Believe it or not, most people do not completely understand the full role of how the steering wheel (its diameter and placement) plays into how the steering system works. Usually “aesthetics” is the basis to decide what type of steering wheel one chooses. Yes, that is important, BUT, the diameter of your steering wheel or the actual radius at which you are turning it becomes a major part of the equation if you go with passive steering. Bigger diameter wheels equals less RIM FORCE in order to turn. Think of it like a longer wrench when trying to get a bolt tight, or loose. Call it “LEVERAGE”. If you only have room for a small diameter steering wheel, then in most cases, you will need more turns lock-to-lock to compensate for the decreased leverage you have turning the wheel. Large diameter steering wheels give the operator more leverage to overcome higher pressures within the system and usually require less turns lock-to-lock overall…
STEERING LINES & FITTINGS
Here is where you will see major differences in what is used or can be used in hydraulic steering installations. Most smaller “production boats ( from 18 ft. outboard powered boats to 40 ft. lower cost diesel powered boats) usually employ common type brass pipe and tubing compression type tubing fittings and un- reinforced thermoplastic hose. Most get by with this type of lower cost equipment, but realize that you get what you pay for. Most of these systems are “barely adequate” as to performance and overall system longevity and we consider the use of un-reinforced thermoplastic tubing (typically nylon) to be applicable only to “lake boats” and outboard engines at best. IMO, using SAE or JIC flare fittings with copper or metallic tubing or pipe or in combo with reinforced non-metallic hose is the right solution for all marine applications. You must also be careful about using any type of brass fittings that are not rated for working pressures of at least 1000 PSI, and are robust in wall thickness especially with internal threads.
Assembly should be done using high quality pipe dopes, anaerobic sealants, & sometimes even epoxy compounds specifically made to withstand petroleum based liquids and are designed for pressures of more than 2000 PSI. Avoid Teflon tapes entirely as you do not want any shredded pieces getting inside the system Passive steering system pressures should be designed so that 90% of the time, line pressures fall under 500 PSI. This is determined by RAM SELECTION or size. Larger displacement rams make for more turns but also keep pressures low. Steering wheel or RIM force becomes uncomfortable much above 5-8 lbs., so sizing the ram to keep pressures low means less rim force or effort to turn the steering wheel…
With power steering, pressures are usually higher and can play havoc with a ram if undersized. The operator, typically, never knows the difference until something back by the rudder breaks. Sized right though, power assisted steering is sometimes the only practical choice when the operator wants 2-4 turns lock-to-lock and needs a small diameter steering wheel.