replace fuel tanks

My wife and I are close to purchasing a 1979 Marine Trader 40' trawler. Survey revealed that the fuel tanks are bad and need to be replaced. I have been researching all day and it seems there are a variety of thoughts out there, material of tanks, size of replacement, costs, etc. If anyone has gone through this process and has some advice for us, we will welcome your thoughts! Thanks

Greetings,
Welcome aboard. Hopefully you will allow for replacement costs in your offer to purchase.

Yes, $10,000 down

Big job. Buying new tanks is easy. Getting the old ones out and new ones installed is tougher. Typically in a twin engine installation the tanks are outboard the engines. Engines need to come out to get new tanks installed. I used Speedy Tanks for two past boats and they are on time and reasonably priced. speedytanks.com No affiliation
Good Luck.
Secondary a yard in Solomons, MD opened up steel tanks that were leaking and coated the inside with some high tech rubberized goo. No leaks in 5 years, quick and cheap.

I went down to 2 , 58 gallon plastic tanks.

With a single engine and 3+ NMPG efficiency, I still have a 300NM range.

By doing this...it made the project an inexpensive, easy DIY evolution.

The big plus was a lot more engine room storage and much better organization for easier access and maintenance.

Twins would have made the project more involved.

sonnyboy said:

My wife and I are close to purchasing a 1979 Marine Trader 40' trawler. Survey revealed that the fuel tanks are bad and need to be replaced. I have been researching all day and it seems there are a variety of thoughts out there, material of tanks, size of replacement, costs, etc. If anyone has gone through this process and has some advice for us, we will welcome your thoughts! Thanks

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I replaced the two in my 77 sedan, single engine Marine Trader. Tough job, had to remove the engine then cut the old ones up in place. Could have gotten them out without removing the engine but could not have put in the new ones.

Thanks for your thoughts! Any chance you know the name of the Solomon marina? I am interested in what process they are using.

Is it a single or twin engine boat?

Have not replace. However I have a plan when the time comes. The old tanks would be cut open and become the fame work support, for several smaller tanks to be placed inside. The replacememt tanks will be sized so there be little taking apart the engine room.

10+ years ago the middle back tank leaked. I cut a 18" hole in the tank using a saber saw, and crawled in side. It was easy to see the leak in the dark tank. I hired a welder who welded up the tank. So I will try repairing the tank first. I know the middle 400 gallon tank is ok which would provide 600+ miles and repair replace tanks over time.

The replacement tanks would be plastic. To repair tank would cost $1000.00. To replace would be $2000.00. I would do most of the work myself.

sonnyboy said:

Thanks for your thoughts! Any chance you know the name of the Solomon marina? I am interested in what process they are using.

Click to expand...

Washburns BoatYard Solomons MD boat was a Seaton 48 Namaste

Four 110 US gallon tanks, aluminum, cost $8,000 in 2012. Shipping extra. Installation was another $8,000 by the time we were done.

With a twin engine installation the engines will need to be removed (or moved) which is not just expensive but a pain to get things working correctly afterwords. Basically the engine room astride the tanks needs to be cleared out.

This is not just an issue of cost, but of your time and frustration. Down time of the boat and problems getting things to work correctly afterwards.

I would reduce the offer price by more than just the cost of the tanks and installation. If the seller wants to save money he should have replaced the tanks.

The purpose of a survey is to look for issues big and small. Purpose achieved it would seem. What else has the owner hidden?

Replacing tanks is no trivial matter and for most is a very good reason to walk from the deal.

In the end, by reducing the sales price to cover tank replacement, the owner winds up paying the price. So, you can contract the purchase based upon the owner having the job done to your surveyor's satisfaction. No guessing at cost and no hidden surprises for the buyer.

I would ask what is your intended use of the vessel?

Diesel that sits in a tank for extended periods is harder to control fuel algae growth.

If you intend on using this as an 'infrequently moved' party platform then go with four smaller tanks, and use just a pair of smaller volume tanks for daily use. Then when you want to go on a trip, you can open up the other tanks for filling and use as you go. As mentioned, you can cut out the old tanks and make it easier to put in smaller plastic tanks in their place.

If you want original sized tankage then you have a whole bunch of stuff to remove and reinstall.

It seems that often sellers will not move much on price due to bad tanks.
In comparison, and older boat with a seized engine can hardly be given away. Yet, replacing a set of tanks can cost nearly as much as replacing a small diesel engine, as it is just as much labor.

I just spoke to the yard in MD. Nice folks. They are tracking down the name of the "high tech rubberized goo" and will call me back. I will pass on what I find out.

Subscribed....Standing by

fuel tank relacement.

O'boy Tanks in my Jefferson leaked after haveing fuel polished and tanks cleaned. Believe that the high pressure washing broke loose rust,tar buildup. Try welding but another leak developed. Got quotes of $30,000.00 plus tank. Figured I could do it my self. Gave fuel away for labor, removed anything in the way of getting to tanks ,measured tank size ,several times. Made template of side, and found that if I cut it down by 1 inch it would fit in the rear window of the saloon. Found a welder to build tanks, aluminium, for $5,000.00, tested and CG approved. Boat put in yard,to be painted,while I got to work below. Setup A-frame in saloon lifted 6cyn Perkin over other engine as I cut out Chinese s.s. with saws-all. 15 blades later tank was out engine back on bed. Next weekend guys helped set tank and started on other side . Did same and had tanks put in a 2 week window. Supported A-frame across the floor and underneath in engine room. Put everything back together and everything worked and I saved $$$$$$ . More cruising and I'm got a knowledge of the boat. Figured the whole thing with tanks,fuel lines ,blades,A-frame(which I sold ) beer and hot dogs for the labor costs about $6,000.00 , yard was another $2,500 plus the paint job$5,000.00. Labor priceless. It can be done ,just have a plan, and help. Measure 6X's and cut once. Pm me if you need more.

I'm familiar with ProSeal. It's used regularly in aircraft tanks which are called wet cells that are formed by the wing ribs and inner structure and it's skin. ProSeal coats all seams and forms a long lasting seal for the tank.

Here's a good introduction.
http://www.vansairforce.net/articles/tank_sealant.pdf

In the early 90's I had the twin tanks of my 34' Marine Trader replaced. Engine came out, tanks came out intact, new tanks went in and the engine replaced. Cost was about $8k and took the entire summer. Excellent job by a local yard that is no longer in business (nothing to do with their work).

Would I do it again? No - I would cutup and replace the tanks with smaller plastic tanks. I would still consider it an excellent job.

Don't tank sealants require clean dry surfaces for application?