Hydraulic Steering in Multihulls

[cat man do]

Originally Posted by fastcat435

We are vvery happy users of the Hydrive system , the pump is the type 105 and the actuators are the stainless steel type cylinder 213 and this combination works perfect.
Our cat is about the same size and weight, we use balance rudders where 25 % of the rudder is forward of the rudder stock.
Greetings

Gideon

Cool, that ties in close enough with my Ultraflex stuff @ 111kg per m as well

Dave

[ssullivan]

Originally Posted by 44'cruisingcat

Don't be envious! Your boat's in the water - mine's still in the shed!

I suppose that is true, but what an incredible length to weight ratio! I'm stunned, coming from the cat I'm on right now.

I keep trying to get as much junk off the boat as possible to maintain speed. with yours, it sounds like you will need nothing more than a gentle breeze to do 10 knots!

Great specs. (yours too, Catmando.)

[trinescape]

hi cooper my tri is 10.6m and she weighs in at 5t all up fully loaded she is 6mm ply on outer hulls and double diagonal on the main hull and epoxied inside and out she is not a speed machine but shes no slouch either we lived on board for 2.5 years till major accident put me on shore hopefull in the not to distant future we will be back living on board and doing some cruising

[44'cruisingcat]

Originally Posted by ssullivan

I suppose that is true, but what an incredible length to weight ratio! I'm stunned, coming from the cat I'm on right now.

I keep trying to get as much junk off the boat as possible to maintain speed. with yours, it sounds like you will need nothing more than a gentle breeze to do 10 knots!

Great specs. (yours too, Catmando.)

Bob Oram tends to make his boats long for their size. It would have less space than most 36-38 foot French production boats, but with longer slimmer hulls.

There are no exotic materials in the boat - none at all - in fact some of the furniture is partly built of plywood. (Mostly the vertical bits.)

It results in an easily driven boat - the rig is relatively modest, (mine will have a 16m mast) as is the sail area - around 80m2 main + jib, from memory.

A sistership, which is probably a little heavier than mine will be, sails at 6 knots in 5 knots breeze, and does close to 10 in 10.

Can't wait to get her in the water!

[cat man do]

Yep, mines the same style of thing, strip plank and ply 50 footer with I would think even less accom than 44fc's.

Skinny waterline (12.5:1) but gets fatter as it goes up to accommodate a well, ermm, rather more portly fella.

Dave

[Strygaldwir]

I'd think there are so many other factors that you're going to have to weigh when selecting the "correct" boat for you, the type of steering would certainly get relegated to the bottom of my list. But, that is after living with cable and using hydraulic. On most catamarans, since there is little healing, the rudders retain balance on most points of sail. This results in significantly less stress on the steering gear. It also means less force is required to steer comfortably. If I had a large mono, I believe, I'd absolutely want hydraulic steering. But, I have been VERY happy with the feel and easy of steering on my cat.

[Nordic cat]

I pulled out the factory mounted teleflex system about 6 years ago, the teeth were nearly totally worn, so I hate to think what could happen if the last bits got pulled out in bad weather - no steering?

I replaced it with a Vetus hydrailicsystem with about 3 turns lock/lock, and got rid of the the wheel pilot with belt drive, replaced it with a Raymarine ST5000 with a rudder sensor, so I can at all times see the rudder position.

When sailing there is no feedback really, but by looking at the rudder position indicator I can trim the sails to balance the boat very easily.

My only beef is the lousy coating on the Vetus helm pump, it started peeling after a couple of years, and we have practically no salt up here in the Baltic.

My helm is only around 50 cm in diameter and it's easy to steer.

regards

Alan

[Splash Gordon]

Any chance of a tie-bar? Then you only need 1 cylinder!
Just another thing: when you reverse a cat- why the heck would you even want to touch the helm if you've got two engines? If you've only got one engine and use the rudders to reverse, then the loads are hugely different! As an example, consider a rudder 2' long by 1' deep, and 3" of bounterbalance. With one rudder, the loads at a given speed are something like 2.5 times more in reverse than fwd. But if you increase the counterbalance, say to 4", the torque on the rudder increases to 4x! Speed in theory doesn't influence the difference so much as the counterbalance effect: while it takes load off going fwd, in reverse it has the opposite effect.
Just my ramblings... dunno if it helps, tho'...

[imagine2frolic]

Cruisingcat,

If you want me to look, and see what system I have for my hydraulic steering I will. You can see my beam that contains the drag link is about 2 feet in front of my rudder posts. The rudders are hung on a skeg, so they are the back half of what you see in the water. Here's another angle too.

[Eleven]

I'm a little puzzled, my brothers Prout 37 had the autohelm working virtually full time. He reckoned about a quarter of an amp typically as this was an electrically driven hydraulic system (Autohelm?). His remote had one and ten degree buttons, apparently the latest ones have a TACK button that can be set to give 'x' degrees.
The autopilot learnt the boat and the weather and optimised helm inputs as a helmsman would.
Don't they work like that anymore.
A lever with a rudder position indicator would be the obvious route for this sytem to allow docking. An (emergency type) tiller would be better for racing where the balance needs to be felt through the helm.
The Prouts generally had a mechanical link (with adjustment) between the rudderstocks. Has this also become obsolete?
Perhaps those transfering from Mono's and racing have more trouble with this aspect of cat sailing.

[44'cruisingcat]

Originally Posted by imagine2frolic

Cruisingcat,

If you want me to look, and see what system I have for my hydraulic steering I will. You can see my beam that contains the drag link is about 2 feet in front of my rudder posts. The rudders are hung on a skeg, so they are the back half of what you see in the water. Here's another angle too.

Sorry, I must have missed this post when you made it. Thanks for the kind offer, but I now feel confident that the system I'm going to use will be suitable. It was only Hydrive's (over) specifying of an enormous system that had given me doubts.

Many thanks everyone who took the time to give information about their systems. It was all most helpful, and greatly appreciated.

[mikereed100]

44,

What system did you decide to go with?

Mike

[44'cruisingcat]

It's not set in stone yet, but most likely an Ultraflex system similar to Dave's (Catmando).

[sandy daugherty]

Thanks Sean, you solved a mystery for me. My last Cat was a 34' Roger Simpson Design built in North Carolina by a skilled craftsman. It had exactly the same hydraulic steering system, and I couldn't figure out how he got it right the first time: he must have copied a catalac!

[imagine2frolic]

sandy,

The man in the Carolinas. Was his name Orville, or something similiar?