AutoPilot questions

[mj81]

Hello, I have a Westerly Falcon which needs a new autopilot. I have been through all the specifications etc and know that I need a linear type drive unit. I will be installing myself but having not done one before this where my questions start...........
Has anybody reading fitted a linear type autopilot to Westerly Falcon? It seems like I will need to build in a new bulkhead to take the load at the correct level?
I think ill need a tiller arm on the stock vs going straight onto the quadrant. Thoughts on the best way?
Looking at the Raymarine system it limits me to 35 deg each way, I haven’t measured yet but think my rudder currently goes further than this, should I be concerned about adding rudder stops?
Finally Raymarine vs Garmin? What would you go for?
Thanks

 

[lpdsn]

Hello, I have a Westerly Falcon which needs a new autopilot. I have been through all the specifications etc and know that I need a linear type drive unit. I will be installing myself but having not done one before this where my questions start...........
Has anybody reading fitted a linear type autopilot to Westerly Falcon? It seems like I will need to build in a new bulkhead to take the load at the correct level?
I think ill need a tiller arm on the stock vs going straight onto the quadrant. Thoughts on the best way?
Looking at the Raymarine system it limits me to 35 deg each way, I haven’t measured yet but think my rudder currently goes further than this, should I be concerned about adding rudder stops?
Finally Raymarine vs Garmin? What would you go for?
Thanks

Out of curiosity where did you get the 35 degree figure? I'd say definitely go for stops if you haven't got them already, even for hand steering.

I went Raymarine (because I had an existing Autohelm drive). Certainly the autopilot functionality seems good. I couldn't fault it when I had to go on the foredeck at 3am to sort out a spinnaker issue. I'm not such a great fan of Seatalk ng and would favour standard DeviceNet if doing things again, but you can join a STng bus to a DeviceNet bus, so you aren't locked in if you go Raymarine.

Garmin seems to be a more recent offering based on, I believe, a Jefa arm and electronics they acquired by buying Nexus. Both Jefa and Garmin would be silly to compromise their reputations with a naff autopilot so it should be good, but I've no experience of it.

 

[pvb]

I had a Raymarine autopilot on my old boat, with a Type 1 linear drive which was 24 years old when I sold the boat, and still worked perfectly. My current boat has a Jefa linear drive and Garmin electronics, which work beautifully (but I'd expect current generation Raymarine kit to work well too).

The linear drive certainly needs a sturdy mounting point. In my old HR, the drive was bolted to a 20mm marine ply bulkhead which was glassed in to the hull all round. In my current boat, the drive mounts on an alloy framework which supports the twin wheels.

You also need a separate tiller arm, don't be tempted to try to attach it to a quadrant. Jefa sell these, and there's masses of info on the Jefa website.

In terms of design, I suspect the Jefa drive is very well engineered. The Raymarine drive is basic and simple, but seems very robust.

 

[prv]

Has anybody reading fitted a linear type autopilot to Westerly Falcon? It seems like I will need to build in a new bulkhead to take the load at the correct level?

Not to a Westerly, but I fitted a Raymarine Type 1 to our Maxi. It was second-hand from eBay, and old enough to have the Autohelm name on it rather than Raymarine, but I believe the current ones are the same design.

The space available, under the aft cabin bunk, was rather cramped. But by cutting a hole through a non-structural partition and lying the ram on its side, I could squeeze it in. Worth nothing that it doesn't have to have any particular alignment to the fore and aft axis of the boat - to fit into the space mine runs about 10 degrees off athwartships, with the central position of the stub tiller offset to match. That also lines the foot of it up with another light GRP stiffener/partition, which I beefed up with epoxy and plywood and bolted through the whole lot.

I think ill need a tiller arm on the stock vs going straight onto the quadrant. Thoughts on the best way?

I got a tiller arm machined by Colin who posts on these forums, but you can also buy them off the shelf.

Looking at the Raymarine system it limits me to 35 deg each way, I haven’t measured yet but think my rudder currently goes further than this, should I be concerned about adding rudder stops?

