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Old 25-02-2003, 09:59   #1
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Compressor on Board

I'm equipping my catamaran with a scuba compressor.

Any suggestions on what model to buy to supply 6 divers for 3 dives a day?

I would prefer a diesel or electric engine.
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Old 31-01-2008, 19:37   #2
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I would like to hear what other people are doing as well.
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Old 02-02-2008, 06:18   #3
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Bauer & Mako are the best ones , I was in the dive bussness for 10 years running dive charters from Palm Beach to the Abacos, I used to haul 30-40 tanks onboard then the last year I was doing it, I broke down and bought the Bauer. The troble with a portabule Air compressor is they take about 35 min to fill a -80 cubic ft tank from empty -and mine had a 5 or 6 hp honda engine that is plenty loud . And you have to let them rest between tanks or you will burn them up-You will really need a bigger michine with a bank to fill as many tanks as you have in mind.
These small Compressors are not cheap I think I paid about $3500 for it, You would need the next size or two up at more then double the $ and dont buy the off brand they dont hold up well .

I regully had 6 divers onboard for 4-5 days at a time and what i found out is after this first day of dive dive dive most everyone was only doing 2 dives a day- tops- and I would put them on a shallow reef for them to snorkel wile I filled the tanks.

BUY the big Ele modle and install a bank thats the only way your gonna make it work for 18 tanks a day , I think your looking at about $15-20 K for the set up (just gessing on the cost )
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Old 02-02-2008, 09:51   #4
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The math is cfm by cf per tank
say 5cfm by 80 cf

The problem is that the higher the psi the longer it takes to get there, a tank filling off a compresser doesnt fill at a steady rate.
The first half fills quick the the process slows down.

some info about size/price
Bauer Portable Compressors

18 tanks a day with out a cascade system means some will be filling tanks allday.
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Old 02-02-2008, 12:17   #5
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Give some thought to steel tanks as well. Lower PSI faster fills much fewer weights needed for divers and lost by divers..... I agree it will be seldom to never that you have 6 divers diving 3 tanks everyday but if you offer it you better have it....
Take a couple trips on some of the big live-aboards and have a look around and talk to the crew .
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Old 02-02-2008, 12:25   #6
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JRII-G4.33.65.0Gasoline
Engine
30-14-1792
$4251


I have this one and it puts out 4.3cfm and its not really enough for what your doing. I have only about 25-50 hours on it and will sell it for $2500
if you want a used one, I really think you need a 6cfm one
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Old 02-02-2008, 18:10   #7
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As a long time lurker gaining very valuable info for my own cruising plans finally a thread that I can pass on some info.
If you will be filling 12 tanks a day you need a comperssor that is rated for continious service, You will also want an auto dump water seperator. You will find that a diesel combo will be too heavy, too noisy and a pain to lug around. This means an electric compressor, with some sort of 'soft start' on the motor, mounted in an engine room with a big fan and good ventilation. Banks are going to be too heavy for a FP 43 and you don't have room anyway, You will want at least two fill wips so you can keep the compressor running when filling multiple tanks....the two main compressor killers are heat and short run cycles. You will also want a high capacity filter or bank of filters if you dive anywhere with a humid climate. Don't use steel tanks, you will get moisture inside them eventually and then they'll rust. Compressors like that final 1000psi/60BAR so no advantage with low pressure tanks.
All this is going to take alot of commitmant and will be very spendy. If you will be diving in areas where you can get air fills from a shop it will always, always, always be more economical to get fills from them.
Having said this when I get my Cat it will have an engine room mounted electric Rix SA6 or Bauer Jnr, triple Lawrence Factor filters (2 moisture 1 combo) and 2 double manifold fill wips with check valves.
Hope this helps. Jonny
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Old 02-02-2008, 18:23   #8
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Lots of people in Florida and On Cozumel ( all over the world actually) are diving Steel tanks. They are not for your average knuckle-headed neophyte or Tourist but actually have a lot for positives for real divers and those who take care of their belongings.
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Old 02-02-2008, 19:05   #9
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Hi Coz.
No, there's nothing wrong with steel and as long as I was filling them myself I'd be happy to use them. The trouble comes from getting fills from poorly maintained compressors that have a broken auto drain, broken hour meter and waterlogged filters.
I love to dive with steel tanks, in fact I've just been diving today with my favorite 40 year old steel tanks.
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Old 02-02-2008, 20:20   #10
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fishpie: wouldnt it be faster pumping 100 cu ft at lower psi because the last 1/3 at the higher pressures takes as long as the first 2/3's
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Old 03-02-2008, 02:30   #11
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"How to Select a SCUBA Tank" ~ by Dive Rite* Fill Express, LLC
This is a detailed article focused on helping select the best SCUBA tank for their specific needs and styles of diving.

