Complete Electronic shutdown

Did the engines shut down while using the thrusters? If so that would indicate a voltage issue.

do you have separate battery banks for both the bow and stern thruster or are they powered by the engine batteries ?

are you running with parallel switch left on? Some people do but it is a lousy habit as it will hide a dialog and until the other one fails

definitely a voltage issue. How old are the batteries? If voltage drops below a certain level, the engine will shut down.

check the voltage on the engine displays as well as the house voltage on the main panel.

Are you sure the stern thruster is on a separate bank? Usually the bow thruster is because of the length of the cables that would be needed but typically builders connect the stern thruster to an existing engine bank. Lousy set up.

So if your engine banks are paralleled and you use the stern thruster on tired batteries, voltage could drop to the point of shutting down the engines.

I have been involved with similar issues on DDEC boats lately (so much for retirement)...
All the equipment comes down to a common (or two) negative buss bars.
You may find these common bars loose, pitted from over amping or green enough to start another life form.
If you truly have, or think you have, separate banks for everything, this may be a great suspect area to look at soon.

Once had several things stop working on previous boat. Turned out a main negative buss bar had its main wire, that was connected on the back of the bar out of sight, loose & corroded.

It has been a season of ugly connections.
Here is a better picture from last December from my new best friends boat.
Just a lil patinia. That 3rd stud was loose.

Since then, I have witnessed buss bars with green shrubbery growing from them.
Sorry I have no pictures of them.
.




From a bar like this, controls from the helm, options from all over the boat, battery charger with one common negative lead, ECUs and heavy loads (engine starters & thrusters) may not have a chance.

Looking forward to an update.

Sort of rings that there is a dedicated bank here that is weak and perhaps has its own main breaker that has tripped. I know I have a primary breaker on each of my battery banks in the vicinity of the batteries as well as on the DC panel...

Depending on how it was wired, your helm control may tap on a common negative buss.

Could you have an electrical schematic of your ship?
Without a print-set, I am still guessing at all of this but it is very familiar failure that I have dealt with.

Where in FL are you?
Your the Owner, Captain, Manager or Ships Tech?

Well Mr Owner, Where are your schematics?

All Batteries?? Enough to start the mains yet shut down everything for a thruster??
Uhheerr, Maybe..

Not really. The battery charger isn’t going to put enough power to help crank.

But 15 minutes at idle means the alternators may not have outputted full power so if the battery are tired the thruster could have caused water to drop. Was the gen running?

Joel,
I too own a 2007 65 Marquis. Unless you or someone else changed the source(s), the bow and stern thrusters are powered by the port and starboard engine batteries. If the batteries and/or connections are of issue, voltage could have dropped enough to the engine brains (ECMs/SAMS, etc.) to shut down the engines. You mention you were using thrusters at the time. The amp draw is large. More amps lowers voltage. As others mentioned, not a good idea to run all the time in parallel. I'd check the power source and IF wired as from factory, load test both sets of starting batteries and all connections. Just one man's opinion.
Scott

It definitely points to a bad electrical design that you may want to revisit. Here are some guidelines:

1) Bow thrusters always on separate isolated batteries. There is no way around this. If you put them on the starter batteries, you will kill the starter batteries. If on the house, do not even think about it. Just think about the current draw. A 10 kW bow thruster running at 10.5V is drawing 1000A. This is way above the starter or the windlass.

2) The starting battery should only be connected to the starter. The engine controls should be connected to the house. If you really want to be independent of house, then a best practice design is to have a tiny 24V battery provide power to the engine electronics via diodes that can isolate the engine electronics from the starter voltage drop. But then, make sure you charge that tiny battery.

3) Ideally, you want completely independent starting battery banks for port and starboard including the engine controls, the throttles, the dash gauges, etc. but that standard is hard to maintain (i.e. in this case you would need 5-6 battery banks at 24V, which is not the most efficient). Still, totally separating port and starboard is a requirement for >200 miles offshore I believe.

4) Since most people will not be replacing that many batteries at the same time, put the freshest on the starter, the next on the house, the next on the bow thruster and the last pair on the stern thruster. Then rotate.

If it helps, I had two similar failures. In one case, one of the starter wet battery cells exploded - it had not been monitored for a long time. Lost all power on starboard. In the second case, the positive lug had corroded and while indicating voltage at low current, it could not provide high current. So, check all you batteries, that they are watered well, check the voltages to identify a potential bad cell and check connections.

I agree that thrusters should have their own battery source. However, the 2007 Marquis 65 has them powered by the port and starboard engine banks. Two 8D batteries for each engine/thruster. I think port engine bank powers bow and starboard powers stern. In my former Hatteras 58, we had a separate sole bank of power for each thruster. No so on the Marquis 65. Prolonged thruster use especially on weak starting batteries could cause a voltage drop enough to affect engine ECU.

That’s what happen when builders of small cheap boats start building “yachts” and slap a “premium” badge on them… they do things on a 60+ footer which maybe acceptable on a 35 footer. No excuse for this. No wonder Marquis is out of business.

Even the builders of "Premium" badged yachts have their share of odd arrangements that gets one wondering how they manage to get it through the scrutiny of various regulatory authorities.