Rebuilding a Cobra Yacht Steering System—Disassembly and Inspection
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- Rebuilding a Cobra Yacht Steering System—Disassembly and Inspection
- Rebuilding a Cobra Yacht Steering System—Reassembly
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Of all the reasons to instead have tiller steering this excellent article is perhaps the most convincing.
A very fair point. Once upon a time a boat the size of Sherpa might likely have had a tiller. Personally, I’d be very happy with a tiller on her, although some of her contemporaries less so,
Fortunately, wheel steering if well maintained is relatively trouble free. Just as well!
Good article, thanks for sharing. I have found that rod ends, seals, bearings, bevel boxes, pillow block bearings and CV joints can all be bought from general engineering component suppliers or motor factors, rather than any of the marine steering companies, with the associated costs being significantly lower (UK based, and as always shop around for best prices). In addition if struggling for parts, search for vintage car restorers as many of the rod end, track end parts were used in steering / tracking systems on older vehicles. From the list of components, you can tell I have centre cockpit with a steering system that predates Whitlock.
Great tip about the shaft locking up and preventing emergency steering system from working, I will note that.
ps Aberdeen Compass Adjusting can service your compass, they have the parts to overhaul, I have no association with the company except as a customer.
Absolutely right. Most parts in all these wheel systems come from some other common source and can be sourced with minor trouble online,
I did the compass myself, but thanks for the tip – there are so few of these good old firms left.
I went that rebuild route about 5 years ago.
I am sharing below a few URL that I did found useful by that time.
I think the more information you have the better.
I was able to buy parts from below, and they provided good help:
https://yachtsteeringservices.com/
Some forum dicussion:
http://www.cruisersforum.com/forums/f55/whitlock-cobra-steering-bearing-replacement-97805.html
In french with lots of pictures:
http://boisbarbu.free.fr/EqtTech/barrearoue.htm
A few more photos:
http://www.elan333.se/2014/11/d-check-pa-styrmekaniken-demontering.html
I also have a few french/english whitlock cobra PDF manual if that can be of any interest, I can share them.
Hi Colin,
I have yet to have to tear into a Cobra system but this will be a great resource if I ever do.
A trick that I have really come to love for getting stuck bearings out if the basic trick of a puller and penetrating oil doesn’t work is to shrink the bearing by welding. To do this, you cut the inner race with a torch or angle grinder and take away the rolling elements and seals so that you are left with a cleaned outer race. Then you crank up your welder and lay a really heavy weld bead around the inside of the outer race. When this cools, it will try to shrink and if the bead is heavy enough, the relative stiffness of the bead to the race will make the race shrink significantly. Once this is done, you can usually just lift it out by hand, I have never had it fail although I haven’t tried on really small (thermal growth techniques don’t work well) or large (requires a more powerful welder than I have) bearings.
As pointed out, things like bearings and seals will almost invariably be standard off the shelf items. There are occasionally good reasons to make these custom but that is pretty rare and you have to have a really strong need or a very high volume to justify it. However, this doesn’t mean that you can always run any old bearing or seal that fits. For example, if you look at a bearing spec sheet you will see that there are tons of different categories for everything from static load ratings to grease type to ball material to radial and axial clearances and more. For many applications, a normal bearing or seal found on a place like McMaster will do just fine but it is hard for the average person to figure out when it is not okay. One of the worst quality issues I have ever been involved with was actually due to an unauthorized substitution of a bearing by someone in purchasing on the basis that it would fit and had the same dynamic load rating. However, it replaced a bearing that had been chosen for a thicker outer race and the thinner raceways of the new bearing were deforming. You can imagine how happy engineering gets when they are told they have a pressing design issue and it isn’t a design issue at all, it is an issue of people not building the design. The best bet is to carefully clean off the face of the bearing or seal and there will almost always be a part number which you can search for. Most of the time you will find that exact part available and if not, you at least have a spec sheet to do a good comparison to find a substitute. I try to start these sorts of projects shortly after haulout so that I can get the parts out then order new stuff without huge time pressure.
Eric
Hi Eric
I’ve seen that trick of welding bearings used on vintage motorcycles – nice idea.
And I agree with all your latter points. One of the reasons I always order from Yacht Steering Services is that I know I have the right ones in advance of starting. Snd my nearing bearing supplier is c. 88 miles away!
But carrying a list of important bearing numbers is a good idea if you’re going long-distance, for the reasons you identify.
Best wishes
Colin
I did the Cobra on my yacht two years ago, though slightly newer than yours. EVERYTHING was VERY stuck, I had to drill and cut most of the bolts and grind out all the bearings… Both inner and outer ring. The bracket for the bottom bearing was broken on mine, but that was easily fixed by handing it to a local welder.
A tip on the lever arm on the bottom that needs to be grinded to remove it: Drill a 3mm hole through it and the pipe. That way when you give it to the welder, just put a bolt and nut in, and it will 100% sure be 100% correct position. Also you won’t lose the markings made when you grind and clean it.
Another tip: everything on mine was stuck, every bolt and all. I welded nuts on the broken heads and the bolts that were impossible to drill out. This welded nut-head heated the bolt so much that the corrosion broke free and the bolts could be removed quite easily.
As you say, access in everything! Replace EVERYTHING that you can once you have this thing out, because the destructive nature of servicing this unit makes it a job that’s impossible to do away from civilization. I also found it impossible to totally seal the unit, so I thought I might as well regularly rinse the whole thing in something like 6-66 spray, and so far everything looks and feels brand new. No idea if that’s a smart move or not, but so far it has worked well. After servicing, I have exactly zero slack in my steering system, and it feels incredibly good to hand steer the boat.
Colin, a half related question. On your OVNI, how did you do it with “parking” the wheel on anchor? Did you lift the rudder? Rely on the wheel brake-lock? Tie the wheel off? On mine, I feel the leverage the rudder have when lifted is enormous, so I keep it down when on anchor, just lift it once a week or something to avoid growth on the cylinder. Then I lash the wheel with ropes in addition to the wheel brake if the supposed to be rougher conditions.
Kindly, Arne
Hi Arne
all very good points. I marked everything on mine with V notches to ensure correct alignment of the drive arm, but the drilled holes etc. is even better.
Welding, nuts, bearing races etc. is a very good way to deal with seized bolts – I was fortunate that none of mine required that and I had a good workshop to turn to. Reinstalling on Lactate or TefGel will help next time.
Older Ovni’s are very prone to problems with the lower bearing in particular, because the pedestal is mounted on a ‘bridge’ that is open underneath, so there is damp/salt all the time under there. Anything you can do to keep it lubed is good. I fitted an inspection plate in the pedestal on ours to allow winter inspection and servicing of the lower bearing. But the exposed nature of the bearings etc probably accounts for the seized bolts too – the base should be under the deck, so drier.
I always left the rudder down except in calm spots (i.e sheltered marinas) where it paid to keep the piton of the ram covered. Anywhere else I put the brake on and lashed the wheel if the boat was left for any length of time unattended. The board and rudder should, as you say, be raised periodically to avoid weed and barnacle growth.
Best wishes
Colin