What is “marine aircondition system”?

You want to install an air conditioning system on your boat or improve the existing system. Those who come to your boat who say they are air conditioner technicians or specialists do not give you satisfactory answers and offer exaggerated prices. As a boat owner, it is impossible not to be nervous about any work to be done for your boat; Is it a correct solution? is it enough? Or is it too much? Having a marine air conditioner installed is one of them…

As the Oggymarin team, we have done detailed research on marine air conditioning systems and we would like to share this information with you. Because we know that a knowledgeable boat owner will more easily understand which offer/suggestion will be useful and affordable for his boat. Oggymarin is an engineering organization that has gained detailed experience by researching marine air conditioners and then having them installed on our boats. Oggymarin can guide you in this regard as well. An “aircon engineer” or an “aircon technician” we are working with will evaluate your boat’s needs in detail with Oggymarin. Together, we can ensure that the most convenient and cost-effective solution is offered to your boat. Get your system without any hesitation.

The basic principle in the operation of an air conditioning system is the transfer of heat, that is, the transfer of energy. An air conditioner extracts heat from the air by transferring heat from the cabin to the refrigerant gas inside the air conditioner. A marine air conditioner is a system that transfers the heat from the refrigerant gas to seawater, unlike domestic systems. The process is reversible, the marine air conditioner can extract heat from seawater and transfer that heat to the cabin. This is called a reverse cycle air conditioner. If you want more details, as a physics engineer, we can explain the details of the laws of thermodynamics :).

There are three basic types of marine air conditioners, they are; 1- Also called package air conditioners (Self Contained Direct Expansion_ DX), 2- Remote System_ Split Gas, and 3- Tempered Water Systems (Chilled Water) are air conditioning systems. It is necessary to evaluate the size and layout of the boat to determine which system is right for you. A/C dealers will likely recommend a system available in their portfolio, no matter what your boat’s actual needs are!

1-     Standalone DX systems are typically the best choice for boats around 50 ft, due to their low cost and ease of installation. With a single unit, you can cool one or more areas by using ducts and connections, saving space and cost. Since they are small in size, places that are idle and unused; can be mounted under the bed, inside the cabinet, bilge, starboard port cabins, and suitable parts of the engine rooms by applying different mounting systems. However, because the air handling unit and the cooling unit are on a single “skid”, that is, in a package, not every packaged air conditioner may be of small volume. Since the compressor is mounted on the same unit, the packaged air conditioner can be noisy if a good compressor is not selected by the manufacturer. As a boat owner, make sure that quiet and space-saving solutions are offered to you. Engines operating with hum, noise, and vibration may cool you down, but they will not be able to offer you a comfortable rest and sleep.

2-     Distance, Remote Systems, (split gas) are generally used on boats around 80 ft. The condensing unit of a long distance system is usually installed in the engine room, while air handling units are installed in areas where cooling is needed. Air handling units are connected to the condensing unit with copper lines. The maximum distance of the line is 50 ft. Long Distance Systems are generally more costly to install. The advantage of this system is that the units take up less space in living spaces and are quieter because they are installed further away, where compressor noise is less likely to be heard.

3-     For larger vessels, the Chiller (Tempered) Water System uses the circulation of cooling water and uses refrigerant to cool the “cooler water”. The cooling water, namely “cold water”, is pumped to the air handling units on the boat, which will distribute the cold air. There is no limitation on the size of a vessel in which this type of system is used, or the length of operation between the cooling unit and the air handling unit, but the insulation of the transmission lines is of course important, the cooling water throughout the line must not be heated. Tempered Water Systems have the advantage of not creating an electrical load and generally have a low peak electrical load.

Electrical Capacity

Many factors are involved when choosing the right air conditioner for a boat. The size of the boat, its insulation, and the available electricity supply (i.e. your generator) are considerations. There are details such as whether your generator will meet the power requirement of your air conditioning system or whether it will eliminate the high peak current values ​​that the air conditioning system will create at the first start-up. A very small air conditioner will run continuously and still not sufficiently cool the space. A very large air conditioner also draws unnecessary power and revs excessively. In short, engineering should be done to take care of all the systems, volume, and insulation that will create a load on the generator on your boat. The air conditioning system that can meet your needs and the electrical capacity of your boat should be evaluated.

Dimensions of Your Boat

Considering these issues, it is obvious that choosing the right air conditioner is very important. When deciding which air conditioner to buy, you should first measure the square footage of each area you need to cool. This measurement should then be multiplied by a load factor, taking into account how well the space is insulated and how exposed the space is (for example, the lounge area with its many windows would require a larger air conditioner than a cabin “down below” due to the amount of surface area affected by outside temperature). Another thing to consider is the climate in which the boat is used. A boat in a temperate climate will need less cooling, ie lower BTU, than a boat in a hot/tropical climate (we define temperate climate as 35C air, 30C water, moderate humidity, and tropical climate as 40C Air, 35C water, high humidity). A study of your boat will be required to determine the correct BTU air conditioner value for the area to be cooled.

A single unit can be used to air-condition multiple spaces. Note that the length of a channel is approximately 4-5 m. If there are multiple bends and restrictions in duct length, the maximum length should be reduced. Incorrect channeling can cause problems. Good airflow is essential! If you are using a single unit to cool multiple compartments, consider which area is monitored by the temperature controller and which areas will be controlled manually by turning the vents on/off. In other words, your master should observe these things. Otherwise, you can either not get efficiency or because the losses are not considered, overcapacity systems are installed, which will increase the cost and electricity load. Avoid masters who do not know basic thermodynamics, electricity, fluid dynamics and will do work by heart.


The air conditioner should be placed in an area with proper return airflow to and from the compressor. Incorrect airflow will cause problems with icing or poor air circulation. Because cold air is “heavier” than warm air, vents should be placed at a high point in the cabin. Make sure there is sufficient space around the unit to service or remove the unit if necessary.

Seawater Components

It is generally recommended that each unit use an independent circulation pump. As a general rule, for one ton of air conditioning capacity, you will need a circulation pump that moves 250 gallons (1000 liters) per hour (one ton is 12,000 BTU). You will also need a properly sized seawater strainer, stems, seacock, and supply/drain hose. If a single pump is used for multiple units, a pump relay box and manifold will need to be used.

In short, a team with a basic scientific approach such as electrical knowledge, thermodynamics, and mathematics and practical skills such as carpentry, wiring, duct laying will be required for air conditioning system installation. As Oggymarin, we can direct you to our “aircon” technician and engineer connections, who will offer the most appropriate solution about “marine air conditioning system foundations and installation”, which we have experienced in detail.