Autopilots

[Island Time 1,246]

I've just written a blog on my site http://www.neptunes-gear.com/blogs/news/14107805-autopilots-and-why-you-should-link-your-gps-plotter-laptop-to-your-autopilot about autopilots. I'm sure for many this is nothing new, but perhaps it'll be a help for some.

How many don't have their AP connected to the wind instruments and GPS? You should!. Anyway, have a look if you are interested...

Cheers

Matt

[wheels 543]

Perhaps you should write a Blog on it as well. Or is it intended for reading while on the Toilet seat

[Island Time 1,246]

Doh! Fixed!

[wheels 543]

Ha, a laugh coming from me, the King of bad writing skills

[Changed 10]

IT I was thinking of ways of using a hydraulic ram in lieu of the traditional worm drive. It would have to be on the cp floor as I cannot mount a quadrant below deck (easily). It would be a mix of components so how would I go about determining ram and pump size? And how does power usage of a pump compare with a screw drive unit?

Also currently I am using a Raymarine 2000+ TP and have Nexus wind gear. Are they able to talk to each other?Thanks for the advice.

[Island Time 1,246]

Changed, yep, you can do that. I did with my one, although its not in the cockpit, its on its own tiller, added to the top of the rudder stock. Due to the space available, I could not find a ram to fit, so I designed one and had it made. It was actually cheaper!!! Than a production version, and is still going fine 10 years later. I could see if I can find the loading specs and calcs for ram and pump sizing if you like? I'd need some data about your boat as well - give me a call sometime 0221539176 if you'd like to discuss it.

The AP computer normally only provides turn port, turn starboard, and requires rudder feedback to work. Some of the ram worm drives get the rudder feedback from the proprietary ram. If the AP computer is of the type that has, or can have, an external rudder feedback unit, then you can use whatever drive/ram type you want. There can be complications with the electrical load, but if the AP computer cannot supply the required current, then it's not hard to make a MOSFET based controller.

Cheers

Matt

[wheels 543]

Although for 99.99% of us all, any standard AP on the market should be capable of controlling any kind of drive size. It has to be a pretty big boat before you need to look at additional electronics to control drive systems.

Like all things, there are compromises, pluses and minuses. Hydraulics have many advantages, but they also take a little more effort to move the oil, so use a slight more current than would a directly coupled Electronic Actuator. But the advantages of Hydraulic are that all Electrical/Electronic equipment can be installed out of the way in a dry location. The Hydraulic Ram is a fairly robust beast and easily replaceable. An Electric Ram/Drive is expensive to replace and although mostly water tight, can also be slightly more delicate than hydraulic Rams. Also in saying that, the Hydraulic system is considered a "dumb" system, in that the AP has no idea where the Ram is positioned and so position feedback is required. That is done internally with Electric, so even with Hydraulic, there is still some form of electronics at the Ram end, prone to wear and water.

My Hydraulic system has been trouble free for over 10yrs and I love the ease and robustness of hydraulic. I used to work on the old Autohelm gear and the actuators were always playing up or failing.

[Island Time 1,246]

I don't 100% agree wheels.

 

There are several AP units with hydraulic actuators that are not well spec'd from the manufacturer. An example of that is the AP26 (now older model) from Simrad. This unit could not drive it's hydraulic motor to the stall point (or even 1/2 the motors max draw!!) - not even for 1 second. So, in heavy weather, if you surfed down a wave and loaded the helm more than a bit, the autopilot would just switch off, as the motor drew too much current. Just when you needed it! Other than that, it was a good unit.

 

The fix was easy - see http://www.robotpower.com/products/simple-h_info.html

for a FET based H bridge. This unit then took only port/starboard instructions from the AP computer, and powered the drive unit separately, so that the AP computer never got overloaded. Any of the Simrad units using a J300X or J3000x computer unit could suffer from this problem. There are also some other brand units, incl Raymarine, that suffer from the same issue - but the model numbers escape me at the moment.

 

Readers should note that pretty much all (if not all) the AP's used by the open 40's, 60's etc are hydraulic. Because of robustness and power. There may be some electric units that are OK, but I have not used them.

 

As Wheels said, they can use a bit more electricity than a purely electric unit though.... And some people don't like them on tiller steered boats because the hoses etc "look ugly".

 

Each to their own of course, I'm just relaying my own experience. I hope some find it useful!

[wheels 543]

Seems strange, especially from older Simrad, as they were more Commercial Orientated in the older days. So I wonder if that was a case of Seller not specing powerful enough product for the job?

I have the very old Horizon AP50 which is what originally sparked off Navman's design and the Horizon products other than Radio, went over to Simrad, hence the very similar designs. Horizon themselves remained in the Radio game.

My Horizon AP has been very reliable so far and has operated a Hydraulic pump much bigger than I actually need with no issues.

I just can't get the NMEA to talk to the Navman gear and so have never been able to have wind talk to the AP. I also don't have Autotack which I really really want and it seems most manufacturers, including Raymarine, are moving away from. Why I don't know. But it seems to leave only Garman from what I have been told, unless someone can update me on that.

[John B 106]

My boat had the wheel removed and original tiller reinstated because it was hydraulic and had no feel. Previous owner did that.

One side effect of that was the loss of the hydraulic rams and therefore the autopilot.

Ryan at Pine Harbour Electrical came up with a great solution and shows what you can do.

He mated the existing st6000 autopilot computer /head/ compass to a new lecomble and schmidt electric/ hydraulic drive. That unit is a pre bled, free standing assembly and was easy to fit. We had to keep the rudder reference because of the old system , but its grunty and reliable.

