Shorepower issues

I'm very familiar with the Neptunus' and they are a chiller boat with 2 chillers. I would start by having the chillers cleaned (acid washed). When they are dirty they tend to use a lot more AMP's to run because they're running higher pressures. This is probably a good majority of your issues. During the winter shutting off 1 chiller and only running 1 chiller is enough to keep up with the heat load, but not in the summer. The other issue is it is possible you have a bad connection on one end of your shorepower cords (either someone replaced the end and didn't get the wire connections tight tight) or I've also seen over time the boat side connection loosen up with the heating and cooling of the wires. How many amps are you drawing when you are having issues. A 50 amp cord is designed to supply 50 amps. It is easily exceeded on a 62' yacht if all a/c's are going, water heater is heating, and you're cooking. The Neptunus' I've run have had Charles transformers and they'd buffer the loads a little bit when compressors started up. Also what is your voltage? If it's closer to 250 volts you'll use less amps and most likely get away with 1 cord......if it's closer to 210 you'll use a lot more amps, especially on compressor start up and 1 cord won't be enough.

On one 55' Neptunus I managed, we had to have the terminal block changed on the main terminal strip where the shorepower came into. It was midship in the port side of the boat behind a panel in the small third stateroom, but this was on a 55' Express but the boat was only 5-6 years old at the time. At this point I would recommend getting a marine electrician out.

Thanks so much for that great advise. Do you know any marine electricians in the Sarasota area?

I just ran a new 66' with everything on, with 8 people staying on board in the exumas without tripping the breaker once on a single 50 amp. We had everything going, 7 air conditioners etc, every ice maker/refrigerator etc. But it wasn't a chiller boat and I've found they'll really tax a 50 amp with one chiller running and the other starts up.

I would speak to your dockmaster and see if they know of a good marine electrician in your area.

If the Neptunus chillers are original they usually used 2-2.5 ton Marine air chillers with no VFD's.

The boat has 3 chillers that are fairly new.
The problem is that the manual says I should be able to run some AC off the main shore power cable, but when I try to run just one chiller and one zone of AC, even with other large draws off such as hot water and stove the breaker in the engine room pops. And I am drawing very little amps when it breaks.

It could be a bad breaker or bad connection on the shorepower cord. How many amps are you drawing when it pops? If it's way under 50 amps, You should easily be able to run all zones of AC as the fan coils use very little amperage and 1 chiller on a 50 amp.

It pops at under 15 amps. works fine with genset. However I can run everything else on the line (stove, hot water, refrig, etc and get up to over 20 amps and it does not pop.
Could it be the wiring of the new chillers?

If the same breaker does not pop while on genset, then the breaker is most likely good. Again, look at your shorepower cord and it's connections. It really screams to me a bad shorepower cord end or connection at the cord end, could also be where the cord attaches inside the boat. It could be the wiring at the chillers too.

We run our 72' ph on one 50 amp cord at our dock with two 4 ton chillers, galley frig, battery charges, plus other small amp equipment. Draws about 48 amps with both chillers running, 25 amps on one chiller with all high amp equipment off. We do use both cords while staying on the boat. Also have a small panel with a transfer switch next to the ER main panel to designate one cord or two cords that must be set. Not sure about your setup, but if you have the same it has to be set to the number of cords being used. Otherwise, you need an electrician to troubleshoot as suggested.

If the chiller runs fine under genny, but breaker fails under shore power....well, you're mind has nowhere to go but to suspect low voltage resulting in larger amp draw through that breaker to get the system to run. Break out the meter and check the power both with no load and then under load. If there's a big drop-off under load, look more closely at that cord. Swap cords and check again.

Reads as it's his chiller breaker that is fine under genny but trips on shore power.

I am finally back on my boat (2008 62' Neptunus) bought in Ft Laud this summer and moved to Sarasota(with Capt Andrew). Capt J knows the boat- blue hull- Alta Vida.
I don't think it is wired as a typical 62. The 2 shore power cords are thinner than typical 50 amp cords. They are only 3 wire instead of 4. The boat has 3 chillers. On the electrical panel the 24 volt charger is under the 120v side and the 12 volt charger is on the 240v side. This seems strange to me.
The manual says I should be able to run the boat on one 50 amp cord- however I am not able to. Seems like one cord is for house and one for AC.
I am also not able to extend the length of the shore power cord with a standard 4 wire 50 amp power cord.
Can anyone explain this setup to me- can I extend the cords and can I run on one 50 amp cord
Thanks so much.