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Old 03-05-2010, 16:33   #16
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Ennhh, thought I'd make it an even nickel. I gave ya 2 cents earlier.
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Old 03-05-2010, 18:41   #17
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Originally Posted by jacket_fan View Post

David, I am curious about your post. It makes sense, but I had not thought that diesel would glaze up the cylinder walls. Although the compressor does not run all night, would the load from the air conditioner fans be enough load to reduce or mitigate the glazing? Or find something else to sequence to keep a load on the genset? Surely some smart person has come up with a way to prevent this problem without the complicated system you described.
I've always recalled the danger warning of running a diesel without a load every time I drive by a truck stop and they all have their engines running all night, every night. Could someone explain why truck engines survive and a marine diesel would suffer damage under similar circumstances?
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Old 03-05-2010, 18:55   #18
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Could someone explain why truck engines survive and a marine diesel would suffer damage under similar circumstances?
I don't know, but possibly because the trucks are idling, and generators run WOT but no load?
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Old 03-05-2010, 18:56   #19
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Mark wrote:

"David, I am curious about your post. It makes sense, but I had not thought that diesel would glaze up the cylinder walls. Although the compressor does not run all night, would the load from the air conditioner fans be enough load to reduce or mitigate the glazing? Or find something else to sequence to keep a load on the genset? Surely some smart person has come up with a way to prevent this problem without the complicated system you described."

Mark: The A/C fans probably draw a couple of amps each. Not much load.

Maybe there is another way to do it, but it won't be much less complicated. You probably have an inverter/charger and a pretty decent sized battery bank (1000 amp hours) planned, right? You can install a small A/C (5-6,000 BTU) for just your berth in addition to one or two large ones for the main cabin and guest berths. Then run the small A/C off of the inverter each night. You will probably consume several hundred amphours each night and then need to run your genset for several hours to recharge. But I understand that you want A/C 24/7 so you will restart your genset when you wake up and start the other big A/C units. Your genset will stay loaded this way.

The Mastervolt hybrid system is a packaged and automated version of the above, but a bit too small for a big boat that you want to keep cool 24/7.

David
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Old 03-05-2010, 19:04   #20
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Truck engines idling- Yes it is because they idle all night (or used to, the EPA has shut down this practice in California at least), but they also go 10 hours (or 15!!!) under fairly high load the next day and burn off the crud.

One of the marine diesel gurus on boatdiesel said that he takes a genset that has been glazed up and runs it for 24 hours at almost 100% load and it will generally burn off the crud. Might be something to consider doing periodically. You would need several 1,500 watt space heaters up on deck to load up the genset sufficiently to do this.

David
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Old 03-05-2010, 19:21   #21
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Truck engines idling- Yes it is because they idle all night (or used to, the EPA has shut down this practice in California at least), but they also go 10 hours (or 15!!!) under fairly high load the next day and burn off the crud.

One of the marine diesel gurus on boatdiesel said that he takes a genset that has been glazed up and runs it for 24 hours at almost 100% load and it will generally burn off the crud. Might be something to consider doing periodically. You would need several 1,500 watt space heaters up on deck to load up the genset sufficiently to do this.

David
Makes the most sense but the duty cycle of a truck engine varies as it runs down the road compared with a marine engine which is at or close to fully loaded so I guess I still can't buy either argument. Do appreciate the comments.
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Old 04-05-2010, 09:42   #22
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Always enjoy trying to solve problems.

My initial problem was to determine the cost and complexity to install air conditioning in a cat that does not already have it. From responses, I need to take in consideration a sufficient genset, account for the weight penalty, and plan on $20k + for cost ( and add another $10k for a new or upgraded genset if required). As usual, any problem can be solved if you throw enough money at it.

It appears it is not a complex solution, but there is more than one solution. Installation of traditional A/C units, fans, drainage and ducting is doable. Using an automotive style solution run off the drive engines is an alternative solution. At a fraction of the cost. The trade off for this solution is convenience.

The problem for those of us who want to live in the "floating condo" and have air conditioning, is that you can muck up the genset by leaving it on during extended periods with no load as the A/C is not on at times overnight.

How about these for out of the box solutions in addition to Davids:

1. Rig a timer for the genset to turn off for a couple of hours overnight to ensure the A/C runs more continuously and a more constant load on the genset.

