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Modding Marine Computer - Heat exchanger cooled

Discussion in 'Modding' started by dacust, 14 Jul 2007.

  1. dacust

    dacust What's a Dremel?

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    I'm posting this here as a response to a comment in a thread in the project logs forum and didn't want to go off topic.

    I mentioned that I was going to be making some computers for my boat and soulmage recommended Pelican.

    Those are really nice, but expensive. My boat is large enough and enclosed (See My Boats on my Home Page in my sig) so I don't need anything that rugged. Here's my thinking:

    The computers will be mounted inside, normally A/C or heated.
    A 36' boat is pretty stable, but can bounce around, so I'll use laptop drives.
    I got LOADS of 12v power, so 12v is the way to go. Don't have to run the genset that way. And they'll work even if the inverter dies for some reason.

    There are times the A/C is not running and the interior can get really hot (120 can happen), so I'm thinking of a slightly different kind of watercooling:
    Use a saltwater/freshwater heat exchanger, probably from a small marine generator. This means the cooling water will often be below ambient temperature, so condensation will need to be dealt with. I'll need to watercool just about every component. Probably make a combination of heatsinks and heatpipes running to water blocks for the unusual places. I don't have much experience with this, so I figure I'll use a temperature probe to check the MB and other components for all the heat generating places.

    Needs: The biggest thing I run on the PC on the boat is the marine navigation software. It supports dual monitors and has 3D graphics. You can easily have 6 windows open simultaneously showing different charts scrolling, some in 3D, some having more than one type of display merged together, including radar, satellite photos, vector and raster charts. Basically I need a pretty fast CPU and a pretty good graphics card.

    Well, I don't have time to lay it all out, but this is a start.

    Anyone in here ever do something like this before? Ideas? Problems? Flames?

    When I start these, I'll post in the log forum so you can all see. (Might be a year before I start).

    I say "these", there will be 2 identical navigation PCs (one is backup), a vessel management PC and then at least 1 Linux machine for normal use.
     
  2. mattthegamer463

    mattthegamer463 What's a Dremel?

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    I don't know if laptop drives are really any more resistant to movement like swelling seas. I think your biggest problem will be finding a 300W+ inverter for each rig. Do you know what kind of amperage you can get out of the boat? You'll need a hell of a lot of battery power to run these nav comps while voyaging, what is your plan for that?

    Sounds like a sweet idea, I would make them into O-ring sealed cases and things to make them super-seaworthy.
     
  3. dacust

    dacust What's a Dremel?

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    I won't be using inverters, straight 12v into multiple 12v power supplies made for carputers. I have 2-120amp alternators so I think I can push a few PCs. If that ain't enough, I can fire up the 6.5kw generator. :D

    And, like I said, these will be mounted inside, so the o-rings won't be needed.

    The swells are not what concern me, it's the vibration from the engines (twin Caterpillar 3208's and the "rock-crusher" diesel generator) and the occasional pounding from hitting waves in an 18,000lb boat going 20kts. I have never had any problems with regular laptops onboard except from overheating. The touchpad on my Vaio goes nuts when it gets too hot. Works fine in the cabin, but has problems in sunlight on the flybridge.
     
  4. Javerh

    Javerh Topiary Golem

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    In the army's comm tanks we had computers in racks that where cushioned from the top and bottom by sets of maybe 20 springs. Each spring was about 3cm in diameter and 10cm in height.
    By having the springs on both the top and the bottom the springs will dampen horizontal vibration and rocking besides vertical. The system was subject to some severe vibration and an occasional heavy bump when the tank's track suspension wasn't enough. I can't say anything about the amount of vibration, except the fact that after an hour's ride the soles of your feet got numb even through army boots.
    We never had any problem with the vibration breaking any components. I think this kind of suspension should be more than enough for your application.
     
  5. ConKbot of Doom

    ConKbot of Doom What's a Dremel?

