Fuel Tank Change

I have a 40 trawler that has steel tanks and I am considering changing them out . They do not leak but look rusty. Does anyone have any thought on the subject . Oh it is twin engines

Almalola7 said:

I have a 40 trawler that has steel tanks and I am considering changing them out . They do not leak but look rusty. Does anyone have any thought on the subject . Oh it is twin engines

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We need more info on the specific make/model boat you have. If they are rusty, then yes, it's probably time to have them check out and replaced. If the rust is on the outside, and the inside looks good, they can be cleaned up and painted. Provided there are no leaks.


Depending on where your tanks are and how difficult it would be to get them out, will determine the best course to take to replace the tanks.

Thanks for the response . This is my first post on TF I don't know if I am responding correctly

DIY or are you going to have a yard do it?


Twin Engines or single?


Replace in kind or willing to change capacity and material?


Budget?


Wanting to cleanup entire engine room spaces/bilge or just tank replacing?

fuel tank change

I am going to do it myself and have some help from a local worker help me . I am also going to clean up the engine room and replace any hose I can lay my hands on. I don't have a budget in mind ,But I think it is going to take between 1 to 2 months

I am also going to reduce cap. a little just to make access easy between the tank and the engine. I am going use marine alum.

As part of a larger refit, I am replacing my steel saddle tanks (200g each) with four fiberglass tanks of 100g each so capacity is about the same (I might lose 10g) with one baffle per 100g tank. Fiberglass is more labor intensive to fabricate , aluminum is more material intenaive/expensive. I'm having the tanks built in Ensenada MX so fiberglass.

Each pair to be connected by 1-inch valves at the bottom. There will be one deck full on each side so each pair will act as a single tank. Pickups will be off the 1-inch valves, return into the top.

If I read your post correctly, you are reducing size to gain some space. One thing to consider is how the tanks will be secured. I found that by using the old tanks as a pattern, allowed using existing bracing to secure the tanks.

This job is bigger than I wanted to tackle, especially with highly capable labor at affordable cost in Mexico (Niza Marine in Ensenada, 70-miles south of San Diego). Total cost is about $7500 plus fittings, but includes remove and replace of single engine.

Its a big job but really just a series of smaller, sometimes nasty jobs. I am pretty sure each engine will have to come out in its turn. Cutting up steel tanks with a sawzall is also pretty easy and not dangerous. Maybe do one side this winter and the other side next year. Might make it a little more bearable.

Good Luck

pete

Depends on how well the tanks were cared for and the steel thickness.

My 1942 steel tanks are still going strong.

I am in process and have ordered a new custom aluminum tank. The original tank was integral to the hull, all but the top which was steel. I have the steel top off.

Almalola7 said:

Thanks for the response . This is my first post on TF I don't know if I am responding correctly

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You're welcome. You doing well here. A lot of good recommendations for your tank situation. Knowing your boat model could help with more specific answers. If you're not using your boat's maximum fuel range, no reason not to hold back on some capacity to make the tank install easier.

ak-guy said:

I am in process and have ordered a new custom aluminum tank. The original tank was integral to the hull, all but the top which was steel. I have the steel top off.

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What was the issue with your tank? Looks like a pretty nifty design but may have flaws I don't see right off.

How dirty was the tank when you opened it up Fritz?.....

ben2go said:

What was the issue with your tank? Looks like a pretty nifty design but may have flaws I don't see right off.

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The tank leaked slightly when it was full or close to full and the boat was rolling/pitching. The fuel leaked from under the top around the perimeter. The steel top was laid on the stringers and then fiberglassed around the top edge to the surrounding fiberglass. There was no sealant or gasket between the top and the stringers underneath. The top was rusting at the interface of the fiberglass and steel thus breaking the bond. The tank held 112 gallons and I only burn 1/2 gallon/hr and it has not been a problem to keep only 20-40 gallons of fuel in the tank and like that it didn't leak. The new tank will be 76 gallons and will hang from the stringers. Like the old tank the new tank top forms the floor of the saloon.

Sailor of Fortune said:

How dirty was the tank when you opened it up Fritz?.....

