Buying a boat with original fuel tanks...

[Steve91T]

Hey guys, I’m starting a new thread on this subject. We are under contract with a 47’ 1987 Marine Trader Sundeck. Some of you remember the previous posts where the boat was a floating condo for several years and the engine room has been neglected. The very slow mechanic in the keys is finally making progress.

So now that we are getting closer to the point of getting a survey, I wanted your advice.

The fuel tanks have 3 yr old diesel in them. On Tuesday they are going to be pumped out and replaced with fresh diesel. Also the fuel guy is going to put in an additive that will help clean whatever junk is growing in the tanks.

Without getting into too much detail again, the tanks hold 300 gallons a side. Nobody wants to open the inspection ports due to their age. We all know someday these tanks will start leaking, who knows when that might be. As of right now they aren’t leaking.

Here’s what I’m thinking. I make them top the tanks off. This will put as much pressure on them as possible. They will be test running the boat before the survey to make sure it’s ready to go, then there will obviously be the sea trial itself. If they hold up and we end up buying the boat, we then will run the tanks down to 1/4 full and keep the minimum amount of fuel in there for our needs. My thinking is that the less pressure on the old tanks, the better. This might lengthen their shelf life. Can’t hurt, that’s for sure.

My other thoughts are if we fill them up, we might be stressing the tanks and might cause problems down the road regardless. Maybe we shouldn’t have them topped off.

I know that if and when they do start to leak, I will be installing bladders or maybe small plastic tanks linked together. I will never need 600 gallons of fuel, not even close.

What would you guys do?

Have them filled?
Leave them less than 1/2
Let them run the boat with fresh fuel and see how often the filters clog?
Demand they find someone to open the inspection ports on the tanks? (Don’t think this is going to happen, and I know cleaning from the inside can actually expose weak welds cause leaks)

 

[Miz Trom]

Hi Steve:


In case you missed it, take a look at this recent thread. The photos & description of the sludge inside the tanks next to the fuel pickup line are incredibly illuminating:



http://www.trawlerforum.com/forums/s6/fuel-tank-replacement-job-39628.html


Pea

 

[jleonard]

When I bought my boat it had 2 year old fuel in it. Bottom line there was nothing wrong with that fuel. I filtered it all myself, but never got anything in the filters.
After 11 seasons I have not had a fuel issue. Filters last a season or more and are only slightly dirty when I change them.
I hope you have the same luck.

 

[Steve91T]

Hi Steve:


In case you missed it, take a look at this recent thread. The photos & description of the sludge inside the tanks next to the fuel pickup line are incredibly illuminating:



http://www.trawlerforum.com/forums/s6/fuel-tank-replacement-job-39628.html


Pea

I did miss it. Thanks for posting that. Great read.

 

[Steve91T]

When I bought my boat it had 2 year old fuel in it. Bottom line there was nothing wrong with that fuel. I filtered it all myself, but never got anything in the filters.
After 11 seasons I have not had a fuel issue. Filters last a season or more and are only slightly dirty when I change them.
I hope you have the same luck.

Hope so! But I’m not hopeful. During the first two test runs the mains were blowing black smoke and not making rated RPM. Injectors have been rebuilt and the bottom is clean.

We’ll know more once they replace the fuel.

 

[Steve91T]

I just spoke with a surveyor. His recommendation was to run minimum fuel and not to top them off.

 

[tiltrider1]

If you are really concerned just pressure test the tanks. If the tank leaks on your watch there are people who can epoxy coat the interior of the tank.

 

[bayview]

Not sure that I would allow someone to pressure test tanks.

 

[BandB]

About all you can really find out is whether they leak or don't. Like many things, no one knows the life of tanks. Don't know the life of engines. We only know it's less remaining life than it was previously. If they're ok now, then you just go in with an awareness they may at some point leak.

 

[Lepke]

My current boat sat 6 years. The main tanks are 1942 mild steel. With a proper additive, filter watch, and about 20% new diesel, burned off the old fuel in a extended sea trial. Details in an older post.

It's not as big a deal, with proper care, as you think. Carry extra filters.

 

[Bay Pelican]

More likely than not you need to start planning the tank replacement now, so that when it is needed you can proceed quickly and have the funds available to pay for it. The first thing to do is see if you can get the day by day history of a tank replacement on another Marine Trader 47. Then figure out what you are going to do.

