Air Conditioning for the TomCat

SouthLake · Posted: Sun Jun 06, 2010 9:14 am Post subject:

We put the CARRIER LOW PROFILE - 13.5K btu roof top unit on our CD25 and I'm very happy with it. It has heat as well which can take the chill off when it's cool. Although not in the heat of summer yet we've had a few upper 80's and high humidity days and this unit kept the cabin very nice.

Mike... · Posted: Sun Jun 06, 2010 10:41 am Post subject:

SouthLake · Posted: Sun Jun 06, 2010 11:48 am Post subject:

We ordered it from PPL Motorhomes. Their customer service folks were helpful. shipping was great, very satisfied.

Captains Cat · Posted: Sun Jun 06, 2010 4:14 pm Post subject:

That is a very nice looking R/V unit. Much less obtrusive than the bigger usual style ones.

thataway · Posted: Sun Jun 06, 2010 4:49 pm Post subject:

Yes, PPL are good folks; I have dealt with them on some difficult to find RV parts and they are first rate.

The 13,500 or 15,000 BTU units will require two Honda EU 2000i generators, or a EU 3000 (which I don't see as really practical because of its weight).

78 degrees is about what you will expect. We leave the AC unit running night and day when the boat is on the lift during the summer--and the mid 70's to mid 80's is what we find--but it will be over 100 under the camper back! We often put the bubble wrap foil in the windows, and it will bring the temp down considerably more. The AC unit also dehumidifies the air, so it seems cooler. I have used "shade cloth" on the sides of the boat, or even taken canvas awnings out to keep the direct sunlight out. I see the AC in the C Dory series as for eveings when you want to keep the bugs out, and sleeping--sometimes just cool the boat down, and get to sleep. That is what we did with the inverter operated unit we had--when the voltage got to a certain level, it shut down--and that was somewhere about 2 AM--we were well asleep--and if we heeded to open up hatches and turn on fans, that worked well.

Yes, we have 4 fans in our Tom Cat--two by the windshield--and 2 in the bunk, plus a "Vantastic " fan. With that you can circulate air all around the forward cabin--and it is fine. You have to remember that there are some trade offs in the C Dory--it is not boat with unlimited resources.

We do fine with the slow speeds--the Caracal 18 cat which is our "Bay boat" often runs at 5 knots--and we have enough breeze to be comfortable.

In the C Dory 25 in Petaluma a couple of years ago, we were very comfortable with the 5,000 BTU window air (also see my photos)--. The outside temp was somewhere over 100 and we had the inside temp down to the mid 70's--which is pleasant. If you come from the PNW--you don't do well in the heat, until you acclimate. We had spent a couple of years in the tropics--and were ready for the long johns when we got to Acapulco and it was down to 72 degrees at night on one trip back up the coast....So it is all relitative!

Generally start up amperage is 1.8 x running amperage. We use the Kill a watt meter to measure our 110 volt power draws. If you have a water cooled air conditioner, you need to add one amp for the raw water pump. , so if the AC unit uses 6.5 amps, with the water pump it will be 7.5 amps, and start up would be close to 13.5 amps. Locked rotor is max draw with the compressor locked due to a hyraulic lock up.

Another option might be to go with the Mermaid 5200 BTU unit--which is made to run with a 1000 watt inverter--and just air condition the bunk area--or perhaps put a curtain to exclude the aft part of the cabin--head and hanging locker--with bubble foil in the windows.

Another factor is to insullate the hull and deck. Using the back packing pads is the best and most effective way. That gets rid of a lot of the hull heat.

There is a true "DC Marine air"--and that is the "DC Breeze" by Glacier Bay--it also uses about 48 amps. http://www.dcbreeze.com/ So about the same as the roof air unit you found. This may be slightly be more effecient than the inverter/RV unit.

If you do the numbers--the cabin of the C Dory needs somewhere about 8800 BTU (windows, not well insullated), and then add in aonther 3200 BTU for an insullated forward cabin (bunk area)--and this comes out near to 12,000 BTU miminum in the heat of the day. Some folks have gotten a 12,000 BTU unit to run on a Honda EU 2000. This requires some "easy start capaciters on the start up.

You take what relief you can get--and make do with it!

Mike... · Posted: Sun Jun 06, 2010 8:04 pm Post subject:

Mike... · Posted: Sun Jun 06, 2010 8:33 pm Post subject:

Hi Dr. Bob.

So as you can see, I finally decided the wannaboat username had to go. Thanks to Tyboo for changing it. Smile

thataway · Posted: Sun Jun 06, 2010 11:56 pm Post subject:

My generator sits on the engine bracket on the port side, on top of a plastic "crate"--this keeps it about 2 feet above any water. The tank goes on another crate. I keep stuff in the crate when not using them for the AC units. Lacking milk trucks in our area, I purchased the plastic crates at West Marine.

Captains Cat · Posted: Mon Jun 07, 2010 9:45 am Post subject:

drjohn71a · Posted: Mon Jun 07, 2010 5:09 pm Post subject:

Mike,

I see you do not want the portable a/c unit like the De Longhi , double tube unit I have had in my TomCat for years now.

However, please note that, even if you could find a 12V unit, it would take many multiples of pounds over the weight of a Honda 2000i and a De Longhi unit.

The De Longhi requires no holes in the hull, nor in cabinets and can be wheeled down the dock and ramp easily with one.

the portable a/c units have another major advantage over the roof air and marine air units - they come with a slow start rotary compressor which limits the start up load greatly. On days in the 80's I can run my a/c on the Honda Economy setting, but have to go to the full power setting in the High 80's and nineties with humidity. Even so, it will run about 8 hours on one tiny tank of fuel and then the Honda shuts itself off, so you do not have to get up in the middle of the night and mess with it.

I use these portable units in my upstairs bedrooms at the farmhouse since no need to a/c them unless my boys are visiting, or other company. They are quieter than most roof airs since the vibrations do not go into the roof. My last houseboat had roof a/c units, but the vibrations were magnified thru the roof mount, so hard to talk and listen to radio/music, etc. when they were on.

Depending upon the size of the portable units, you can place them in the cabinet aft of the dinette, atop that cabinet, in front of the front dinette seat or even one fits under the bow roof sitting on the base of the foward bunk.

You could install more permanent tubing entries using those air cowls, but I kind of like just pulling mine in and closing the bunk window to keep bugs and wasps out of the venting system. The tubes run above the bunke enough that they do not interrupt normal leg room bunk space.

so, an inexepensive, KISS method of a/c is just finding a portable that fits.
They also come with a "dehumidify" setting which keeps your boat smelling sweet and dry.

John

Mike... · Posted: Tue Jun 08, 2010 1:08 pm Post subject:

thataway · Posted: Tue Jun 08, 2010 6:45 pm Post subject:

So the sleeping plan is three kids and one adult on the forward bunk--and one adult on the dining table? There are some who cruise with that many on the C Dory 22, but it is crowded.

I also assume that you will be doing a lot of marina hopping if the cooking means that you are going to eat out. For your use, I would still think that the roof air would be the best--it just depends on which size you want, and how big or many generators you use...There are prices to pay.

Mike... · Posted: Tue Jun 08, 2010 8:08 pm Post subject:

Captains Cat · Posted: Wed Jun 09, 2010 8:23 am Post subject:

Mike, mount it on the armstrong bracket on a secure mount of sorts with a visible lock. You can make a cover for it if you're not in a covered berth. You'll only use it for about 4 months anyway and the cable can be run up the stbd side to the shore power receptacle.

No sense in carrying it around for the other 8 months. You could plumb it into the fuel system back there and not carry a gas tank.

Charlie

drjohn71a · Posted: Wed Jun 09, 2010 11:03 am Post subject:

Mike,

Have you checked out my generator box installation on my TomCat, in the photo album? I got an aluminum underbody box from Tractor Supply and cut some hinged doors in it. I have used it in the Gulf of Mexico in 6-8 foot waves as well with no problems since I put some aft drain holes in the bottom and the intake vents are up against the stern of the boat.

John

Also, in my houseboat, I could never get my three boys to sleep in the bunks. They wanted to sleep in the cockpit or on the floor of the cabin - yes right in the way to the bathroom! I got some of those foam pads and sleeping bags and they were very happy with that.