Boat fuel tank ????

[W.olly]

So i have decided to have a new fuel tank ( petrol ) made for the boat. Reason is after a good clean of the original there is a few to many corroded spots and pin holes. Although i pressure tested it and all fine but not worth the risk and had two areas plated over it is a new one for me.

The tank is 1400mm L x 650mm W x 300mm H

We have 2mm aluminum and will be fitting two baffles. Maybe tree baffles yet to add more strength.

I can it made at work for free which is a bonus and one perk to the job

Any thoughts on this. good or bad. not that i need say that.

 

[tom2207]

Id be putting a sump on it with a drain if you have room , and a sight glass or dipstick ,, depending on your fuel gauge sender / pump an extra baffle wouldnt go amiss ,, and curved corners rather than hard edges / corners. Oh and a decent removable inspection hatch ,, Vital.

 

[addjunkie]

Id be putting a sump on it with a drain if you have room , and a sight glass or dipstick ,, depending on your fuel gauge sender / pump an extra baffle wouldnt go amiss ,, and curved corners rather than hard edges / corners. Oh and a decent removable inspection hatch ,, Vital.

Nothing Id disagree with there, though both Ive made in the past had square edges welded. That volume of liquid will be quite heavy. Make sure that its well supported and or baffled so it doesn't deform when full.

Cleanliness is essential…….

 

[cheb]

Consider making it two separate tanks, then you could have a redundancy in the fuel supply system.

 

[W.olly]

This the original tank which i will be copying, reason is there is only a small inspection/access for the sender under the deck. think ill move te filler as its a pain to get to once fitted.

.

 

[W.olly]

So that size tank two baffles will be enough on 2mm ally ? i see now that it is usually 3mm walk thickness ally

 

[tom2207]

This the original tank which i will be copying, reason is there is only a small inspection/access for the sender under the deck. think ill move te filler as its a pain to get to once fitted.

.View attachment 403521View attachment 403522

View attachment 403524

id make that with a sealed baffle and two take off points , or at least a baffl thats is almost sealed , say a small hole half way up ,,, then you would have a built in reserve , no use if you get a bad fill ,,, but better than nothing on a bad day . or fit a take off point with a tap and two height pipes , like a motorbike tank idea . but then again if its only cruising canals it wouldnt matter as much as if your sea fishing ,,, maybe you have a spare outboard , or a pair of oars ,,,
I like redundancy , but I like simplicity on boats too ,,,, two sides of the same coin though.

 

[Bullet2012]

Consider making it two separate tanks, then you could have a redundancy in the fuel supply system.

Also that allows one tank per engine

 

[W.olly]

id make that with a sealed baffle and two take off points , or at least a baffl thats is almost sealed , say a small hole half way up ,,, then you would have a built in reserve , no use if you get a bad fill ,,, but better than nothing on a bad day . or fit a take off point with a tap and two height pipes , like a motorbike tank idea . but then again if its only cruising canals it wouldnt matter as much as if your sea fishing ,,, maybe you have a spare outboard , or a pair of oars ,,,
I like redundancy , but I like simplicity on boats too ,,,, two sides of the same coin though.

the last bit i 100% agree with and simplicity. the tank now has one baffle with corners open. thats it. as for cruising it will be used anywhere, more rivers and sea really, sick of canals now. i will have a aux engine as therh is two engines lol.

 

[tom2207]

Also that allows one tank per engine

has it got two engines ,,, then two tanks is totally the way to go ,,, even if its one tank with a sealed baffle

my last boat had two tanks 550 gallons each , and an inspection hatch you could reach into with a mop to clean them ,,, I liked that set up and it worked well ,,

 

[W.olly]

Also that allows one tank per engine

is that a benefit tough. i cant see it being but happy to have it explained. these boats ave been single tank for ever so that doubling trouble

 

[tom2207]

is that a benefit tough. i cant see it being but happy to have it explained. these boats ave been single tank for ever so that doubling trouble

if you get a pipe that leaks ,,, and your link pipes closed ,,, yep very handy

if you can run two totally separate systems without too much bother , its the way to go

 

[cheb]

has it got two engines ,,, then two tanks is totally the way to go ,,, even if its one tank with a sealed baffle

my last boat had two tanks 550 gallons each , and an inspection hatch you could reach into with a mop to clean them ,,, I liked that set up and it worked well ,,

That's a long handled mop, did you use it as a bargepole too?

