Auto pilot

T

tollycraft

New Member
Feb 24, 2008
281
Ontario,Canada
Boat Info
1988 30Ft Weekender
2004 21 1/2 Weekender
Engines
Twin 5.7s Mercruiser Inboards
5 Litre Mercruiser Alpha 1
I have twin inboard screws. I use the boat mainly to fish and therefore shut down one engine to troll. I have mechanical steering and am interested in hooking up an auto pilot. How well do you think this will work with running only one engine with rudder steering? Will it keep the boat straight in chop, not heavy seas but say 1-1/2 foot chop. Will it be too hard on batteries correcting! I have 3 on board, will it compensate fast enough to keep the realitivly straight, not dead straght, but close. What are your thoughts. And if its doable, any suggestions as to make or model.
 
I have never run my AP with only one engine in gear. On a regular basis, when exiting my development, in order to minimize my wake, I manualy navigate with one engine in neutral and one engine in gear.

There is no doubt that running with only one 'trans in' is a challenge. However, after some practice, I have been able to master the technique.

Also, when running with both 'trans' in', the AP is leaps and bounds above the average human's ability to keep a straight line track....especially when set and drift are present.

All that said, IMHO the AP would be able to keep a straight track with only one 'trans in'.....at least as good, if not better, than any human.....
 
Tollycraft, I just installed a Garmin Autopilot on my boat last month. I do know that you can hook up the unit with only one tach input so it would work with only one engine running. The only thing i am not sure of is the sterring setup. Most autopilots work with hydraulic steering. The new units work off a compass ball instead of the old rudder arm sensors. Good luck!
 
Autopilots will hold or attempt to hold whatever course or bearing to whatever way point you set. They do this by giving the rudder the input it needs to adjust to hold the desired course. This means that are not heavy power consumers and will easily run on a single engine alternator output.

The limiting factor is going to be the effectiveness of the rudder not what type pf seas you encounter. One foot or 10 ft, the autopilot doesn't care, but the rudder and the speed of water over the rudder must be enough to control the boat. If you can control the boat on one engine right now by hand, then the AP will as well, only the AP is going to do a better job of holding the set course than you are.

THe one thing an AP cannot do is anticipate seas. The AP can only correct to a desired course. That means is you are wallowing along fishing away and you steer into waves as you see them approach to keep the boat in a straight path, the AP won't do that. You can set a course correction for winds and seas, but the boat is going to move off course as waves pass, the AP will correct and hold course until anotther wave washes you off course again.

Your gotcha in adding an autopilot is that almost all use hydraulic servos which means that more than likely you are going to need to change to hydraulic steering. The few mechanical AP's I've seen use DC stepping motors for steering input and are both expensive and hard to keep working in a wet enviornment.
 
The autopilot on my boat works fine while trolling with a single engine. The problem I have is there is only one hydraulic pump on the system so you have to always troll with the starboard engine and turn off the port engine. Take that into account if you are moving to a hydraulic autopilot. A cool mod for my boat would be to add a hydraulic pump to the port transmission so I could actually lose an engine and still steer the boat.

I have a saying that I can always get home on one engine as long as the starboard engine stays running.
 
I don't understand Mick's comment about the tachometer, but maybe that is particular to Garmin. I have a Raymarine AP on my boat and there is no connection whatsoever to the tachometer or anything engine related. The AP is completely independent of the engines and will attempt to steer the boat even if both engines are shut down. The AP uses its own hydraulic system so it is not an issue whether you have mechanical or hydraulic steering - there will be a model to suit your needs.

As for controlling the boat on one engine, this should be no problem as long as the AP system is sized correctly for your boat. Because of the small rudders on this type of boat some APs have trouble keeping a good course at very low speed, especially in a beam or quartering sea. In open water, this should not be a big issue for you, but again, proper sizing is key.
 
All current AP's require hydraulic steering.
I do have a Raytheon Sportpilot + on my Chris-Craft which I'm getting ready to part-out in the next few weeks, which fits behind the wheel and is for mechanically steered boats. It's been discontinued for quite a few years, but actually works fairly well and will steer a compass heading or by NMEA input. Mine includes the rotary rudder reference transducer.

Here's the manual for it, if you're interested pm me. You can alos find them on Ebay sometimes...
http://www.raymarine.com/SubmittedFiles/Handbooks/Autopilots/SportPilot.pdf

To correct the above poster, it DOES matter whether you have hydraulic steering. The AP has it's own hydraulic pump- but you still need the hydraulic steering ram to operate the rudders.
 
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Sea Gull said:
As for controlling the boat on one engine, this should be no problem as long as the AP system is sized correctly for your boat. Because of the small rudders on this type of boat some APs have trouble keeping a good course at very low speed, especially in a beam or quartering sea. In open water, this should not be a big issue for you, but again, proper sizing is key.
Click to expand...

I'll be the first to admit I may be wrong on this as the one system I've never taken apart on my 480 is the Autopilot... other than hearing the thing work under the helm. I thought the hydraulics on the autopilot essentially took the place of the hydraulics on the steering wheel and, as such, controlled the master hydraulics on the rudders. Am I wrong on that? The hydraulic steering on the boat is essentially a two stage system with a small pump telling the valves what to do tied to the big pump on the transmission. The small pump being on the backside of the steering wheel in manual mode and a small electric motor for the autopilot... I could be wrong... I thought that is how it worked but I haven't dug into it.

