A bit unhinged by Colin Archer rudder hinge-lines

[geconParticipant @gecon]

[geconParticipant @gecon]

Good morning,

yesterday I bought a 'snake' to operate the rudder on the Colin Archer. I am now bending up the brass vintage-style? rudder hinges.

As the photos show, the two hinges have different hinge axes. The small 90* bracket market as F92M is the 'control horn' and protrudes about 1cm out from the rudder surface. It's position aft of both the hinge lines probably gives more rudder movement for less travel of the 'snake'.

When the pushrod (snake) acts on this, it does not push/pull at 90* to the hinge axes. I note however, that the bracket is 90* to the line of the tiller (handle) which can be seen to the left on the photos. So maybe movement from this bracket simulates the helmsman moving the tiller. They are not parallel to each other and the axes differ by about 10*.

Perhaps the resultant home-made (slightly sloppy) hinges absorb all these discrepensies?

If anyone should wish to advise on the mechanics of the above I would like to be enlightened.

George

 

Edited By gecon on 28/01/2022 08:24:12

[Ray Wood 3Participant @raywood3]

Hi George,

When I owned a Colin Archer for a couple of years, It had a chain steering system, like a closed loop attached to the the little brackets you refer to . Unfortunately I have no pictures of it but the chains coming out of the topsides at the rear were so high up water ingress was not an issue, I may have said before the rudder is fairly ineffective in actually turning the boat, a removable extension would be a good idea, or you'll be using the motor to tack.

Regards Ray

[Richard SimpsonParticipant @richardsimpson88330]

Hi George, It reminds me of a lengthy conversation I once had with a UK model manufacturer regarding exactly the same issue with one of his model rudders. The drawing clearly showed the two rudder pintle bearings were not concentric. Theoretically the rudder should not turn. His argument was that it did turn and no-one else had ever complained. The only reason that it turned was because there was so much slack in the bearings that the inaccuracy was absorbed, I am really surprised to see your drawing of the Colin Archer rudder, which appears to indicate the the rudder pintles are also not concentric.

If I was building this model I would adjust the angles of the two bearings so that they became concentric. A straight rod of the same diameter should pass through them both and be able to rotate. If you think about it if the two are not concentric and you bend the rod so it passes through them both then you have created a crank with a throw equal to the offset of the bearings! You may be happy to allow the slack to take up the discrepancy and I am not suggesting what you do but simply saying what I would do. I would get hold of a straight rod of the correct diameter and set the two pintles onto the stern frame using the rod to align them.

As regards turning, anything can be used to turn the rudder as long as the connecting point on the rudder is offset from the rudder stock centre. If you start with an offset of the same distance as the linkage is away from the servo spindle then you should get the same degree of movement either side of the central position, usually around 45 degrees. If you want the rudder to move more you can either move the connection to the servo arm further out or the connection to the rudder arm further in. Usually more than 45 degrees however is a waste of time as it acts more like a brake.

If you are using a snake then I assume that you would want it to be hidden and so will require a hull penetration but, as Ray suggests using a chain would give a more scale appearance and could be on the deck, thereby maintaining the hull integrity.

Don't think you are locked into mounting the tiller arm where it is shown on the drawing, you can mount it anywhere you want on the rudder to suit your preferred method of turning.

[Richard SimpsonParticipant @richardsimpson88330]

Just a couple of pictures of showing the arrangement below the gunwhale with penetrations or above the gunwhale without the need for hull penetrations.

[geconParticipant @gecon]

Hi Ray and Richard, many thanks for the info. Just came in from Friday shopping, but will read through and absorb the info then take the plunge and do something. Moving the rudder servo further aft for chain operation will involve too much cutting an adjusting and won't be scale. I'll look at the mechanics and sloppy hinge solution this afternoon.

Thanks again,

George

[geconParticipant @gecon]

I wonder if the fact that each hinge operates at 90* to the respective hull/rudder edge, compensates for the non-aligned hinge axes.

Not exactly precision engineering, but that's what I can produce for now. I had better hinges on the Keil Kraft Mini Super in 1968 and they were made with woven cloth and balsa glue!…Now there's an idea! Brass painted woven cloth! Might add some of that to tighten it all up a bit. Or brass dolls house hinges! or brass-painted robart hinges? I'll see how much slop there is in the unit when all is attatched and work on from there.

Otherwise I'll just popp over to London and borrow a sign from the nearest tube station. "Mind the gap". A bit irritated so take a brake until tomorrow.

Thanks agian for inputs earlier, why did the text change to blue…and back to black? So many questions today.

Taking the afternoon off (to calm down the grey cell) and chat up the Admiralty.

George

Edited By gecon on 28/01/2022 14:49:26

[Author]

Posts