Hydraulic or cable??

[dogcatfish]

We have had our rescue RIB fully serviced this winter, including a much needed replacement of steering. It was on cable (god knows how old) up until now, and has been getting progressively stiffer and more play in the wheel. We decided to replace it as I was sure it would give up soon (this is a 90hp Johnson on SR5.4). This part of the boat has never received any maintainence whatsoever for at least the 4 years we had it, and the previous owner didn't exactly take great care either.

Anyway, we asked the mechanic for his views once he had dissembled it, and to give us a quote for each. For this size of engine, the power of cable would be sufficient, so that's not an issue. The cheaper cost of cable was a definate advantage to us, however we were looking at long term costs too. If the rod is removed each winter and cleaned/greased, it should last 5 years in perfect condition. After that, it can be replaced by itself (around £60 we were quoted!). Obviously people that use theirs daily will probably wear out sooner, but I think it would still be cheaper this way.

The reason our old system had failed was a washer had not been installed that prevented water ingress to the cable, and as such it was rapidly corroding. Regular winter maintainence would have shown this up. We also have a hydraulic system on another boat, and for me (who has to maintain the lot of them) it's more hassle than it's worth. The cylinders are fairly fragile, and they have to be installed, filled, purged and inspected by someone that really knows what they are doing.

I will sit on the fence here, hydraulics all the way for those that operate commercially or very regularly, as long as it is fitted and looked after by someone that knows. For the weekend only people, I would say that the price of hydraulics is probably not worth it, and cable has fewer parts to worry about needing regular expert inspection. This is based upon my experience only, and this is a hotly debated subject with some people holding militant views one way or the other.

[pathalla]

Originally Posted by Pete7

In Mats defence I agree with him. On a five and a half metre rib with 115 hp there is no need to fit hydraulic steering. A good cable system as you say properly greased up when fitted will be a delight to use, easy to helm and last five years with little maintenance. It also provides feedback from the engine which will show up torque steering if the the engine trim tab hasn't been set up properly which may have been your problem, through lack of experience. Whilst excess grease might be unsightly, leaking hydraulic oil is a nightmare on a deck.

IMHO on this size of boat hydraulic steering is an expensive optional extra and £300 would buy a lot of fuel for this boat, but each to there own view point.

Tim, if your worried about the existing cable steering and don't know its age then replacing the cable isn't difficult and would provide 5 years trouble free use. Do pack grease into the steering unit and into the outboard steering tube where the cable fits during assembly. On the water take some time to experiment and adjust the trim tab behind the prop to counter any torque from the prop, thats what its there for.

My Yamaha 115 is a delight to use on cable steering and whilst I might renew it because I don't know its age, I have no plans to change it to hydraulic steering for a 6.4m rib with a medium sized outboard, its the KISS approach and a new VHF plus GPS a greater priority.

Pete

You can get by without hydraulic on lower horsepower setups, I have run boats with cable setups up to 150 hp. Is it better? No. Yes hydraulic is expensive, but you get don't get a lot of choices. Teleflex has a virtual lock on the market and companies like Vetus don't make the pricing situation any better with their product. Show me one boat manufacturer today selling larger horsepower motors or twins with a cable setup and I'll show you someone who isn't in step with the technology. Take a walk through a major boat show Miami, New york, see what's installed. If a hydraulic system is properly setup by a someone who knows what they are doing you aren't going to have hydaulic oil on your deck...

[Pete7]

Pathalla,

This boat is 1992. Its 18 feet long and its a single 115 outboard, he is a student on a budget. Its going to be used around the Solent.

The real answer he is looking for is a safe, cost effective answer that will do the job. £60 for a new cable or £120 for complete set up, that will last five years is my recommendation.

Some of Tims earlier photos.

CLICK




.

[pathalla]

You are right Pete, In his case I can agree with your asessment. My point is hydraulic is less maintenance intensive and in higher power applications safer. Do you need to use it? no.

[pathalla]

Originally Posted by MadMat

No No, I know nothing.

I'm aware of power assisted steering, and the difference between power assisted and non. Clearly you don't since you're getting the 2 confused. Power assisted steering is not the same, and certainly a £399 seastar system is not power assisted. Would you like me to explain the difference to you? In fact, I've just fitted external hydraulics - but still have the cable to the power assist unit maintaining a direct mechanical connection in case of loss of hydraulics. I could have fitted a priority valve and put a pump on each engine, but I like to live dangerously.

Let's go a drop a diving cylinder, or an anchor, on someone's hydraulic steering hose and see if it's OK. Hydraulic steering systems, typically, work at up to about 1200 psi. They also tend to have increased turns lock to lock, have a dead zone in the middle as the valves in the helm open and shut to turn alternate directions, and have a steady loss meaning over time the wheel steadily needs turning, even in a straight line.

My point still stands, damage a hydraulic steering system while out and you'll most likely need rescuing. Damage a cable system and you'll probably still be able to get home. Agreed, there is a limit where cable is no longer appropriate, Tim M also is also not running "big" horsepower - 115hp, on a rib (the assumption therefore being the engine is running quite low) is well within scope to not "need" hydraulic.

I suggest you also take a look at the scream and fly guys, since they know a thing or 2 about fast boats, and regularly use cable steering, although I accept it's more usually a dual cable NFB setup. I will also pass your advice on to the guys running mannefelt B23 raceboats, and the circuit boys as well - they run cable steering too, usually closed loop, and clearly, they need to benefit from the wisdom of your knowledge to instruct them that hydraulic is the best solution.

