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Explorer Yacht Electrical System Design

Updated: Mar 16, 2023

We had to specify our explorer yacht electrical system. Oh dear, I was quite stumped. But I did know a man who could help, enter Rob Westermann, CEO of Artnautica Europe, and, over the months that followed, a friend of mine.

Vessel Electrical System Design: Abstract

How to design a hotel or residential electrical system for an ocean-going LRC/XPM

vessel? This document covers the steps a qualified Electric Schematic marine electrician (from now on, “ES designer”) takes for an ocean-going LRC/XPM vessel that can be used to implement an electric system. We assumed Chris had no prior knowledge when designing an ES for such a vessel. He is probably in good company!

Solar MPPT controllers, 24VDC bus bar, and

distribution rail for Vanguard 24VDC system.

CE / Code of Practice - the Boundaries to Work Within

Firstly determine the applicable Code of Practice. This will form the baseline for the ES designer. For instance, in Europe, leisure vessels must adhere to the CE standard/certification, or the owner may opt to comply with the Netherlands' Human Environment and Transport Inspectorate (ILT) Code of Practice. The Maritime & Coastguard Agency (MCA) Code is often chosen in the UK and in the US, the American Boat & Yacht Council (ABYC) Code. A European owner may opt to have the vessel comply with the MCA or ABYC Code besides the CE certification.

The chosen Code of Practice will ensure that the resulting ES drawings meet the chosen Code of Practice requirements. The Certifying Authority will test the resulting ES as one of the steps required to grant the vessel a CE/MCA/ABYC certificate.

List all Consumers and Add Power Requirements for the yacht electrical system

Begin by listing the consumers (12/24/48VDC and 120/220/400VAC), preferably with their position in the vessel. There are several ways to perform this task. One is to put together a list for each DC and AC consumer and add their power requirements and the amount of time they will be on every 24 hours. Three versions are needed when sailing, at anchor, oh, and using shore power.

Example energy balance for an LRC58 considering "at sea" and "at anchor" conditions. Note the positive contribution of Solar when in full sunlight.

Another way is to list all vessel compartments, plan each compartment's planned consumers, and determine what voltage they need. The latter is the preferred approach because it enables the ES designer to lay out and determine the length and, by definition, the size of the DC/AC cabling in the vessel.

Note that if the vessel is equipped with diesel-electric (hybrid) or electric propulsion, the ES will require an additional format to cater to this setup. It will also provide the opportunity to arrange the system around a much larger battery bank. This raises the possibility of considerable time at anchor with no generator running and near total silence. However, charging such a high storage capacity by generator or shore power becomes a more intractable issue.

Shore Power and Solar / Generator Power

Shore power requirements will depend upon the cruising grounds, this can be quite a workup, but for this article, we will look at 120 and 240VAC requirements. We will need both an isolation transformer (mandatory for aluminum vessels) and to allow for 50/60Hz input. It is often a simple solution to convert everything to DC and accept some transmission losses to remain independent of frequency and independent of potentially serious electrical accidents when connecting.

For worldwide ocean-going vessels, ideally, the system must cater for 120/240VAC, 50/60Hz single phase, and depending on the vessel's power requirements, 400VAC 50/60Hz 3 phase must be added. Look at this Blog for further reading, including 3 phase power considerations.

Next, decide how much solar power the vessel can accommodate. And decide whether a generator (or two) is needed (hybrid yachts offer the prospect of removing the generator completely).

Solar power schematic for an XPM78, approximately 6 kW peak capacity providing near 24-hour energy independence.

Yacht Electrical System-Specific Data

The last step is to collect the system manuals and datasheets that outline system installation and operational specifics.

For each consumer, this will make available the voltage (12/24/48VDC, 120/240/440VAC) and the consumer's power requirements. It will also make available information about which breaker/fuse to use to protect the individual consumers/systems in case of malfunction.

