refrigeration

Suggestions on keeping the cook happy
tuskie
Posts: 23
Joined: Sat Jun 05, 2010 3:38 am
Location: Brisbane

refrigeration

Post by tuskie » Thu Sep 09, 2010 1:06 am

Hi Paul,

Some of the frig door water dispensers have a small tray inbuilt to catch drips. This could be emptied occasionally and negates the need for a plumbed waste.

I would definitely go for a seawter outlet at the sink. Either electric or foot pumped. For rinsing off dishes, etc it's better than using fresh water or going aft to rinse things off the back of the boat. On a fishing boat we had a cook who lost a heap of cutlery overboard whilst rinsing on the duckboard. She was saving water so she could have longer showers. We nearly lost her to a large tiger shark which latched onto the duckboard while she was rinsing the dishes. Amazing what hangs around a boat after a long filleting session. We didn't lose any more cutlery after that however!

You're a bit keen making moulds for one off fabrications such as the frig.

It's more work to make a mould than to make a frig. Why not just glass over the foam, cove, bog and fair it. Then spray with 2 pack? If this method is good enough for the finish on your hull it's good enough for the inside of a frig IMHO

The same fishing boat I was on had a "stubby door" on the main frig. This small door allowed vital cold refreshments to be retrieved off the top shelf of the frig without the need to open the whole door. It looked like a "cat flap" but who cares.

Mark

mahnamahna
Posts: 579
Joined: Wed Aug 02, 2006 4:48 pm
Location: Gosford NSW

refrigeration

Post by mahnamahna » Thu Sep 09, 2010 4:10 am

tuskie wrote:Hi Paul,
Some of the frig door water dispensers have a small tray inbuilt to catch drips. This could be emptied occasionally and negates the need for a plumbed waste.
I would definitely go for a seawter outlet at the sink. Either electric or foot pumped. For rinsing off dishes, etc it's better than using fresh water or going aft to rinse things off the back of the boat. On a fishing boat we had a cook who lost a heap of cutlery overboard whilst rinsing on the duckboard. She was saving water so she could have longer showers. We nearly lost her to a large tiger shark which latched onto the duckboard while she was rinsing the dishes. Amazing what hangs around a boat after a long filleting session. We didn't lose any more cutlery after that however!
You're a bit keen making moulds for one off fabrications such as the frig.
It's more work to make a mould than to make a frig. Why not just glass over the foam, cove, bog and fair it. Then spray with 2 pack? If this method is good enough for the finish on your hull it's good enough for the inside of a frig IMHO
The same fishing boat I was on had a "stubby door" on the main frig. This small door allowed vital cold refreshments to be retrieved off the top shelf of the frig without the need to open the whole door. It looked like a "cat flap" but who cares.
Mark


Nah Mark, male molding is simple as. You can knock one of these molds up in about 2 hours and using about $50 of mdf (or malomime chipboard) especially if it is a one off and can be destoyed to get the fibreglass box off. People think (I know I did too) that making anything out of material that will be thrown away after use is a waste but it actually saves a heap of hard work and time later. Imagine having to fair the inside of a narrow (300mm x 900mm x 1300) cube. When you can fair the outside of a male mold so much easier. And then the item comes off the mold already faired and painted, much much easier. And if you are having steps such as I am it is all the more easy to fair an mdf mold than the inside of the cube steps. You can also mold in the lid rebates so that it all fits and seals beautifully off the mold.



My issue now is that Multil panel is sooo damn expensive. It has an R value of about 6 for 30mm sheet and ideally you want about R20 - R25 so people use 150mm (5 layers) for freezers and 100mm 4 layers for fridges. I have worked out that at this rate I need 10 sheets (1300mm wide x front and back x 900mm high plus 900mm high x 600mm deep sides plus 1300mm x 600mm top and bottom) and at $450 a sheet, thats near $4000 in foam insulation. Surely this is not what it costs to build your own fridge. Add to that the $3000 for the eutectic system and you are at $7000. Surely not. Any advise anyone? Are people using multi panle or are there other polyurathane sheets that are much cheaper? Heeeellllp!!!

Jim
Posts: 691
Joined: Fri May 19, 2006 8:25 am
Location: Cairns

refrigeration

Post by Jim » Thu Sep 09, 2010 6:18 am

Why not just buy a production fridge/freezer?

