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Tubing vs. Pipe for steerage

Old 03-22-2020, 09:29 AM
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Default Tubing vs. Pipe for steerage

I'm re-habbing the steerage of a 40' Gibson and want to replace the 3/8' soft copper tubing with something I can sweat. I've had no end of problems with leaks by all the unions and couplings required. I know it's me. I'd just rather use sweatable pipe instead.

So .... 3/8' pipe is a special order and more than 3 times the price of 1/2'. To my mind, the only downside is the additional fluid that would be required.

Or is there something I'm missing?

thx
Old 03-22-2020, 09:36 AM
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soft copper is not prone to vibration failures. rigid copper is.
Rigid tubing is made stronger and rigid by adding other alloys. Soft copper is pure copper which is weaker and must be made thicker to withstand same pressure as the rigid. That is why it costs more. You can sweat soft copper too but it is vulnerable to breakage at the area heated by the soldering torch. if you want to stay with fittings but done want leaks, why not use AN fittings with stainless mesh flexible hoses like on aircraft and race cars?
Old 03-23-2020, 08:37 PM
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Alright -- I'll bite the bullet, figure out how to simplify the layout and play it by the book. I appreciate your response. thx.
Old 03-23-2020, 08:47 PM
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The difference between hard and soft copper is the temper. Rigid tubing comes in type M ( thinner wall) and type L (thicker wall) where soft copper tubing isn’t made in type M.

A sweated soft copper joint messed up the annealing process A little but is not inherently weak.
Old 03-24-2020, 11:11 PM
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The larger ID tubing will give a smoother feel, oversized is the bomb here.
boat manufacturers tend to cheap out on stuff like that, OEM is often less than ideal.
the quantity of fluid is not a dealbreaker, as it’s not a consumable.
Undersize it and you get a notchy feel, and more resistance at the helm.
Old 03-24-2020, 11:51 PM
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This tubing used to be popular up here :


Now most guys use hydraulic hose.
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Old 03-25-2020, 08:18 PM
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Originally Posted by Bob1957 View Post
Now most guys use hydraulic hose.
Here's a tree i'd like to bark up against just a bit.... Seastar cautions against 'just any hose'. Understandable and for a blue water, performance application justifiable. But I'm a really (really) slow boat in a fairly shallow pond with little to no torque -- torque/pressure being (i think) the operative bit. What sorts of rips in the time/space continuum would I risk by going into my local hydraulics fabricator and asking for a couple of 40 foot hoses that couple to a 3/8 compression fittings?
Old 03-27-2020, 12:11 PM
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I have never had Sea Star steering.
I have 3 station Wagner steering, flying bridge is hydraulic hose down to wheel house steering, hydraulic hose from there to autopilot pump,
short hydraulic hoses out of pump that convert to 1/2" copper tubing, that runs back to cockpit steering but converts back to hydraulic hose just before that Wagner steering pump, then hydraulic hose to the steering ram. Boat was built in 91 and most of the steering hydraulic hose is original, all of it is 3/8" .
A good hose shop will know what you need.
Old 03-27-2020, 01:06 PM
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When I built my 38, I used 3/8" copper refrigeration tubing and flare fittings. Two helms, AP, power steering, pressure reservoir, rudder cylinder, a bunch of tees. All that stuff meant a LOT of flares. Filled and bled and pressurized the system and NOT one leak. And that was 14yrs ago. And the first time I did flares on copper. Made me a believer in simple flare fittings.

System relief valves are set at 1000psi, and I occasionally test by going hard over and forcing wheel til I hear the relief valves "squeak". So system is good to 1000, highest it can go.
Old 03-28-2020, 04:30 PM
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Originally Posted by Corndog38 View Post
System relief valves are set at 1000psi, and I occasionally test by going hard over and forcing wheel til I hear the relief valves "squeak". So system is good to 1000, highest it can go.
That's convincing re: flares... but I gotta ask -- the 'refrigerators coils' i'm seeing today are rated at 650psi. Are you pushing that or have today's refrigerators just gotten that wimpy?
Old Yesterday, 05:58 AM
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I did not bother even investigating the tubing pressure rating. Being rated for 650 probably includes a safety margin for burst pressure and also a margin for cyclic loading. What I knew is that the local boatbuilders had been using this stuff for decades with the same relief valve setting and there had not been a rash of failures. Good enough for me!!! The hard-over test to relief valve setpoint is pretty brutal, but if system holds then, it gives you a lot of confidence.

In normal operation, I bet the steering line pressure never gets more than a couple hundred psi.
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