Includes: Tank Definition, Tank Choices, The Big Lie About Capacity, Sport Diving with Air, Sport Diving with Nitrox, Technical Diving, Aluminum versus Steel, Low-Pressure versus High-Pressure, Yoke and DIN Valves, Dimensions, Paints, Coatings, and Finishes, Manufacturers, Recommendations

Goto:
Dive Rite Express -- How to Select a SCUBA Tank

* Dive Rite Express sells “Luxfer” Aluminum and “Worthington” Steel gas cylinders, and more.
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Old 03-02-2008, 05:23   #12
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If you are really going to be doing 3 dives a day for 6 people on a regular basis then that is quite a commitment in space and weight, but if only occasionally then renting additional tanks for the dive trip makes more sense.

Key issues to consider in choosing a compressor:
Make sure the compressor has an oil pump rather than just scavenging from a small sump as the scavenging type will not tolerate as much incline and movement underway. On the Bauer’s I think the Junior just scoops up and the Oceanus has an oil pump. Check to make sure.

On all 3 stage compressors an important wear factor is if you are continually cycling thru the stages by filling empty tanks. That’s why the commercial guys have a cascade system to bulk fill and keep the compressor working in the upper stages. You can help matters by having an extra set of dive tanks and use them to keep the compressor working in the higher stages by cascading into the empty tank.

I would pretty much default to an electric version because of the noise and fumes in such a small environment. Depending on the model you select make sure you can service your filters by using bulk materials rather than buying the much more expensive proprietary cartridges.
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Old 19-02-2008, 17:02   #13
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What a conversation, I used to own a dive shop… a million years ago in a galaxy far far away.…

I used to have a big Bauer compressor ran on three faze power no way you could put that beast on a sail boat under 100ft….


So how much would you budget for you compressor say one large enough to handle 4-6 fills in a day (figure something like 2 hours of running) would you go Gas, diesel or electric?
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Old 20-02-2008, 04:24   #14
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I am still contemplating, but thinking the Bauer jnr. But I am only looking to fill tanks for two divers.I am still not sure if the diving in remote areas will be worth the extra weight hassle of compressor and gen set to drive it, maybe better just to carry a bunch of tanks, and fill them when convenient. Did a lot of diving off the boat when based at Bougainville Island in PNG. No on board compressor but took upto 12 tanks for a weekend for 4 divers. Many divers gradually changed out their 80's for 60's, I did too and never went back as the in the warm water consumption wasn't a problem, dives actually became shallower, around 10-15m with experience, unless there was a wreck or real good reason to go deep and the smaller 60's were just so much nicer to live with.

Anyone been down this path and have a comment on the pros & cons of going the compressor route ?
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Old 07-04-2008, 13:42   #15
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First off all I am a scuba instructor and have been scuba diving for 21 years. The last 14 years as owner of scuba diving store and also a compressor technician for Lenhart & Wagner, Bauer, Coltri and other brands.

As of the discussion on filling 200/300 bars, concerning filling time and filling rate. The first 100 bars are slowest then the pressure fills faster and faster. This due to the compressibility factor of air.

A higher pressure give higher temperature on the last stage butt the advantage is faster filling time if you don’t start on zero bar (for example 50 Bar left as many scuba centers recommend or demand).

One installation method in boats (if one mount or have hydraulics) is to use a hydraulic ”engine” on the compressor run from a hydraulic output from one of the engines. If this is from the same you charge the battery bank you can cower the to aspects in the same time.

As to heat a smaller compressor running on higher rpm (then a bigger one) will eventually need to have a cooling period if you will fill many bottles. Even a storage tank need filling and at a scuba diving shop we can sound insulate and have that running at night but on a boat that will not be possible. And heat need to be vented from the compressor space.

At Lenhardt & Wagner GmbH you will find the cooling requirements for all deferent’s (size) compressors. Like a L&w 100 minute/liters need 660 M2 air for cooling with electrical motor. A hydraulic system don’t need that much cooling though.

Concerning capacity if you cont on the bottles being 50 bars left on a 10 liters 300 bar bottle you need to fill 250 bars or 2.500 liters to fill it on a small compressor like Bauer Junior (100 M/L) you will need 25 minutes (and some more for venting filters every 10-20 minutes. That gives approx 6 hours filling time for 12 bottles. A 225 minute liters compressor will do the work in approx 2 hours and 10 minutes (that is a big different and a lot less wear on the compressor)

A bigger compressor gives higher weight and more electricity (16 amps 1 face for the 225 for example) or bigger hydraulic system.

All in all it come down to ones need and how much money one need to spend. But a good rule is that a smaller system for many filling will cost you the same price as a bigger systems, giving it a few years in the running, do to wear and replacements.

My home page is Polardykk BodÝ AS (sorry for a old fashion site, but I rather go scuba diving and work on repairs then construct web pages hehe).

Erik
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