Steering unit for a fantail launch

[wsmcycle]

That is what I have seen also. If I turn the tiller really sharply it will turn almost without moving forward. The maximum angle of my tiller rotation is about 65. So, my 60 wont be out of reason.

Thanks

[S. Weaver]

Edson stuff:
http://www.edsonmarine.com/marinestore/ ... c69b2e8dec

[Steamboat Mike]

A further thought on hydraulic steering with regard to boat handling. When considering all of the published literature Teleflex puts out about selecting components for a system, it should be kept in mind that the examples they cite are for either high power very fast boats or high power slow work boats. The common theme is high power. We do not come close to what they are specifying for their equipment in the wonderful world of steam. One result of this is that in order to have sufficient mechanical advantage to handle the forces involved with high shaft horsepower and not have a steering system that is squirrelly and unsafe at high speeds they end up with about four turns lock to lock on most of their suggested servings of components for various boat scenarios. By choosing the size of the cylinder and the displacement of the pump it is possible to get about three turns lock to lock. This was what I installed. The hydraulics were wonderful to use but the three turns really was not to my liking when maneuvering. I thought about the problem for a while, I was worried that I might not have sufficient mechanical advantage or that the steering would be ultra sensitive. I began by laying out a new system and doing some simple calculations. The things I could change were the cylinder displacement, stroke and the throw of the tiller arm. Since the displacement of the helm pump was known, I then juggled numbers around for the bore and stroke of the cylinder. The problem was to balance keeping the stroke reasonably long in order to keep the effective length of the tiller arm long enough to not strain the rudder post excessively while at the same time coming up with a bore that was of a standard quad ring size for the seals. I settled on 13/16" I.D. brass tube. I figured the swept volume that was equal to the pump displacement and fine tuned the length of stroke to match. I think it came in at around 5 9/32". I then made a bushing from some polished brass tubing. The wall thickness was 3/32" so I made three collars of brass that were a very close slip fit in the existing 1 1/4" cylinder bore and soft soldered them to the tube. Knowing what the stroke was I could now figure the location of the pivot pin on the tiller arm. I assembled the whole thing, bled it well and tried it out. The wheel now makes just a whisker over one turn, steering at turtle-like steamboat speeds is completely stable and quite sensitive when under way, it almost seems that you think a correction to course and the boat responds. There is sufficient advantage at the wheel for most situations, the only issue is that if you go astern at full throttle, full steam with the rudder full over you may need to use two hands on the wheel to get the rudder off the extreme position. It can't hurt the system as the pump has built in relief valves that limit the pressure to safe amounts and even in this extreme situation they do not come close to opening. I use rather small 6" wheels that seem very satisfactory. It works well for finding midship on the rudder, just turn to either stop with the wheel and pull back a half a turn, very quick and easy to do when maneuvering in tight quarters. Because of the very small amount of internal hydraulic slip in the helm pump and the cylinder it is not possible to have a "king spoke" that always point up as is possible on cable or push-pull systems. I also have two steering stations so the wheel position is never the same when using either helm.

With regard to boat handling as mentioned in an earlier post about the boat turning before gaining weigh there are some handy tricks that are related to this. I think this effect is more pronounced when turning to the right assuming a right hand prop. This is because the turning effort of the prop wash over the rudder is augmented by the prop walk to the left. I often hear boaters complain about prop walk and wonder how to minimize it. It is a force of nature, a function to some extent of the prop design but always there. One way to use it to advantage is in turning your boat around. In tight quarters it is possible to turn around in very little more than a boat length. Start by turning hard right. If you do this at low speed the pivoting effect of prop walk will help to swing the stern to the left if you give the engine a burst of full throttle going into this first step. Next throw the wheel full over left, reverse engine and give full throttle astern. The stern will start to walk left as the boat gradually gains stern weigh. Set engine forward, throw rudder over full right and proceed to finish a very compact U-turn in a very limited space. It is basically a K-turn as done with a car but with the advantages of being in a fluid medium. This maneuver is also the fastest way to turn around at speed and return to a point as for picking up man overboard. There is no danger of slicing and dicing that there is in backing up. Go out in a nice calm lake and try harnessing the forces of nature to your advantage, and maybe perfect a new trick to impress your passengers and bystanders.
Happy turning and steaming, best regards, Steamboat Mike .

[wsmcycle]

Thanks for the thoughtful reply Mike