Which Autopilot?

[osirissail]

- - Linear or hydraulic? Linear uses an electric motor to move the ram/quadrant. That takes a lot of electricity. Hydraulic uses an electric motor to pump hydraulic fluid to move the ram/quadrant. It also can use a lot of electricity. The deciding factor is going to be where your rudder quandrant/tiller arm is located and how much space you have to mount the power units.
- - You can normally download the installation and other such manuals from the websites of the manufacturers. Then see what configuration will fit with the type of rudder installation you have in your boat. Hydraulic systems can come in to parts - ram and pump and be mounted separately if necessary. Linear drives are one piece and that piece needs to connect with the rudder and fit in the space **** including a strong mounting point.****

[s/v Jedi]

I can only repeat it: don't go linear drive, you will regret it (you have a lot of boat to steer). Go hydraulic and this works on any type of steering you have.

The only exceptions for not going hydraulic: small boat or Python (or similar) steering systems that have a gearbox with prepared connection for electric motor from autopilot (autopilot = AP from here on).

For the hydraulic drive, there's two ways to go

1. if you have hydraulic steering: simple, buy the hydraulic pump from the AP manufacturer and plumb it into the circuit.

2. if you have mechanical steering: you're lucky because you will have an extra way to steer the boat when the cable/chain breaks. You can buy the AP manufacturers solution which often is an all-in-one unit but you can also install a hydraulic ram + reservoir (Hynautic reservalve) like if you are building hydraulic steering, and next connect the AP manufacturers hydraulic pump to this. I think the latter solution is better (this is what WH Pilots does too).

ciao!
Nick.

[ciclon1942]

Thanks Nick for your help. It was suggested to me that it would be better for us to use a linear drive rather than a hydraulic set up. I am not sure how you would install but we were told that there was not enough space for anything other than a linear drive. It might be that it is easier for the engineer to fit a linear drive?

We have a machanical Edson setup but I am unsure of the best way to couple this up to a hydraulic pump?

Thanks again for everyones help and suggestions.

Regards

Ross

[osirissail]

- - Please do not buy Raymarine, you have a high probability of regretting it.
as to "linear drives" they actually come in two versions: Electric and Hydraulic. Electric have a ram/rod that is driven in and out by an electric motor mounted on the end of the unit. The Hydraulic units have a hydraulic pump mounted on the end of the ram/rod. There are probably some minor dimensional differences between the two type, but not much.
- - "Hydrauic drives" come in two pieces: a ram/rod that is dimensionally smaller then the "linear drive" packages; and a separate hydraulic motor that can me mounted anywhere convenient and then hydraulic hoses connect it to the ram. These types have the lowest profile for fitting into tight/restricted spaces since there isn't the big "box" at the end of the ram/rod.
- - The most challenging part of any autopilot installation is the attachment to the steering system. The simplest is the wheel pilot that just turns the steering wheel. The others need to be attached to the rudder stock inside the boat. This is normally done by attaching the drive unit to the semi-circular "quadrant" mounted on top of the rudder stock - if you have a quadrant; or to a tiller arm that is attached to the top of the rudder stock. Each version of "drive unit" has a maximum "extension" of the "rod" that varies with the models of drive units. This dimension must be matched to the attachment point on the "quadrant/tiller" so that the movement distance from rudder "stop to stop" matches the drive unit maximum extension.
- - Important - if the drive unit is attached so that only a portion of the maximum extension of the drive unit ram/rod is used, it is highly lightly that the drive unit will fail at worst and steering will be erratic at best. If the drive unit ram/rod is positioned so that you cannot achieve maximum stop to stop movement of the rudder then you will lose slow speed maneuvering ability of the boat. Sometimes it is necessary to add a form of "tiller arm" that is attached to the quadrant to achieve this requirement of the conversion of rotational distance to straight line travel distance to match the drive unit.
- - P.S. the dual rams shown are for boats like catamarans with dual rudders. For mono-hulls you would only use one ram.