If the internal size of the fridge is reduced because of the wall thickness, then consider this.

The CSIRO did research as to why Braham cattle can stand out in the blazing sun and with the aid of temperature probes, the temperature of the meat below the skin/leather was only slightly warmer than normal body temp, whereas the skin temp on the back was through the roof. The reason is that their back (I don't know if it is all over the beast) consists of leather, fat, air, fat, air and then finally meat. The perfect esky, and with most things in nature, they do things so much better than we can.

My point is, would it be possible to make your fridge walls, top, bottom and door out of layers of thinner material with an air gap between them? If the theory works then it should work out cheaper with less wall thickness, so more room inside for a given fridge size. Or you could find out what NASA use to insulate their fuel tanks, because I read somewhere it would take years for ice to melt inside the tanks.

Or you could just buy a production one and save thousands.

Jim.

mahnamahna
Posts: 579
Joined: Wed Aug 02, 2006 4:48 pm
Location: Gosford NSW

refrigeration

Post by mahnamahna » Thu Sep 09, 2010 6:33 am

Jim, I very nearly did based on what 44c contributed to the forum, and whilst I have not given up yet as many people build their own fridges, I wont be paying $7000, you can buy an awful lot of lithium battery bank, solar cells etc with that much. For some reason, I thought about $1000 of foam etc and about $3000 for eutectic or $1500 for condensor plate compressor etc. The problem I have with galley up is I dont have the height for a stand up fridge, but I might investigate side by side shorter fridges that can fit under a standard 900mm top height. The problem is front door fridges are not very thermatcially efficient, top loaders are much more efficient. We dont worry about it at home because power management is not the issue it is on a boat. Anyway, still working it out.

Dreamtime
Posts: 62
Joined: Sun Jun 20, 2010 6:22 pm

refrigeration

Post by Dreamtime » Thu Sep 09, 2010 6:57 am

What about the two part foam stuff that fridgies use??? I have not seen it for a while but I do remember one of my mates when he was a fridgie apprentice had his locker filled with the stuff.



Found this - may be of help??? Common insulating materials, “R” values, advantages and disadvantages



Insulating material

“R” value per inch (2.54 cm)

Advantages

Disadvantages



Polyurethane, board

6.25

Very good R-value, can be used with fibreglass resins

Not always easily available, relatively expensive



Polyurethane, spray on

7.0

Very good R-value, can be used with fibreglass resins, easy application with spray equipment

Not always easily available, expensive, requires special spray equipment



Polyurethane, poured (two-part chemical)

7.0

Very good R-value, can be used with fibreglass resins, relative ease of application

Not always easily available, expensive, requires very careful volume calculations



Polystyrene, sheets (smooth)

Trade name “Styrofoam”

5.0

Readily available, low cost, reasonable R-value

Cannot be used with fibreglass resins unless protected, easily damaged



Polystyrene, foamed in place and expanded moulded beads. Known as Isopor, Polypor, etc.

3.75 to 4.0

Reasonable R-values, lower cost than smooth surfaced sheets

Cannot be used with fibreglass resins unless protected, easily damaged



Cork board

3.33

Availability in many markets, reasonable cost, can be covered with fibreglass

Lower R-values than polyurethane for styrene foams



Fibreglass wool batts

3.3

Low cost, ease of installation

Readily absorbs water or other fluids, loses insulating value when wet



Rock wool batts

3.7

As above

As above



Wood shavings

2.2

Readily available, low cost

Absorbs moisture and loses R-values when wet, decays



Sawdust

2.44

Readily available, low cost

Absorbs moisture and loses R-value when wet, packs down under vibration



Straw



Readily available, low cost

Absorbs moisture and loses R-value when wet, host to insects, etc.



Air space

1.0 approx.

No cost

Has to be completely sealed to prevent air circulation causing heat infiltration
Scotty & René

mahnamahna
Posts: 579
Joined: Wed Aug 02, 2006 4:48 pm
Location: Gosford NSW

refrigeration

Post by mahnamahna » Thu Sep 09, 2010 7:11 am

Actually on to thiis. Wasnt going to mention it until I had some more info but I rang the boatbuilder sharing my shed that will be fairing my boat and he suggested we just make an inside and outside mold with a screw on top and just fill it with 2 pack expanding foam and just put enough in to get the density we need for the correct R value. The texts I have all state that the only issue with this is that if you get an air void from skin to skin it is just like having a tap in the bottom of a tank and you will leak cold out through it as if you have a tap open, which means your fridge cycles more than it should which of course has 2 problems, you wear it all out faster and use too much power. But assuming you dont get air voids this may be the way to go. Much cheaper than polyurathane sheets and you have the added advantage of being able to seal the outside of the entire structure with glass before glassing it into the boat ensuring you dont get moistrue into the foam, which is what causes most R value degradation.



