Mariner 38 in New Zealand with DC battery air conditioning in refit
A Blue-Airco system powered directly by the battery bank for nighttime comfort in the forward cabin
On a 1982 Mariner 38, which underwent a refit in New Zealand, a 12V DC Blue-Airco marine air conditioning unit was installed in the forward cabin. The solution allowed for the use of an unused space in the existing layout and for powering the air conditioner directly from the service battery bank, without resorting to an inverter and without using the generator as a direct power source for the unit.
The challenge
The forward cabin offered limited space and had not been designed to accommodate an air conditioner. Therefore, the intervention had to fit within the existing layout, while also ensuring proper return air and effective distribution of the airflow.
To this requirement were added the typical aspects of a refit: building the seawater circuit, bringing the power supply from the service battery bank, and containing noise, vibrations, and visible modifications to the furnishings. The solution had to be compact, technically correct, and consistent with the nighttime use of the cabin.
Project details:
Boat
Mariner 38 from 1982, a recreational boat in trawler style
Type of intervention
fore cabin refit, with internal volume of about 4.5 m³
Geographical area
New Zealand
Market
nautical refit of pleasure boats
System
self-contained Blue-Airco unit at 12V DC, powered directly from the service battery bank
Seawater circuit
dedicated intake and discharge, DC pump with filter and hydraulic path designed to promote a smooth flow
Installation
unit installed in a hidden compartment of about 300 mm at the base of a cabinet, with front intake grille and ducting of the discharge to the upper part of the cabin
Objective
Improve nighttime comfort on an existing boat by integrating air conditioning into the layout and onboard electrical system
The Blue-Airco solution
During the refit, an unused compartment of about 300 mm was identified at the base of a cabinet. The space proved sufficient to integrate the Blue-Airco 12V DC unit without substantially altering the cabin layout.
A front grille was created for return air, while the supply was channeled along the side of the cabinet up to the upper part of the room. This configuration allowed the available space to be used and the air conditioning to be distributed in the sleeping area.
The water cooling required an intake below the waterline and a discharge near the waterline. The DC pump with filter was installed taking care of the circuit layout to limit the risk of air pockets and discharge noise. The electrical connection was made with wiring of adequate cross-section from the service battery bank to the unit.
Why 12V DC makes a difference in the refit
On many existing boats, the service bus is already at 12V. Using an air conditioner at the same voltage allows the unit to be powered directly with direct current, avoiding conversion through an inverter and simplifying integration with the onboard electrical architecture.
Variable speed technology and ECO mode also allow consumption to be adjusted based on the actual demand of the cabin. In a refit project, this advantage must be accompanied by the proper sizing of the battery bank, cables, charging systems, and the seawater circuit.
Onboard results
In the first documented night test, the cabin started at 23 °C at 21:00. With a set temperature of 17 °C, the environment quickly reached a comfort condition, and the unit continued operating in ECO mode for about nine and a half hours, with an overall indicative consumption of about 80 Ah at 12V.
The checks carried out over five nights recorded an average consumption between 70 and 90 Ah per night, varying according to the initial temperature of the cabin. The data refer to this specific installation and the related conditions of use: actual autonomy and consumption depend, among other factors, on the external temperature and that of the seawater, insulation, system sizing, and the condition of the battery bank.
A solution for the refit of existing boats
This project shows how a 12V DC marine air conditioning system can also be integrated on an older boat, taking advantage of already available technical spaces and limiting modifications to the layout.
The result depends on careful design of the entire system: space for the unit, proper air circulation, seawater circuit, electrical supply, battery bank capacity, and charging systems must be evaluated together.
When these elements are properly sized, the air conditioner can significantly improve nighttime comfort, without using the generator as a direct power source for the unit and without requiring a complete interior redesign.
Do you want to integrate 12V DC air conditioning into a refit project?
Blue-Airco supports shipyards, refitters, dealers, installers, and boat owners in evaluating available space, necessary power, and onboard electrical architecture. Contact the Blue-Airco technical team to identify the configuration best suited to your vessel.