Innovations in air conditioning for smaller boats, plus the latest gear
We look at advances in low-power aircon for smaller yachts before exploring some more conventional means to keep your cabins cool
A practical, air-conditioned cabin is no longer exclusive to large yachts.
Until now, self-contained air-conditioning units of a size that can be installed in cabins of smaller yachts have been left behind by advances such as inverter drives and variable speed compressors that have become available for centralised chilled water systems on larger yachts.
That has changed with the launch of Frigomar’s BLDC VFD self-contained chilled water marine aircon systems that have both these systems. The inverter drive ramps up power to the compressor slowly, which avoids the high peak start-up loads when the compressor of a conventional system kicks in. This invariably required generators to be sized to handle the peak compressor start-up loads, even though this means they run well below capacity for most of the time.
Traditional systems that cycle on and off also produce temperature fluctuations, whereas the variable speed compressor can produce exactly the right amount of cooling to maintain a constant temperature. The result is quiet running, a longer compressor lifespan and impressively low power consumption, especially overnight when the load on aircon units is reduced.
The overall power consumption, compared to previous stand-alone models is reduced by around half, with Frigomar’s smallest selfcontained unit, suitable for cooling a smallish double cabin, drawing only 150W of power in eco-mode. As a result on a boat with large battery banks it’s possible to run a couple of units from an inverter overnight, without resorting to a genset. Alternatively a small 2.0kw generator will supply more than enough power to run three units.
Rod Boreham of UK distributor Advance Yacht Systems says he has been able to offer a client with a yacht in the Mediterranean a three-cabin aircon system run from a compact and quiet 2.0kw genset. He has also quoted a catamaran builder for a system running from a big battery bank charged by solar panels. This would be able to run at high power all day in the sun, then continue to cool the boat in ECO mode at night without recourse to a generator.
The BLDC VFD system won the 2019 Product of the Year award at the British Marine Electrical and Electronics Association Conference.
Price: £2,794 (7,000 BTH/H) to £4,320 (27,000 BTU/H). www.advanceyacht.co.uk
Even the latest and most efficient air-conditioning systems are not practical for most of us to run 24/7 when not connected to shore power. Fortunately, there are well-established alternative methods of cooling a boat’s interior.
The classic solution is a wind scoop, ideally rigged over a hatch at the forward end of the saloon. This can be extremely effective, especially at anchor or on a swinging mooring and in areas that tend to have stronger winds, such as the Aegean or Caribbean.
Oysters have a neat feature based on this principle – the forward deck saloon windows open to funnel air into the interior.
The drawback of wind scoops is when there’s no wind, or when moored in sheltered marinas and Mediterranean-style quays. Also air temperatures also tend to be higher next to land, rather than anchored further offshore where the water temperature has a cooling effect.
Aft cabins, whether a traditional double in a centre cockpit boat, or quarter cabins in aft cockpit yachts, are much more difficult to cool with natural ventilation. Therefore they often need fans, even if the boat’s at anchor overnight and therefore lying head to wind.
Many people champion different fans – I’m particularly keen on Caframo’s Ultimate range. These have blades made of a soft material, so a safety cage is not needed, giving impressive airflow, with low noise and vibration levels. I tend to use mine with the suction cup provided (rather than the solid bulkhead mount) which seems to dampen vibration. Power consumption at full speed is only 5W. The biggest downside is the price – expect to pay around £60 in the UK.
Other highly rated fans include the Meacofan 360. It’s a mains powered unit, so would need to be run through an inverter when at anchor, but the noise level is only 15db on low power, when it draws 25W.
All fans tend to get noisier as they age, so there is an argument for putting new units in sleeping cabins and then moving them to the saloon/ galley/chart table areas when they start to wear.
The choice of boat can also make a big difference to the ease of cooling the interior. Big deck saloon windows can be a real boon when cruising in high latitudes, wet and windy British summers and even the very ends of the season in the Mediterranean. However, despite advances in glazing, large dark windows significantly heat a boat’s interior, which is far from helpful on a sweltering tropical afternoon. This is a key reason why Michael Schimdt’s Y-yachts range of large performance cruisers have conventional coachroofs. In any case in hot climates we’re most likely to spend as much time as possible living on deck.