Replace Fridge with AC. What challenges to expect?

[wahoo33417]

ttles: Good question. But on my 282, it won't fit behind the steps unless you go further back towards the microwave. From there you would have a lot of runs for everything like intake and return air, cooling water and drip pan water, etc. And I'd have to cut a fairly large working hole to get my head and arms in there to make all the connections. And I'm not sure I'd have wide open spaces behind that hole.

When I looked immediately beneath the steps, I thought there would be some fairly open space besides the small storage box. Nope. There are a couple of 2x4's at 45 degree angles making that space unavailable for anything else. That pretty much put me off of pursuing that area any further.

At least in my opinion, it is best placed behind the rear panel in the aft berth. You don't have to lose anything. The cooling water and drip pan water and electrical runs are shorter. The AC itself is accessible, although the holding tank is less so. What I have not yet figured out is how to run the cold air ducts around the port side to come out beneath the stairs. This will probably require making some new inspection ports.

I haven't actually done any of this yet. So when I do, I'm sure I'll encounter more issues than I have thought of so far.

Rob

 

[ttles714]

Where did grady actually install AC and hot water heater on the sailfish ?? My marlin has AC behind the cabin stairs and is accessed by removing the fridge.... the HW heater and fresh water pump are located under the helm chair ( both 2001 and 2007 models) I have had the AC unit in and out several times ( unfortunately) !! but it's not that bad a job.. Not sure about the space in the sailfish ...

 

[ttles714]

on another note>>>>>> When I was hunting for the 2007 Marlin, I looked at a Boston whaler Conquest .... I seam to recall that the AC unit was installed under the v- bunk in the bow

 

[wahoo33417]

At least on the latter year sailfishes, the hot water heater is in the most forward under berth compartment.

I’m not sure where the factory put the AC. It may have been behind the fridge as in the Marlin. I do know that the intake air grill is in that panel in the aft berth. I may be showing my own ignorance about AC systems here, but I believe it would be quite a project to run a 10” square duct from the area behind the aft berth to behind the fridge. Might be easy to do at the factory, but not now.

At least from AC people I’ve spoken with, it is preferred to have the intake grill up close to the unit. Or fashion a short run with insulated fiberboard and masking tape with smooth insides so you don't heat up the incoming air before it hits the unit. And at least one cold air grill needs to be no more than 4'-5’ of ducting run from the unit. Again, the longer the ducting run, especially the more turns there are, the more friction losses there are both to heat and to force of air coming out of the grill.

In any case, I think I have foreclosed the area behind the fridge as an option. I pulled the old 12v-only fridge and replaced it with a custom storage cabinet. To make full use of space, the cabinet goes quite a bit deeper than the fridge did. Organized storage is at a premium on our boat trips and the fridge was not.

Rob

 

[jmain]

What am i missing here ???? Why not install the AC ( Mermaid as described) in the area behind the steps and keep the fridge ????

@ttles714, I'll have to defer to Rob, but we are talking oranges and tangerines here. He has a Sailfish 282 and I have a Marlin 30. From what he described, he doesn't have enough room to install the A/C behind the stairs.

 

[jmain]

on another note>>>>>> When I was hunting for the 2007 Marlin, I looked at a Boston whaler Conquest .... I seam to recall that the AC unit was installed under the v- bunk in the bow

@ttles714, I looked at that as well. It would have fit, but there were three reasons that I didn't go that route...
1. Primarily, because it took a lot of the very limited storage space in the boat.
2. It would have been harder to route the vent hose to the aft berth.
3. I figured it would be louder at night, given your head would be about 9" from it.
Not sure if those are good reasons, but that was my thinking at the time. All in all, I am glad I put it behind the steps. Just my $0.02.

 

[wahoo33417]

Well I took ttles comments seriously and gave a second look under the steps. At least I looked as well as I could. I'm more convinced that this isn't a good placement on the 282 for several reasons.

This view is from just over the top of the small storage box at the bottom of the steps. Note the monkey fur at the bottom of the photo. It appears that 2x4 could prevent mounting the unit up tight against the aft berth bulkhead for a good fit with an intake grill. Further, there isn't a flat floor. Looks the plywood base would have to be built up several inches at least. That puts that 2x4 even more in the way. And, apparently from the photo, space is quite tight. I couldn't get a measuring tape in there, but once you built up a level base, I'm not sure there is 18"L x 12"D x 12"H. It might be possible if you took out the storage box at the base of the the steps.

A bit more of a close-up view:

The one selling point for this placement, assuming you could get a unit in there, is there would be a really short run for cold air ducts to exit at the steps. The detractors are that that cooling water runs would be quite long. Access to the side of the boat for a cooling water exhaust is not easy. I could see it when I pulled the fridge, but my old discs said no way to get there. And the run for condensate water to the shower sump is also quite long.

There are many positive points, in my opinion for placement behind the aft berth. The cooling water run is less than two feet, as I intend to use the existing waste tank overboard discharge through hull. Cutting a hole for the line to exit the side of the boat is very accessible through the aft berth side panel.

This is what you see when you open that aft berth side panel. Just don't mind the old mud wasp nest!

