Circuit Breaker labeled APS?

'Fiuaskme, that APS thing is a solution to a problem that doesn't exist.
I mean, it's clearly meant for one very specific thing (BTW, I can't understand why the debate goes on about other funny alternatives), and nothing else:
keep the engine controls working in the event that one of the battery banks powering them (either "Power Source #1 or #2, in the diagram I previously posted) goes down for whatever reason.
Which is OK, and I guess it made sense back in the days of mechanical diesel engines, that could keep running also in the event of a total loss of DC power: it would be funny to have an engine still working just fine, and lose completely any way to control it - hence the idea behind the redundancy that the APS unit can provide, I suppose.
But fast forward to modern days, in the event of DC power loss, an electronic engine stops working there and then, becoming only an expensive ballast. So, I struggle to think of a reason for having redundancy on the levers to keep controlling an engine which, the moment its DC power is lost, becomes a sitting duck...

One more question to the OP;
Are these DDEC engines?

Well, Not our favorite product but I will still type to you.
It is still an electronic engine.
No telling what was on the mind of the tech who installed this mess.

I was thinking AmTrack. With reservations, they will stop in Palatka.
When your ready, Send me a ticket and have a real car waiting.

Just don't tell anybody I'm coming.
I'll have it figured out and back out of state in 48 hours.

Logic ??
It's a boat..
There is nothing logical about boats, boating, maintaining a boat, trouble shooting a boat, purchasing-selling a boat or paying for any of it.

Insanity would be the better descriptor.

Now imagine this, Still SWAG;
What is the most important device on a boat;;;; The auto bilge pumps with high water alarms...
What a sweet system this could be to auto select battery banks to keep the pumps and hopefully alarms going till the last volt.

Really??? The ZF actuator box and also the diagram I previously posted are referred to the MicroCommander controls, which are 100% electronic.
If you are sure that this is NOT what you've got - and mind, by describing your levers as "Palm Beach style" before, you neither implied that they are mechanical, nor electronic - then forget what I previously said, and also the diagram I posted.

There are two big BUTs, though:
First, it would make no sense whatsoever to have the APS unit of which you posted a photo, if the levers are mechanical.
Second, Cat C12 engines are controlled by electronic governor, unless I'm mistaken.
This means that at least the throttle control MUST be electronic (while the gearbox control could still be mechanical, depending on the gearbox model).
So, fitting mechanical levers with those engines means that the throttle cables must be connected to a sort of reverse actuator, that converts the cable movement into an electronic signal for driving the electronic governor.
Now, I can't rule out that such thing exists, but pretty sure I've never seen one.
And in any case, using mechanical levers to control an electronic engine sounds mental.

Two Big levers on either side of the helm pod.
My 1959 ChrisCraft had similar controls for the clutches that helped me later in getting used to these modern sport fish controls.
I luv it when their at my height, I can turn around facing the cockpit, a control lever in each hand waist high and chase fish down,, backwards.
You also look cool backing into your dock slip.

I remember pushing a Hatt GT with PB controls, They were electronic with synchronizer function.
So they are not automatically manual cable push-pull.

The original real Sport Fishing boats were designed and built around Palm Beach (lake Worth).
Towers, fighting chars and these controls were developed here.
And, it just sounds cool when you say it.

Yup, also my understanding is that "Palm Beach style" refers to that setup, with two side mounted single levers.
But I asked the OP if he's sure they are mechanical because I'm pretty sure that those levers alone don't imply mechanical cables behind them, and they can also be electronic instead.
A choice that would make much more sense when mated to C12 engines, explaining also the APS unit, that would be pointless with mechanical levers.

Yep,
I wonder if Cat has some box replacing the Mathers box and this APS services that.

Back to AmTrack. Never been in one of those sightseeing cars before. Hope the bar & grill is not to far away.

What powers those 3 pump breakers?
And pump auto functions?
Need a bigger shovel, keep digging and start thinking more out of the box.
Soon your going to find it.
AND, you will know your boat much better.