Lowrance Auto Pilot with twin outboards

[Ozz043]

GDay and happy new year Grady people !

I have a Marlin with a couple of OX66 engines purring like kittens still, for electronics I have Lowrance Gen 3 HDS 7’s with an old Sitex autopilot that has gone bung. I was wanting to install a Lowrance Autopilot but the Lowrance product guide says single engines and wondered if anyone has the Lowrance installed with twins

The now redundant Sitex pump is down in the bilge and was thinking I would use those connections to plumb the Lowrance unit into the hydrolics ..... if anyone has any thoughts on that too would be great.

 

[Halfhitch]

My previous boat was a World Cat. I installed a pair of HDS 7 plotters and when checking out the Lowrance autopilot to finish out the set-up, I noticed that same thing about single engine only. This led me away from that brand. I figured Lowrance must have included a pump in the kit that was inadequate for the volume of two steering cylinders and if they went cheap there then ???. In doing my homework I read several warnings that too low pump output would cause the engines to move too slowly to be able to react quickly enough in some conditions for the course computer to be able to maintain course. On the other hand if too large of a pump is used then the engines move too quickly making for a jerky response and is hard on the steering apparatus. If the pump is too small there is no fix for that. If the pump is too large, a flow restrictor can be installed to slow the steering response but since you have not purchased your equipment yet you can purchase a pump that matches your cylinder displacement. My World Cat had two Seastar HC5345 cylinders. I installed a RU80 pump and it worked like a charm.

 

[Ozz043]

Thanks Halfhitch
Yes there are a few complaints about the Lowrance units but you never do really know what to believe on the internet. One positive response I read claimed they had their motors connected in series rather than parallel and this would make sense when considering pump sizing as you have done.

When replacing the hydraulic oil recently ( trying to get the Sitex working ) the local marine steering manufacturer commented on the same “series” installation would reduce my steering lock to lock by a third ... I currently have 12 I think ...

 

[Halfhitch]

Be sure you understand what these fellows are talking about. In a two cylinder system where you use the return fluid from the cylinder being pressurized to power the second cylinder which sends its return oil back to the helm, there will be exactly one half as much thrust available compared to having helm pressure being applied to both cylinders. It will required half as much fluid from the helm to cycle lock to lock. It will cycle twice as fast given the same flow volume. The sticker is that while it travels twice as fast, it has half the thrust. It is no different than removing one cylinder from one engine and just using a tie-bar from the engine with the cylinder. Bringing a pair of 250s back from full lock with lots of throttle on can take a bit of grunt.

 

[Ozz043]

Oh well that’s no good !
Gee thanks HalfHitch

 

[ROBERTH]

I have been wondering the same for my setup if the Lowrance system would work with my twins. Twin 200 HPDI's with one cylinder on tie bar. I can turn the wheel with one finger in mostly all conditions. Very easy. Seems it would be able to do it, but don't want to throw the clams at it if it can't keep up.
A while back, I checked the cylinder capacity to the pump and as I recall, it was adequate, but not sure it was considering a tie bar scenario.

 

[Ozz043]

Ive looked at the Lowrance / Simrad pump which is 0.8L whilst the Sitex pump is 18CI which worked fine. The conversion ( litres to CI ) indicates all should be good.

 

[ROBERTH]

So it seems the navico pump is about 2.5 times larger per the conversion, which elicites it should handle the job, right?

 

[Ozz043]

Ive ordered one so will let you know

 

[ROBERTH]

Great OZZ! Eager to find out how it performs!

 

[ROBERTH]

Something I now see on lowrance site that they reworded regarding linked twins is promising:
Outboard Pilot is an MFD Autopilot add-on system designed for boats up to 30ft with a single or dual-linked outboard motor.

 

[Ozz043]

I know it’s only just been updated, a week ago it did not clarify that it works with linkage ..

 

[ROBERTH]

This is promising. Perhaps they have done some testing and can now make that statement. Gives me more confidence that it will work.

 

[Ozz043]

The kit arrived and is partly installed, temp went over 40c so I called it a day....
Major drama though, I had an existing Sitex Autpilot pump plumbed in so I swapped fittings of both pumps so I could use existing hydraulic install. Well the 1/4” NPT (tapered) fittings fitted fine but I over tightened and split the housing Just holding the pump in one hand and spammer in the other ...... mmm

Notice when you search Pump-1 there are two different pumps, one has moulded cast (the one I split) and the other has a block (the one I’ve now ordered)

A very expensive mistake Far Out !

 

[Ozz043]

Ok so the outcome ...
The housing didn’t leak, not sure why other than the thread is long enough to seal it, I have done a sea trial and it works no worries in a calm sea.
I have the new pump so I will swap it over before the next outing ...

 

[ROBERTH]

Hey Ozz, update. I have installed my Lowrance Autopilot and tested on local lake. Seem to work perfectly. I like the ability to adjust the output strength of the pump when commissioning. I think I have it set on 5 now and it is pretty quick to respond. Turns the motors with what seems no effort, so the pump is very adequate. I did crank up the strength when commissioning and it would really move the motors very quickly, actually shaking the boat while on the trailer, so it has the power for sure. The default setting was 3 which I thought might be a bit slow.
Once out on the ocean in hopefully a couple of weeks, will see how it performs.

How is yours doing so far?

By they way, I have the RC42 already, so used it instead of the Pilot 1 AP what comes with the autopilot kit.

 

[ROBERTH]

Hey Ozz, you still out there?

By they way, if anyone has this autopilot, the Default setting of 3 is the way to go. On 5, it over-reacts and is constantly trying to correct when it the seas. Overall, it has been great. Been offshore over 50-60 miles each way last two trips and it was flawless. Especially great when trolling and maintaining a heading while fighting a fish.

 

[Ozz043]

Hey Ozz, you still out there?

By they way, if anyone has this autopilot, the Default setting of 3 is the way to go. On 5, it over-reacts and is constantly trying to correct when it the seas. Overall, it has been great. Been offshore over 50-60 miles each way last two trips and it was flawless. Especially great when trolling and maintaining a heading while fighting a fish.

Yes I’ve been around i didn’t see the response for some reason, my autopilot is fantastic. I still sit at the helm and order others around but you have a lot more freedom. It’s pretty good in smaller seas and I think it gets you there quicker as there is less wandering

 

[ROBERTH]

Good to hear! We did one sea trial for about 7 miles out and then back in rough 4-5' seas on day and it did pretty good. That was the roughest trial so far.

 

[Ventura4949]

Ozzo and RobertH are you happy with your autopilots after 16 months? Do you have them interfaced with an MFD or do you have a separate control head?

I have '97 Marlin with 2 x 250 OX66. I was thinking of downsizing and upgrading but boat really runs sweet and I think I will dial it in instead of changing boats. Both the Simrad AP and Seastar power steering have gone kaput in the past year. I think rather than fix, I will update. Based on this old thread the Lowrance AP is my leading candidate. Interested in your feedback.