Boat compressor advice

[Gcsi]

I frequently travel to areas in the Bahamas Via boat that are not supported by dive shops. Rather than carrying 20 tanks on board, I'm considering installing a compressor and would appreciate any feedback offered. So far, my thoughts are as follow:
1) boat has 20kw generator, hopefully enough to power electric compressor, don't mind reducing ships electrical load if required. A self powered unit is not out of the question, however, I'd like a cleaner install and would rather not clutter up the deck.
2) Would like to fill an 80 in about ten minutes
3) In an ideal install, system would be under cockpit deck or inside of engine room
When I last looked at doing an on board install (1996), I recall not being overly impressed with the available options. I'm assuming the technology has come along to make the whole process both easier and safer. Thanks in advance for any help. Brett

 

[CraigAClark]

A 20kw generator will support a maximum of 5 hp @230v, single phase. Bauer wise, you are looking at an Oceanus or CII-E. You may have to turn off AC and other equipment to start the unit. You could install a frequency drive to help with the start up load, which might allow you to run other equipment when the compressor is starting. The frequency drive would have to be oversized to deal with your single phase power. A 3 phase motor is installed on the compressor and the frequency drive "creates" the third power leg. At startup, the frequency drive allows the compressor speed to ramp up over a longer period of time. This reduces the startup load. There isn't any power savings. I would have to check, but you might be able to run a 7.5 hp motor with a frequency drive off of your 20kw. You would need 25kw to start a 7.5hp straight up. Bauer wise, that would be a MII-E, which will get you into the range of 10 minute fills @ 8.4 cfm. However, space requirements may be prohibitive.

 

[Wookie]

I know a number of sportfisherman who use a Mako 5405 or equivalent Bauer driven off a auxiliary drive from the main. The main burns very little fuel at idle, but makes plenty of hP to drive a compressor. Be sure to install a clutch so you can decouple the compressor when you want to go somewhere.

A more expensive but cleaner install is to but a hydraulic pump on the generator or on one main and a hydraulic motor on the compressor. That way you can run the compressor even when you are running a main for propulsion.

Sportfish enginerooms tend to be hot. Heat destroys compressors. My buddy with a Luhrs 36 removed his compressor cooling coils and made custom coils. He ran them in the bilge, and let bilge water cool the coild. You can also get a number of raw water cooling systems from many different vendors and cool your compressor from seawater.

 

[rjack321]

You really don't want a breathing compressor in a hot engine room (in FL no less). Or really in any confined space at all. Is there any way you could make a seperate section for it and air condition that space? If you had a hydraulic drive off your mains you'd have enough generator capacity to cool your new compressor room. Hot installations go through breathing filters rediculously fast on the best of days and make CO and other volatile narcotic gases in your breathing gas on bad days.

 

[Dr Dive]

2) Would like to fill an 80 in about ten minutes

I don't know much about the other specifications, but my LDS can't fill an 80 in 10 minutes. Not for lack of capacity, or reserve pressure, but because the tank would be too hot to touch. I'm not sure you could do it with an ice bath. Once it cooled you would have a short fill. If I'm wrong, let me know, so I can get the LDS to pick up the pace.

 

[CraigAClark]

I don't know much about the other specifications, but my LDS can't fill an 80 in 10 minutes. Not for lack of capacity, or reserve pressure, but because the tank would be too hot to touch. I'm not sure you could do it with an ice bath. Once it cooled you would have a short fill. If I'm wrong, let me know, so I can get the LDS to pick up the pace.

It's all in the compressor output. We are talking 8.4 cfm direct fill and your LDS probably has a storage system. Yes you are going to get warm fills, but not screaming hot. Your LDS's storage system could probably fill a bottle in less than two minutes, but you already know the reason they slow fill. They could also be using a hyper-pure system after the storage, which will give about a 20 minute fill.

 

[Gcsi]

After everyone's comments, I looked into doing a water cooled compressor driven by one of main engines via PTO. To make a long story short, got crazy expensive real quickly. After that reality check, I'm now back to a portable self powered system placed on foredeck (sportfish) or in cockpit. Given the desire to fill an 80 in ten minutes, does anyone have specific recommendations? Brett

 

[spoolin01]

This is an interest of mine as well - one day soon I'll need a compressor on the boat I sail around the South Pacific. So far I've got the compressor...

If you're talking portable, I wonder if 10' fills are realistic. I've got a gas-powered RIX oil-less SA-6 that does around 6 cfm, but I wouldn't want to be moving it around much, it must weigh 125lbs if not more. It has a smaller brother with half the output, SA-3. That one with electric motor I can dead lift myself - with two it could be moved around a boat fairly readily. It draws 11A at 230V, so I'm thinking it might be suitable for the typical cruising sailboat's generator. 20 or even 30' to fill an 80 should be fine unless you're outfitting a large crew on multi-dive days.

 

[clownfishsydney]

I think you will find that even the smaller one will not run powered by a sailboat generator. We had a Bauer Junior II on a cruiser with a 5kw genset. It would turn over the Junior II but that is it. The Junior II motor is 2.2kw. Seems they need much more for initial starting grunt.

 

[Dondon462]

I have the upgraded Stainless frame 220v Bauer Junior II for boats, with a sump that allows 15degree angle opperation on my currrent boat "ICE", fills 80 in 20 minutes and I just have it in a deck locker aft with special screw out side pannels for ventilatation..you must keep them cool..so to opperate I just lift the locker lid, unscrew the side pannels beside the cooling fans and electric motor and we are away...very easy and it is still portable if needed, as I have the power outlet plug in the deck locker...I use a similar unit with petrol engine as backup and for onshore camps..have used Bauer of all sizes all my life, but ... Shift+R improves the quality of this image. CTRL+F5 reloads the whole page.for fun I just bought two reverse engineered Bauers?? built in China!!...don't ask me??..I have not tried them yet??..still on a ship...