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    Below ambient temperatures wont be a probem with good thermostatic control. I'm not sure what kind of pump you would need for pumping seawater around, probably something a little more rugged then the normal watercooling pump. I would make a normal WC loop with a rad in a box for the water-water heat exchager. using a simple on/off thermostat,
    Turn the seawater pump on when the water in the heat exchanger reaches 10C above ambient, and turn it off when it reaches ambient. You could do it with a relay, transistor/diode for driving the relay and catching the spike. A comparitor for comparing ambient and the heatexchange temp, and an op-amp to add the 10C bias to the ambient temp.

    Or you could make an aircooled PC, put it in an enclosure, put a rad in the enclosure, and pump the cool/cold water though that and make an air chiller.
     
  6. The_Beast

    The_Beast I like wood ಠ_ಠ

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    It isn't done and it's extremely crude but you could do a "HDD Hanger". I forgot to put on there but there should be rubberband/surical tubing on all the sides and the bottom including what is already on there


    All you would need is a medium size box, rubberbands/surical tubing and your HDD. The yellow is the rubberband/surical tubing which is like a shock.
    http://i40.photobucket.com/albums/e236/Chevelle3233/SeagateBarracudaHDDSmall.png

    Edit: don't laugh
     
    Last edited: 15 Jul 2007
  7. Soulmage

    Soulmage Minimodder

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    Another thing you could think about (course debending on your funds) are solid state hard drives. I know the military are starting to use them in their "rugged" tough books. If not those, then honestly, since the whole boat will be moving, as long as the case(s) are fastened to the deck you should be fine. Maybe use silicone dampners likes those found in a p180.

    The other thing you need to worry about is sealing the computers tight. Being on the sea, there is a lot of salt in the air and no matter where you are, it will be very humid. BAD juju for components imo. My recomendation for that, aside from a modded pelican case, would be a wooden case with the wood sealed with a marine paint. Then a rubber seal around the access door to the case. Last but not least, a somewhat soft rubber seal going around the edge of a door that will seal around the cables coming out. Then for cooling, you can just use a standard water cooling loop with the rad on the out side. These are just ideas running through my head.

    Edit: also, in regards to The_Beast's idea, it won't work (no offence mate). Reason being is on the sea, the movement can change at any second. So when the boat gets knocked one way, the drive is going to go the same way. Then you will get a sudden change of movement and its going to jar the hdd the opposite direction. Esseentially the arm in side the drive (the only thing that is affected by these types of movements) will recieve whiplash.
     
  8. identikit

    identikit Minimodder

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  9. ConKbot of Doom

    ConKbot of Doom What's a Dremel?

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    I would be careful using surgical tubing for suspending the hdd. Constant oscilation that results after the drive being moved would be even worse then the bumps for the HDD. Plus with that desigh it would sway back and forth and possibly start hitting the hdd into the sides if it gets swinging enough. The thing to remember about shocks, is that they are dampers, they absorb the motion. Spings in cars hold the weight, and absorb the initial jolt. The Shock dampen the oscilation. Just using surgical tubing would the be equivalent of an old car with blown out shocks that just keeps bouncing after it hits a bump.
     
  10. Cheapskate

    Cheapskate Insane? or just stupid?

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    Would it be possible to build a sealed unit with a LARGE radiator inside? The inside radiator could be attached to an outside cooling system, but there would be no condensation inside the 'pooter. You could also add silica jel bags to absorb any moisture from pressure equalization valves.(If used..)

    (edit)- I know this would require almost as much sealing as a oil sumbmerged rig, but I've never seen it done.
    --and the OUTSIDE of the case would sweat like a pig.
     
    Last edited: 14 Jul 2007
  11. jakenbake

    jakenbake full duplex

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    check out www.mp3car.com, they are a car-computer website, and they also sell DC-DC power supplies, 300 watts is the biggest i think made by Opus Solutions.
     
  12. saltynay

    saltynay What's a Dremel?

