Rack, Rotary, or Hydraulic steering ?

[Shorebase]

Hi,
I have a Sealine 23 with a single AQ205A V6 4.3l petrol engine on a DPA duoprop outdrive leg.

The original non-power assisted steering is via a rack and pinion cable, operating directly on the tiller arm over the drive.

There's around 2" to 3" of play at the edge of the 15" wheel before the cable moves at the tiller arm, so I guess it's 20 years wear in the middle position of the rack.

This makes course corrections more tedious than normal, even for an outdrive on a planing boat at displacement speeds.

I'd rather not convert to power steering, as I think the boat and the single drive are maybe light enough to not need it. It's fairly easy to turn, apart from the free play.

I'd go for hydraulic, but that seems to run out at about £500 or more, so a new cable and helm at less than £200 is much more appealing, if it'll be man enough for the job. I've fitted heavy duty three planetary gear rotary helms before, and found them to be quite positive, and would seem much more robust engineering-wise than single pinion.

My question (finally ), is do you think a single HD cable rotary control would be man enough for the DPA 290 leg on the 200hp engine, or should I go for a dual cable, or even a dual rack maybe ?

Or have I got it completely wrong, and are dual cable and dual rack helms designed for twin outdrives/outboards ?

 

[Dave_Seager]

I have a simple rack and pinion cable on my Princess 32 controlling two 270 legs with 106 hp each. I would imagine that this imposes a greater load than your single with 200 hp.

Mine was replaced a couple of years ago after the steering gears were stripped when both propellers were fouled by a large rope. The replacement seems a lot lighter to steer and has less slack so I should think that your boat would be quite satisfactory if you renew the steering to its original specification.

 

[GrahamHR]

Boat rack and pinion steering seems a lot less precise than automotive ones; my current one, a 2004 boat is actually worse than the 1999 one I had and has always been so from new; the +/- tolerances between the gear wheel and the rack on the steering cable in the "steering box" at the helm must be pretty dire. I've yet to find any recommendations how to impriove it (apart from trying a new one !)

Graham

 

[stelican]

Hi,
I have a Sealine 23 with a single AQ205A V6 4.3l petrol engine on a DPA duoprop outdrive leg.

The original non-power assisted steering is via a rack and pinion cable, operating directly on the tiller arm over the drive.

There's around 2" to 3" of play at the edge of the 15" wheel before the cable moves at the tiller arm, so I guess it's 20 years wear in the middle position of the rack.

This makes course corrections more tedious than normal, even for an outdrive on a planing boat at displacement speeds.

I'd rather not convert to power steering, as I think the boat and the single drive are maybe light enough to not need it. It's fairly easy to turn, apart from the free play.

I'd go for hydraulic, but that seems to run out at about £500 or more, so a new cable and helm at less than £200 is much more appealing, if it'll be man enough for the job. I've fitted heavy duty three planetary gear rotary helms before, and found them to be quite positive, and would seem much more robust engineering-wise than single pinion.

My question (finally ), is do you think a single HD cable rotary control would be man enough for the DPA 290 leg on the 200hp engine, or should I go for a dual cable, or even a dual rack maybe ?

Or have I got it completely wrong, and are dual cable and dual rack helms designed for twin outdrives/outboards ?

I believe dual cable/racks are for twin helm stations.
A hydraulic set up removes most mechanical linkages (play) and thus more sensitive response

 

[captain tomas]

Hydraulic would be my choice, but it is dependant on what you want
to pay. (usual quote- you only get what you pay for)

 

[PCUK]

Hydraulic is by far the best. Vastly superior to anything else. You can usually find a new pump and ram at boat jumbles for about £200!

 

[Shorebase]

Thanks for the very quick and helpful replies (as is often the case on here )


Yes, hydraulic is still an irritating temptation, with other significant advantages, like non-critical cable/pipe runs.


Staying with the mechanical option though, I'm thinking about the difference between racks and rotary again.