[Island Time 1,246]

Not sure where you got that idea Wheels, the Simrad AP24 and 28 both have Auto tack feature, and so does the ST6002 Raymarine ??? And the B&G H5000 series (only pretty sure on that, not certain)

 

Is your boat still up here? Perhaps I could help with the NMEA in/out of the Navman gear??

 

Matt

[Absolution 7]

I've been thinking about a below deck AP for Fineline which is also tiller steered i.e no quadrant. I'm looking at engineering a "fake" rudder stock next to the "real" rudder stock with a steering arm and a connecting rod to the tiller above deck and then the autopilot attached to the fake stock via another steering arm below deck. With the power of a below deck unit the steering arms don't need to be that long.

 

I'm considering using a Jefa electric drive but may still end up with a hydraulic unit. Simrad, Garmin and a few others sell re-badged Jefa drives BTW:

 

http://www.jefa.com/steering/products/d ... ct-dd1.htm

http://www.jefa.com/steering/products/drives/linear.htm

[Island Time 1,246]

Fineline, they both look interesting! I've no experience in them though. One point is that, if they failed in a remote location, you are stuffed. Most countries you can find hydraulic parts....

 

Also, re the earlier comment about steering feel. Yes, hydraulic steering is known not to provide much feedback. Feedback is good! On Island Time, removing one pin removes the hydraulic connection and we are back to mechanical steering only if we want. I've also seen a ram disconnect system with the use of the solenoid and connection hook system taken from a Nissan Patrol sway-bar disconnect system. That was - turn the AP off, hydraulic ram is completely disconnected. Turn it on, reconnected. Pretty cool. The only thing was you had to connect and disconnect with the helm amidships. Still, give him the best of both worlds!!

[Guest]

I've been thinking about a below deck AP for Fineline

May I ask why? Just to get something below deck?

 

I have to make a AP call, which will dictate instruments to a fair degree, any day now so your comment intrigues me.

[Island Time 1,246]

Why will it dictate instruments KM? All new instruments should speak NMEA 2000, or at least NMEA 0183, and any new AP will as well. You should have complete interoperability between them, even if different brands...

I would have thought that a plotter and AP are more closely tied, if you want to be able to control your AP from the plotter...

[Changed 10]

The Jeffa drives look neat but they're pretty expensive (I thought). I'd have to know that it was going to be a performer.

[tuffyluffy 76]

Why will it dictate instruments KM? All new instruments should speak NMEA 2000, or at least NMEA 0183, and any new AP will as well. You should have complete interoperability between them, even if different brands...

I would have thought that a plotter and AP are more closely tied, if you want to be able to control your AP from the plotter...

 

Seatalk? I've got a full Raymarine setup on my boat including an electric ram below deck AP (6002 and S3G course computer). The ease of the Seatalk network is great, its pretty much plug and play. I have spent zero time setting the system up and the AP happily sails to wind angle, autotacks etc etc. Theres an NMEA input/output on the course computer but I've never bothered with it as its just another distraction. I've never had a problem with any of my Raymarine gear and the electric drive AP has been bloody great.

[Island Time 1,246]

Actually Tuffy, as I understand it, the Seatalk you are using IS NMEA 2000. Same as Simnet, which is Simrad's version. Both provide some extra stuff outside the NMEA 2000 specs, and both use different connectors, but it is basically the same thing. Both systems are NMEA 2000 compliant and will read and write NMEA 2000 PGNs (the equivalent of NMEA 0183 sentences), so you should have no issues connecting NMEA 2000 products to either system, or with them understanding each others data if you do so.

If you run a true NMEA 2000 system, you will need adapter cables to connect either system to it, or vice versa.

The advantage in using NMEA 2000 as your bus instead of the two proprietary ones above, is that you can mix and match products from different manufacturers as you please... and plug in anything that is NMEA 2000 compliant.

[Absolution 7]

I've been thinking about a below deck AP for Fineline

May I ask why? Just to get something below deck?

 

I have to make a AP call, which will dictate instruments to a fair degree, any day now so your comment intrigues me.

 

Performance and reliability mainly. I have a Simrad TP22 at the moment which replaced a TP30 that broke just before the SSANZ. There were no TP32s in stock at the time unfortunately. The TP30 was a whole lot faster that the TP22 but still fairly crap in terms of course holding and sailing performance.

 

Below deck APs (generally) have WAY more grunt then a tiller pilot is ever going to. I've also found that most tiller pilots seem to be absolute rubbish at holding a course in the light too because they don't have proper rudder feedback so the just end up over correcting all the time and you keep doing bigger and bigger S curves over the ocean. Yes some of them have adjustment for damping etc but generally these just make them slightly less sh*t.

 

The other issue with all of the "all-in-one" units is that they tend to have a fairly basic course computer and compass inside the unit and if you want to run an AP head unit with any more smarts (i.e corrects for heel or wave action etc) and a good flux gate compass then you are already buying 2/3 of a proper AP setup so you might as well get a proper drive too. The Raymarine SPX stuff seems to be the only real entry level option for a system with separate electronics and an above deck drive unit... but look how well Cory's unit has gone for him

 

IT... if my below deck unit fails then I just have to pull the pin out of the steering arm and I can go back to using the above deck tiller pilot... and swearing at it repeatedly.

 

Changed... yes they are expensive (hence while I'm still at the considering stage) but they have some pretty good data available in terms of performance and they appear to need a lot less electricity to run when compared to a hydraulic unit.

[Absolution 7]

Have a look at this as an example: