Projects: C34 Air Conditioning

Southwest Florida has wonderful cruising grounds, but it can be a little hot in the summer, especially in marinas where we can’t swing into the wind. After two summers here, we finally decided to install A/C in Yet To Be, our 1990 C34. Even though we sleep forward in the V-berth, we wanted to cool the aft cabin also for our occasional overnight guests. We also wanted to preserve as much storage space as possible since the C34 doesn’t ever seem to have enough. After looking at several installations, we decided to put the A/C unit under the V-berth and run a duct down the port side to the aft cabin.

We selected a Mermaid 16,500 BTU side discharge air conditioner because it was one of the smaller units available and Mermaid is manufactured in nearby Fort Myers. The weight of the A/C unit far up in the bow doesn’t seem to have made much difference in the sailing of the boat, but we don’t race any more either.

	I glassed in a platform as high and as far forward under the V-berth as the A/C would fit to preserve some storage in the aft end of the compartment. I replaced the drawer unit with a custom return air grill mounted on hinges to give easier access, and it's worked out great. However, you do have to be careful not to allow anything stored to stick up above the grill to block the return air.
	The A/C is a side discharge unit mounted fore/aft on the platform with the water pump right beside it on the platform. The electrical control box is mounted on the same platform opposite the water pump. The through hull is under the small floor panel just to port and forward of the mast. Water discharge is as high as possible under the V-berth on port side near A/C, about 6" above the waterline.
	For the supply air, I used a "T" splitter directly aft from the A/C with 6" to starboard and 4" to port. The 6" goes through the forward hanging locker and up to a 6" to 4x10" transition fitting from Home Depot which connects to a 4x10" hole in the counter top above the hanging locker. We can still hang clothes in front of the 6" duct. I built a teak plenum box about 5x12x12", open on the back and bottom, that fits over the hole and against the bulkhead.
	There is an 8x10" grill in the bulkhead opening into the main cabin and a 4" round vent in the plenum opening into the forward cabin. That takes care of the 6" side.
	The 4" side from the A/C runs through the lower compartment on the forward cabin port side,
	through the upper, outboard corner of the forward under settee storage compartment in the main cabin,
	along the top, outboard corner of the holding tank to the open area near the macerator pump.
	I used a length of 4" rigid aluminum duct to span the area under the chart table since it was likely to get kicked. It is wrapped in a piece of vinyl that matches the hull liner color and is not very noticeable.
	I switched back to 4" flex duct in the aft hanging locker (there were already slide out baskets in this locker - see the Shelves for nav. closet project)
	and used a "Y" to split off a 4" round vent over the chart table into the main cabin. I also mounted the thermostat over the chart table but away from the vent.
The biggest problem was cutting holes for the 4" duct down the port side. I borrowed a 90 degree 1/2" drill and hole saw and cut 4 1/4" holes in all the bulkheads down the port side before I found that 4" duct needed a 4 1/2" hole to fit. I was able to enlarge each hole, but it wasn't easy. I guess I should have tried the duct through a test hole before drilling. Surprisingly, the 6” duct fit through a 6” hole.
	The other side of the "Y" behind the chart table continues out the aft side of the hanging locker behind the hull liner in the head. If you remove the compartment where the toilet paper holder is, you can get access to this area. I used another "Y" to split off a 4" round duct in the head and continued the other side to the aft cabin.
	The 4" round duct in the aft cabin is in the top, port corner of the forward bulkhead behind the head sink.

I can adjust the dampers in the vents over the chart table and in the head to direct more or less air to the aft cabin. We sleep forward in the V-berth, so the aft cabin is usually used for storage unless we have guests on board. I used rubber pads to isolate the A/C from the mounting platform and the platform from the hull, so the noise and vibration in the V-berth is only a mild hum. It has not been a problem sleeping.

I was able to find a 15A breaker that matches the other AC breakers in the electrical panel and wired the A/C to that. Everything runs on the original, 30A shore power. I looked at Mermaid's Condensator to siphon the condensate overboard, but it looked to me like seawater could come back into the boat through it. Since my drain is pretty far up in the bow and gets hit by waves when underway, I decided not to use it and I ran a drain tube back to the bilge sump in front of the mast. I usually have a little water in the sump anyway because of the keel-stepped mast.

We have been very pleased with the A/C performance. If we have guests on board, we partially close the chart table and head vents and the aft cabin cools nicely. We used a reverse cycle unit and we even took advantage of the heat a couple of times this winter. The hinge down return air grill to give easy access to the remaining under the V-berth storage was an added bonus. With cool air ducted to every cabin and minimal impact on storage space, we’re more than happy with the results.

Karen and Terry Clark
Yet To Be #1095

Important: The opinions expressed here are those of the individual contributors to this page, and not those of the Catalina 34 National Association or Catalina Yachts, Inc. Additionally, this material has not been reviewed by Catalina Yachts, Inc. for technical accuracy. This page's maintainer cannot guarantee the accuracy of this information or the desirability of suggested modifications or upgrades. Please obtain assistance from a competent marine mechanic or boatyard prior to making any significant modifications to your vessel.