The Right System, Correctly Installed
A marine AC system that performs well for ten years and one that fails in its second season usually started out the same way — with a sizing decision and a raw-water plumbing decision made before any equipment arrived. Get those two right, and the rest of the installation goes smoothly.
Fixar Inc. is a licensed NYC HVAC contractor with EPA Section 608–certified technicians. We bring the same refrigerant discipline we use on land to marine installations, combined with the marine-specific work that home HVAC never sees: bonding against galvanic corrosion, vibration-isolated mounting, raw-water plumbing with a proper seacock-strainer-pump-condenser-discharge path, and condensate handling that will not back up in a seaway.
Pick the Right System for the Vessel
Marine AC falls into three categories, and the right choice is almost always determined by the size of the boat and how the cabin space is laid out:
Self-Contained — Boats ≤ 45′
Compressor, evaporator, condenser, and blower in a single chassis tucked under a bunk, in a locker, or beneath a settee. Simple plumbing, fewer failure points, and the most common system on cruisers and sportfish under about 45 feet.
Split Systems — Boats up to ~80′
Condensing unit in one location, evaporator/air handler in another, joined by insulated copper refrigerant lines. Better placement flexibility and quieter cabins, common on vessels up to roughly 80 feet.
Chilled-Water — Yachts 80′+
One or more chillers feed a closed water loop to multiple air handlers across the vessel, each independently controlled. Standard on yachts roughly 80 feet and up.
Yacht Chilled-Water Details →Sizing — The Step Most Installs Get Wrong
The single biggest predictor of marine AC satisfaction is whether the unit was sized correctly for the cabin. Undersize it and the system runs constantly and never gets the boat cool. Oversize it and the unit short-cycles, leaves the cabin clammy, and wears itself out fast.
For a marine cabin we factor in:
- Cubic volume of the cabin — not just floor square footage. Cabin height and shape matter.
- Insulation — a well-insulated trawler is a different load from a thinly-cored sportfish.
- Hatches, ports, and glass area — especially south- and west-facing glass on a hot summer afternoon.
- Number of people and cooking load — significant on liveaboards and overnighters.
- Vessel use pattern — a slip-bound liveaboard has a different profile from a weekend cruiser running offshore.
Our BTU Calculator is a good starting point for ballpark numbers, but a marine cabin is not a room in a house — final sizing is done on the boat.
The Raw-Water Plumbing Has to Be Right
On a marine AC install, the refrigerant work is the easy part — it is sealed and tested at the factory. The plumbing that runs from the sea to the condenser and back out the hull is where most long-term problems begin. We install (or upgrade, on a retrofit):
Seacock & Thru-Hull
Properly sized, properly bonded, accessible for operation and inspection. A small seacock starves a large unit; a buried seacock is a maintenance nightmare.
Raw-Water Strainer
Mounted in an accessible location so it actually gets checked. Strainer fouling is the most common cause of "AC not cooling" calls — and the easiest one to design out of a job.
Raw-Water Pump
Centrifugal pump mounted below the waterline so it stays primed. Vibration-isolated, with corrosion-resistant electrical connections.
Discharge & Vented Loop
Overboard discharge above the waterline with a vented loop where required to prevent siphoning. The visible stream is your one-second diagnostic for years to come.
Retrofits & Repowers
A lot of older boats came from the factory with marine AC that was undersized, badly placed, or simply worn out. We retrofit and repower these systems with modern equipment that fits the existing footprint where possible — or with a redesigned layout where the original installation is the problem.
Typical retrofit work:
- Replacing a tired self-contained unit with a new, more efficient one of the same or different capacity.
- Stepping up from a single unit to a split system to free up cabin storage space.
- Adding a second zone or unit to a vessel whose owners spend more time aboard than the original spec assumed.
- Replacing corroded copper raw-water plumbing and an aged pump while the system is open.
Our Marine AC Installation Process
On-Boat Survey
We come to your slip, measure the cabin, look at access for the unit and plumbing, check the electrical service, and discuss how you use the boat.
System Design & Quote
You get a written proposal with the recommended system, sizing rationale, raw-water plumbing layout, and a clear price.
Parts & Scheduling
We order equipment and parts and schedule a haul-out or in-water install window that works for your marina and your calendar.
Install & Plumbing
Unit mounting with vibration isolation, raw-water plumbing, refrigerant lines on splits, electrical, controls, and condensate.
Commission & Test
Pressure-test the raw-water side, verify refrigerant charge, measure supply/return temperatures, and confirm a strong overboard discharge.
Walkthrough
We show you the seacock, strainer, breakers, and discharge so you can do basic checks yourself — and we leave documentation behind.
Frequently Asked Questions
What size marine AC do I need?
Marine AC sizing depends on cabin volume, insulation, hatches and glass, occupancy, and how the boat is used. Our BTU Calculator gives a ballpark, but final sizing is done on the boat — cabin shape and access details that matter for marine installs do not show up in a generic room calculator.
Self-contained vs split marine AC — which is better?
On a boat roughly 45 feet and under, a self-contained unit is usually the right call: simpler, fewer failure points, and easier service. Above that, split systems give you better placement flexibility and quieter cabins because the compressor lives away from the sleeping area. The vessel layout often makes the choice for you.
Can you retrofit AC into an older boat?
Yes — this is a big part of what we do. We assess the existing layout, electrical capacity, and access, then propose a system that fits the boat. Sometimes the right answer is replacing in the original footprint; sometimes it is rerouting plumbing or moving to a split-system layout.
How long does a marine AC install take?
It depends on the system and the boat. A straight self-contained replacement in the existing footprint can be a one- to two-day job. A new install on a vessel that has never had AC, or a multi-zone split-system project, runs longer. We give a realistic timeline as part of the written quote.
Which marine AC brands do you install?
We install and service systems from manufacturers including Dometic, Cruisair, Marine Air Systems, Mermaid, and Webasto. We are an independent service contractor and recommend based on the boat, the budget, and parts availability — not a dealer relationship.
Ready to Install Marine AC?
On-boat survey, written quote, and a system sized for how you actually use the vessel.
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