Fuel Tanks

[CFarrah]

All,

Found a leak in one of the fuel tanks in our 1946 Elco 47' Deluxe cruiser. There are original... 3-100 gallon tanks, they are gasoline and are made of a copper derivative. I've had issues with sludge and water in the fuel (evidenced by the seperator and fuel filters.

The leak is a pinhole, not on a seam at the bottom of the tank. I've used a significant amount of waterweld (amazing stuff), but I'm taking this to be a sign from above to do the right thing and fix the problem by replacing the existing tanks.

The tanks are pretty large and will not be extractable intact. I'm assuming that they will have to be cut up and removed piecemeal. In addition, I'm expecting that I'll either have to have a new set fabricated or that I can connect and stack a few smaller ones...any opinions on this?

I've read the old posts on others who have dealt with tank issues and am unclear on the merits of plastic vs stainless...since it is gas and I'm likely (down the road) to covert to diesel, are there any strong opinions for me to chew on?

Finally, I haven't found a yard that combines the quality of work I'm looking for with a reasonable cost position. I'm located in New Castle, NH...any thoughts on a good fit for this kind of work?

In advance, I appreciate your counsel.

Regards,

Cliff.

[ion barnes]

I would try to find a Tempo or Todd plastic tank, however aluminum is available. Stainless is astronomical in price. Look in a West Marine catologe first and then the web sites for the previously mentioned for more info.

When extracting those old tanks - if one has gone the others should not be trusted either, make sure you dont spark anything!! And dont patch a fuel tank, thats real scary too.

I replaced the tank in my Bayliner a couple of years ago. Was about 80 gallons and replaced with two tanks of about 45 gallons each. I had to pull the motor to do it and yet had 'good' advice to cut the deck!! as the reasonable way. Yeah right! No structural strength after that. I was much happier with two tanks in case we had contamination. Each one has its own filter and a crossover. Never rely on a single system.

[sdowney717]

The bottoms of the tanks is where the corosion is I assume. Since they are a nice copper, monel pehaps? I would be tempted to remove the tanks intact and repair the bottoms.
Silver solder works well on copper alloys. You could cut off the bottom with an abrasive disc, examine the tanks and silver solder on a new copper or monel sheet. You would have to pressure test it with a few pounds of pressure to see if it leaks.
You might find it not worth the trouble of fixing. I am asuming you may end up needing new custom tanks. I would avoid aluminum tanks.

[Gresham CA]

I am in the process of changing out my black iron tanks right now. To take them out whole would have meant cutting out the sole. I cut them in half with a sawzal but they were diesel, I wouldn't recommend a sawzal with gas. If you look in the West marine catalog there is a company that does their aluminum tanks, if you talk to them directly you can get a better price.

[Gary E]

You say there made of a copper material? If so they are well worth repairing.

You say they cant come out in one piece?
They went in in one piece.

If you cut them into smaller chunks, just how are you going to get a new tank in? Small chunks and then solder or weld them ? Connecting a few smaller tanks together with hose under the deck is not a good idea.

[ion barnes]

Working on any container that has contained gas, at any time, is dangerous to work on at a later date. Grinding, welding, any kind of open flame is the route cause of explosion and fire. Especially in cramp and confined quaters. Dont be tempted!!

[sdowney717]

Since a replacement tank is going to be fitted in one piece it makes sense to pull the original tanks out in one piece unless you go for a bladder tank.
putting in small tanks will give the boat no range

You might want to think about a fuel bladder type of tank

http://www.atlinc.com/marine2.htm

[MarEng]

For safety sake - drain the tank of fuel and then fill the tank to overflowing with water and let it flush before any cutting or manhandling. The water will displace any remaining fuel and/or vapor.

[MarEng]

Clarification - you can drain the tank once flushed. It makes the cutting easier.

[SC-Lion]

If you do go with plastic and plan to convert to deisel later on stay away from the Todd tanks. They are only approved for gasoline only. The Tempo tanks are approved for both gas and deisel.

-Gary

[CFarrah]

All,

Thanks for the replies. They were extremely helpful. We've figured out how to remove them intact. They are Monel, but I've got little/no faith or interest in reparing them. It seems that the only time we've been very stressed on the boat has to do with the fuel tanks!

While emptying the tank (rigged a 20' fuel line to the other tank fills from the fuel pump), we discovered another pinhole.

So...we've come to the conclusion that as much as we love the sweet sound of our twin 1953 331 hemis purring in the background, it is time to bite the bullet and repower Merc with diesel this winter.

The only experience with diesel I've had is in our sailboats, and they were relatively low weight/low power...so, lots of questions.

I've reviewed the earlier postings on repowering, so I have dangerous knowledge, but again ask if there are any yards that specialize in work of this kind in the Northeast. I'd like to get at least 300hp in each engine, and currently have V-drives. This is obviously a big deal, so any additional counsel would be much appreciated.

FYI, the idea we were considering to cut the tanks with were air shears for metal cutting after filling and draining the tank with diesel.

[ion barnes]

I would not deep six the hemis just yet. If you are concerned with fire hazards, consider this:

While gas has a lower flash point, diesel when it is ignited burns at a higher temperature.

You are not going to save anything if it catches light!

Now that you have pulled the tank, you must consider the others to be damaged too. Do not ignor the warning! I would find polybutyl tanks that come close to the original or use seveal with a fuel manifold and multiple filters. I did this on my Bayliner, reducing one 90gal tank to a pair of 45gal tanks.

About the switching to diesels, it is not the answer in most cases with smaller engines and I include you baby hemis in that catagory. The problem that most over look is the duty rating of alot of the diesels. Medium rating is considered adiquat for sailboats that just need a kick away from the wharf or buck a tide. Powerboats need a continuous rating and that equates to a much bigger engine.
Check out the following;

www.yachtsurvey.com (http://www.yachtsurvey.com)

www.marineengine.com (http://www.marineengine.com)

//boatdiesel.com

[SC-Lion]

A few years ago I watched a 35 foot gas powered cabin cruiser explode a couple of hundred yards away from me, blowing the two owners and their dog of the back of the boat and half way across the channel. Both of owners where hospitalized for burns but they lived.

I have no problem with those that choose gas power and respect and understand the dangers of using it on boats. There’s no doubt gas is a valid fuel for boats and there’re plenty of boats out there to prove it, but to compare its safety to diesel because when ignited diesel burns hotter is simply not valid, don’t fool yourself. There’s a real world difference between a fire and an explosion, if the gas goes you won’t have much of your boat left to put out. If you run gas engines take the precautions necessary and keep your gear in excellent working order.

If you think I'm off base search this forum for the boat named "Spark".

Just my two cents,

-Gary

[ion barnes]

I dont have an issue with anyones views except the ones that over look the rules in place. Yup, gas and diesel are both flamable, gas is explosive, but so is propane and CNG.

If one is to use non-ignition protected items in the engine space, they are asking for trouble. If you can smell gas onboard, your asking for trouble.

A case in point, an inlaw of mine had a leaking fuel tank(steel) embedded in foam and never though anything could happen. It rusted through ad soaked the foam. They could smell gas but just shrugged it off. One cold day of fishing, they stopped for a little warm-up with the propane stove and WOOF the gas vapour lit off, not an explosion because the cuddy cabin was not sealed. They all had various degrees of burns etc.