This is just my (hopefully logical) deductions, but I've been thinking about the mechanics of how they work.

A rack and pinion has the same single tooth contact point as the cheaper rotary helms, whereas the rotary helms with three planetary gears (like the T71FC) have three teeth meshing, so slackness and point wear must be reduced ?

Also, with a rotary control, about 8" of cable is meshing with the main gear wheel, so I'm thinking that is a more positive contact than a single tooth on a rack ?

My other thought is that they are also available in "no-feedback" versions with some sort of mechanical clutch on the wheel spindle.

Has anyone any experience of those ? Is there any "notchiness" ? anyone had any of them fail and lock up ?

 

[LittleShip]

Ok.....

I fitted a Linier drive to Little Ship last winter. The reasoning was thus....

I also have cable steering and a rotary motor would be fitted at the wheel end of the steering assembly. If one of the cables were to break I would be left with having to fit the emergency tiller and stand outside to steer the boat. The biggest difficulty with this is the controls for the engine are inside.

I decided that fitting the Linier drive to the rudder stock would enable me to steer the boat from insideusing the auto pilot head near the controls, if indeed a cable was to break.

Hope this helps out.

Tom

 

[MapisM]

Hydraulic is by far the best. Vastly superior to anything else.

Absolutely, but a proper hydraulic steering has to be FULLY hydraulic - i.e. with the wheel directly connected to the pipes, and you obviously can't fit that for 200 quids or so.
Otoh, I'm not sure I would bother fitting a mixed system, 'cause you'd still have the disadvantages of cables, albeit to a lesser extent.

 

[Shorebase]

Thanks again for the further replies, all ideas and suggestions gratefully received !

I priced up the hydraulic option, and using ultraflex, the ram is around £300, and the pump about £200. I could save money on the pipes by using 8mm copper, but it still runs out at over £500.

I'm going to try the Ultraflex T71FC cable system, with the three planetary gears, and a new HD 66 cable. That runs out at about £120, with the bezel.

I nearly went for the no feedback version with the clutch, but luckliy the information gleaned via Google and the manufacturer's website showed that was unnecessary on my boat, and would even make the steering "notchy", according to many users.

It's not clearly mentioned in all of the various brochures, but the non-reversing "no feedback" mechanism is primarily designed to combat the torque (paddlewheel) effect of a high power single prop.

Since my Volvo leg is a duoprop, with contra-rotating propellers, there is no paddlewheel effect anyway. Indeed, according to the blurb, the planetary gear system reduces and feedback anyway to less than half, even without the no-feedback clutch.

I have fitted two of them before, one to a 50hp hardy Pilot, and the other to an ex-hire inboard powered cruiser. There was a significant reduction in free play at the helm end.

 

[Shorebase]

I went ahead and did it, so I thought I'd resurrect my old thread on here to report back my findings, in case anyone else has ever mulled it over.

I fitted a new Ultraflex T71FC cable helm with the three planetary gear system, (but no anti-feedback clutch), together with a brand new M66 cable.

(This was to replace the Sealine OEM fitment of a rack helm, with morse cable and no power assist.)

It is much better now, very easy to turn (at displacement speeds anyway), and virtually no free play at all.

When I researched it, I found the various manufacturers recommendations very confusing, always advising power assistance or hydraulic with high horsepower sterndrives, "to combat the extreme torque feedback that can be experienced with non-power assisted cable systems".

I still deduce, ( IMHO) that surely Duoprop drives must completely negate that problem, with their neutral paddlewheel effect from the counter rotating props ?

Coincidentally, I have now chanced upon a good secondhand Hydrive hydraulic helm and ram, which I could now fit, but I'm in two minds now.

Should I stay with the absolute simplicity of the planetary gear cable helm, or fit the hydraulic ? I'm wondering how much improvement there would be (if any), over my very simple, short, single station cable, coupled to the single duoprop drive on the 200hp V6 petrol engine ?


(I used to be indecisive, but now I'm not so sure.... )