[Randyonr3]

I've got the linear drive Type II and the smart pilot with the flux gate compass.. Installed it myself, works like a charm and been using it for 7 years.. a couple great issues about the system.. It all talks to the rest of your Raymarine system and is a joy to use with the chart-plotter.. On the chart-plotter, use the cursor to find your point, click "Go To" , and push "track" on the auto-pilot.. couldnt be simpler..
With the smart pilot, in following seas, if the same reaction happens more than a couple times within a minute or so, the smart pilot reacts befor the next time it happens..
Example,... in following seas, under auto-pilot, when the wave comes up under the rear of the boat, the boat will twist off the wave and then the auto-pilot will pick it up and stear back on course.. so you are always doing an "S" motion..wave turns the boat-auto-pilot stears it back.. But with the smart pilot, it only happens a couple times until it starts to think and compute.. The third time as the rear of the boat lifts, the flux-gate compass picks up the movement and course corection is already in progress and the wheel starts to move keeping you on course.. the boat sails a streight course off the wave with out deveation...
another great part of the raymarine system...If hooked up to the chart-plotter.. when you set a course, you also set the "Rum Line" and the smart-pilot will follow the rum line and not the compass course..

[Randyonr3]

If you are going to install the linear drive yourself, give me a shout and I'll get you a few shots of mine.........
Also, I used the Edson arm to conect the drive to the rudder post.. I used the type II (in the long version) as its larger than what I needed but I also made a slight mod to the system.. I shortened the distance from the pivot point to the rudder post giving it a faster "hard over" reaction..
The type II (short) is geared for displacement of 33,000 or less.. where the type II (long) is geared for boats up to 44,000.....

[s/v Jedi]

Hi Ross,

Originally Posted by ciclon1942

Thanks Nick for your help. It was suggested to me that it would be better for us to use a linear drive rather than a hydraulic set up. I am not sure how you would install but we were told that there was not enough space for anything other than a linear drive. It might be that it is easier for the engineer to fit a linear drive?

I think with linear drive we all mean electric-linear. Your dealer is misinforming you because a hydraulic RAM is the smallest and easiest to find room for. Hydraulics are always smaller with same or more power. Yes, a linear drive will probably be quickly popped in by the dealer: his interests are not the same as yours!

Simrad Robertson is one of the few pilots that can be called top of the top. WH Smith is another one. RayMarine is way lower on that list, but if you plan to sail weekends along the coast it might suit you and it's cheaper too. Extra's like a rate gyro are what makes the difference and this is included as standard with the Robertson.
All the pilots integrate perfectly with plotters no matter the brand of either component. I have a Raytheon (yes, old) radar/plotter and just point the cursor and press "goto" and the pilot receives the command and only asks for confirmation, just like with all Raymarine components. I even feed the Robertson gyro compass info to the Raytheon to improve the radar overlay feature.

I don't know how handy you are but it is worth a lot to do the installation yourself. It is not difficult at all and you will know your pilot in&out after that.

You will probably need to make two brackets: one for the hydraulic ram and another one for the rudder position sensor. The bracket for the ram must be very strong as all the forces of steering are transferred to the hull at this point. We have a welded aluminium bracket (out of 3/8" thick aluminium) that is bolted onto the transom and a stringer. You normally make one out of plywood and bring it to a workshop for replication in aluminium. We have an Edson bronze quadrant and a Hynautics K2 ram is bolted to that at about 8" from the center of the shaft.

The rudder position sensor looks easy to install but requires some precision. The manual explains it clearly. I used a small stainless shelf-bracket to attach the small rod to the rudder shaft and a bracket from 3/8" King Starboard to attach it to the hull. This allowed me to install the sensor at the same side as the ram (above the ram).

We have a machanical Edson setup but I am unsure of the best way to couple this up to a hydraulic pump?

You can mount the pump in any convenient position and run two hoses to the ram. I use the Hynautics "reservalve" which makes filling and bleeding the hydraulic fluid easy. You can find these parts in any catalog, even West Marine, under hydraulic steering. You also need a valve to engage/disengage the drive from the rudder. You can use a solenoid valve from the AP manufacturer (the AP operates it automatically) or a manual valve with morse cable. I use the latter and use it for locking the wheel at anchor too.

ciao!
Nick.