I also had problems with built in fiberglass.

For the fuel tanks, unless you are concerned about weight I would suggest that steel tanks are preferable to aluminium tanks.

Aluminium can suffer badly from poultice corrosion, and you need to be very careful about how they are installed. Painting aluminium can be tricky, and any defects will lead to corrosion as well.

With good prep and using the epoxy primers and paints available these days, steel tanks will outlast a lot else on a boat. Painting steel is quite straightforward. As FF says, build a sump into the design. I have inspection ports, but would not bother putting them in if I was doing it all again.