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What you see in the photo is what it looked like when opened. When I first got the boat a few years ago it had a bad algea problem. I jury rigged a temporary polishing system and cleaned it up pretty good. The inside looks dirty now but what is there is pretty well stuck on. I do plan to hit it with a pressure washer before installing the new tank, we'll see how much it cleans up.

One thing about this installation before and after the new tank is the easy access to the tank's lowest point through the 2.5" fill right on the floor of the wheelhouse.

ak-guy said:

What you see in the photo is what it looked like when opened. When I first got the boat a few years ago it had a bad algea problem. I jury rigged a temporary polishing system and cleaned it up pretty good. The inside looks dirty now but what is there is pretty well stuck on. I do plan to hit it with a pressure washer before installing the new tank, we'll see how much it cleans up.

One thing about this installation before and after the new tank is the easy access to the tank's lowest point through the 2.5" fill right on the floor of the wheelhouse.

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It seems Homer Hughes did a lot of things right on those boats.Solid systems, easily accessed for maintenance and repair. I would love one of those brought over to the east coast

ak-guy said:

The tank leaked slightly when it was full or close to full and the boat was rolling/pitching. The fuel leaked from under the top around the perimeter. The steel top was laid on the stringers and then fiberglassed around the top edge to the surrounding fiberglass. There was no sealant or gasket between the top and the stringers underneath. The top was rusting at the interface of the fiberglass and steel thus breaking the bond. The tank held 112 gallons and I only burn 1/2 gallon/hr and it has not been a problem to keep only 20-40 gallons of fuel in the tank and like that it didn't leak. The new tank will be 76 gallons and will hang from the stringers. Like the old tank the new tank top forms the floor of the saloon.

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I completely understand that. I would have done the same thing. I really dig those Allweather boats. I looked for one around '07-'08 and couldn't find one with a trailer to bring to the ASE.

I have replaced the tanks on my 44 foot Sun deck Cruiser without removing the twin cats. Remove the old steel tanks with a sawsall. Fabricated 3 fiberglass tanks to replace one steel tank. By removing the tailpipes I was able to get them around the back of the motor and in place. Glassed then together and to the hull. Feels great to get rid of the leaking steel tanks

We replaced both port and starboard iron fuel tanks on Sanderling in 2015. Had a well-respected yard do the work and in the process reworked a lot of the engine room. Had a single so just put the engine in the saloon. In 2005 we had the tanks on a smaller trawler with twins replaced and the engines sat outside the boat on engine stands during the work

You can read about our replacement at out web site:
Replacing Fuel Tanks - MVSanderling.netMVSanderling.net

Sanderling is for sale!

Almalola7 said:

I have a 40 trawler that has steel tanks and I am considering changing them out . They do not leak but look rusty. Does anyone have any thought on the subject . Oh it is twin engines

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Fuel tanks

Almalola7 said:

I am also going to reduce cap. a little just to make access easy between the tank and the engine. I am going use marine alum.

Click to expand...

The previous owner of my boat broke out the old cast iron tanks and replaced with aluminum tanks that fit through the main cabin door so replacing them if required, will be quite simple.

Our tanks had to be cut up to extricate them since the boat was apparently built around them! I had each single tank replace with two heavy-duty aluminum tanks with 2" between each tank - lost only 10 gallons from the original capacity on each side. Also added double-crimped USCG passenger vessel approved fittings on all the new lines.

Sanderling is for sale.

Bryant said:

The previous owner of my boat broke out the old cast iron tanks and replaced with aluminum tanks that fit through the main cabin door so replacing them if required, will be quite simple.

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Fuel tank change

Hi: here is the short answer to a very expensive project: Our 35 ft boat has twin engines that could not be moved to gain any amount of extra space. Up here in eastern Canada we do not have the qualified boat yards to tackle this job so had it done in Upper New York State. Had a new (only one) stainless steel tank made in Canada due to lower cost. Built by a company that makes them for the trucking industry.
The US boat yard cut a huge hole in the hull and dropped the old tank out the bottom. Gave me a chance to see a side of the diesel i had never seen before. Cleaned and repainted everything.
New tank installed and boat resealed better than new. Cost $10,000 US$.
Next time i will cut out the old tank and replace with 2-3 tanks joined together. Less painful me thinks.