The cheap hydraulic systems also do not address one of the weakest links - the small single bolt that attaches the steering to the engine tiller arm. No system fully addresses this becasuse of the need for a pivot, but "race" systems utilising wing plates go use a much larger pivot bolt.

Finally, as referred to above, read this. http://www.maib.dft.gov.uk/cms_resou...l%20report.pdf
Obviously, I don't know much about boats, so most of it went over my head. I however will pass your comments regarding my lack of knowledge back to the University of Plymouth marine engineering department and suggest they alter their curriculum to suit you.

Thanks
Matt

You and I will disagree on the steering Matt. I apologize for the comment about you not knowing much about boats, it was unfair, uncalled for, you did have the good sense to buy a Formula!

[Jono]

Originally Posted by pathalla

..... Show me one boat manufacturer today selling larger horsepower motors or twins with a cable setup and I'll show you someone who isn't in step with the technology. ....

Like this one..? Owned by NWR's very own "Popeye"

[Alex-341]

Arnt the cabbles rated to a certain speed? Aswell as power.

[jwalker]

Originally Posted by dogcatfish

The reason our old system had failed was a washer had not been installed that prevented water ingress to the cable, and as such it was rapidly corroding.

I'll go along with that. The big nut which holds the cable to the steering through tube gives a pretty much watertight connection but the other end does not. I've seen nothing on some systems. There needs to be a terminating nut with a lip seal or an O-ring inside it. Keep it well greased at that end and check it's condition each time the neez gripples get a shot... which should be often. There is suction at the end as the cable extends outwards so it does try to work as a pump and suck in water.

After the sytem is fitted, it is worth undoing the big nut and turning the helm. This will cause the outer cable cover to move back along the inner cable. A liberal coating of water resistant grease can then be applied. It is possible to over grease it get a hydraulic lock after reassembly, so the steering needs to be swung side to side after completion to check for this.

However, as I've said before, a steering system with no play is a delight to use and a single cable just can't do this. There is play in the helm unit gears and the cable has slack at each bend. When pulling, it runs on the inside of the curve and when pushing it moves over to the outer side. As the cable gets older, it gets worse. This is where twin cable has an advantage because it can be set up to compensate.

I sit on the fence too, though. My present boat has power assisted hydraulic with 2.7 turns lock to lock. It's light and has no noticeable creep and gives very good handling. My previous boat used single cable initially and was capable of nearly throwing the occupants from the boat in beam seas but it was quickly replaced with twin cable and it then gave good handling and, since there were two cables, it was failsafe. It gave good service and the cables didn't ever need replacing. But, it was fekkin heavy at low speeds and if playing silly bu**ers with very tight turns, it could lock on on a left turn. Only backing off the throttle would make it light enough to be returned to centre.

My advice for the single bolt attaching to the steering arm is to use a high tensile one and keep it greased. Stainless steel isn't really the right choice. I know there are strong stainless bolts but the tensile strength is not the most important characteristic of this bolt.

The hydraulicly steered outboards I've driven had noticeable and irritating creep and the low gearing was a pain but other folk seem to get used to it so perhaps I just needed more time to accustom myself.

Phew...

[Matt]

It's a balance. Sitting on the fence is the right place, although maybe a bit uncomfortable. Choosing hydraulic by default without looking at the big picture is a fools errand. Cable is perfectly suitable for many situations and that both systems have their pros and cons depending on lots of factors. IMVHO there is no "ultimate" system since the cons of each system are significant.

[codprawn]

What about feel? Which is better - a good cable setup or hydraulic? I suspect the former.

[Matt]

Only if a traditional (ie non NFB) helm.

[jwalker]

Originally Posted by codprawn

What about feel? Which is better - a good cable setup or hydraulic? I suspect the former.

I notice little difference. It's not like a car. You're not feeling the road surface or the adhesion of the tyres.

[BogMonster]

Originally Posted by Pete7

Stephen, we seem to get about 5 years out of a cable and then its scrap. This is in a dive club boat totally unloved and little maintenance, but used regularly, privately owned and cared for they will last longer. The cable tends to go over the winter and sieze up, its almost impossible to get grease into the cable so the best you will be able to achieve is clean and grease the outboard end, then take the cable out of the helm unit and get the grease into these parts too. The helm unit is normally overlooked but makes a huge difference. Worth checking the engine does turn freely with the steering disconnected as a fault here could lead to a mistaken fault diagnosis.

Heavy pulling or torque steering at your normal cruising speed (Jono steady ) can be removed by moving the trim tab behind the prop a few degrees. 5 should be plenty but have seen badly set up engines at 45 degrees which created appauling if not amusing handling characteristics before it was sorted.

Pete

I am gonna pull it all to bits over the winter and see whether everything is OK, not going to do it while the boat is in the water in case I drop something

I have no problems at all with pulling to one side in mine, I can go from nothing to full speed without touching the wheel and it stays more or less in a straight line, so I don't think there are any hidden problems, the boat doesn't even list to one side at all under full power, which surprised me as the Wildcat I nearly bought was a pig of a thing, the first time the owner opened it right out I thought we were going to sink it was listing so far!

[DM]

Originally Posted by Jono

Owned by NWR's very own "Popeye"

You shouldn't laugh. Tsk, tsk.

He's earning a fortune in arm wrestling competitions.

DM