Hydraulic Steering design

There's a bit of difference in tubing. There are 6 different types of copper tubing: K, L, M, DWV, ACR, and MED. Of these, M, L, and ACR are the ones you'll find at the big box store. Your choice of K is good, as it's the thickest wall and typically called pipe, though it's technically a rigid tube (hard drawn). The ACR tube is capped and nitrogen filled, to prevent corrosion and moisture, which needs to be avoided in ACR applications and likely why the manufacture asked for ACR tubing, rather than plumbing pipe (tubing). ACR is also delivered cleaner and smoother inside. Your oil choices are all over the place, but expect to pay $15 - $18 a quart if purchasing a gallon and $20 - $25 if separately. Go to your local airport and buy as much as you need (MIL spec), though it'll be pumped from drums, so bring your own clean container to carry it home. I've done this and gotten oil for $5 bucks a quart.



Available online (aviationoiloutlet.com), this is $35 a gallon.

 

Great info PAR, thank you!

 

Update: Lines ran & system filled & purged. the system took a little over 2 qts so 1.5 qts or so of the gallon left. The only concern I am having at this point is the number of turns. With the H25 Helms and the K-2 Cylinder, the book states 6.5 turns lock to lock. I am right at 8 turns right now after 2 bleeding efforts. Should I Be concerned that I don't have a complete bleed? Or is it likely that I was a little undersized on the pressure lines for the volume needed to support 6.5 turns lock to lock?

 

I wanted to post the final status as I launched over the weekend. All I can say is wow... What a difference. The boat handles like a sports car. All of my following sea struggles are gone. This system is so precise it is amazing. On plane, the mere flick of the wrist will result in the desired course correction. Most of the maneuvers can be accomplished within one full turn of the wheel in either direction. At slow speeds, the added rudder travel has greatly added to the handling characteristics. Needless to say, I am kicking myself for not doing this sooner.