 

[Aquabelle]

Why did he say that?

 

[Steve91T]

Why did he say that?

He said that there’s no gaurantees that will prove one way or another and if it starts leaking then I’ll have a bunch of diesel to deal with.

 

[bayview]

There is a reason that used boats don't cost the same as new.

 

[jungpeter]

Hi Steve91T,

Yes, there are lots of good reasons used boats cost less than new ones. Amongst others is the potential for a VERY big bill, should the fuel tank(s) leak in the near future. How far off is the "future"? As others have stated, your guess is as good as mine. Personally, I feel the service life for fuel (and water) tanks of ANY material in recreational use is 25 years. Beyond that, the tanks exist on borrowed time.

ALL tankage will leak, eventually. It's naive to think otherwise. It's also naive to think the fix for leaking fuel tanks is simply to open them up and coat them with some kind of mouse milk and voila! all is well. Planning for, and realistically budgeting for replacement is sound advice.

Regarding the likelihood of a surveyor locating a potential leaking fuel tank, no, it's unlikely. Good ones can locate failed tankage (sometimes), but they typically will not perform any testing on tankage that might reveal real issues. Pressure test during survey? Nah, I doubt it. Opening the tanks for a visual? Nah, I doubt it. Most surveys state in writing that no disassembly of the vessel will be performed during the survey. And certainly no potentially destructive testing is commonly performed. Topping off the tanks (again, pre-survey?) won't do squat to reveal leakage, unless it's caused by a gross failure of the tank(s) at, or near the top. And it seems unlikely that a seller would volunteer (how do you "make them"?) to fill the tanks at his expense pre-survey.

So, you're on your own with an older (31+year) boat such as you're contemplating. Plan to replace the tanks accordingly.

Regards,

Pete

 

[Giggitoni]

It all depends how the tanks and the rest of the boat were maintained through its lifetime. If the outside of the tanks were kept rust free and dry and the insides were cleaned regularly, the likelihood of competent, non-leaking tanks is high. If so, the tanks will outlive the owner. Without good, honest maintenance records, it’s a crap shoot.

 

[Dalem]

There is a big difference between steel, stainless and aluminum tanks. I had a boat with an aluminum tank from 1984. It had a lot of algae. I scrubbed the tank and found out that the algae sticking to the bottom was all that was keeping it from leaking. I fixed it by removing the tank, sanding inside and out and coating inside with epoxy and epoxy/glass on outside.

Current boat has SS tank from 1971 that doesn't leak but no algae problem. If it does, it is a big deal to remove. That is the risk with old boats. Dale

 

[OldDan1943]

Off the boat fuel polishing, cleaning and inspecting the tanks. I suspect the current owner will not object.

 

[Steve91T]

Here’s what I’m torn with. Do I have then open the tanks or not.

If we do, I know we are going to see sludge. That’s a given. So what do we do then? Have them cleaned? We all know that alone might cause a leak.

I know we are buying a boat with old tanks and the price reflects that. About $70-80k. If they are actively leaking, $40-50k. If the boat is in prestine condition with new tanks, $100k+.

 

[BruceK]

If the seller will let you play with the tanks at sellers risk, you have some freedom. As a seller I would not, and I would try to have the sales agreement provide the boat at the buyers risk during survey.

If you buy as is, don`t get too aggressive with the tanks. They might leak tomorrow or not for years. People don`t go replacing tanks not leaking because they might at some future time, unless there are real reasons to act now. You could seek an allowance off the price towards replacement,the seller might say that is priced in, but I reckon you`d get an allowance.

 

[Bay Pelican]

Bruce's comment about an allowance is right on. I assume a 47 ft Marine Trader has twin engines which mean that the tank replacement process will either have to remove both engines or cut out the sides of the hull. Expensive in either case. Also the down time is a cost factor unless it is planned to be done in a normal off season. From start to finish it took six weeks to replace the tanks in Bay Pelican and being a single engine boat we did not have to remove or move the main.

 

[Wxx3]

Yes, but OP already stated that if the tanks do leak, he will used bladder inserts.
I think that is a very good plan and cost effective.

Also, I agree with surveyor to not fill the tanks.