2. Find a fuel additive that helps prevent cylinder glaze.

3. Rig a circuit that cycles between A/C and the batteries. A current switch and relays. When the A/C is not running it charges batteries. I think this is similar to the Mastervolt solution you described.

4. Get multiple sets of rings, ring squeezer and a hone brush, and get good at rebuilding the genset.

I gotta belive there is a simple, low cost solution.
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Old 06-05-2010, 20:52   #23
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Hi Mark,

AC in the Caribbean is not a necessity, but we find it useful for knocking the humidity down during meal preparations, or at the end of a day when the wind dies. We never run it all night or even during the day. As others state, it would be very useful at a dock, but we are never at docks.

We have a Manta that had AC added post factory. It is not rocket science, but it is not a piece of cake. The installation of the compressor and evaporator requires proper space, air return and cooling considerations, but the duct work is the major issue. Running duct work is very boat dependent and can be a make or break for AC efficiency. Your question is difficult to answer until you name a specific model of boat and provide details on available utility spaces and unused chase spaces. You might be able to locate several compact systems throughout the immediate areas they will be used to cool, or you might have to locate large systems remote from the areas to be cooled and run duct work. To be the least bit efficient on a catamaran, the duct work has to have straight uninterrupted runs and be well insulated due to the length of the runs necessary. And the air returns have to be situated where they can function properly. These considerations are extremely boat dependent and the final costs will bear little to do with the listed costs of the units themselves

Rigging a timer for a genset is not a trivial matter. Fuel additives don't exist to prevent the glazing discussed earlier. You DO NOT want 30-40 AC amps hitting your batteries through an inverter at any time. This will quickly destroy any reasonable sized small boat cruising battery bank (and whatever size boat you buy, it will be a small boat, relatively speaking, in this context).. Running an AC compressor off of one of the engines is not a viable solution for overnight or more full time AC usage.

I usually stay far away from this issue, but since I am encountering many people out cruising who are not making it, I will be the one to point out the elephant in the room: If one of you is absolutely set on constant AC as a requirement for cruising, your cruising life will be a short one.

Mark
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Old 06-05-2010, 21:37   #24
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I'm not a cruiser, just another want to be, but you might concider switching to a power yacht.

Power yachts over several advantages to the cruiser with a "wife" problem. (In other words, ME.) Just take a thought of crossing to the darkside.

When your looking at a sailing yacht with an aux. engine, your looking at a boat that lives two lives. It can sail, and then also be a power boat. Power yachts remove the sailing gear, and all of the expense and space required for them. This opens up weight, and space requirements for liveing space, or alternative equipment.

At least in looking at advertizements, I'm seeing much larger gen sets, and much more fuel tankage on power yachts. I'm also seeing a/c advertized more commonly.

As far as fuel glazing, I dought that simply running the gen set at idle for a few nights makes much of a diffrence. I strongly suspect that boats with fuel glazing problems never throtal up to full ever. Raw water cooled marine diesels are double succeptable to the fuel glazing problem. As I understand it, the deposits on the cylinger walls happen because the cylinder walls are too cool. For a raw water engine, the water has to stay cool, or it will deposit scale on everthing. Only way to get the clinder walls up to temp while having the water jackets cool is to get a heat flux through the cylinder walls to get a temp diffrence between the cylinder walls and the water. Freashwater cooled engines should get warmer when their idleing, but I wounder if it's enough. I suspect that at best it simply lows the build up when the engine is idleing.

If on the other hand you have it throtal up, and get it good and warm fairly regulary, it should be OK. Most of the gen set builders seem to indicate that there is a specific time peroid of idleing, before you need to put a load on the engine and get it up to full temp.

I guess the point of my post is that if your going to run an a/c set, run the heck out of it every day, or don't bother running it at all.
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Old 06-05-2010, 22:59   #25
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The best way to go with a genset if you need A/C, watermaker, SCUBA compressor is to go for a smaller 5kw 1500rpm (not 3000 rpm) genset coupled to a Virton Quattro Invertor/Charger system. This has up to a 5kw boost to start electric motors and the smaller genset runs a reasonable load avoiding glazing of cylinders and at max fuel efficienty.

