Air Conditioning for the TomCat

[Mike...]

Hello everyone.

I have read through many, many posts regarding this subject, but I still don't see what I am looking for. Hopefully someone here can help.

I want to install air conditioning in the TomCat, but I don't prefer the portable or window unit solution. I also don't prefer swamp coolers, ice coolers, or anything that requires drilling holes through the hull.

My first preference would be a split unit, were I would mount the coils outside under the raw water washdown connector.

My second choice, would be roof mounted like Dr. Bob's, but I prefer to not lose the roof space. And the thought of cutting a big hole in the roof freaks me out.

If possible, I would like a DC/AC unit that can also run on shore power, when it's available.

But before we get into options, here is my first question. All the posts I read implied that a generator is necessary for Air Conditioning. Are there not units will run off the current generated from the Honda outboards?

I have two Honda 150s, but I am a little embarrassed to say that I don't know how many amps each puts out. I guess I should have tracked that little bit of info down before I started typing.

Anyway, any suggestions?

All help and heckling appreciated
---
mike

[Alok]

When you are under way with the outboards running, you won't need the A/C. We just got back from a 700 mile round trip down the ICW from Galveston to Port Isabel in the Texas summer, and the Tomcat running at 30 MPH generates more than enough breeze

You will need A/C at anchor. Even if the Hondas put out enough amps (I have no idea if they do), are you planning to idle your motors all night long?

[Mike...]

[thataway]

Agree with Alok (almost all of the time anyway)--with widows open, even in 110 on Lake Powell, or 95 in S. Florida--you don't need AC. We cruised the tropics for years in our sailboats, with no AC--just a good breeze thru the boat, even at night. No breeze a problem.

With the Roof Air, you can use the Honda EU2000i, Cutting that hole does not weaken the boat--especially if you do it the way I did (putting a glass flange on the top, and woodend frame under the AC unit. If you just bolt the AC to the top, there is substantial risk that it will change the contour of the top.

Loss of top space is not a problem--if necessary you could put a rack over. But we have put the inflatable over the aC (not when running).

The Roof top--will run when the boat is on a trailer (tom cat camping)--or aground, or on a lift. It gets away from mud, sea weed, critters etc. I have owned several boats with built in AC--and it can be a pain with the sea water pumps etc.

It makes no sense to separt the coils and the compressor--you can use direct sea water cooled cooled, like keel cooler--but not practical in the C Dory.

You might be marginal with the Hondas with 35 amps output per engine. The Suzuki's are 45 amps. BUT this is hard on the alternators. You will need somewhere near 80 to 90 amps from a good inverter. At that pace your house batteries will not last long. Golf carts are OK--I used them with an inboard and 5,000 BTU super effecient (Mermaid)--and could get about 5 hours out of 6 Golf carts (420 lbs weight).

Some of the C Dory boats have used standard marine AC units, but they take up at least one cabinet-sometimes two.

I also used a 15,000 BTU roof air on the enclosed Flying Bridge of a 42 foot trawler we owned at one time. But there we had about 40,000 BTU of AC below decks and a 9 KW genset.

Look at my photos of how to install.

[Mike...]

By the way, it looks like 30 to 40 amps each for the Honda Outboards.

[Sea Wolf]

wannaboat-

I've looked at all these AC alternatives and solutions over the many years on this and other sites and Bob's RV style Polar Cub AC installation is the Blue Ribbon Winner, hands, down!

You'll need a generator if you ever decide to run at anchor or underway, but for plug and play at the dock you'll be all set with a minimum investment with an RV style unit.

The thought of cutting a hole that big in your roof is indeed a bit scary to many, but beats the heck out of all the other installations in the overall analysis.

Read about it and give yourself some time to get comfortable with it.

Good Luck!

Joe.

[Mike...]

Hi Dr. Bob!

[Mike...]

[Mike...]

Would someone please explain what "Compressor Locked Rotor Amps" means?