Still on water lines, the drip pan water has maybe a 3' downward run to the shower sump. Easy.

And all the water lines are easy to keep an eye on. Most of the important parts can be seen by lifting the forward bilge panel in the aft berth. Pulling the side panels in the aft berth should, I anticipate, give reasonably easy access to all points on the rest of the unit.

Lastly, this location is much closer to electrical panel. This is where I hope the instructions are very clearly spelled out, as this is where I easily get lost.

Rob

 

[SouthFork]

My A/C is behind a panel on the port side of my mid berth. Plenty of room there. The intake was cut into the middle of the removable panel and there is a lot of room to run the duct work. I will saw that I have no idea how many BTUs it is

 

[wahoo33417]

SouthFork: I would love to see a photo, even it's just with the panel on. Also, what year is your Sailfish?

My aft berth has a storage net with an indentation on the port side and no panel. That indentation would lessen the space behind it. But not many other things run up the port side, compared to the starboard side.

Tx, Rob

 

[SouthFork]

SouthFork: I would love to see a photo, even it's just with the panel on. Also, what year is your Sailfish?

My aft berth has a storage net with an indentation on the port side and no panel. That indentation would lessen the space behind it. But not many other things run up the port side, compared to the starboard side.

Tx, Rob

It’s an ‘01. If I can get over to the boat today I’ll snap a pic

 

[SouthFork]

Just so happened I needed to drop something off there. Let me know if you have any other questions

 

[Richard1572]

I have a 1997 272 Sailfish with factory air. It’s located under the steps that go from the cockpit to the helm, not the steps leading down into the cabin. The return duct is in the middle of aft wall of the mid berth and the duct work for the cold air vents is routed to either side of the V berth. One vent is just forward of the head on the starboard side and the other is just forward of the microwave on the port side both blowing air forward. The control for the AC is on the wall just to your right as you come down the companionway.

The AC still works but is getting a bit cantankerous and isn't as cold as it used to be so I'm looking to replace it. It’s a 6000 BTU unit and runs very well off either shore power or the factory 1k inverter. The easy fix would simply be to replace with a new marine unit. I'm a do it yourself-er so could replace with a new unit for under $2k USD. However, I'm very seriously considering putting in a window unit in the same place as the current unit and return vent.

5,000 BTU is significantly more than enough to cool the small cabin area of the boat. I suspect the reason the poster said 5k BTU didn’t cool enough is because there was not enough airflow cooling the portable unit and\or the portable unit cold air supply was from inside the cabin which sucks hot air from outside to the inside and routing the exhaust into the bilge is going to be a problem too. At least in my boat there really isn’t any air tight separation between the bilge and the cabin, it’s just all cosmetic walls and hatches but the cabin space isn’t sealed from the bilge, it’s more of a finished portion of the bilge. The analogy would be simply placing the window/portable unit in the middle of a room and expecting it to cool the room. It doesn’t work that way. In order for a window unit to be effective the cold air intake and hot exhaust need to be ducted and routed outside of the bilge and forced air needs to be incorporated, like wahoo33417 mentioned, to increase airflow and keep the unit cool. There is a good video on a YouTube channel called Out on the Reef on how to create a box and effectively route the ductwork to make a window unit effective in a boat. The forced air essentially replaces the raw water used by a marine unit to cool the evaporator coils.

There are several reasons I’m considering changing to an air cooled (window) unit over a water-cooled unit (marine). While cost is not really an issue it won’t hurt that I can do a quality, remote controlled window unit including purchasing all the ductwork, inline blower and materials to build the box to hold the unit for under $1k. The primary reason I want to go air cooled is (1) I want to be able to turn on the AC while the boat is on the trailer which you can’t do with a water-cooled unit (2) the marine unit loses prime and shuts down when on plane as the water intake isn’t fully submerged or experiences a lot of aeration and the same thing happens on the hook if it very lumpy out as the bow exits the water from time to time. The raw water intake is under your feet just outside the head so very far forward. I have recently replaced the raw water pump with a new one, so the issue isn’t a bad pump. I suspect that aeration problem was exacerbated when the original 2 strokes were replaced with heavier 4 strokes making the boat sit a little lower in the aft. And (3) I keep my boat to shore power all the time when at home on the trailer so I would like to leave the AC on set to a high temp to act as dehumidifier which again I can’t do with a marine unit. I think, but not sure yet I need to take some measurements, I can drain the water from the window unit out the same drain the current marine unit raw water drains, but it may be too high. If so, I’ll drain to the shower sump. The key is I don’t just want to drain into the bilge as I want to get the water out of the boat ASAP.

Looking forward to following this thread as I plan to replace my AC in Jan or Feb when its no longer 1 million degrees and 1000% humidity here in south Florida.

 

[wahoo33417]

Southfork: Thanks for the picture. We do have different designs on the port side of our aft berths. I believe my boat would not have as much room behind that panel (which I don't have) as your boat seems to.

Richard: Interesting thoughts you have on putting a window unit below deck. I never gave that any thought. I hope you start a thread when you begin that project. I just bought a Mermaid 6500 as they had a boat show sale going on. So like you, I have my winter project lined up.

Rob