Hydraulic steering prob.

Richard B · 07 July 2003, 23:02

Hydraulic steering is all new to me, and so I've got a little problem with it that I don't inderstand.

Let me explain...

At low (displacement) speed, it all works as expected, but once up on the plane and doing over 25kts, the following happens:

To steer to port, turning the wheel to the left is very stiff, but is effective in steering (like being in a "high" gear)

To steer to starboard, turning the wheel to the right is very loose, but was less effective in steering (like being in a "low" gear).

This gives a strange steering effect, where I compensate half a turn to port, than a full turn to starboard...

Could it be that the system just needs bleeding or perhaps something else?

thewavehumper · 08 July 2003, 00:23

Is she still in the Water? If so take Jasper out and he will tell you if it's a problem and what it is.

Is the steering Graunchy at all, and does she favour one side when she leaves the water

Richard B · 08 July 2003, 06:44

No, she's out of the water now Stuart.

I didn't think that the steering "felt graunchy" - all quite smooth and at slow speed everything was normal.

Draki · 08 July 2003, 08:04

I've noticed a similar effect but in reverse - i.e. at low speed it turns to starboard very easily, to port like treacle. (or vice versa - I can't remember exactly!) I have no problem at higher speeds

I've found this to be the engine trim - at low speed by playing with the trim I can equalize the steering to both port and starboard. Equally at higher speed when the engine is badly trimmed the steering varies.

I would guess that this is similar to your problem - try playing with the engine trim at speed.

I've always assumed that this is normal - I sincerely hope it's not a symptom of something else!!!

Max

-<=[Tw18]=>- · 08 July 2003, 08:15

no forgive me if I am wrong but I have always understood this eagerness to one side and reluctency to the other to do with the prop spin and which way it turns in the water?

So say your prop spun to the right (clockwise when looking from the stern), the boat would turn easily to starboard, and with an effort apparent in turning the boat to port.

This is a very basic analogy, but thats what I was always told?

Lee

Draki · 08 July 2003, 08:22

I agree entirely that it's the prop causing the imbalance and I think that trimming in/ out amplifies the effect.

Max

Richard B · 08 July 2003, 19:52

Thanks for the suggestions, guys. I've got to admit that I'm sceptical... I was out on Sunday in a variety of sea conditions, head sea/following sea, and varied the trim to suit all conditions, but I'm pretty sure the problem was there all the time once up on the plane.

Max/Draki - was that you I saw out on the river at Lymington in a yellow & blue DS21?

Draki · 09 July 2003, 08:29

Richard,
Yep - that was almost certainly me. Which day was that? I was out pretty much all week doing a spot of fishing (with unusually great success - LOTS of mackerel!)

Max

Richard B · 09 July 2003, 09:10

Max, we were there on Sunday quite late, tied to the outer end of the Berthon pontoon for half an hour. Enjoy the mackrel!

Richard B · 11 July 2003, 21:30

OK, quick update... I gotta bit of a leak on the ram. Small slick of hydraulic fluid in the transom well was the giveaway. It's at the union which seems to be screwed into the body of the ram, so I'm going to try to undo it tomorrow, pack it with PTFE tape and bleed the system. Does anyone know what type of hydraulic fluid to buy, and where to get it (in Southampton)?

thewavehumper · 11 July 2003, 23:47

If you were to go to our unit in Saxon wharf you pass, right at the entrance, The Rib Service Centre. I am sure they would have some stuff. failing that there are a lot of marine engineers in Shamrock try APAS.

Richard B · 11 July 2003, 23:59

Cheers, Stuart. I Tried Halfords in Staines this evening, got a funny look from one bloke (I'm used to that

) but quite an intelligent answer fom another - apparently auto transmission fluid is very similar spec. All I need is a syringe or something similar...

Dirk Diggler · 12 July 2003, 07:25

Quote:

Originally posted by Richard B
All I need is a syringe or something similar...

I can see this turning to rats sh*t, why on earth would you need a syringe?

All the hydraulic systems I've ever fitted have been filled/topped up from the helm. You need a bottle of oil with a length of plastic hose that screws into the helm unit. There is then a procedure involving opening bleed screws and turning the wheel. It's a bit fiddly, but you need to do it in the correct sequence, or you'll never get the air out.

A call to Hypro Marine in New Milton would be a wise move.

Cookee · 12 July 2003, 07:40

Dirk is spot on - It's fiddly as anything and different systems have different methods!

I know how th eseastar system works but others such as Latham have a different way of doing things I think!

ATF or TQF work in most systems (I think!)

Good luck,

Dirk Diggler · 12 July 2003, 08:40

These are the reccommended oils for a SeaStar system,

SeaStar oil part number HA5430
Aero Shell Fluid #41
Univis N15 or J13
HO15
Aviation Hydraulic Fluid A
Aero HFA
Harmony HV115 (In Canada Only)

Substitution of non-recommended fluids may result in heavier steering and/or irreparable damage to your steering system.

gavin · 12 July 2003, 11:02

Syringe( less sharp) are used to REVERSE FILL Hydraulic systems, without bleeding, without the use of someone to help and without having to top up at the helm unit, the bleed screw is opened at the ram a tight piece of tube is fitted over it and connected to the Syringe (less sharp) and you very simply force the fluid backwards tro the system with the cap off at the helm unit , by compressing the syringe plunger.

Richard B · 12 July 2003, 11:39

What I don't understand is this need for an airtight seal at the helm filling cap. When I look in there, there's quite a lot of room (which I assume shouldn't be there - I guess the leakage accounts for this) and I thought the first job would be to top it up before startiing the bleeding. The syringe idea was to get the fluid cleanly into the helm reservoir.

BTW - I didn't get any ATF in Halfords! Taking advice from Ali G isn't on the agenda

Dirk Diggler · 13 July 2003, 16:30

I don't know which steering you have, but here's a link to one of the most popular, showing you how to fill & purge a system,. Not a syringe in site!!!

http://www.seastarsteering.com/REPLA...TS/replace.htm

Richard B · 13 July 2003, 17:13

Wait for this...

Thanks Diggi

Weekend work on the steering postponed as I didn't know what the heck I was doing

Mind you, I did print out Charles' description of how to bleed a system.

I hadn't found either the distributors or the manufacturers web sites unti you pointed me to them, but I'll probably give Hypro Marine a ring on Monday to see if i should do anything to the "bleed tee" where the fluid is comning from. I'm not sure if it's coming form the base of the tee where it screws into the ram, or from the union nut. Simply tightening these may be all it needs, but I feel a bit better informed now!

Just found this on the "Fill & Purge" section: "Filling the helm full of oil can be done faster if oil is poured into the helm prior to connecting filler tube and oil bottle to the helm"
- so I did need that syringe after all