If that is start-up current, well then wow!
---
mike

[Mike...]

Well I had to look for quite some time to find a DC unit, but here is one:

http://www.dcairco.com/DC9000.html

It draws 50 amps @ 12v. I am beginning to see why a genset is needed.

Might one of you know how many BTU are appropriate for the TomCat?
---
mike

[Tom Little]

Our TomCat has an 8000btu roof top RV air conditioner. Recently when cruising in southwest Florida with daytime temperatures around 90F, this unit barely held the interior to 78F in direct sunlight. We closed the curtains to help with the temp.At night, after sundown with the temp in the 80s, the interior temp dropped to 72F except for the berth. The circulation forward next to the lockers is poor and the temp there was about the same as the exterior. Our Honda 2000 powers the air conditioner OK.

When underway under these same summertime conditions, we are comfortable with the middle hatch just cracked and the side windows open. We cruise with the rear door closed. When at idle for those pesky manatee zones, we open the center hatch and find the boat comfortable. We could run the air conditioner while cruising with the Honda, but do not find it necessary.

We have had marine air conditioners for more than 20 years. It is nice to get away from the problems and high maintenance of those units. I can replace the roof top for less than a service call on one of my marine units.

[Alok]

Yes, the forward berth gets no air flow even when the cabin is frosty. We use a small table fan placed on the floor of the cabin about a foot in front of the forward berth to blow cold air into the berth area. Works great.

BTW, we only use A/C at anchor or in the marina. We place a $100 window A/C in the front hatch and employ life jackets to make a seal around the unit. In June in Texas, the night cabin temperature rapidly goes down to 72 degrees or lower. When not in use, the A/C is stored in a plastic box in the cockpit.

Not the most elegant solution, but it is inexpensive and works for us. Takes less than five minutes to set up and even less to take down. Once summer is over, the A/C goes off the boat so we are not carrying the weight around.

We have a 2 KW Honda generator. It runs the A/C and the fan, charges the batteries, and has plenty of juice left over.

[Sea Wolf]

Notwithstanding the differences between AC and DC currents, the 12 volt DC unit is going to use 10 times the amperage that a 120 volt AC unit would to do the same work, since volts x amps = Watts= power = work done over a time period.

Stated otherwise, it simply takes ten times the amperage to do the same work with a 12 volt circuit that it takes to do with a 120 volt one, since the (electromotive) force of the 12 volts is one-tenth that of the 120 volt one.

There are very few DC air conditioners made because the amperage demands are so huge.

Yes, the compressor locked up rotor amps is indeed the surge current needed by the electric motor at start up with a AC unit with the compressor locked up on the compression stroke.

Joe.

[Mike...]

Well I have been searching and reading for a few hours now, and I have caught up with the rest of you on this.

Joe, you are correct, a DC air conditioner is not practical.

And an AC air conditioner will take a big inverter, that will be a heavy load on the batteries, which was Dr. Bob's point. So an AC air conditioner with a generator is the way to go.

See? I do catch up eventually.

Joe, the Polar Cub looks interesting. However, Tom's comment makes me think that I might be better off with the 9203 or 9204 Polar Mach (13.5kBTU/12.7A and 15KBTU/14.8A respectively).

For those of you who have mounted roof air conditioners, is there any interference problems with the radome? Obviously, I'd need to make sure the radome is elevated above air conditioner, but by how much?

I do have a height-on-trailer issues to deal with here.
---
mike

[Sea Wolf]

Mike-

Bob can tell you much more about the capacities of these units in relation to the Tomcat.

The Polar Cub is a smaller unit (9200 btu's) probably more suitable for a CD-22 or maybe a CD-25 depending on the climate and intended use.

As I remember, Bob was using about an 11-12K btu unit in his Tomcat. (But my memory may not be what it used to be, at least I don't think so, but I'm not sure, because I can't remember what I used to remember.)

Yes, you do catch up/on quickly!

Joe.