Copper versus hose

S

Seamonk

Member
Joined
17 May 2025
Messages
28
Location
Sligo
Visit site
I’ve got a lot of copper pipe in the diesel-fuel and hydraulic lines in my boat. A lot of it is hose->copper->hose type runs.

My initial thought is that I should replace all the copper pipe sections and just run hose from point A to point B. Is there any actual advantage to copper pipe sections over all-hose runs in “fluid delivery” system?

I feel like copper pipe is like hemp or Manila line in the rigging. “Antiquated” is the word that comes to mind.
 
My first thoughts are that hose has a finite life, whereas copper does not, assuming it is properly clipped. I'd have to look it up to see what the life of fuel hose is mind.
The connection between the copper pipe and the engine needs to be flexible of course to deal with vibration.
 
For hydraulics, hard pipe is more precise at transmitting power to the desired function, as soft walled hoses can expand and impact performance. If changing to all soft hose, make sure it is specified for hydraulic use at high pressures and you will be fine. Hydraulic hose tends to be braided inside the hose material. External braiding is not an indicator of a suitable hose.

For fuel, when I had my engine space upgraded, all copper pipe was removed and fuel complaint hose was fitted. The only hard pipe left is on the engine itself. I have seen no deterioration in performance over 7 years as a result.
 
RunAgroundHard said:
For hydraulics, hard pipe is more precise at transmitting power to the desired function, as soft walled hoses can expand and impact performance. If changing to all soft hose, make sure it is specified for hydraulic use at high pressures and you will be fine. Hydraulic hose tends to be braided inside the hose material. External braiding is not an indicator of a suitable hose.

For fuel, when I had my engine space upgraded, all copper pipe was removed and fuel complaint hose was fitted. The only hard pipe left is on the engine itself. I have seen no deterioration in performance over 7 years as a result.
Click to expand...
+1
 
If it is straight forward to change for a continuous fuel line, then I'd do that. Less potential for isues in future.

The life of fuel hoses is quite long.
 
My copper fuel lines were 42 yrs old before i changed them to rubber fuel hose and added a vacuum guage..
 
When I first bought my boat several years ago I was told that flexible fuel was a no no and it had to be copper - then when I re-engined a few years back I was told copper was a no-no and it had to be flexible.
 
bedouin said:
When I first bought my boat several years ago I was told that flexible fuel was a no no and it had to be copper - then when I re-engined a few years back I was told copper was a no-no and it had to be flexible.
Click to expand...

I think it was something to do with fire? But always seemed pretty stupid to me when it inevitably had a bit of rubber connecting the copper pipe to the engine.
 
Seamonk said:
Will it break in a bad storm with heavy seas?

Not much breaks on the hard or in a marina.
Click to expand...
I suppose it might depend on the boats history (it might not have spent all its time on the hard or in a marina) and on the details of the installation. I believe copper pipe can work -harden and embrittle from vibration, but flexible hose can also degrade.

As an example, I understand there is a steel fuel pipe on my 1GM10, with rigid connections at both ends (so no hose connection) which often corrodes through and is commonly replaced with copper. I'll have to have a look at this when I get back to the boat, which has been about 5 years unused on the hard but with the bottom of the engne in freshish rainwater. If it isn't too far gone I'll give it my standard aluminium and sunflower oil treatment, which has done well on cars but is untested in a marine environment. Otherwise I have some kunifer brake pipe that might do.

Rather bizarre argument about flexible brake hose as a boat engine fuel line, odd because its on a motorcycle forum I used to frequent, where you wouldnt think they'd get so annoyed. Though I know almost as little about motorcycles as I do about boats. logic seemed to support my reservations, though it was probably OK.

Internal oil resistance of "steel" braided brake hoses?
 
Last edited:
Copper fuel & hydraulic lines were used for many years as they were simply the best of the available options, and as a bonus it was cheap. If you vessel was built to class (LR etc) standards, it is likely that solid fuel and hydraulic lines were specified. They would always have a flexible connection to the engine.

More recently, flexible fuel lines have taken over. Provided they are routed, fastened and terminated correctly they are every bit as good (and cost) as copper lines and have the advantage of being easier to route, and don't transmit vibration. RCD allows for flexible hoses which is why most modern pleasure boats have switched for production.

In summary, it's your preference. Both are good, each have advantages and disadvantages. Personally, we removed the solid lines on ours and replaced with flexible. It will take me an afternoon to replace them in 5yrs or when I decide to. To make copper lines with the required bends and to physically get them into the space would be a major operation.
 
Moodysailor said:
Copper fuel & hydraulic lines were used for many years as they were simply the best of the available options, and as a bonus it was cheap. If you vessel was built to class (LR etc) standards, it is likely that solid fuel and hydraulic lines were specified. They would always have a flexible connection to the engine.

More recently, flexible fuel lines have taken over. Provided they are routed, fastened and terminated correctly they are every bit as good (and cost) as copper lines and have the advantage of being easier to route, and don't transmit vibration. RCD allows for flexible hoses which is why most modern pleasure boats have switched for production.

In summary, it's your preference. Both are good, each have advantages and disadvantages. Personally, we removed the solid lines on ours and replaced with flexible. It will take me an afternoon to replace them in 5yrs or when I decide to. To make copper lines with the required bends and to physically get them into the space would be a major operation.
Click to expand...
I don't disagree but our copper fuel lines are 45 years old. We have flexible lines for final connections. Good quality flexible lines throughout would be fine but the boat was built to LR 100A1 so i guess that was the spec
 
geem said:
I don't disagree but our copper fuel lines are 45 years old. We have flexible lines for final connections. Good quality flexible lines throughout would be fine but the boat was built to LR 100A1 so i guess that was the spec
Click to expand...
I also agree with you. There is little doubt that copper lines (installed correctly) will outlast flexible lines.
In our case, replacing solid lines would mean removing some of the interior furniture, whereas flexible lines I can do in a few hours with no major disruption. A purely personal choice to go with flexible :)
 
Suspect the change is due to degradation of fuel containing FAME in contact with copper, rather than the integrity of the installation over time.
 
I don't know about fuel lines, but hydraulic hard pipes (on my old Case for instance) get ditched because the cost of hoses is in the fittings, not the hose. To go from A to B in hose is two fittings, to do it in hose-pipe-hose is eight.

Chafe is a concern, fitting hose through a pipe gap can be awkward, and it's not pretty, but the longevity of the installation is determined by the lifespan of the hose any which way.
 
You must log in or register to reply here.

Share this page

Top