wheel electric autopilot vs. hydraulic autopilot

G

gianenrico

Well-Known Member
Joined
12 Dec 2003
Messages
510
Location
Northern Tyrrenian sea
Visit site
Dear fellows,
as I might finally upgrade my boating resorces to a Ben 393, I have to pose a question to the wise and experienced forumites:

what are the advantages to install a Raymarine autopilot with hydraulic piston and all the installation it requires in the rear locker, instead of the more traditional "wheel-on-spokes" plus electric engine at the foot of the wheel column and a rubber belt?

A)In case of motoring? /forums/images/graemlins/confused.gif
B) In case of reaching? /forums/images/graemlins/confused.gif
C) In case of running? /forums/images/graemlins/confused.gif
D) in case of heavy sea? /forums/images/graemlins/confused.gif

From data earlier published, boat weight does not seems to be the problem (of course, if the boat is kept well balanced!!).

Thank You in advance,

Gianenrico
 
Wheelpilot:

Easy to fit, cheap. has limitations in capability especially in heavier weather. needs to be set up (rubber belt version). Really designed for 24 hr useage at a time (cross channel, although well set up boats have used them on much longer voyages. Good sail set-up is essential.
Raymarine ST3000 is being discontinued at the end of this year and ST4000 will be entry level. (Guess there will be some bargains at LIBS)

Hydraulic Pilot
More difficult to fit. much more expensive. If the Gyro version fitted, it is vastly better at all points of sail, and especially in bad weather
 
i originally fitted a Navico wheel pilot gave probleme @ 6 months completely u/s @ 11 months & given a new unit, this px ed for a Autohelm 6000 this is now 6 seasons old & faultess , its in total charge no devation from course what ever even down hill (under white sails)

PS electric ram drive
 
I have experienced steering failure on wheel steering (cable turning blocks casting broke) and was very glad to be able to use the Autohelm ST6000 which was attached to the quadrant in the Lazarette. The emergency tiller snapped off after a few hours so we only had the autohelm.

I've used an ST6000 for over 10,000 miles myself and can't fault it, its out of the way in the dry of the locker. The belt ones I've used have always seemed in the way and vulnerable, and also spending alot of time under water when its rough.

I'd choose electric ram onto quadrant.
 
Forget wheel pilots, go for a hydraulic one if possible. Used one on a Ben 423 and was really impressed! Was a great help on a delivery to the canaries, even in bad weather.
 
Again I agree with Talbot but would add that in addition an autopilot fitted directly to the tiller arm gives a back up steering method if your main steering system fails.
 
Have you not considered an electric ram straight onto the quadrant (or better still to a separate tiller arm)? I was going fit hydraulics but got tangled up in the conundrum of the load on the wheel when steering manually (but maybe this is just imagined).

It seems to me that engine-electric-hydraulic pump must be less efficient than engine-electric drive?

I agree with the views on wheel pilots. They always seemed a Heath Robinson solution to me.
 
I know that the linear drives attached to the rudder will provide an alternative steering system in case the link between the wheel and rudder is broken, but what happens with a hydraulic system?
does it disconnect the wheel and or is the integrity of the hydraulic system integral to the performance and thus requires the power to spin the wheel as well as the rudders?
 
I cruised full-time for three years with a wheel pilot with toothed belt and it never let me down. The boat was a heavy displacement 32 footer. I then cruised for two years on a 41 foot boat with a hydraulic pilot, actuator directly onto the rudder quadrant. It also never let me down. The hydraulic system was less obtrusive, more powerful, rugged, reliable and would continue steering in the event of a steering cable failure. This would be my system of choice.
 
Whilst the wheel pilot may not be as robust the power consumption for a 6000 can be imense.
My 6000 with a series 3 course controler on a 40 ft boat says it can use up to 40 amps, create 400kg thrust thru the linear drive on to a below decks arm and the clutch takes 5 amps momentarily to engage. whilst it doesnt use 40 amps it does use more than the 4000 it replaces the additional benefits of having the fast update compass to make the Raymarine MARPA work also need to be taken into consideration
 
We must be careful here to discern between the various types. On my system I have cable steering and a Robertson electro-hydraulic actuator for the autopilot acting directly upon the tiller link rod ( it's a cat with two rudders for those who only have half a boat) Therefore if a cable breaks I can still steer with the autopilot controls. If you have hydraulic steering already and use the existing actuating cylinder for the autopilot then any failure in the hydraulic system will cause you to fail completely. I considered this the ideal when building the boat as it gave me maximum "feel" and feedback when steering manually and 100% redundancy back up. The other post that implied you have to overpower the hydraulics when manually steering if you fit a seperate hydraulic actuator to the system is confused. Purely electrical systems are a problem as you have a ballscrew or other device to deal with. With an electro hydraulic system the pump only runs when the autopilot is engaged and the oil for the cylinder by-passes the pump when its not running causing almost no resistance at all. The only downside is that the wheel rotates when the autopilot is steering. If this is a problem you can fit a dog clutch. I just allow mine to rotate.
 
This is indeed true. The actual power drain will depend on the characteristics of the boat too. An easily steered boat which holds it's course well will consume a lot less power than one that doesn't and a boat that needs two hands on the tiller to wrestle with to windward will consume more than one that needs two fingers! Angle of heel is important too as some cheapies have compasses that are a bit naff while an expensive Giro-compass in a better system will keep the boat on course even when heeled to windward. My cat holds course very well, needs little effort to steer and of course does not heel. When I owned a 36 tonne gaff rigged pilot boat it was a different story! General rule. If it knackers you it probably knackers your batteries too.... But if the power is not available it will give up when things get rough anyway. Most cheapie wheel pilots won't keep a big boat on course to windward in anything above a F6-F7 without wallowing about like mad. They just don't have the welly.....
 
Gentlemen,
thank You very much for the advice.
Ram will then be. Choice to make between hydro or electric: 400 A/Hr for a night work seems a lot of consumption. I'll check if a purely electric actuator does any better.
Gianenrico
 
Real-world power consumption...

Real-world power consumption is nothing like 40A. The Raymarine Type 1 electric linear drive is quoted as having a typical average power consumption of 18-36 watts (ie 1.5 to 3A average). Add on half an amp or so for the computer and display head, and you should still be below 4A as an average figure in typical usage. If you need the more powerful Type 2 or 3 drive, the average consumption is quoted at 48-72 watts (4 to 6A), so it's still not huge.

I have a 6000 with Type 1 linear electric drive; it's one of the most indispensable bits of kit on the boat.
 
You must log in or register to reply here.

Share this page

Top