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  1. #11
    Join Date
    May 2007
    Posts
    37,742

    Default Re: Steering pulleys (sheaves)

    What kind of preload tension do you expect to run the wire with?
    I suspect fat wire with low preload will give more slack as it mves around the sheaves.

    We had an Edson system on a 42ft boat. I think the wire was 5mm.
    5mm s/s 7x7 has a breaking load of about 1.5 tonnes? Might have been galv wire?
    Our wheel was about 4ft, the sprocket in the middle about 2 inches?
    Say max 300kg on the wire would be 12.5kg at the rim of the wheel? That would be pretty physical to steer?
    Work out the stretch for sensible steering forces?

    I think machined ali sheaves will corrode and wear if not anodised, but you could get that done, or even DIY.

  2. #12
    Join Date
    Dec 2010
    Location
    South Oxfordshire, Gosport and Wellington New Zealand.
    Posts
    8,113

    Default Re: Steering pulleys (sheaves)

    Just a couple pf points.

    In my long, long experience of cable systems for motorcycles it is clear to me-and the manufacturers-that twisted wire cable of the Bowden type has no, or only infinitesimal, stretch.

    What happens with motorcycle cable systems is that the outers compress.

    This gives effectivly the same effect.

    I see no reason for a boat system with an outer to act any differently.

    Our American boat uses an Edson cable steering system, with both inner and outer cables. It is a 12 metre heavy Motorsailer and uses 10mm-or perhaps 3/8th inch-cables. It has screw in lubricators in the outers.

    The boat is 12 years old, has 1,000 hours on the engine and has no appreciable play in the steering-perhaps an inch of backlash.

    It has never been adjusted-its got sealer on the threads of the adjusters-and I dont intend to adjust it untill the backlash more than doubles. It has remained the same in four seasons and 5,000 plus NM. It is lubed by turning the greasers down regularly-every time the oil and belts are checked.

  3. #13
    Join Date
    Nov 2013
    Location
    Perth WA
    Posts
    2,125

    Default Re: Steering pulleys (sheaves)

    [QUOTE=rotrax;6867181]
    Our American boat uses an Edson cable steering system, with both inner and outer cables. It is a 12 metre heavy Motorsailer and uses 10mm-or perhaps 3/8th inch-cables. It has screw in lubricators in the outers.

    The boat is 12 years old, has 1,000 hours on the engine and has no appreciable play in the steering-perhaps an inch of backlash
    . .[/QUOTE

    I wouldn't compare motor-cycle bowden cables with yacht steering cables. (I reckon they are like chalk and cheese)

    You say your boat is "12 metre heavy Motorsailer". Is that a center cockpit? How long are the cables from helm to quadrant?
    Last edited by coopec; 07-08-19 at 11:08.

  4. #14
    Join Date
    Dec 2010
    Location
    South Oxfordshire, Gosport and Wellington New Zealand.
    Posts
    8,113

    Default Re: Steering pulleys (sheaves)

    [QUOTE=coopec;6867197]
    Quote Originally Posted by rotrax View Post
    Our American boat uses an Edson cable steering system, with both inner and outer cables. It is a 12 metre heavy Motorsailer and uses 10mm-or perhaps 3/8th inch-cables. It has screw in lubricators in the outers.

    The boat is 12 years old, has 1,000 hours on the engine and has no appreciable play in the steering-perhaps an inch of backlash
    . .[/QUOTE

    I wouldn't compare motor-cycle bowden cables with yacht steering cables. (I reckon they are like chalk and cheese)

    You say your boat is "12 metre heavy Motorsailer". Is that a center cockpit? How long are the cables from helm to quadrant?
    It is an Island Packet SP Cruiser, a modern motorsailer with a huge pilothouse and only an internal steering position. The cables must be over 6 metres long. They are vertical from a sprocket behind the 30 inch wheel. They are attatched to a piece of motorcycle chain which goes around the sprocket. They then turn through a gentle right angle and go either side of the engine bay, into the lazarette area and then onto a large split plastic wheel clamped direct to the rudder stock.

    Why would marine cable be any different to smaller bowden cable? It is made in EXACTLY the same way.

    I made a test length of motorcycle inner cable years ago, before deciding to make cables for customers-I had trusted my life, and First Mates life-to cables I had made for our race bikes.

    The test length was exactly 412 mm long, with 3/8 inch barrel nipples each end, dip soldered using a solder pot with an aggresive flux and a hard solder-not electrical solder.

    One nipple was fixed into a 3/4 inch steel bar across the top of my Churchill 100 Ton 2 speed hydraulic press, the other end to the same sized piece of bar screwed into the piston end.

    When the press was operated it tightened the cable, dead straight downward push. IIRC it exceeded 3 tons on the gauge before I stopped. No human hand working a motorcycle control lever could apply such pressure. When measured, the cable was still 412 mm long-measured top of barrel nipple to top of barrel nipple.

    That was good enough for me. My hand made bespoke motorcycle control cables have been sent all over the world, perhaps thousands of them, never had a failure.

    Had customer failure when they sent the wrong dimensions though!
    Last edited by rotrax; 07-08-19 at 14:51.

  5. #15
    Join Date
    Nov 2013
    Location
    Perth WA
    Posts
    2,125

    Default Re: Steering pulleys (sheaves)

    I am progressing with the chain and cable steering for the yacht.

    The "V" belt pulleys cost $50 and the roller races $3 but then there is the machining. Fortunately my Son has just bought a lathe and while he is inexperienced he is doing a great job. (I can't guess what a Fitter and Turner would charge per pulley)

    I've shown the pulleys to the professional yacht rigger who examined them carefully and he can see nothing wrong with them.

    The cost of an Edson 8 inch pulley (with needle roller bearing) is $285

    IMG_1681.jpg

    IMG_1682.jpg

  6. #16
    Join Date
    Nov 2009
    Location
    Home UK Midlands / Boat Croatia
    Posts
    19,811

    Default Re: Steering pulleys (sheaves)

    Looking good.

    Richard

  7. #17
    Join Date
    Nov 2016
    Posts
    17

    Default Re: Steering pulleys (sheaves)

    My yacht when acquired had a tiller. I replaced it with pull, pull cables which was good until the mild steel sheaths rusted. I now have sheaves and use dyneema instead of ss cable. Smooth, easy to maintain and check at any time.

  8. #18
    Join Date
    Sep 2001
    Location
    Me - Zumerzet Boat - Wareham
    Posts
    12,215

    Default Re: Steering pulleys (sheaves)

    Maybe a silly question, but have you googled Pully Wheels?
    A large selection comes up at sensible prices.
    MontyMariner.co.uk
    Facilitated by AWESEM WP Agency

  9. #19
    Join Date
    Nov 2013
    Location
    Perth WA
    Posts
    2,125

    Default Re: Steering pulleys (sheaves)

    Quote Originally Posted by LadyInBed View Post
    Maybe a silly question, but have you googled Pully Wheels?
    A large selection comes up at sensible prices.
    Thanks for the suggestion but 99.9% would not be appropriate. For example:

    • Anything less than 7 in, (180mm) diameter is no good.
    • "V" belt pulleys -no
    • less than 10mm cable groove is not acceptable.
    • Pressed metal - not appropriate.
    • capable of handling large forces 500kg+?
    • many are not affordable ($285 ea. is out of the question as I need X10 of them)

    For Stainless Steel cable the diameter of the pulley must be a minimum of 7 in. otherwise the strands start to fray.
    Last edited by coopec; 04-09-19 at 11:48.

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