The next step is to install a LiFe phosphate house battery system which will allow higher charging rates and shorter genset run time) and the weight saved on battery bank covers for the weight of genset. Whilst these battery are expensive at present when you look at whole of life or if your house bank is due for replacement they are affordable now.

Check these links

From My Design to My Installation: New AC Power System

Quattro / 3kVA - 5kVA - 8kVA - 10kVA - Victron Energy

Marine Generator Test - Victron Energy
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Old 07-05-2010, 06:43   #26
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I'm in the HVAC business and have always wondered why they don't zone air conditioning systems on boats. When you cool the salon you don't need to cool the berths and vice versa. If you where installing the systems yourself, just put a 6" wye on the outlet of the air conditioner with two hand dampers. Then, when night comes, force the air into your cabin. You could effective cut the size of the a/c units in half.

I would think on any 40' cat your going to have plenty of room to install two a/c units and a generator somewhere. The a/c's can be installed by you if your fairly handy then have someone do the plumbing. Wiring is a cake walk.

On the generator, Northern Lights has a new 5kw which is 20% smaller then their current unit. It will be available next month and runs about $9500 without installation. I've communicated with a fair number of people about the Nextgen and the consensus is to spend the extra for the better generator. It will be about $3000 more.

It always makes me laugh when a thread is started asking advise and the first post is someone trying to talk you out of it. When I bought my boat the previous owner advised me that the most important thing was when my wife first came on board she be comfortable and enjoy it. Otherwise, your on your own.
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Old 07-05-2010, 07:41   #27
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Back to the original question of how much and how complicated - Installation is rather easy these days as the two big marine air conditioner manufacturers - Cruise Air (ESystems) and Mermaid are right there in Florida. They both make totally complete units on one pallet/pan that comes in different BTU and pallet footprint dimensions. You mount the pallet in a closet or other area where it will fit and then you simply have to connect electric power up to it and a raw water hose and pump then you are done. Of course, there are details like air grills and return availability but they are not difficult. The hardest part is sitting down and deciding exactly which compartment/closet you are going to put it in. The single pallet units are quite heavy so some models have provisions for mounting the unit on the floor of a closet and running a "dryer hose" up to the top of the closet to exhaust the cold air into the cabin.
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Old 07-05-2010, 09:20   #28
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Back to the original question of how much and how complicated - Installation is rather easy these days as the two big marine air conditioner manufacturers - Cruise Air (ESystems) and Mermaid are right there in Florida. They both make totally complete units on one pallet/pan that comes in different BTU and pallet footprint dimensions. You mount the pallet in a closet or other area where it will fit and then you simply have to connect electric power up to it and a raw water hose and pump then you are done. Of course, there are details like air grills and return availability but they are not difficult. The hardest part is sitting down and deciding exactly which compartment/closet you are going to put it in. The single pallet units are quite heavy so some models have provisions for mounting the unit on the floor of a closet and running a "dryer hose" up to the top of the closet to exhaust the cold air into the cabin.
Yeah, you can just plunk a unit down anywhereor you can make it look good and fit really well (ie..split systems). From experience there's a huge price difference!!
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Old 07-05-2010, 09:51   #29
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Mark, thanks for the comments. Did you do the installation, or was that done before you got your Manta? (By the way, Mantas seem to be great boats)

"If one of you is absolutely set on constant AC as a requirement for cruising, your cruising life will be a short one."

Could you elaborate a bit on this comment? Is it because to enjoy the cruising life you must forgo air conditioning or is it because cruising is like camping for the rest of your life which includes minimal creature comforts?

VirisbusUnitus, your comment about sail versus power is interesting. My wife and I both enjoy sailing. So a sailboat is in our future. We will have to work around the requirements to allow amenities.

downunder and Palarran. thanks for the input, I will do some homework and get smarter on the equipment you suggest.
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Old 07-05-2010, 10:22   #30
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Tell you what, best idea would be to sail on down and check out the environment firsthand for a couple weeks. Then you'll have a better idea of what you will need before you shell out that much cash. Better that than to pay for something rarely/barely used. You may want cabins only or the whole boat. Also, would probably be better to run coolant lines than ducting and use "local" control in the areas where it's needed.
JMHO
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