Barrie

"Next time i will cut out the old tank and replace with 2-3 tanks joined together. Less painful me thinks."


A good choice might be multiple plastic tanks.

JUSTAHUG said:

Hi: here is the short answer to a very expensive project: Our 35 ft boat has twin engines that could not be moved to gain any amount of extra space. Up here in eastern Canada we do not have the qualified boat yards to tackle this job so had it done in Upper New York State. Had a new (only one) stainless steel tank made in Canada due to lower cost. Built by a company that makes them for the trucking industry.
The US boat yard cut a huge hole in the hull and dropped the old tank out the bottom. Gave me a chance to see a side of the diesel i had never seen before. Cleaned and repainted everything.
New tank installed and boat resealed better than new. Cost $10,000 US$.
Next time i will cut out the old tank and replace with 2-3 tanks joined together. Less painful me thinks.

Barrie

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Sounds brutal Barrie! I’ve heard of holes being cut in the topsides, between the waterline and gunwhale, to remove side mounted tanks, but going down through the bottom sounds extreme.

BobMc said:

We replaced both port and starboard iron fuel tanks on Sanderling in 2015. Had a well-respected yard do the work and in the process reworked a lot of the engine room. Had a single so just put the engine in the saloon. In 2005 we had the tanks on a smaller trawler with twins replaced and the engines sat outside the boat on engine stands during the work

You can read about our replacement at out web site:
Replacing Fuel Tanks - MVSanderling.netMVSanderling.net

Sanderling is for sale!

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Hi Bob, I’ve just read through your very detailed tank replacement story from your blog, and really appreciated the extensively documented article.
Top marks for your efforts, and good luck with the sale

Going thru the bottom is not so unusual and in fact that's my plan when the time comes (not too far away I suspect ). Much faster and therefore much cheaper for both removing the old intact (making templates unnecessary....just send old to the fabricator as is) and installing new. New tank kept out of way in engine room while 'glass guys follow a naval architect's laminating schedule to maintain hull integrity when making good. Having a walk in engine room helps. I'll go plastic rather than steel or aluminium.

Southern Boater said:

Sounds brutal Barrie! I’ve heard of holes being cut in the topsides, between the waterline and gunwhale, to remove side mounted tanks, but going down through the bottom sounds extreme.

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Aquabelle said:

Going thru the bottom is not so unusual and in fact that's my plan when the time comes (not too far away I suspect ). Much faster and therefore much cheaper for both removing the old intact (making templates unnecessary....just send old to the fabricator as is) and installing new. New tank kept out of way in engine room while 'glass guys follow a naval architect's laminating schedule to maintain hull integrity when making good. Having a walk in engine room helps. I'll go plastic rather than steel or aluminium.

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Interesting AB, everyday is a school day, as they say. I'd only heard of the topside extraction recently from a Bobbin Head (Sydney) yard involving a couple of Kong Halvorsen renovations.
Yes the plastic option does sound a very permanent and practical solution.

I kept our boat at Bobbin Head some years back. In my time there, I saw the yard guys cut one side out of a beautiful 55' Halvorsen to remove both saddle tanks. This Halvo had "plank-look" fibreglass sides and all the dock experts--myself included--thought it would be impossible to close up the hull again and maintain this look. We had to eat our words....the owner challenged those who didn't know to pick which side had been cut open and no-one ever did, even when she was hauled out. Mind you, the shipwright in charge at the time was an exceptionally skilled guy: you wouldn't want to trust an operation like that to just anyone. Same with going through the bottom....needs serious skills but if you can find a quality yard that will follow an engineered laminating schedule, it can be a highly cost-effective solution. The boat has to suit too....unnecessary in smaller vessels where engine extraction is no big deal and doesn't require major demolition of super-nice interior joinery and furnishings, etc etc..

It’s always about the skill level.
We recently surveyed a KH 50 at Empire Marina which had the saddle tanks extracted through the sides, 1.6 x 1.2 metre holes cut and new alloy tanks fitted and whole boat resprayed. While the repair appeared good, the 2006 paint job was average. The tank fabricator didn’t even fit inspection plates on brand new tanks?
Anyway the boat failed survey on many issues, which was a shame because she would have suited us well.