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Old 03-19-2023, 09:24 AM   #16
City: Rochester, NY
Vessel Name: Hour Glass
Vessel Model: Chris Craft 381 Catalina
Join Date: Aug 2019
Posts: 6,688
Originally Posted by SteveK View Post
Do you have specs from 37 years to compare to current rudder position?
Steering is something I am working on. Bleeding air has made the wheel more responsive, but it still wants to wander, requiring corrections. I am used to when prop rpm is balanced the boat goes straight. That is not happening, so next is rudder adjustment.
A while back TF had a thread of a tech setting rudders toe out, mistaking toe for heel. How can you be certain in 37 years a well meaning person saw they were not parallels so made them so.
IMO the shudder you feel is from prop wash and air in hydraulic lines.

I know the history of the boat pretty well, and from everything I know, the only work that's ever been done on the steering prior to my ownership was new hydraulic lines. There are no tool marks on any of the hardware around the rudders or steering cylinder save for the packing nuts on the rudder posts, so that further points to nothing being touched. And while I'll be able to measure it this afternoon, I don't think the toe setting is wrong, as the steering behavior near the center point is as good as I could ever hope for. It tracks like a car when on plane, and at slow cruise (6.5 - 7 kts), as long as the sea state is calm, I can take my hands off the helm (no autopilot) and go 3 - 5 minutes without touching the wheel and not end up more than about a degree off course.

I don't think the shudder is air related, as bleeding the system has no effect on it. And the shudder isn't felt in the wheel anyway, it's felt through the deck. So yeah, some combination of water flow over the props and rudders at that combination of speed and rudder angle is likely the answer. Simple solution is just to not use full rudder above 1000 RPM in most situations.
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