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    well you will want a mini-itx computer board I would reccomend the Commell lv-676 or the commell lv-677 one is mobile Core 2 duo the other is desktop core 2 duo standard 2.5" laptop drives should be fine.

    To seal and cool it you could mount the majority of the pc behind a panel in the boat and seal it up and fill with oil resulting in a pc that is completely submerged. You can then just have a slimline slot loading optical drive mount it behind the panel so all you do is push your disks into the wall and it is read by a pc that is hidden in the hull of the boat
     
  13. dacust

    dacust What's a Dremel?

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    I just got back in town. Wow, more replies and more ideas that I was expecting! THANKS TO ALL!

    I'll respond more thoroughly later as I got to get some sleep before going to work. But here are some quick replies.

    As to salt air and humidity. For the last 6 years I have had nothing but normal household appliances including tvs, vcrs and dvds in the boat. No problems. I figure it DOES shorten the life, but if a computer will last 3-4 years before I have to replace it, that will be fine. I'll want to get something newer and faster by that time anyway. So, I will not worry about sealing a system or doing anything at all about humidity or salt. It just doesn't seem to be a big of an issue to worry about. And definitely not worth the extra cost and effort.

    As for vibration, some of the ideas you have given are good to think about. Maybe I can just use normal drives after all. (But I haven't looked at the link given by identikit, I'll do that).

    I am familiar with the carputer power supplies that jakenbake mentions. Those are the ones that I was referring to when I said I could just use multiples of them for powering a large system. One for the main board, one for drives would probably do it.

    As for cooling, the ideas of using a radiator in various forms is really what I was talking about in using a heat exchanger. For those not familiar with this, it is like a radiator, but instead of a water-air transfer, it is a water/saltwater transfer. A heat exchanger for a small generator is about the size of a soda can. For the saltwater side, I can use a small pump designed for a small A/C unit. They are expensive (about $250), but are specifically designed for continuous use pumping saltwater for cooling. The really expensive part is getting the boat hauled to install a new thru-hull fitting.

    Now to ambient temps and condensation. If the ambient temperature is 120-130 degrees F because the boat has been sitting at the dock in the sunshine, but the saltwater temp is 80 degrees, I could end up with the cooling water below ambient. The idea CronKbot of Doom has of using a thermostat is a good one. Especially in basing the switching on the ambient temperature instead of a set temp. However, the saltwater pumps are normally run continuously, just as the cooling pump in a PC is. I'll just have to see what manufacturers say about how intermittent use affects their pumps. If they are best run continuously, I can put in a thermostat loop like a car has, where the water pump runs all the time, but when the thermostat is closed, it just loops back on itself.

    Since watercooling loops only raise about 1-2 degrees after going over a CPU, 130 degrees should be OK. But I'd really like to get it lower than 130. When running my system here at home I'm seeing temps more like 125. That's why I'm thinking I might need to think about condensation. It wouldn't come into play often, but it wouldn't be just once a year. So this last point is really the one I have more questions about. Does anyone see a problem with the cooling water being as high as 130 degrees once in a while? If it was that, it would just be when cranking up the system before leaving the dock. Within half an hour, the ambient temp would be below 100 probably, either because of opening windows or from turning on the A/C. Or at worst, the temp wouldn't go down until the boat starts moving. Your comments on this would be helpful.

    Once again, thanks so much for all your comments! Dang, I got into this and am staying up later than I should. Gotta install a client for a new SQL server in the morning.
     
  14. tech3312

    tech3312 Where's my dremel o.0

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    i don;t want to sounds like a noob but how bout if ur case is watersealed and have like a valve and drown it in vegeble oil since it is non conductive but there's con to that draining it can be a pain in the ass, next it is is not water sealed oil will leakout and you will have of occasionally check it for any problems with the hardware
     
  15. saltynay

    saltynay What's a Dremel?

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    thats what I was talking about but hiding it behind an actual panel
     
  16. dacust

    dacust What's a Dremel?