For the manual steering aspect, the system is plumbed so that technically the small pump can apply pressure to the rudders if the big transmission pump fails... but in the real world, the small pump behind my steering wheel requires a breaker bar to turn if there is ANY force on the rudders so it's pointless. I would be surprised if the AP pump could control my rudders if the big primary transmission pump failed (or if the starboard engine was turned off)... but I don't know... never tried it.
 
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I'm sure there are different systems w/ different components. My helm is Sea Star (Teleflex). As you said, it's the manual wheel pump (valves operated by turning the wheel) that controls the flow of hydrualic fluid to the steering ram at the rudders. The AP has an electric pump which takes the place of the manual "wheel pump" when the AP is activated. This disables the helm pump, and allows the AP computer to control the flow of the hydraulic fluid to the steering ram. So, on the Teleflex system, there is no electrical hydraulic pump as part of the "steering system"- it's actually a part of the AP.

The one thing I really liked about the mechanical AP was the ability to just grab the wheel when I needed to dodge a trap float, and the AP would just resume course when I let go of the wheel. With the hydraulic system I'm constantly turning the AP off and on as I dodge the thousands of stone crab traps heading offshore...
 
tobnpr said:
I'm sure there are different systems w/ different components. My helm is Sea Star (Teleflex). As you said, it's the manual wheel pump (valves operated by turning the wheel) that controls the flow of hydrualic fluid to the steering ram at the rudders. The AP has an electric pump which takes the place of the manual "wheel pump" when the AP is activated. This disables the helm pump, and allows the AP computer to control the flow of the hydraulic fluid to the steering ram. So, on the Teleflex system, there is no electrical hydraulic pump as part of the "steering system"- it's actually a part of the AP.
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Click to expand...

OK... so on the bigger boats, which may not be applicable to the original poster, is the steering wheel's hydraulic system is not hooked directly to the rudders but instead controls the main hydraulics (much bigger) powered by the engine so it's essentially a two-staged system.
 
Does your AP not have a dodge feature? I have a B&G on the 450 and had a Robertson on the 390EC and both have the ability to dodge either by pressing buttons on the AP or by turning the wheel. You can/could effctively dodge a log or crab trap by turning the wheel, but the AP will try to correct the course, so manual dodging only lets you dodge something in your immediate path.
 
The Raymarine has a plus or minus 1 or 10 degree button... but it doesn't work for crab pot dodging here. The crab pots are so thick in some areas it looks like a Chinese checker board. Grabbing the wheel doesn't do much either.... The newer Raymarine systems have a dial so that may work better to dodge things.
 
fwebster said:
Does your AP not have a dodge feature? I have a B&G on the 450 and had a Robertson on the 390EC and both have the ability to dodge either by pressing buttons on the AP or by turning the wheel. You can/could effctively dodge a log or crab trap by turning the wheel, but the AP will try to correct the course, so manual dodging only lets you dodge something in your immediate path.
Click to expand...

I have the Network Pilot, it does have +/- one degree and ten degrees buttons; maybe that's what you're referring to as dodge feature? I always thought that was for permanent (rather than a quick) course correction; I should read the manual...

My wheel becomes absolutely useless when the AP is engaged. I can spin it like a top in either direction and it has no effect, it's totally disengaged. I guess others may be different.
 
Four Suns said:
The autopilot on my boat works fine while trolling with a single engine. The problem I have is there is only one hydraulic pump on the system so you have to always troll with the starboard engine and turn off the port engine. Take that into account if you are moving to a hydraulic autopilot. A cool mod for my boat would be to add a hydraulic pump to the port transmission so I could actually lose an engine and still steer the boat.

I have a saying that I can always get home on one engine as long as the starboard engine stays running.
Click to expand...
One would think they would have thought of that at the design stage?
 
tobnpr said:
I'm sure there are different systems w/ different components. My helm is Sea Star (Teleflex). As you said, it's the manual wheel pump (valves operated by turning the wheel) that controls the flow of hydrualic fluid to the steering ram at the rudders. The AP has an electric pump which takes the place of the manual "wheel pump" when the AP is activated. This disables the helm pump, and allows the AP computer to control the flow of the hydraulic fluid to the steering ram. So, on the Teleflex system, there is no electrical hydraulic pump as part of the "steering system"- it's actually a part of the AP.

The one thing I really liked about the mechanical AP was the ability to just grab the wheel when I needed to dodge a trap float, and the AP would just resume course when I let go of the wheel. With the hydraulic system I'm constantly turning the AP off and on as I dodge the thousands of stone crab traps heading offshore...
Click to expand...
Stone crab traps in new port ritchie area your kidding.
There ought to be a bounty on those guys. All I do whenever I go out is dodge crab traps.
Didn't mean to pirate the thread just had to complain.
Jack
 
Thanks all for your imput. I really like the mechanical steering as it allows me to run on either engine I chose when I troll. I'm not sure about all Weekenders or Express Criuisers, but the Sundancers of this vintage seem to all have one power steering pump and therefore running on the engine that does'nt have the power steering pump can get tiring. Four Sons, I agree re the Starboard engine, came home on the port once and it was a chore, not just docking (had lots of dock neighbours waiting for me when I returned due to a radio call ahead) but just trying to run a straight line for a while. I guess the advantage here really goes to the IO guys.
 
im trying to locate the Circuit breaker for my B&g autopilot on my Sea Ray 310 sundancer 310 (1998)
Maybe a silly question but cant seem to find it???
 
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