RUDDERS AND STEERING
Well, it's time to talk about how to keep a sternwheeler between the banks. I'll break this into two parts. One will be about rudders and the other will look at some ways to turn them.
RUDDERS
Rudders are a crucial part of any boat and this certainly holds true for sternwheelers. When rudders are properly designed and constructed, the vessel will handle and maneuver quite well. However, poorly designed rudders can make a boat not only difficult to operate but even make it dangerous.
Propeller driven vessels require only small rudders for two basic reasons. One, most of these boats travel at faster speeds than sternwheelers and this speed produces adequate force on the rudders to produce good response. Second, the rudders are located where the prop pushes a lot of water directly against them thus producing the force necessary for good response.
Slower moving sternwheelers require much larger rudders to produce adequate force for suitable handling. Also, since the paddlewheel is turning much slower than a propeller, this too necessitates larger rudders. Therefore, it's almost impossible to get rudders on a sternwheeler too large.
All personal size sternwheel boats will have a hull size which can be controlled with a compliment of four rudders. Two of these should be positioned between the wheel and the hull. These will do most of the steering when going ahead and backing. A second smaller set should be positioned behind the wheel to assist maneuvering at slower speeds. They will also swing the stern when the vessel is being parked against a river bank and there is no forward motion.
The 'main steering' rudders should be about 10 feet long with the front sloped to match the stern rake of the hull. The aft end should be cut in a radius to match the paddlewheel with 2 to 3 inches clearance. Their height should be based on the size of the vessel and will vary between 18 and 30 inches. The rudder post should attach at a point which divides the surface area so that there is thirty to forty percent forward with the remaining aft. The bottom of the rudders should be even with the bottom of the hull. The space between the rudders shouldn't be less that 4 1/2 to 5 feet or they will block the flow of water from each other when they are fully turned or 'hard over'.
The rudders aft of the paddlewheel should be in-line with the 'mains' and connected to them. Therefore, whatever the mains do, the secondarys do. That's why they are referred to as 'monkey rudders'. Get it? "Monkey see, monkey do" Clever, huh? Well, I didn't have anything to do with naming them. These 'monkeys' are usually 18 to 30 inches high and 30 to 40 inches long with the same split on surface area as the mains. They should be mounted a little higher than the mains because they need to be in the 'wheel wash' or the roller that the paddlewheel makes when it is going ahead.
The normal operating force on any of the rudders is not great, however, they and their posts should be built to withstand things like submerged logs, ice, sandbars and downed jet-skis. Oops, perhaps I shouldn't have included that last one. Oh well, the point is, make them stout!
STEERING SYSTEMS
This is the device, which turns the rudders thus, causing the vessel to change course. I have chosen three systems that we'll take a look at. One of these is hydraulic and two are mechanical.
The first is a manual hydraulic system. This system is comprised of a pump, which is located in the pilothouse. Attached to the pump shaft is the pilot wheel. Two hydraulic lines connect the pump to an actuator, which is located at, or near, the rudderposts. The actuator then, is connected to the rudders. This actuator can be either a cylinder, which produces a straight-line motion, or a geared unit, which produces a curved motion via a crank-arm. Turning the pilot wheel in one direction causes fluid to be forced through a line to one side of the actuator while fluid is returned from the other side of the actuator to the pump through the other line. Reversing the direction of wheel turn reverses the direction of fluid flow.
This system produces a smooth and easy way to turn even moderately large rudders. Also, since the hydraulic lines can be routed via many locations, the system is excellent for triple decked boats. On the negative side, the components are a little 'pricey' when compared to most mechanical systems. Also, the motion is so smooth that you can't 'feel' the rudders. Consequently, if a rudder gets jammed, you may not realize it in time to prevent damage.
Next, we'll look at a popular and often used mechanical system. This system consists of a worm-gear gearbox, or a steering sector gearbox, usually taken from a heavy truck, and mounted at or near the rudderposts. There is also a shaft which runs fore-to-aft in the vessel and which is connected to, and is turned by, the pilot wheel. This shaft also connects to the input of the gearbox. Mounted to the output shaft of the gearbox is a crank-arm, which connects to the rudders. If this sounds just like the steering in your pickup truck, that's not surprising because there isn't much difference.