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    @ saltynay and tech3312 - In my haste last night I missed this. Believe it or not, I have thought of this. I have one more con to add. If the oil gets up to 130 degrees, it might take a little while to cool it back down. I use the boat all year around. If the oil gets down to 35 degrees, it'll solidify. But maybe I could use engine oil? Mineral oil?

    It would have to be a very sturdy container to survive the bouncing. It's an idea, I'm not totally ruling it out, but I'd rather do it a simpler way if possible. The "cool" factor is definitely there!

    @ soulmage - Pelican case - I had a brain fart on this last night. I googled pelican pc and came up with a ruggedized/weatherized laptop for thousands of dollars. I put this down to it being 2:30am after a 5 1/2 hour drive. I am NOT senile. Hey, WATCH it, I can see you sadly shaking you head, thinking "denial". I repeat, I am NOT senile.

    If I was going to seal it up, the Pelican case idea is perfect, and obviously I had not though of that one. Actually, it's such a clean idea I may go that way anyway. A rugged case, waterproof, built in pressure release. Cool.

    Once again, I got no time. Gotta run to work for a few hours. I'll try to sit down this evening and go over this a little more thoroughly this evening.
     
  17. saltynay

    saltynay What's a Dremel?

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    ok how about you make a wooden rack to hold the components as an internal structure you then make a sealed cube you place the wooden rack and computer inside the cube and drill holes for the optical drive cable, monitor cable and power cable you then fill with vegetable oil then seal the cables with some soft rubber filament. You then do your seawater cooling idea by placing a radiator inside the cube to absorb the heat from the oil and have it routed to the radiator on the outside of the boat, essentially cooling the oil. If your worried about leaks you could then make a second acrylic cube for the original cube to go in.

    Random tangent but if you used the above idea suspended the internal cube using springs to cushion the vibrations, have lights on the inside of the "internal cube" and make the external cube out of acryan one-way mirror acrylic. it would look like a mirror until you turned on the internal lights and then you would see the suspended computer which would look cool
     
  18. tech3312

    tech3312 Where's my dremel o.0

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    DO NOT USE ENGINE OIL!!!! you'll regret it the reason is engine oil is flammable and is conductive even if it's non conductive but still flammble it can explode out of the blue causing damage to the computer injury to yourself and other people and may cause death and if u go out alive ur boat will sirely not i don't kno bout mineral oil what i qould do is take a old electrical meter (I perfer the meter that when u touch the postive and negative meter it moves) and pour mineral oil onto a container and test it or here's my version of vegeble oil that just requires some part apart from the computer componet but to a watercooling store and buy NON-CONDUCTIVE COOLING LIQUID i forgot what was the brand name just send me a picture and i'll see if it works here's trusted website i purchase water cooling componet from (www.frozencpu.com) pump and radiator no tubing required since it's going to be sewaled check out the video =] PM me if u have any questions

    also i mihgt add adding a radiator helps cool some of the heat when it reaches over 100 degree
     
    Last edited: 16 Jul 2007
  19. Cheapskate

    Cheapskate Insane? or just stupid?

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    Most army surplus stores have cases similar to pelican cases. They even have the pressure equilization valves. They make great camera cases.
     
  20. dacust

    dacust What's a Dremel?

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    Thanks. Before doing EITHER I would have researched carefully to make sure it would be OK. BTW, vegatable oil is flameable as well. I would not be too surprised if mineral oil is conductive. But they use some type of oil in transformers that is a low viscocity, non conductive, non-spoiling oil, but it IS flameable (illustrated by what happes when it's hit by lightning). If I decide to go that route I'll just have to find out what type has the properties I need.

    And I agree that frozencpu.com is a good outfit to deal with. (The pump cushioning I used in the WaterPlant project was forzencpu sound mats.) I've bought several things from them. And performance-pcs.com, although I buy most from directron if they have it.
     

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