And Jim, I admit to only knowing what I have read, and in theory voids make sense, but according to the text books you cannot have those voids in contact with the outside atmosphere because it is not the air that is the issue it is moisture in any air that can get into your insulation. And furthermore you have to be able to remove any moisture from the air in the voids before locking it in. Sounds too hard. And I am sure it is not supposted to be this hard. I though litterally hundreds of boat builders built their own fridge/freezer. I just had no idea they were paying this much for them.

Jim
Posts: 691
Joined: Fri May 19, 2006 8:25 am
Location: Cairns

refrigeration

Post by Jim » Thu Sep 09, 2010 9:05 am

You are correct about the chest fridges being more efficient as they don't spill cold when opened. I knew this before I bought a conventional upright fridge/freezer as I spent some time on my mates Lightwave which has a chest fridge and freezer. What I did find out and it really annoyed me, is that everything you want in a chest fridge is on the bottom, (see Murphy's Law) so maybe the extra time you are in there pulling stuff out and stacking it on the bench until you find what you are after and then re-stacking it negates the advantage of a top lid. I just bought bigger solar panels to compensate.

Jim.

mahnamahna
Posts: 579
Joined: Wed Aug 02, 2006 4:48 pm
Location: Gosford NSW

refrigeration

Post by mahnamahna » Thu Sep 09, 2010 4:22 pm

Jim wrote:You are correct about the chest fridges being more efficient as they don't spill cold when opened. I knew this before I bought a conventional upright fridge/freezer as I spent some time on my mates Lightwave which has a chest fridge and freezer. What I did find out and it really annoyed me, is that everything you want in a chest fridge is on the bottom, (see Murphy's Law) so maybe the extra time you are in there pulling stuff out and stacking it on the bench until you find what you are after and then re-stacking it negates the advantage of a top lid. I just bought bigger solar panels to compensate.
Jim.


Jim you are dead right there. I thought about this and thought I had a remedy (dont we all). I figured if you know what is where by mapping it (you know, milk, butter, last nights chinese top shelf, cheese, salami, tomato paste etc middle shelf, etc) and I had 2 or even 3 wire trays in the fridge you could very quickly pull the baskets out until you get to the one which contains the needed item, yes the bottom one, get your item, re open fridge and put trays back in. Not to big a deal, and mapping is not too hard. But all the time that the trays are out they are absorbing heat across the entire surface area of every item which then gets transferred into the fridge which then needs to be heat exchanged back out, meaning the fridge cycles. So yes there is no easy way out of this.



For those still interested (I am rapidly losing interest) in building their own fridge, here is a good starting point.



http://www.fishingandboats.com/boat-refrigeration.html

terryk
Posts: 320
Joined: Wed Jan 10, 2007 10:37 pm
Location: Gosford

refrigeration

Post by terryk » Thu Sep 09, 2010 6:33 pm

Hi Paul, the Cold war is over :!: realistically how many times are you going to open the fridge or freezer door :?: not too many times a day. Mapping is a good idea, I am having a 140 litre upright fridge with all the door devoted to VB, I don`t have to open the door so far to reach in :wink: and from then on the food is Catherines problem :) If you are still bent on building your own freezer use thinner sheets of polystyrene and glue them together to get your required thickness, use aquadere wood glue it doesn`t have solvents. I made my outboard bracket extension pods from closed cell polystyrene and had no problems with using epoxy and glass.

cheers

terryk

terryk
Posts: 320
Joined: Wed Jan 10, 2007 10:37 pm
Location: Gosford

refrigeration

Post by terryk » Thu Sep 09, 2010 7:06 pm

Hi Paul,

If you are still bent on building your own check out this website

http://www.foamsales.com.au/shop/browse ... =6&next=21

Have a look at the Isoboard range, good prices and you can buy online.

Cheers

terryk

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