Anyone know approximate CU FT?

[RussGW270]

So, budgeting for an a/c and am curious as to an approximate Cu Ft of the cabin. Anyone have a good guesstimate?

We have used a 10k btu portable and it worked fine, and may be a good size, but wanted to make sure I did not under or over-size and am not sure of the cu ft of the 270 cabin.

Thanks

Russ

 

[Fishtales]

My Marlin has a Dometic Vector Series self contained ac unit that uses seawater to cool. They made 6 sizes (5, 7, 10, 12, 16 and 24K BTU). Grady uses a 8K BTU today. My guess is likely a 7K in the past. I think you will be fine with 8-10K BTUs.

 

[Fishtales]

Duct diameter gets larger with size. Per the manual it was 4" for the 5K, 5" for the K and 6" for the 10 and 12K back then. I'm guessing that the Marlin is 5" duct if memory serves me right. I can picture it (small circular with adjustable fins). There are two ducts which air flows (they must Y the output) and send one stream toward the V birth and one into the aft berth.

 

[RussGW270]

Thanks. The sizes I am seeing are like 6k, 10k 11k etc and on up. I think a 10k would be plenty as well, if it fits

Thanks Fish

R

 

[Fishtales]

Good luck. Hardest part seems to be the raw water connections if you go that route.

 

[RussGW270]

Thanks. Yea....not going to be a fast process, but I think there is enough info out there I can make it happen. I also see they are installing an 8k in the 30ft Marlins, so I think a 6k will work fine for mine.

R

 

[DennisG01]

I know Sea Ray's and their specs for things like this better than Grady. But when you boil it down, it's not a Sea Ray or Grady thing - it's simply a space thing. For example, if I look at a Sea Ray Sundancer of about the same size as your boat, I'll typically see a 7K to 8K AC unit. However, that cabin space is going to be larger than in a Grady. So, if I go to a smaller boat (overall length), then I'll see between a 5K and 7K unit. However, that boat would still have a mid-berth cabin (under the forward cockpit area), so it still would have a larger cu.ft. space. Thinking along those lines, I think you'd be totally fine with a 6K unit. If you think about it, it's really a pretty small space in terms of cu.ft. Heck, a 5K window AC unit is more than adequate to cool a 10x12 room in a house (granted, it's insulated better).

 

[glacierbaze]

Good luck. Hardest part seems to be the raw water connections if you go that route.

If you don't want another hole thru the bottom, you could get raw water from the livewell feed by using a Rule pump with the second port. Never occured to me to not have raw water for AC, but I guess if only used at dockside, a hose could eliminate both the raw water and the pump. As long as someone didn't turn it off, or disconnect. Might need a low pressure switch to turn it off, in that case.

 

[RussGW270]

These comments are right along the same lines I was thinking. While I had a 8k and a 10k "portable" setup, that worked plenty fine with the door open. Installed, I think a 6k would be more than enough to break the heat and we have a 12v fan to circulate air. That would be enough to make it a lot more comfortable at night.

As for the pump, was thinking along those lines as well, but will look at all that when I get to that point. Right now, I was thinking a 6k unit and a soft start to keep the max amp as low as possible, just in case we ever decided to have it on when not connected to shore power.

For now, I have a budget ballpark, thanks.

I think Dometic and modernaire are the choices and sounds like dometic may be the main go-to.

Thanks for the input guys.

Also, btw.. folks have them behind the frig.. how do you all change filters if it is behind the fridge?

R

 

[teaklejr]

Our 305 Express has a 7k unit and works just fine.

 

[DennisG01]

As nice as it would be to use fresh water for the cooling aspect, I don't think that is very feasible, nor enviro friendly, as the water would be running non-stop. I don't see any problems with sharing the livewell input (BEFORE the livewell pump, of course), but be sure to use a strainer and the appropriate A/C pump.

Not being familiar with where/how the A/C compressor is installed, I can't answer that question about the filter. However, you have the advantage of being able to put it anywhere you want to. For example, it's not uncommon to see it mounted under one of the V-berth cushions.

Russ, the Air Con is ONLY AC powered - meaning, it doesn't work away from the dock when you're no longer on shore power.

 

[glacierbaze]

You are right Dennis, a lot of water would run through a hose in a night’s sleep. Russ, the raw water circulation pump will also be connected to the AC side of your distribution panel.

 

[Fishtales]

I don't use it a ton, but the blower fan is louder than the raw water pump. I'd stay away from the fresh water idea. On the surface it seems better, just too many unknows (warranty implications, water level requirements, water temp rise, competing use cases (water for use vs AC) - not sure if this affects pressure. If you put one in, it probably outlasts the boat at this point. Just my 2 pennies.

 

[DennisG01]

You are right Dennis, a lot of water would run through a hose in a night’s sleep.

I was thinking about this some more... "Is" there a way to use fresh water? Because of the materials used in the cooling loop of the system, corrosion isn't typically much of an issue, but clogging up with growth can be. Sure, phosphoric acid is a common go-to in preventative maintenance once or twice a year, but is there a better mousetrap? This is really just some "outloud" thinking here, but why couldn't a heat exchanger be used? The expense would be the HE and another pump to push raw water through the HE. But a coolant mixture could be run through A/C system. Although the A/C system isn't particularly hard to keep clean, I would think the HE would be even easier?

 

[Late Again Grady]

Just a FYI, my 27 Sailfish uses a 5800 btu unit that is raw water unit.

 

[RussGW270]

So, I am looking at two solutions

A 6000 btu a/c and heater installed behind the frig (still curious how the filters are changed.. heh)

A portable unit that can sit on the counter top that someone on FB told me about.

Really steering towards the installed version as I am tired of lugging things back and forth heh.. and.. I like freeing up space.

So, thanks for all the input guys. I think I have a couple directions... just gotta figure which. Will post photos of the install if/when I decide to go that route.

R

 

[Fishtales]

Good luck. If you can do the 6K, do it - smaller and higher chance of clean install. I like the perm solution as well.

 

[DennisG01]

I'd go for the installed unit, as well... 'course it's easy when I'm spending other people's money! But, seriously, that's the direction I would go. The cabin is not exactly "spacious" - especially when there's two of you in there moving around, getting dressed, making breakfast - or even a trip in the dark in the middle of the night to the head. That portable one, while a neat idea, is just going to be in your way.

Can you cut an access hatch (as big as possible) in aft end of the port-side v-berth compartment to access the unit? Possibly even install it that way?

 

[RussGW270]

Hey Dennis, I am leaning the installed way, honestly. I agree, it seems the best, just trying to "keep an open mind", but.. I really do not see myself lugging around a "portable a/c" when I go camping or something.

That being said, I am trying to figure on the best install method. Now that I have it nailed down to needing a 6000 or 7000 btu (whatever the size is of the unit)...I need to see which model is the best quality and which is easy to service, so I can then figure out how best to install it. Like you mention, in my mind.. I see the ongoing service is something to plan for, so an access port is essential. Will be looking over it and documenting and taking pictures as I go along so anyone else that is thinking of doing this will have some sort of an idea what we went through.

Anyway, heading out to get the kids going. Will be roaming through the boat a little today to clean her up, update software, etc.

R

 

[DennisG01]

Sounds like a plan, Stan!

If you think of it, snap a few pictures of the cabin, the galley and the v-berth area. It might help with ideas on access.

Do you have room to (and want to) put the unit under the v-berth?