Steering ratio

[Lopez Mike]

The steering gear in Folly is so frightful in design and execution that I'm starting over from scratch. I'll spare you the gory details.

The question is: What is a reasonable ratio? I'm assuming that 45 degrees each side of center is the base reference and that I'm going to use a side mounted wheel about 16 to 18 inches in diameter with cable connections and a rudder shaft quadrant. There will be an emergency tiller.

The boat is 24 feet long. I'm guessing at less than 2000 pounds all up. The rudder is a simple blade behind the 18 x 20 or 24 three blade prop.

I've sailed boats with about two turns stop to stop. Is this too quick for a small launch? Should I provide some adjustable friction for course keeping while firing?

Mike

[fredrosse]

The sidewheeler Margaret S has a 1:1 ratio on the rudder, turning the wheel 90 degrees swings the rudders 90 degrees. I made it this way so the steering shaft runs fore & aft, I get confused with the wheel shaft oriented athwartships. The wheel itself is only a partial wheel, so the shaft can run close to the hull sheer, and not get into the way of other machinery on a small boat. I use the same setup on my 14 ft electric boat, and both work well with the 1:1 ratio. I use ordinary Heim joints in the linkage, no cables or ropes to deal with. This gives virtually no free-play in the linkages.

The steering shaft runs in wood bearings, which can be pinched to tighten them up, so the rudder position stays in place if the pilot leaves go of the wheel.

[DetroiTug]

I've read that for a pleasure craft, about 3 turns bank to bank is about right.

Also, for a steering system, the Teleflex systems (which are three turns) are hard to beat for ease of installation and reliability. Once one purchases all the pulleys, cables, fasteners etc. for a cable system, the cost is probably the same. The Teleflex system in my tug was picked up new off of Ebay for 140? with a 20' cable, systems with shorter cables are cheaper. I racked my brain for months trying to come up with a period correct or close to-it, steering system, that I could make, without some outlandish engineering due to the contour of the keel, it wasn't going to happen. The Teleflex push pull system, was very easy to mount and works great. Even the stainless steel barrel on the end of the push/pull cable slides right in 1/2" schedule 40 pipe - what most old powerboat steering systems used for linkage. There are lots of old steering arms and clevises around with 1/2 NPT internal threads.

-Ron

[Lopez Mike]

Interesting ideas.

The partial wheel would get me in trouble with my partner. She already bought a small wood wheel off of EBay. The shaft and Heim joint system might work for me if I can cobble together a right angle reduction box to go just behind the wheel. The wheel is to be mounted with the shaft athwartships with the wheel out of the way against the side of the boat to save room. Hope I can remember which way to push and pull.

I'll do some looking around for a used Teleflex box and cable on Craig's List. Or something like that. I suppose it wouldn't be that big of a job to shorten one of those cables. I'm a machinist and hate to spend money!

I'm dispensing with a forward steering station. I fire and steer from back by the engine. Nothing going on in front except sipping mint juleps and watching Orcas.

My default setup will probably just a drum on the wheel and a sector on the rudder shaft with cables and a couple of pulleys. I have a fairly deep hell box from years of sailing. I'll just use a v-belt pulley on the rudder shaft. The ratio is what I'm looking for.

Mike

[barts]

For Otter, I've considered a simple push-pull system using a curved laminated wood bar, and a pinch rubber roller on the wheel. We already use a push-pull tiller attached to the rudderpost crossbar with a pushpin, since the original swinging tiller needed to go to allow the use of a rear canopy support. When navigating unfamiliar shallow waters alone sans canopy, I like to stand up since it's so much easier to spot underwater obstacles, so I'd like to have a way to steer Using push pins at both ends makes that easy.

[Lopez Mike]

I'm not doing well at visualizing all this, Bart. Wheels and push pull and everything. I know, from poking about in your boat that it is all very ingenious and devious and perhaps even evil but try again for my 68 year old brain.

Mike

[barts]

Hardly devious...

The push-pull tiller is like this (I don't have a good photo of mine):



My pull-pull stick attaches with a universal end made w/ a stainless quick release pin:



What I'm suggesting is that the other end can be also connected via quick release
pin to either a pinch roller and bar, or a rack or pinion, or similar that converts the rotary
motion of the wheel to the push & pull needed. On my boat this mechanism would be
on the outside of the coaming, so something both attractive and salt water proof would be
needed. Note that on our small boats, the forces are quite small so a rubber roller acting
against a wood or metal bar would work fine; the drag from the rubber hysteresis would
serve to keep the wheel in one position.

[Lopez Mike]

Ah! I see. I'll give this some thought. And you are devious and capable of all sorts of low cunning but not this time.

Meanwhile, has anyone here ever tried shortening a Teleflex push-pull cable? I've found a used assembly but the shortest cable listed for sale is still too long. I'm guessing that there is some sort of over sized speedometer cable inside that housing with the end rod crimped on?

I would throw away stink pot steering wheel but the rest of it seems usable.

Mike

[Lopez Mike]

I bought that powerboat steering gear. It is a lot stouter than I was expecting. It's not Teleflex but an old Mercury Aqua Guide with a rack and pinion upper end that is as well built as some car steering gears. I have it all torn down and am getting up my nerve to take apart the cable to shorten it. It was not made with that in mind.

From looking at it, it looks like my best bet is to shorten the inner cable at the box end but to shorten the housing near the box end. Either way will involve some careful grinding to take apart some swaged conections and some easy machine work to get it all back and operating and strong.

Anyone need a very 'art deco' 60's steering wheel? Looks like something out of an early sixties american sedan.

[87gn@tahoe]

Post up a pic of the wheel and diameter/spline count for the steering shaft.... I may have a Buick use for it