Steering unit for a fantail launch

[DetroiTug]

Quote: "I see two cables coming out of your gear box. What is the second one for? The push/pull system is just one cable isn't it?"

The second housing that appears to be another cable is just a tube for the internal "chain" to run in and out of. Some of the higher end units do use two cables I think?

These are typically used to steer large outboards, simply turning a rudder it works very smooth and easy and as mentioned has been no trouble at all. I would use one again. Thanks for the compliment, looking forward to getting it out on the water this year.

Quote "I'm such a tightwad that I never thought of buying a new one."

Those cables aren't too expensive (now). I think the whole unit was around $150. They used to be expensive, but thanks to the devaluation of the dollar and Teleflex not really raising the prices very much, they are now pretty cheap.

-Ron

[Lopez Mike]

We have a nineteenth century boat in the Northwest, Uno, which has a steering cable that is all on deck. The rudder post has two bronze arms opposite each other, the cable runs up each side deck tucked in against the cockpit coaming and the wheel is centered in the front on the coaming. There is enough friction in the system that it holds course well and can be steered from anywhere you can put your hand on the cable.

[wsmcycle]

"pull the cable" That is interesting. I could mount something like that just under the tiller and retain the tiller.

[Lopez Mike]

Yes. When I acquired my hull it was set up with something like that. One steering station (near the engine) had a lever and there was a wheel up front where I never used it. The tiller rope made a loop around the boat.

The fatal flaw in this design was that it was so poorly built that none of it worked. The only way I could steer the beast on my first sea trials was to use an emergency tiller that I found in the bilge. Even the pulleys were crudely hacked out of a stack of junk plywood scraps.

It all went into the boiler. Along with the original boiler lagging. Sad waste of effort on the part of the builder. The hull is of equal quality and workmanship. I don't fret too much when steaming but when I hit a big pot hole when trailering on the public roads I look back to see if there are any plywood panels flying about.

For now I'm just using it and having fun. Except for when I'm around other steamers and can't see well through the bag over my head.

[Steamboat Mike]

For me the biggest advantage of hydraulic steering, aside from meeting all of my bread slicing needs, is that because of the design of the hydraulic helm (in Teleflex at least) there are internal check valves that hold the rudder position wherever you set it. I believe some push-pull systems achieve this with an adjustable drag brake. This makes life ever so much better for solo operation with regard to tending to fire and water as well as avoiding fixed and moving objects in your vicinity. It also makes backing a (good) dream since the rudder can't be violently flopped over in the prop wash. A real knuckle saver.

One thing that helps to reduce the initial "ouch!" factor of the cost of the system is to do your homework on the web first. I needed two different models of helm and the cylinder. The cylinder I found very reasonably on flea-bay, new in box, nobody else wanted it. The helms I found at two different suppliers, each at a price lower than what used units often were going for on the flea.

One last comment. That is a most ingenious installation of push-pull in DetrioTug. It has a very traditional look when assembled and all the modern elements are safely concealed beneath the floor plates. It would work well with hydraulic steering as well, eliminating the need to bury the somewhat bulky helm in a place where there is not much room. Nice job, I wonder why I never thought of that?
Best regards, Steamboat Mike

[Mike Rometer]

I like that Mike, it puts a different view on it, which I hadn't appreciated previously. Thumbs-up Smiley (if we had one).

[S. Weaver]

I'm using a side mounted Edson system with cable and a quadrant - no slop at all. The Edson helm station comes with a brake knob that I am modifying to look old school. Should realize the same single-handed advantage as Mike's hydraulic system.

[wsmcycle]

I do not understand the jargon but i would like to know how you set yours up. Can you take some pictures of the installation? please. In my boat, i have a fiberglassed in steering tube that runs from the deck down to the bottom of the boat. The steering post is inside this tube and protrudes out the top of the deck where it fits in a nice bushing and attaches to the tiller. I have 28 inches between the deck and the bottom of the boat. I want to install a a cable steering system within that area. I have a push pull cable and steering head that I am working to adapt. The steering head has about a 5/1 gear reduction and the cable has an 8 inch travel. I calculate that in order to get 120 degrees of rudder turn, I can have a five inch lever arm to attach to the rudder shaft.

Thanks

[fredrosse]

The radius of the rudder arm, "R", (center of rudder shaft to pivot of cable attachment) follows the relation between the length of cable travel "T", and the desired total angle of motion travel, "ALPHA". according to the formula:

R = (0.5 X T) / Sin(0.5 X ALPHA)

Using this formula, with an 8 inch cable travel and 120 degrees total rudder angle, I get 4.61 inches for the center to center rudder arm length.

With 8 inch cable travel and 90 degrees total rudder angle, I get 5.65 inches for the center to center rudder arm length.

So the 5 inch lever arm you mention would give something in between 90-120 degrees, which is OK, I would think 90 degrees total rudder swing would be adequate for a launch.

The other issue is total torque on the rudder shaft, compared to the rated allowable force on the cable mechanism. Probably not much of an issue here, but on my 15 horsepower inboard the rudder forces (with a partially balanced rudder) are high, about 50 pounds force at 6 inch rudder arm length. That rudder is only about 8 inches high x 5 inches long, but is directly in the wash of a 14 inch prop.

The sidewheeler has twin balanced rudders, about 10 x 8 inches each, but force on this slow boat is only a few pounds.

Outboard motors do not produce much rudder turning resistance, as the entire lower unit & propeller turns, but an inboard engine setup produces far more potential rudder turning resistance, especially if it is not a balanced rudder.

[Lopez Mike]

Most of the time I find that 90 degrees (45 degrees each way) is enough but I have discovered that when trying to turn around in a restricted area, deflecting my rudder a full 90 degrees to one side has an interesting effect. The boat has very little forward thrust but the boat continues to turn with almost no forward motion. Sort of like having a stern thruster.

That's why I am building a system that allows me to exceed 45 degrees from center. Cables, roller chain and sprockets.