Edson Steering Conduit Pull-Pull System Evaluation

[Cadence]

I guess I am somewhat lost. I'm not sure delrin is used for strength. It has a self lubricating surface property. Not however meant for abrasives like cable lay scrubbing on it. Delrin, delron is great for use against something like a shaft similar to use like an oil-lite bearing.

[acove]

According to the Edson site, the smaller conduit end fittings are Celcon (Conduit End Fitting for 853-250 Conduit [854-250] - $34.00 : Edson Marine Store). This is another trade name for Delrin. Here is just one of many sources indicating that: Acetals | Delrin, Tecaform, Ultraform, Celcon | Plastics International.

Celcon/Delrin has good compressive and tensile properties. The compressive part of this fits quite well into bearings and bushings. Use as rudderpost bearings, as Cadence suggested, is spot on. Another place you could find it is in Harken cam cleats, as ball bearings, or in a number of production marine sheaves. Delrin can also be found as the material for lower load nuts and bolts.

The aluminum is, without a doubt, stronger. However, a proper installation puts little more than tensile and compressive stresses on this fitting. This is because the conduit is secured and any bends near this fitting should be gentle (as along with the rest of the length). However, if the conduit was not secured along its length or if it was bent severely, I could certainly see a fair amount of torque being applied to this fitting. I have honestly yet to see one fail in a proper installation. That aside, I alway prefer gear being a little over-built... so, I do like the larger aluminum fitting they have. Sounds like you're on the same page with me there, colemj. However, there is quite a difference in price, understandably... and it may be a bit overkill, considering the relatively small forces in play on the smaller system.

[atoll]

thanks for all the replies!
after spending the day onboard yesterday doing a bit of measuring and working out angles it appears that with a bit of jiggery pokery a direct cable system is possible.

this was my first preference as it is a system that has minimum friction,and would be repairable at sea.
it would also work out quite a bit cheaper!

I will probably use dyneema/amsteel line and barton blocks for the long runs.
I will have to use 5mm 7x19 cable attached to the chain with 2 sheaves from the helm sprocket due to space issues.

this system should work out a lot lighter,and will be able to leave a spare set of lines in place in the event of breakage also spare cables as they will be quite short.

will post progress on the other thread.
thanks again

[Rubikoop]

When I purchased my Freedom it had the Edson pull-pull system. I couldn't steer the boat with one hand because of the friction. After time online and on the phone with very helpful people at Edson, I switched to a simple cable and sheave system. Now I can literally steer with my pinky!!! I can't recommend the pull-pull stuff.


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[acove]

That's great, atoll. You are really going to enjoy that system. Best of luck with the install! I'll look forward to following progress as you post it.

A few words of caution on steering cables...

Dyneema and Vectran have been used successfully on a number of boats. Some hsve even gone as far as to remove the chain and use a drumroll steerer (the Swan 45 comes to mind as an example, if I am not mistaken). However, these synthetic cables require constant inspection (and frequent tuning). So, if you are not racing or do not want to add another item to your daily checklist, I would suggest going with 7x19 stainless wire rope.

The issue is stretch. The splices and line itself (in the case of Dyneema or Vectran) will have an initial set the first time you really load them up. This is also true for 7x19 stainless wire rope - referred to here as structural stretch. As a side note, the aerospace industry does offer pre-stretched cables. Come to think of it, all of Edson's new wire assemblies are now pre-stretched too (recent change). So, this initial stretch does need to be tuned out of the steering after it is loaded up.

For stainless wire rope, there isn't much tuning to do beyond that. Certainly check it though at the beginning of each season, before any big trips, etc. Dyneema and Vectran, on the other hand will continue to stretch (ie: creep). So, especially on a long cable run like yours, you will need to re-tune regularly to keep the proper cable tension. You don't want the unloaded cable falling off a sheave, if it gets to be too slack. I can't say that I have tried Dux (used in standing rigging applications, mostly), but this may end up to be a compromise between the two... I'd recomend some more research on that though.

End game, keep life on the water simple by going with stainless wire rope, unless you really want to shed a few pounds for racing (and there's probsbly easier ways to lose that weight).

Also, a quick word on sheaves/blocks in steering systems... You want them to be fixed (ie: no articulation or swiveling once they are lined up). Since only one steering cable is loaded up at a time, the other loosens up a bit, and you run the risk of jamming or fouling up the lazy wire if the blocks can droop or twist a bit. This is a requirement for boat builders according to American standards. So, just be careful which blocks/sheaves you use.

[atoll]

Originally Posted by acove

That's great, atoll. You are really going to enjoy that system. Best of luck with the install! I'll look forward to following progress as you post it.

A few words of caution on steering cables...

Dyneema and Vectran have been used successfully on a number of boats. Some hsve even gone as far as to remove the chain and use a drumroll steerer (the Swan 45 comes to mind as an example, if I am not mistaken). However, these synthetic cables require constant inspection (and frequent tuning). So, if you are not racing or do not want to add another item to your daily checklist, I would suggest going with 7x19 stainless wire rope.

The issue is stretch. The splices and line itself (in the case of Dyneema or Vectran) will have an initial set the first time you really load them up. This is also true for 7x19 stainless wire rope - referred to here as structural stretch. As a side note, the aerospace industry does offer pre-stretched cables. Come to think of it, all of Edson's new wire assemblies are now pre-stretched too (recent change). So, this initial stretch does need to be tuned out of the steering after it is loaded up.

For stainless wire rope, there isn't much tuning to do beyond that. Certainly check it though at the beginning of each season, before any big trips, etc. Dyneema and Vectran, on the other hand will continue to stretch (ie: creep). So, especially on a long cable run like yours, you will need to re-tune regularly to keep the proper cable tension. You don't want the unloaded cable falling off a sheave, if it gets to be too slack. I can't say that I have tried Dux (used in standing rigging applications, mostly), but this may end up to be a compromise between the two... I'd recomend some more research on that though.

End game, keep life on the water simple by going with stainless wire rope, unless you really want to shed a few pounds for racing (and there's probsbly easier ways to lose that weight).

Also, a quick word on sheaves/blocks in steering systems... You want them to be fixed (ie: no articulation or swiveling once they are lined up). Since only one steering cable is loaded up at a time, the other loosens up a bit, and you run the risk of jamming or fouling up the lazy wire if the blocks can droop or twist a bit. This is a requirement for boat builders according to American standards. So, just be careful which blocks/sheaves you use.

great post!
I think I should be able to use high quality fixed cheek blocks(x4)for under the aft cabin bunks,and fixed wire sheaves(x2) from the helm.

i might have to use an articulating block(x3) at either end of the cross tie bar which has a 15 ft span,with the attachment point about 2 ft off center,plus a tensioner.
as the tie bars center not only moves side to side but fore and aft slightly

hopefully dyneema will have minimal stretch.
,when delivering the cat as temporary steering I used normal yacht braid through a series of pulleys and the helm driving a bit of 30mm shaft with 5 turns on it,worked really well,but there was considerable stretch!

a few photos of the bits I have to play with,and the aft cabins

you can just see the tiller arms and cross bar in the 2 cabin shots