Select a Qualified ES Designer

With all the information in hand, find an experienced ES marine electrician with a proven track record for similar vessels. Sometimes, the yard where the vessel will be built has a working relationship with one or more qualified ES designers.

ES Design Process (Block Diagram)

Supply the ES designer with all the information collected thus far. They will then draw up a high-level overview or Block Diagram (BD). This BD will identify all significant elements of the ES, such as shore power details, isolation transformer, and inverter(s). It will also show the various battery stacks of the vessel's power system. Moreover, it will show the number and positions of DC/AC cabinets needed to distribute and control the power.

Block diagram for Vanguard. this includes the 120/240VAC* single-phase shore power connection but not the 3-phase option. Note three "Victron Multiplus," used to convert 3-phase to DC, will also operate in reverse converting single phase or residual 24VDC power to charge the power batteries as a last resort. Also, some tiger power AC loads are retained at 3-phase (bow thruster, galley oven & cooktop) to better balance the three 240VAC phases.

Lastly, the BD highlights significant components such as engine(s), generator(s), thrusters, and winches and their global position in the vessel. Judge the first version, adapt and detail further, and keep doing this until both the owner/yard and the ES designer agree upon the BD.

Note: Total potential load is 165 amps, but not all equipment operates simultaneously. Thus the likely load is (-)20 amps. Why is it less than zero? Look at the large solar panel installation; when operating in full sun, it will power all systems and charge batteries with little remaining.

The ES will be augmented with a "load balance" (LB) sheet. This determines how the various components, such as isolation transformers, inverters, and battery stacks, must be quantified in electric power. Lastly, the BD must be presented for review by the Certifying Authority. After approval, the ES designer can move on to the next phase.

Yacht Electrical System Production

With the approved BD in hand, assign the ES designer to extend and detail the BD. This again will be a step-by-step process, and during this phase, each version will be shown to the owner/yard and can be commented on. So supply him/her with questions/suggestions/remarks found each time. Judge the version the ES designer will produce, give feedback to the ES designer, and keep doing this until all parties are content.

Yacht Electrical System End Result

The result will be a fully-fledged description of the ES that a marine installation company can use to perform the actual installation of the ES. The ES will contain all systems, cabinets, and cabling requirements governed by the length and size of the cables in the vessel, detailed lighting, and system position plans. Again, this version will also be approved by the Certifying Authority before installing the ES.

Extension of the block diagram showing shore power isolation transformers and DC chargers with a focus on cable specifications. These components will later be made controllable via a Victron Cerbo device.

* for practical purposes 110 & 120VAC are interchangeable. The same applies to 220/230/240VAC.

Final Recommendations

Update yacht ES while installing

While installing the ES, changes will be made to the schematic, such as cable routing with a possible change in cable thickness, system additions/changes, and the like. Make sure that all the changes are immediately reflected in the electrical drawings.

Keep updating vessel ES while sailing

Since things will change during the vessel's lifetime (most notably, systems will be added/cable runs will change/breaker functions will change), it is good practice to update the ES at regular intervals. When selecting the ES designer, make sure that they have the potential to do so ongoing.

Lastly, take it all one step at a time; it's not that difficult, and ... good luck!

Rob Westermann - Artnautica Europe

About MCA

"It is a legal requirement that UK vessels (up to 24 meters load line length) in commercial operation or charter use, carry no more than 12 passengers and cargo, comply with the Maritime and Coastguard Agency (MCA) Small Commercial Vessel and Pilot Boat Code of Practice and be issued with valid Certificates by a recognized Certifying Authority."

About ABYC

“The ABYC is a non-profit, member organization that develops voluntary global safety standards for the design, construction, maintenance, and repair of recreational boats.”

About CE

“All new and used boats (up to 24 meters in length) being sold in Europe must be certified as conforming to one of four CE (European Conformity) categories: A, B, C, and D. CE-A rating covers largely self-sufficient boats designed for extended voyages with winds of over Bf 8 (over 40 knots), and significant wave heights above 13 feet, but excluding abnormal conditions such as hurricanes."

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