I do not think changing fuel will clean up the way the engine runs.

I don't know how big or where your inspection port is, but at some point, I'd open it up and take a look. My Kadey Krogen tanks are tiled forward and inside enough, so that what sludge was in there, was pretty much by the inspection port in the first baffle. It was easy to suck out with my Bucket Head shop vac.

 

[FF]

"Also the fuel guy is going to put in an additive that will help clean whatever junk is growing in the tanks."

So you plan on replacing the fuel a second time as this majic goop "cleans" the tank?

I would simply set up a "polishing" system and run it till the fuel is clear.

Then burn it after a set of OK filters. Carry a case at least.

"ALL tankage will leak, eventually. It's naive to think otherwise."

Guess I am very naive, Monel and modern plastic seem to have an indefinite life.

At least I have seen 75 to perhaps 100 year old monel fuel tanks.

Iron tanks will usually rust from the outside in , deck leaks or crap mounting sitting in water.

If a sump was installed (rare on TT) and serviced ,the tank can be rust free also almost indefinitely .

That leaves Asphalting as a fuel clump hassle , EZ enough to filter out with a home brew transfer "polishing " system.

If the tanks do not have a visible leak now , there are many things you can do to prolong their life.

Bio Bor or similar bug killer will help , but the biggest help is removing water from the tank.

This may require a hose down to the bottom of the tank from the deck , or carefully disconnecting the fuel fill hose from the top of the tank.

If the tanks eventually fail , try to install a genuine fuel tank, with a built in sump, instead of just a box for fuel.

 

[fryedaze]

Here’s what I’m torn with. Do I have then open the tanks or not.

If we do, I know we are going to see sludge. That’s a given. So what do we do then? Have them cleaned? We all know that alone might cause a leak.

+.

Having just cleaned the sludge out of my tanks while cutting them up, I would have opened them up and cleaned them out if I had manways. Taking the sludge out is no big deal. I just scooped it up with a 6" drywall blade. I then sprayed down with a degreaser and wiped down. If the tanks leak after that then they were marginal anyway and you want to know that before buying. The question is, can you access all of the tank with the manways you have?
On the drain and fill question. If I did that to my tanks I am sure I would have significantly stirred up the sludge. The sludge is normally covered by at least a foot of fuel. If the tank was emptied and then you filled it, the initial fuel would hit the sludge and move it around.

 

[Steve91T]

Here’s the only picture of the tank with the inspection port. I believe there is only 1 per tank.

I don’t know if opening that port could cause problems.

 

[Steve91T]

What really sucks is that it isn’t my boat yet, so my opinion on what needs to be done is just that, an opinion. Maybe just having the fuel polished will be the least stressful on the tanks and provide the best results.

 

[High Wire]

The fuel itself will be fine after three years. I don’t understand the thoughts of babying the fuel tanks. The first few boat wakes will put large dynamic loads on the tanks far exceeding the static head of a couple feet of fuel. The exception being if the boat never left the marina again.
Buy the boat, use the boat, and if they leak deal with it.

 

[Steve91T]

Here’s the latest.

I’ve spoken to 3 different surveyors now. Nobody recommended topping the tanks off because if they do leak you now have a ton of fuel to deal with.

They do recommend having the ports opened up and taking a look.

One recommended having the tanks pressure tested.



The latest a from the broker:
The tanks are going to be drained on Tuesday, Techno will be added and the new fuel be added, maybe to the half way make (150 gallons a side). Then they are going to take it out for 2 hours while monitoring the filters.

 

[OldDan1943]

Here’s the latest.

I’ve spoken to 3 different surveyors now. Nobody recommended topping the tanks off because if they do leak you now have a ton of fuel to deal with.

They do recommend having the ports opened up and taking a look.

One recommended having the tanks pressure tested.



The latest a from the broker:
The tanks are going to be drained on Tuesday, Techno will be added and the new fuel be added, maybe to the half way make (150 gallons a side). Then they are going to take it out for 2 hours while monitoring the filters.

Try to be there so you can observe the filters.

 

[sbu22]

"because if they do leak you now have a ton of fuel to deal with."

It happened to me with near full tanks. Pump it off, drum and store it until necessary repairs to the tanks are effected. Polish the drummed fuel and reload the boat. Not a big deal.