Can I drill a hole in a stainless fuel tank?

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firstascent2002

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Hi guys,

can I drill a hole in the top of my stainless fuel tank without the deseil going boom? I really do want to fit a dipstick hole and was planning to drill a hole in the top. I would use chemical metal to secure a dut around the hole then plug it by screwing in a bolt. Checking fuel levels would then be a doddle....

The tank is a really complex shape so I'm never quite sure of it's volume...all I know is that I can motor of 27 hours with out running out of fuel...so far! If I can't drill a home, what are the alternatives to give me a quide to the volume of fuel within?

Kind regards

J
 
Yes you can.Start with a 3mm cobalt bit and proceed with larger ones until you get to the size you need.Use cutting fluid and a higher speed for the smaller bits,keeping the pressure high.This will stop it from overheating.If you don't put enough weight and speed on the drill you'll work harden the steel and ruin your chances of a clean hole.You'll introduce swarf into the tank though.Instead of using chemical metal use Araldite and a bit of glass tape over a large area.Make sure you abrade well before drilling.You don't want sandpaper grit in your injection pump.
 
J, I have a suitably scribed garden cane that works quite well when stuffed down the filler cap. It is flexible enough to go round the silght bend and marked every 5 gallons.

If you drill a hole why not go the full hog and fit an full inspection plate, you will need to get inside anyway to get the swarf out.

Pete
 
Why not just record your engine hours, at least as accurate as a dipstick. Your tank is unlikely to explode but unless you take the inspection hatch off and put a plastic ice cream carton or similar under the hole you will probably get swarf in it.
 
Quandary said:
Why not just record your engine hours, at least as accurate as a dipstick. Your tank is unlikely to explode but unless you take the inspection hatch off and put a plastic ice cream carton or similar under the hole you will probably get swarf in it.
Click to expand...

My tank meter went down last season when on the continent. Nothing going there, so I topped up and measured the hours running thereafter. When I got to Dover and retanked, I was chuffed at the accuracy of the countdown method - assuming 2.7 lit/hr which is a bit "fat" for my consumption but better to over-read I reckoned than the other way! This is the painless solution to your prob.

Diesel has a high burn temperature - over 300 degrees - so you are not likely to set fire to yourself if you drill holes in the tank. But one word of warning - if you do not make a 1st class job of sealing the inspection port you will have diesel vapours in the air, even if you don't have spills. This, as you know, promotes mal de mer.

If you go for a hole, why not go the whole hog and put in a meter - very straight forward. Even with a funny shaped tank you will soon come to interpret your meter reading for what it is. Plenty of different pieces of gear for this - and not expensive. PM me if you want me to look up sources for you.

PWG
 
Stainless fuel tank

Yes, nothing to stop you drilling the top of the tank for a dip stick. I wouldn't go along with those who calculate hours run, and therefore fuel remaining. I like to know how much fuel I have.

The most straightforward device is a sight glass, but be aware that British Waterways Boat Safety Scheme doesn't approve of sight glasses for some reason.
 
30boat said:
Yes you can.Start with a 3mm cobalt bit and proceed with larger ones until you get to the size you need.Use cutting fluid and a higher speed for the smaller bits,keeping the pressure high.This will stop it from overheating.If you don't put enough weight and speed on the drill you'll work harden the steel and ruin your chances of a clean hole.You'll introduce swarf into the tank though.Instead of using chemical metal use Araldite and a bit of glass tape over a large area.Make sure you abrade well before drilling.You don't want sandpaper grit in your injection pump.
Click to expand...

I doubt the tank will be thick enough to warrant multiple attempts with cobalt bits. - I used an ordinary HSS drill of the correct size with grease (which captures the swarf) when I drilled a hole for my heater pickup tube.
 
If you keep cleaning the swarf away as you proceed and smear grease on the drill bit as BGW advises above the amount of swarf getting into the tank will be almost negligble and shouldn't cause any problems.
Do use a lubricant on the metal to protect the drill and stop hardening of the steel.
 
firstascent2002 said:
................ what are the alternatives to give me a quide to the volume of fuel within?

J
Click to expand...

just tap the side of the tank from bottom to top to located the level.
(one less hole on your boat, and a few extra drinks in the cockpit) just a suggestion :)
 
Use a rivnut smear sealer between it and the tank before setting and put a washer under the bolt head.

TM-10-5411-224-14_67_2.jpg


pete
 
Hello Mariners,

If this was my predicament, I would drill two vertical holes on a convenient part of the tank.

Then install a glass sight gauge. Never an error in these.

This is why Amel still uses them on fuel tanks.

PS: Monique is the name of my old (RIP) dog.
 
Monique said:
Hello Mariners,

If this was my predicament, I would drill two vertical holes on a convenient part of the tank.

Then install a glass sight gauge. Never an error in these.

This is why Amel still uses them on fuel tanks.

PS: Monique is the name of my old (RIP) dog.
Click to expand...

2 horiziontal holes surely monique?
 
I think it is 2 horizontal holes but the connectors then form a ventical axis with which to connect the glass sight gauge. Vertical holes would be in the top and bottom of the tank!
 
NormanS said:
The most straightforward device is a sight glass, but be aware that British Waterways Boat Safety Scheme doesn't approve of sight glasses for some reason.
Click to expand...
Because glass like plastic, could be destroyed in a fire, allowing the contents of the fuel tank to flood out where it would be immediately more combustible than had it stayed within the 'protection' of the tank. Similar considerations apply to such items as water separators which have glass bowls although these may be located more remotely from the tank.
 
firstascent2002 said:
. . . . Checking fuel levels would then be a doddle....

The tank is a really complex shape so I'm never quite sure of it's volume... . . . . .
Click to expand...

If it was my project, and as you are an off-shore type and don't have to coply with British Waterways, I would 'T'-Branch of the outlet pipe and fit a thick walled clear plastic tube and mount it up the side of the tank.

The clear plastic tube needs to be longer and go up higher than the tank. You could even restrict the top end of this pipe to a millimetre to allow any pressure change when filling and running the engine and to limit any spillage or slop whilst underway.

Fluid finds its own level and the new sight-pipe will do the job very precisely. ;)
 
pheran said:
Because glass like plastic, could be destroyed in a fire, allowing the contents of the fuel tank to flood out where it would be immediately more combustible than had it stayed within the 'protection' of the tank. Similar considerations apply to such items as water separators which have glass bowls although these may be located more remotely from the tank.
Click to expand...

Yes, but sight glasses should always be fitted with spring loaded normally-closed valves, so the only fuel exposed to a fire is the very small volume in the actual sight glass, not the contents of the tank. (Same as any central heating oil tank)
 
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