Possibly/Probably disastrous steering problem :(

[vas]

Cardo this ram is scrap!
I'm afraid you have to fork out for a new setup

V.

 

[sarabande]

that isa total operational failure waiting to happen. You need to dump the cylinder and the whole moving works and start afresh.

The ram looks as if it has caught against a moving steel rope which has abraded it to uselessness. Cost of parts will more than exceed a new, properly designed unit.

The torsion on that bolt in pic 2 is madly unsupported and a single nyloc nut on a mission-critical piece of kit....

OK, it's going to be expensive, but not when you weigh it against the guaranteed failure at sea.


If you can take a few more pics, some of the engineers here might put together a few thoughts. I am sure there is an easy, elegant, and effective answer. Achievable locally, too.

 

[rosssavage]

I really don't wish to be rude, but that is one of the worst bodges on a crucial system I've ever seen!!

The cable securing system for the ram is totally unsuitable and a very odd way of doing things, and set to fail.

The rudder brackets are also totally unsuitable. The fork on the rudders should fit snugly with the mounts on the transon, yours seems to have two or three inches of vertical play.

Really, the only option is a complete redesign - I understand cash is an issue, but what you have currently WILL fail, quite possibly with the loss of a rudder.

Sorry to be negative and again, I don't want to be offensive, but that really is a very bad set up

 

[Cardo]

Thanks for the responses, all. Sadly, I didn't really know much about this when I bought the boat, and whilst I still don't know much, I have learnt that the system isn't exactly well thought out. I have been thinking about redesigning it with the ram on the inside with some sort of pintle and two arm linkages to the rudders. I saw something very similar on a boat in Ruone, unfortunately I didn't take a picture!

As for the play on the vertical axis of the rudders, this is intentional. The boat has a lifting keel and is designed to dry out on its grounding plate. The bottom of the rudders have the same depth as the hull, so the play is there just in case a rudder ends up on a stone or something so it doesn't take too much load.

Whilst at some point I'd like to redo the rudder brackets in a better way, I do not believe they are at risk of imminent failure. The hydraulic steering system itself, well, that's another matter entirely...
I'll see if I can post more pictures and post a diagram of how I think it should have been done...

 

[rosssavage]

Ok, I assume there are lower brackets for the rudders too?

Probably the simplest solution at the moment would be to keep the ram mounted on the transom (the environment really isn't a problem with the correct materials - exterior rams are used all over the place on ships, with no problems), but actually mounted to the transom on one end, the other end attached to one rudder and a bar connecting the two rudders. This is not the most elegant solution, but it is easy, quick to install and about five hundred times more suitable for the job...

All the above is easily available off the shelf and a simple job to fit.

Your crazy wire rope system is really most odd!!

Good luck!

Edit: make sure you get a BALANCED double acting ram

 

[Cardo]

Ok, I assume there are lower brackets for the rudders too?

Yes, there is a bracket just above the water line. Even I would've picked up on the issue of there were only one bracket!

Probably the simplest solution at the moment would be to keep the ram mounted on the transom (the environment really isn't a problem with the correct materials - exterior rams are used all over the place on ships, with no problems), but actually mounted to the transom on one end, the other end attached to one rudder and a bar connecting the two rudders. This is not the most elegant solution, but it is easy, quick to install and about five hundred times more suitable for the job...

Interesting. I hadn't thought about doing it this way. However, how would I attach the ram to the rudder in such a way that it'll accommodate the movement of the rudder as it turns?

All the above is easily available off the shelf and a simple job to fit.

Whilst I'm slowly learning this stuff, I feel nowhere near comfortable enough carrying this work out myself. I'd still need to find someone to do the work for me. But who should I approach here in France? :/ A standard boatyard?

Your crazy wire rope system is really most odd!!

Tell me about it!

Good luck!

Thanks. I feel I'm going to need it!

Edit: make sure you get a BALANCED double acting ram

Sorry, I don't know what this means?

