Marine Air Conditioning Duct Routing for Two Cabins
The short answer
Have the installer size the supply and return paths for both cabins using the equipment airflow requirements. Keep duct runs appropriately sized and supported, with gentle bends where possible. Check performance with doors in their normal sleeping positions; do not restrict one outlet by guesswork to force air into another.
Boat AC Duct Routing for Two Cabins — Requirements and Limitations
Air can only go into a cabin if it can get out. A cabin with the door shut, no undercut and no return grille will not cool no matter how much you send it, and this is a surprisingly common omission.
Agree in advance who fixes it if a cabin does not cool. Undersized or over-long ducting is the usual cause and the usual argument.
Steps for Boat AC Duct Routing for Two Cabins
- Measure the run to the furthest grille before agreeing the layout; if it is much more than about four metres, question the design.
- Minimise bends — each one costs airflow, and flexible duct crushed behind joinery costs more.
- Fit balancing dampers so the near cabin can be throttled in favour of the far one.
- Cut a return-air path from every cabin: an undercut door or a proper grille.
- Insulate every collar, elbow and grille boot, not just the duct itself.
- Measure the air temperature and flow at each grille on commissioning, and have any imbalance corrected then.
Related Sizing, Installation and Service Guides
Each of these answers a different part of the same problem.
- when one cabin does not coolthe diagnostic path if it happens anyway
- why ducts dripthe insulation detail, and where it stops
- one unit or twothe decision ducting is trying to rescue
- weak airflow generallyfilter, coil, ducting, fan