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Old 01-21-2013, 01:03 PM   #41
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I just got off the phone with a wonderful guy named Allen at Si-Tex (30 years with them). He gave me over :30 minutes of his time explaining the finer points of their systems and, obviously, are sold on their very simple SP-70 system. It's a very mature system that has lots of great features (but not too many) and is used by lots of commercial vessels due to it's bullet-proof reliability. He mentioned that the only repairs they are getting from these units now are just fleet captains just wearing out the motors from tens of thousands of hours of continuous commercial use.

He spoke a bit about the "arms race" that the software guys are in between companies like Garmin and Raymarine to turn out features that 99% of us will never use, but they add to an already inflated price point. That most of us are just looking to go straight ahead or follow simple courses off a chartplotter. The idea that someone would ever need to do something like a cloverleaf pattern was a comical point he made. Usually, people call the help desk screaming as their boat is stuck going in a cloverleaf and they don't know why as they flip thru menu after menu of crap looking to turn off the cloverleaf function. Hypothetical I am sure, but still quite funny.

Anyway, One other point about Si-Tex is that there is no need for a second head unit for, in my case, the lower helm. A $70 cable kit will let you just carry the one unit between stations. NIIICE

We talked a little about the "dodge" feature too, a feature the SP-70 does not have. He says the hydraulic motors don't create nearly enough pressure that you can't steer around any obstacle. They do lots of installs where they add an emergency "kill switch" on the DC power lead to the motor itself. A good idea that I will probably use.

Finally, rudder feedback is not what I thought and is only a rudder position sensor and I will still need to run a long wire to the rudder box from the flybridge *sigh* Oh well, if THAT'S the hardest thing about the install, I should be golden. He explained that "virtual feedback" is not for inboards and is mostly for outboards because of the difficulty to put feedback sensors on them. Easy enough, I suppose. Nevertheless, just thought I'd pass it along.

Ok then... off to Defender. Bess has literally TOLD me to go and buy it. It's hard to be married to a woman that wants to force me to spend money on cool toys for the boat... Very hard indeed.
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Old 01-21-2013, 07:08 PM   #42
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Ordered! Hoping the install is straight forward enough. The only thing it doesn't come with are the hydraulic lines and fittings. I hope the nearby hardware store will have them.
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Old 01-21-2013, 08:18 PM   #43
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SomeSailor said: Some older units still require rudder position in order to work. This adds another level of complexity and issues with constant calibration. Without the need for rudder position the system uses the flow rate and direction of the fluid in the system to point the boat in the right direction. Once on a course, the system simply "hunts" for a place where the boat stays pointed in the right direction and requires no flow to keep it there.

If the engines are trimmed, then that must be zero rudder angle (or a slight crab depending on the currents). The really cool thing is it doesn't lock you out of the wheel when engaged. You can still turn the wheel (which causes a temporary disengagement). Another nice thing is you can watch your rudder position, and use engine balance to trim for zero rudder. That is the most efficient of all trim setups. It's a clever way to go.



Gonz, you've got a great point about the over-accessorized, over-technical aspects of the software driving the auto pilots these days. I've got lots of tech toys that I don't care about the features of, and I'm also asking myself what I really NEED in an Auto-Pilot.

I'll have to think it through, but I'd like to hear what members think about Garmins philosophy of looking elsewhere for the control of the boat outside of rudder position feedback. Anything one can eliminate in the mechanicals that can wear out or fail would be a positive, but how would such a system behave with air or low fluid? All things equal, would it work harder or easier than a system based on rudder feedback. Since the rudders take hits from current and other things in the water, would Garmins technology allow less impulsive reactivity in the system to adjust? I find this a very interesting approach that, just like flying by wire, its time may have come,
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Old 01-21-2013, 08:55 PM   #44
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We covered that too. Yes, the SP-70 does use a rudder position sensor, but it is capable of being fully functional without it. It uses what is called a Ghost Rudder mode. Here is their description of it:

Ghost Rudder backup allows autopilot to use memory of rudder movements to calculate new movements in event of rudder feedback failure

What it does is take a heading with the compass, then it waits about two seconds and adjusts the rudder a degree or two then takes another reading. After just a couple of times doing this, the control unit has enough info to operate well enough to get you where you are going.

The rudder sensor only shortens the time it takes the control unit to understand what is going on. And by the description, it sounds like it's just there to verify it.

Rudder feedback verifies autopilot's commands

He then reiterated how robust their units are and he doesn't recall a rudder sensor failure.

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Old 01-21-2013, 09:15 PM   #45
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...I'd like to hear what members think about Garmins philosophy of looking elsewhere for the control of the boat outside of rudder position feedback. Anything one can eliminate in the mechanicals that can wear out or fail would be a positive, but how would such a system behave with air or low fluid?
I can answer that one first hand. When I first installed mine, I picked up a few bubbles. Since it's an open loop system, it simply purges through the fluid until the air clears. If you operate it with air in the lines, it just gets less accurate in it's course correction.

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All things equal, would it work harder or easier than a system based on rudder feedback. Since the rudders take hits from current and other things in the water, would Garmins technology allow less impulsive reactivity in the system to adjust? I find this a very interesting approach that, just like flying by wire, its time may have come,
You can adjust gain and counter-gain (how strong it reacts, and how far it allows the system to over-steer). You also set things like how close it holds it's course. You can set it so tight that it's constantly steering, but I let mine wander a bit more loosely and it steers only when off by a degree or so. You can look back at the wake and see a slight serpentine to it, but on AIS or the chartplotter you'd never see it.