 

[Bullet2012]

if you get a pipe that leaks ,,, and your link pipes closed ,,, yep very handy

if you can run two totally separate systems without too much bother , its the way to go

Tom types faster than me, but that would be the main reasons.

 

[W.olly]

so you think 2mm wall ally with two baffles ok for a single tank. . or if two tanks a single baffle in each ?

 

[tom2207]

so you think 2mm wall ally with two baffles ok for a single tank. . or if two tanks a single baffle in each ?

nope ,, id be starting at 4mm alloy ,,, 2mm stainless maybe .
cheesie does a lot of tanks , but there are folk on the site who do a lot of boat work , wait till they chip in , their opinion counts , my tanks were 1/4 steel plate

 

[addjunkie]

Only issue I see with two tanks….two Fill points, two senders, two take offs. Twice as many leak points. But two independent engine-set ups is 100% redundancy if one fails. The original looks steel, why ali unless its free

 

[W.olly]

Only issue I see with two tanks….two Fill points, two senders, two take offs. Twice as many leak points. But two independent engine-set ups is 100% redundancy if one fails. The original looks steel, why ali unless its free

Thats my thought for two tanks., twice as many problems. This system has one feed from tank no joints but for exit and to a flexi line in the engine bay to filter then pump. very simple. i like the idea of two tanks but still cant see why its needed yet. only for balance etc in a boat if tanks are large. then they are usually connected wit a balance pipe. The 2mm ally is free, but 3mm minimum is needed so ill buy some, couple hundred quid. not to bad to get a new tank wiich is usually closer to £700..
Stainless is crazy money now. aluminum is near as good, many marine tanks are made from Ally or stainless, benefit of Ally is the weight of them, i want to stick with wat it has due to weight as it will add to the pay load for towing. I would try HDPE but i dont trust my welding skills as never done it before and i want tis to be 100% safe, its petrol after all. .

 

[addjunkie]

Actually from a naval architecture point of view two tanks with a balance pipe isnt a good thing. It can add to the “free surface effect” if rolling. On a larger scale fore and aft framing or baffle’s, reduces this quite substansially. If my memory serves me correctly 1 baffle 1/4s the effect, it was many years ago I studied such things.

Free Surface Effect is what caused the Herald of Free Enterprise to roll over.

 

[Keith 66]

Having been in the boat trade since 78 i have seen a few fuel tanks, Few comments! Access, the number of boats i have worked on with appalling access to tanks (and engines) is legion, you have to be able to get at it & to be able to remove it. Tanks will leak, corrode, split & get full of crud, Diesel tanks especially so, I remember a job i had cleaning out a tank on a 40ft motor yacht, She spent most of her life on the upper thames then came down the tideway, engines conked out. Basically rolling about in waves stirred up all the sludge in the tank & blocked the filters solid. Lifeboat job.
I took about 40 gallons of goop out of that tank the consistency of oxtail soup. At least it had a decent hatch in the top of the tank.
A friend has just had a grp tank split on his motor yacht, guess what no access.
Another rich man i know had a big very expensive motor yacht, tanks were built in & had been painted inside with some form of sealer, It broke down & at 3 years old the boat became inoperable because the stuff kept coming off & blocking the filters. Because the tanks were built in & access was all but impossible the whole accomadation aft had to be destroyed to get at them. Nearly bankrupted the builder.
As for petrol, they got to be perfect with good bilge blowers too.
Not many people running big petrol engines in boats these days & often seems to be the kiss of death when its time to sell.