 

[Rivers & creeks]

The system on our last boat (Heavenly Twins) was for a single steering control to the starboard rudder, then a stainless bar connected to the port rudder. I suspect that's the usual method for cats large and small. The connecting stainless tube on 'Muddy Paws' was very light weight but absolutely within spec and worked a treat. I think the steering loads on a cat may well be less than a monohull but as you've no doubt discovered, one of the joys of twin rudders is that you make very small rudder movements. A ram acting on one rudder and a connecting rod/bar to the slave rudder shouldn't be a difficult piece of engineering.
As for previous owner bodges, sadly we all live with them.

 

[Talbot]

The situation you have is similar to that on a motorboat outdrive, or on an outboard with hydraulic lift. The piston shaft is extremely susceptible to corrosion, and once pitted, there is a high probability of seal failure leading to complete non-operation. The motorboat fraternity are advised to leave their boats with the rams retracted as far as possible, and that does slow down the onset of the problem, but does not eradicate it. The outside of the cylinder needs to be a very high quality powdercoated finish, and even then is eventually going to rust due to the salt water.

It is for these reasons that autopilot manufacturers demand that their drives are housed in a clean dry place (as if that is totally possible in a boat!).

Thus a redesign with the gear inside will definitely help, I am sure the twin rudders add significant stability when dried out, but at the same time, the sideways load will also be significant - perhaps leading to eventual blade failure.

If it was mine, I would e doing my best to revert to the original configuration, or asking a boat designer to re-visit the design specs

 

[Bilgediver]

Some of you may be aware our Southerly 105 was modified by the previous owner from a single transom hung rudder to twin transom hung rudders. Whilst doing this, he also changed the steering system from cable to hydraulic.
When we bought the boat, the surveyor had a look at the system and seemed happy with it as it was working. Unfortunately, having owned the boat for a year and a half we have discovered various problems with the modification, with differing levels of seriousness.
Our latest issue is pretty serious, I believe.
QUOTE]

Generally Hydraulic cylinders are not so much custom made but a selecion of standard catalogue componects assembled to give the customer
the configuration required.

Your cylinder is probably easily serviced by someone who recognises the components used. Check your Yellow pages forsuitable companies like this.

http://www.hydraulicpower.co.uk/home.html


You could also google Images in google using the search Hydraulic cylinders. This will give you a selection of pictures from the web and might
indicate possible suppliers.

I am not sure what you mean regarding the securing of the cylingder with wire!!! Usually the fixed end is attached with a trunnion and pin or ball joint.

 

[MASH]

Bilge, have you not looked at the pictures...?

 

[Bilgediver]

Bilge, have you not looked at the pictures...?

They don t show the wire. Seem quite normal basic cylinders. Usually there are repair companies in big cities especially where there is a market in Diggers, waste compacters and the Oilfield industry.

These cylinders are probably of the shelf if you can find the right shelf with a threaded attachment at both ends for a rose joint plus an extension at the fixed end.

The rams will be a standard item and just a matter of material selection!

 

[rogerthebodger]

If the cylinder is to be outside specify stainless steel rod so any pitting will be eliminated. Also specify rod gators on both rods.

With a single cylinder steering you would normally have a through rod cylinder so the cylinder volume is the same in both directions.

 

[rosssavage]

Yes, there is a bracket just above the water line. Even I would've picked up on the issue of there were only one bracket!


Interesting. I hadn't thought about doing it this way. However, how would I attach the ram to the rudder in such a way that it'll accommodate the movement of the rudder as it turns?


Whilst I'm slowly learning this stuff, I feel nowhere near comfortable enough carrying this work out myself. I'd still need to find someone to do the work for me. But who should I approach here in France? :/ A standard boatyard?


Tell me about it!


Thanks. I feel I'm going to need it!




Sorry, I don't know what this means?

Attach one end of the ram to the transom with a ball joint, and the other end to the rudder with another ball joint - this would allow the ram to pivot around its attachments in sympathy with the rudder movement. Again, totally standard stuff for steering hydraulics.

A balanced double acting ram is what you have at the moment. Double acting means it is driven in both directions (ie not relying on a spring or gravity to move in one of the directions). Balanced means that the area of both pistons is the same, and is accomplished by having the rod extend out of both ends of the cylinder. In your application, one end of the rod would be encased in a load bearing tube, the end of which forms part of the transom attachment.

 

[rosssavage]

http://www.foreandaftmarine.com/1-HC53223.htm

Above is the ram used on my boat. This is a specific marine ram built by Hynautic, and is the sort of thing I mean. Price is a bit steep, you could get a non marine specific version cheaper.

 

[rosssavage]

Better picture / spec

http://www.hillarysboatshop.com.au/product.php?productid=296118&cat=2369&page=1

 

[Gordonmc]

I was going to reassure you that rebuilding a hydraulic ram is not a major problem.
The one on my boat is of unknown make, but a local (to me) hydraulic shop rebuilt is using a mix of spares off the shelf and bespoke seals. The ram cylinder was reamed out. Total cost was about 80 GBP.
However, your pictures tell a different story.
Of most concern is that there appears to be no provision at all for an emergency tiller.
I would go along with others who suggest a re-think of the whole set-up.
Did the original configuration have a link through the tramsom?

 

[Cardo]

http://www.foreandaftmarine.com/1-HC53223.htm

Above is the ram used on my boat. This is a specific marine ram built by Hynautic, and is the sort of thing I mean. Price is a bit steep, you could get a non marine specific version cheaper.

I think I need something like that. I've been pondering the suggestions and I think I have a decent idea in mind.
Essentially, as per this picture:

If I can get a boat yard to weld a ball joint onto the bracket more or less as in the picture, then mount another ball joint at an appropriate place on the transom, then the ram can directly act on the rudder. The existing ram will for now even do as a link between the two rudders as this shouldn't change in length. All I need to do is remove the wires holding it in place.
The issue is what ram to get. One like the one you linked looks like the thing I need, a marine one so it won't rust to bits with a bit of salt water splashing on it. The schematic the previous owner drew up states the current ram has 8.8 Cu In in travel to provide three turns of the wheel lock to lock, so I guess I'd need a ram with a similar fluid travel. That part isn't so hard, the harder part is working out how much travel I need in the piston. Is this just a case of measuring the distance between where the ball joint on the rudder would be when turned to one side and then turned the other side?

Also, a further consideration. The current installation has hoses with 1/4 inch fittings on them. As I'm now on the continent, will I be able to find parts that will fit the empirical fittings I currently have? Or is this going to be a real ball ache?

 

[Cardo]

I was going to reassure you that rebuilding a hydraulic ram is not a major problem.
The one on my boat is of unknown make, but a local (to me) hydraulic shop rebuilt is using a mix of spares off the shelf and bespoke seals. The ram cylinder was reamed out. Total cost was about 80 GBP.
However, your pictures tell a different story.
Of most concern is that there appears to be no provision at all for an emergency tiller.
I would go along with others who suggest a re-think of the whole set-up.
Did the original configuration have a link through the tramsom?

And here you have stumbled upon the other big pain with this crazy steering system! The lack of emergency tiller! At the moment my emergency plan involves locking the rudders in place and using the bow thruster for turning. It's not ideal, however should get me there in a pinch. If I can sort something out as per the above idea, I then have a further idea to sort out an emergency tiller fitting onto the bar that will go between the two rudders (currently the existing ram).

 

[Bobobolinsky]

Ok, I assume there are lower brackets for the rudders too?

Probably the simplest solution at the moment would be to keep the ram mounted on the transom (the environment really isn't a problem with the correct materials - exterior rams are used all over the place on ships, with no problems), but actually mounted to the transom on one end, the other end attached to one rudder and a bar connecting the two rudders. This is not the most elegant solution, but it is easy, quick to install and about five hundred times more suitable for the job...

All the above is easily available off the shelf and a simple job to fit.

Your crazy wire rope system is really most odd!!

Good luck!

Edit: make sure you get a BALANCED double acting ram

Agreed. Vetus do a bronze ram, I just sold one that had been on the shelf for ever

 

[Bobobolinsky]

You need to pivot the ram, otherwise it just moves up and down the shaft

Imperial pipe fittings are still quite standard all over the world.

For emergency steering, you will need a valved crossover line between the in and out hoses (close it and remove the handle, so it does not get accidentally opened, handle chained to the valve and then taped in position, or it will clap like a bell). Open valve for emergency steering and then a simple tiller on one rudder. If you don't have a crossover line, you need a much longer tiller to overcome the steering pump.