Garmin has a very cool auto-routing feature that you simply type in a few characters of your destination, and it searches it database for matches. You select it and asks "Guide To?" you say yes and it asks "Engage Autopilot" and off you go. You can then fine tune the route on the chartplotter, or add way points wherever you want. Having them tied together natively is a big plus.
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Old 01-22-2013, 09:40 AM   #46
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When's it going to stop..?

Panbo: The Marine Electronics Hub: Garmin Quatix, best 'aquatics' watch yet?
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Old 01-22-2013, 10:57 AM   #47
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Can't wait. My wife is a triathlete and is on her third generation of Garmin GPS watches. The technology is pretty amazing.
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Old 01-22-2013, 11:16 AM   #48
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Greetings,
Aw, that ain't so impressive...

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Old 01-24-2013, 09:15 AM   #49
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YAY!!!!

Now I just have to figure out where to put it all. The fluxgate compass will be a real trick. Not sure yet where that will go. There is a compartment in the v-berth that would normally be perfect, but the soleniod for the windlass is in there and I don't know what affect it will have on it. In fact, I can't really think of a place on the boat where there isn't metal, voltage, and sometimes magnetism.

Then, there is the comment in the book saying the drive motor needs to be 4' from the ship's compass? I don't know how that is possible without it being in the bilge or the rudder box. I wanted to mount it under the flybridge helm station, but no matter where I put it up there, it will be within 4'. Still, I guess I am not REALLY navigating with a magnetic compass anymore and perhaps it won't matter.

Maybe I am over-thinking this.

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Old 01-24-2013, 07:57 PM   #50
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That looks just like my Comnav.
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Old 01-24-2013, 08:16 PM   #51
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You really wanna keep the compass away from everything magnetic. Just after I installed mine and was still working the deatils of the calibration, my wife stowed a bag of tools in our aft head. Directly across the bulkhead from my compass.

It wasn't magnetic, but just a big bag of steel. Sure screwed up every attempt at getting it to auto-cal
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Old 01-24-2013, 08:27 PM   #52
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Greetings,
I've run another boat with AP (NOT the WF) where going under a steel bridge caused a severe course deviation....Wakes you up REAL quick.
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Old 01-25-2013, 10:28 AM   #53
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That looks just like my Comnav.
It is a 1420 built by Comnav with a different control pendant, SiTex labels, and a larger price tag.
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Old 01-25-2013, 11:42 AM   #54
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It is a 1420 built by Comnav with a different control pendant, SiTex labels, and a larger price tag.
I beg to differ, Sir. ComNav didn't start making autopilots until 1982. Si-Tex has been doing it since 1975.
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Old 01-25-2013, 11:42 AM   #55
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I don't like using AP in tight quarters, that is, anything but open ocean water. Personally, I don't like setting it to the GPS either, except for very long legs,(several hours) if then. I need to stay engaged and prefer to make the little course corrections due to current, wind, whatever myself. APs have caused a lot of accidents by careless skippers, including hitting the day mark used as a way point when set to the GPS.

Remember, the plotter presents you with a somewhat accurate theory, not necessarily a reality. Buoys go off station, day marks get destroyed, boats sink, shoals develop, and so on. And where you are on the plotter is not necessarily where you are in actuality.
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Old 01-25-2013, 12:09 PM   #56
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Sure makes trawling easier though...
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Old 01-25-2013, 12:10 PM   #57
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I beg to differ, Sir. ComNav didn't start making autopilots until 1982. Si-Tex has been doing it since 1975.
But likely built by ComNav, who I believe are a bunch of ex-Robertson engineers.
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Old 01-25-2013, 07:50 PM   #58
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I beg to differ, Sir. ComNav didn't start making autopilots until 1982. Si-Tex has been doing it since 1975.
That..... autopilot was built and designed by Comnav. It is a 1420 with a different pendant. That is also an Octopus pump with a Si Tex label. It is a great autopilot.
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Old 01-25-2013, 08:07 PM   #59
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I don't like using AP in tight quarters, that is, anything but open ocean water. Personally, I don't like setting it to the GPS either, except for very long legs,(several hours) if then. I need to stay engaged and prefer to make the little course corrections due to current, wind, whatever myself. APs have caused a lot of accidents by careless skippers, including hitting the day mark used as a way point when set to the GPS.

Remember, the plotter presents you with a somewhat accurate theory, not necessarily a reality. Buoys go off station, day marks get destroyed, boats sink, shoals develop, and so on. And where you are on the plotter is not necessarily where you are in actuality.
Don't blame AP's for skipper inattention...

There are hundreds of miles of the AICW that you can use AP for stretches that last 5 minutes or so to do all kinds of things....

I can't believe how hard some people make out of the most simple of boating operations....the use of auto pilot is no different than turning the helm over to an inexperienced boater who can steer where you tell them to...just don't expect the AP or inexperienced boater to know when something out of the ordinary happens.
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Old 01-25-2013, 08:18 PM   #60
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It won't steer me to Alaska, will it? I hate the cold!

It has steered me to Alaska once. Maybe could do the same for you. Get a heater.

The model I have is the Commander P2. This was the model recommended by my local distributor. This is the web site:

ComNav

Click on the Commander P2. Can I make it any easier for you? Check out web sites selling it for prices. I bought mine about 5 years ago and have had no problems.

Ron
Looks like a great product but pricey
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