Yes, you need stops to keep the rudder within the range of the drive. Otherwise when hand-steering or, worse, letting the rudder take charge when reversing, the drive will act as the stop and it's not built for this.

Pete

 

[mj81]

Out of curiosity where did you get the 35 degree figure? I'd say definitely go for stops if you haven't got them already, even for hand steering.

Hi, I got the 35 degrees from the installation manual

 

[lpdsn]

Hi, I got the 35 degrees from the installation manual

Just found it in the installation manual. I hadn't noticed it before. I'll have to check what my limits actually are. Obviouly you don't want the arm of the linear drive reaching its max or min limit before the rudder reaches the stops, but I don't know why they explicitly state 35 degrees.

As part of installation you 'teach' the autopilot what that limits are by going to full lock either side. I'm sure mine's over 35 deg but it didn't object to whatever it is. I'm out at the boat tomorrow so will power it up and see what the maximum values are.

 

[LadyInBed]

Re stops, I made two hardwood blocks with holes through which fitted over the bolts either end of the quadrant frame.
I think the limits are needed to stop you over driving the rudder reference unit.

 

[knuterikt]

Hi, I got the 35 degrees from the installation manual

2 * 35 degrees I would guess.
It's limited by distance from center of rudder stock to attachment point on tillerarm and max travel off drive unit.

Larger rudder angles than 35 is not efficient on most boats.
You need stops to prevent damage to the drive unit.

 

[lpdsn]

I'm sure mine's over 35 deg but it didn't object to whatever it is. I'm out at the boat tomorrow so will power it up and see what the maximum values are.

I remembered to check this, but forgot to report back until now. Setting the wheel to max lock either way I got values in the RSA sentences of 38 deg and 37.2 degs. Not sure why the small difference, the topology in my steering compartment is quite complex so the rudder reference arm may see full lock as slightly different on each tack, but it is also very likely that the strong tide running moved the rudder slightly whilst I made my way to the chart table.

I didn't test to see how far the linear drive would move the rudder. The p70 only displayed up to 30 degs either way. I wouldn't really expect the autopilot to apply full lock anyway.

 

[knuterikt]

I remembered to check this, but forgot to report back until now. Setting the wheel to max lock either way I got values in the RSA sentences of 38 deg and 37.2 degs. Not sure why the small difference, the topology in my steering compartment is quite complex so the rudder reference arm may see full lock as slightly different on each tack, but it is also very likely that the strong tide running moved the rudder slightly whilst I made my way to the chart table.

I didn't test to see how far the linear drive would move the rudder. The p70 only displayed up to 30 degs either way. I wouldn't really expect the autopilot to apply full lock anyway.

The problem is that if you turn the rudder past the max for the linear drive with force (going astern) you might damage the drive unit.

 

[lpdsn]

The problem is that if you turn the rudder past the max for the linear drive with force (going astern) you might damage the drive unit.

No, the drive did full lock both ways during the commissioning process. I re-used the drive from the original installation (Autohelm) so it's been there since 1992, although I did replace the quadrant it attaches to with one of the same dimensions but better material.

 

[pvb]

I remembered to check this, but forgot to report back until now. Setting the wheel to max lock either way I got values in the RSA sentences of 38 deg and 37.2 degs. Not sure why the small difference, the topology in my steering compartment is quite complex so the rudder reference arm may see full lock as slightly different on each tack, but it is also very likely that the strong tide running moved the rudder slightly whilst I made my way to the chart table.

I didn't test to see how far the linear drive would move the rudder. The p70 only displayed up to 30 degs either way. I wouldn't really expect the autopilot to apply full lock anyway.

As others have said, you must have robust physical stops to prevent the rudder turning more than 35 degrees either way. It's unclear whether you have these. If you don't, the linear drive may reach its end stop and be damaged.

 

[Cantata]

...............You also need a separate tiller arm, don't be tempted to try to attach it to a quadrant. ...............