This is a good, simple and inexpensive system, however, a word of caution. There must be no 'play' or lost motion in the steering system on a boat! If there is play in the system, when you go to 'neutral' or centered rudder, this play will allow the rudders to drift side-to-side off center and the boat will travel like a snake even though you haven't moved the pilot wheel. Therefore, I suggest that you don't use an old, worn-out gearbox or you'll have your hands full trying to keep your boat between the banks. Been there, done that.
Now, to the mechanical steering system that I like best. It'll control vessels up to 65 or 70 feet in hull length and, if you're clever, will also work on triple-deckers too. It's simple, inexpensive, and easy to build and maintain. It has the added advantage of applying more force to the rudders when they are 'hard down' or full over, where you may need it, than in the neutral position where you don't need it. Yet, this system will still give you a good feel of the rudders at all times.
Say what? Well, remember I said that properly designed rudders are 'un-balanced' (please don't confuse this condition with the state of the writer). That is, they have more surface area behind their pivot point than in front of it. This is done to improve control of the rudders. Due to this imbalance, when the rudders are turned full over or hard down and the boat is moving ahead, the rudders want to come back to center. Also, when hard down and backing, the rudders want to stay in the full-over position. Therefore, a steering system which will apply more force in the hard-down position yet still allow a good feel of the rudders in all positions is, in my opinion, a desirable system.
Now, how does this work? First, it requires a shaft located in, or just below, the ceiling of the main cabin. This shaft should run from a point just under the pilothouse and is connected to the pilot wheel shaft by means of chain and sprockets. The other end of the shaft should terminate 3 to 4 feet forward of the rudderposts. At this point, it connects to a drum of 5 to 6 inches in diameter and 4 to 6 inches long. So, when you turn the pilot wheel, you are turning the drum. Located at each side of the engine room at the ceiling and in line with the drum, are two pulleys (one each side). These pulleys should be 4 to 6 inches in diameter and have a deep groove. Steel cable 3/16 or 1/4 inch in diameter is wrapped around the drum 4 to 5 times (wraps) then the free ends go out and over the pulleys and back to the center of the engine room. The ends of the cable attach to a 'traveler' via clamps, eyebolts and springs. The eyebolts should have forged eyes and the springs should be Chevrolet valve springs or equivalent (Ford works okay too). Now, when the drum is turned, this traveler moves in a straight line from side to side on the ceiling of the engine room. Located in the traveler and pointing fore-to-aft is a bronze bushing with an internal diameter of 1 1/4 to 1 1/2 inch.
The main rudderposts must extend up to the height of the traveler. Their 'tiller-arms' project forward and terminate just behind the traveler. A 'tie-rid' connects the tiller arms together and passes in line with, and directly behind, the traveler. A round solid steel post matching the internal diameter of the bushing is welded to the center of the tie-rod and projects forward through the bushing in the traveler. It should project through 8 to 10 inches. Now, when you turn the drum, the traveler pulls the post, thus the tie-rod, from side to side, causing the rudders to turn. Since the tiller-arms travel in an arc, the tie-rod moves away from the traveler as the rudders are moved off center. This motion pulls the steel post back through the bushing and effectively increases the length of the tiller-arms by several inches at the full over position. The result is more leverage to control the rudders when they encounter their greatest forces.
By selecting the length of the tiller-arms, the diameter of the drum and the ratio between the main steering shaft and the pilot wheel shaft, you can establish how many turns of the pilot wheel you want to turn the rudders 40 degrees either side of center. This is the recommended amount of rudder swing.
My experience with this system has demonstrated that with a 4 foot pilotwheel, 4 to 5 turns of the wheel lock-to-lock and 42 inch tiller arms, you'll have excellent control and a good feel of a full compliment of rudders.
Well, that's all I've got to say on that subject.