Wondered why you say that? I fitted a Type 1 to a Moody 36 last year (where there was no autopilot before) and attached it to the quadrant. Works perfectly. Am I missing something?

 

[pvb]

Wondered why you say that? I fitted a Type 1 to a Moody 36 last year (where there was no autopilot before) and attached it to the quadrant. Works perfectly. Am I missing something?

Quadrants for cable steering systems are often made of cast alloy, which may not have the strength to cope with the potential stresses inflicted by a linear drive. Raymarine recommend that anyone contemplating attaching a linear drive to a quadrant should check with the steering system manufacturer first.

 

[howard easton]

I wouldnt see the question as binary - Raymarine or Garmin. What about Simrad / B&g?

My boat has an under deck hydraulic pilot originally designed by Robertson for fishing boats. Its been 100% reliable over 20 years and a pal who is in the hydraulics business described it as a beautiful piece of engineering when he examined it. It can be powered by the Simrad /B7G computer or by the Raymarine one. http://http://www.simrad-yachting.com/en-GB/Products/Autopilots/Drive-Units/HLD350-Drive-Unit-en-gb.aspx
Not cheap but good.

I wouldnt trust Garmin as far as I can throw them. I have had Garmin kit in the past and been left out in the rain when it came to chart changes and system updates. They behave like a typical yankee multinational, which is of course what they are.

As for Raymarine - have you used their customer service recently?:disgust:

 

[pvb]

I wouldnt see the question as binary - Raymarine or Garmin. What about Simrad / B&g?

My boat has an under deck hydraulic pilot originally designed by Robertson for fishing boats. Its been 100% reliable over 20 years and a pal who is in the hydraulics business described it as a beautiful piece of engineering when he examined it. It can be powered by the Simrad /B7G computer or by the Raymarine one. http://http://www.simrad-yachting.com/en-GB/Products/Autopilots/Drive-Units/HLD350-Drive-Unit-en-gb.aspx
Not cheap but good.

I wouldnt trust Garmin as far as I can throw them. I have had Garmin kit in the past and been left out in the rain when it came to chart changes and system updates. They behave like a typical yankee multinational, which is of course what they are.

As for Raymarine - have you used their customer service recently?:disgust:

Simrad seem to have concentrated more on hydraulic drives than some other brands. They do offer mechanical drives too, but note that their DD15, described as having "Simrad Yachting Construction - Brutally strong and built to withstand the environment", is actually built by Jefa.

Garmin also chose a Jefa linear drive for their autopilot system, which in my limited experience has performed brilliantly. As for their system updates, I've been incredibly impressed by the simplicity of their update procedure. Download an update to a card, pop it in the plotter, and it automatically updates every bit of Garmin kit on the boat's system. So simple.

 

[Cantata]

Quadrants for cable steering systems are often made of cast alloy, which may not have the strength to cope with the potential stresses inflicted by a linear drive. Raymarine recommend that anyone contemplating attaching a linear drive to a quadrant should check with the steering system manufacturer first.

Oooh. Perhaps I didn't read all the small print! But the quadrant (cast alloy) does have a reinforced area provided where the drive coupling needs to be positioned. So perhaps Whitlock thought of that anyway.

 

[lpdsn]

As others have said, you must have robust physical stops to prevent the rudder turning more than 35 degrees either way. It's unclear whether you have these. If you don't, the linear drive may reach its end stop and be damaged.

Stops are very robust - I made damn sure of that. Linear drive doesn't reach the end of its travel in either direction.

 

[bobthecook]

If the stops prevent the drive extending /retracting fully.Does this cause any problems with burning out the motor?
I never fitted the rudder position sensor and noticed that if I was stopped still in the water the drive would go to its stops on either tack and I always shut it off but wondered if it would do any damage if I did not

 

[LadyInBed]

Wondered why you say that? I fitted a Type 1 to a Moody 36 last year (where there was no autopilot before) and attached it to the quadrant. Works perfectly. Am I missing something?

Another reason why I used a stub tiller was to get the correct height and length.