My uncle just bought at 50' boat in the Carribean and I am going to be heading up the crew. I am a DM and am beyond excited about the prospect of sailing around the Carribean and doing all the diving I want, but I am now realizing that we need a compressor and tanks. There will be max 4 people diving off the boat, so we don't need anything big, but we want something that will do the job reliably. So, does anyone have any recommendations? The boat is located in St. Maartin, and we will have to buy the compressor somewhere in that area. How much should we expect to spend? Any brand or model recs? Thanks so much for your help!
compressor for sailing
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Don Burke
Contributor
I've heard good things about both of these outfits:
http://www.tankfill.com/
http://www.bauercomp.com/
There are quite a few others.
The Curly One
Registered
It may be inappropriate for me to post this here but you have asked. I believe the ALKIN is the best portable compressor made. You can run them 8 hours a day if you want to and it will not hurt them. I have some on sale right now and some of my customers are on this forum, maybe they will chime in with their opinions.
If you would like to know why they are the best then e-mail me. Thanks, Bruce
If you would like to know why they are the best then e-mail me. Thanks, Bruce
pescador775
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Margo, there is nothing special about a compressor for a sail boat as opposed to a power boat. Unless the boat has a humungous 220V genset you will want a compressor powered by a gas or Diesel engine. The compressor should weigh about 100 pounds or less and have an output of 3.5-4.0 cfm. If the compressor uses cartridges for the final filter you will want to pick up a half dozen with the basic package, all depending on the length of the trip, of course. Bring gas cans and compressor oil also. Make sure that the unit comes with an intake hose or snorkel as exhaust gas is toxic. Always orient the engine exhaust downwind.
The Alkin is a nice unit but may not be available in the Carribean. The Bauer Junior II, while more expensive, may be the most practical option in that area.
My portable compressor is built up from a military surplus 4 stage Kidde aircraft pump and B&S engine. I was testing it the other day and performance of the carefully rebuilt 40 year old Kidde is still pretty amazing at 4.5 cfm, true FAD, cold fill. (The Kidde is rated 4.0 cfm "minimum"). The entire compressor consisting of full steel crash frame, pump, drive gear, two condenser/filters, 5 hp engine, whip, valves, etc is 85 pounds. I take pride in having the highest output, lightest weight compressor available, and is basically home made, or at least home assembled. Even the expensive Bauer Oceanus, at 110 pounds gross wt and 4.0 cfm cannot match the Kidde performance except when running at 4500 psi continuous, something that portables are seldom used for. Of course, the build-it-yourself route is not for everyone. I'm sure that you will find something suitable for your needs.
One thing I've noticed about the industry. Most mfgrs make outrageous claims about the compressor performance. They either predicate the output on filling an "80" (77.4) tank from 500-3000 psi or tie their performance claim to a hot fill. Bauer does both of these. I own a Bauer Capitano advertised as 5.1 cfm (FAD). I know from testing that number is a hot fill rating. On the same basis, my little Kidde is pumping 4.9 cfm (measured while filling hot tank). That means that the Kidde, at 1/3 the weight of the monster Capitano, is pumping almost as much air. The difference is about 1 minute for filling the average tank. Small high revving compressors like the Kidde are said to have shorter lives. Possibly, but the Kidde was built with cost as no object, these being used in jet aircraft. I know of one that is still pumping with 6000 hours on the clock. However, I would expect average life to be about the same as Bauer, around 2-3000 hours. I'm just rambling. Been working on that hummer since Feb (I work slowly but exceeding carefully, heh), and now it's perfect(famous last words).
The Alkin is a nice unit but may not be available in the Carribean. The Bauer Junior II, while more expensive, may be the most practical option in that area.
My portable compressor is built up from a military surplus 4 stage Kidde aircraft pump and B&S engine. I was testing it the other day and performance of the carefully rebuilt 40 year old Kidde is still pretty amazing at 4.5 cfm, true FAD, cold fill. (The Kidde is rated 4.0 cfm "minimum"). The entire compressor consisting of full steel crash frame, pump, drive gear, two condenser/filters, 5 hp engine, whip, valves, etc is 85 pounds. I take pride in having the highest output, lightest weight compressor available, and is basically home made, or at least home assembled. Even the expensive Bauer Oceanus, at 110 pounds gross wt and 4.0 cfm cannot match the Kidde performance except when running at 4500 psi continuous, something that portables are seldom used for. Of course, the build-it-yourself route is not for everyone. I'm sure that you will find something suitable for your needs.
One thing I've noticed about the industry. Most mfgrs make outrageous claims about the compressor performance. They either predicate the output on filling an "80" (77.4) tank from 500-3000 psi or tie their performance claim to a hot fill. Bauer does both of these. I own a Bauer Capitano advertised as 5.1 cfm (FAD). I know from testing that number is a hot fill rating. On the same basis, my little Kidde is pumping 4.9 cfm (measured while filling hot tank). That means that the Kidde, at 1/3 the weight of the monster Capitano, is pumping almost as much air. The difference is about 1 minute for filling the average tank. Small high revving compressors like the Kidde are said to have shorter lives. Possibly, but the Kidde was built with cost as no object, these being used in jet aircraft. I know of one that is still pumping with 6000 hours on the clock. However, I would expect average life to be about the same as Bauer, around 2-3000 hours. I'm just rambling. Been working on that hummer since Feb (I work slowly but exceeding carefully, heh), and now it's perfect(famous last words).
My-way
Contributor
Bruce,
What is the capacity/kilowatt rating of the electric motor pictured?
What is the capacity/kilowatt rating of the electric motor pictured?
The Curly One
Registered
ALKIN rates the portable W31 compressor at 3hp, 2.2 KW and I think it draws 12.7 amps or less.
As for some of the manufacturors grossly overstaing their performance figures is kind of a pet peeve of mine. One is claiming 4.3** SCFM and actually produces less than 3 CFM and it is a hot fill because the thing is turning 2800 RPM and has very little cooling coils. And to top it off the thing is noisy!
I have measured 6 ALKIN compressors on the same day and they all put out 3.3-3.4 or better actual. At sea level on a fairly dry day they should produce the 3.5 we advertise. Unless you live in Denver Colorado your results will be close to mine. When I tested them we used a 80 cu ft SCUBA tank that was COMPLETLY empty and filled it, we drained the moisture separator as needed which was on a very humid day. If I used the same figures and formula for ** SCFM as some people do then no telling what the ALKIN would put out! If it does not fill an 80 cubic foot tank from completly empty in 18.6 minutes it aint no 4.3 CFM!
I have mesured the air temperature going into the purififer at less than 10* warmer than the intake air. The ALKIN has over 40 feet of Stainless Steel cooling coils and that really helps to draw the moisture out of the air and to give you less of a "Hot Fill" There is some heat created when the tank is being filled and pressurised you certainly do not need to add more heat from the compressor to.
I had one customer tell me he decided to buy a different brand because they put out 4.3** SCFM, I thought boy if he only knew.
I have had atleast two customers that I know of sell their 4.3** SCFM compressor to buy one of the ALKIN's and now they are happy customers. They asked me if I would take them in trade and I just had to say I was not interested in them at all. The ALKIN's are factory approved to run for up to 8 hours straight if needed and fill cascade systems. Sure it is a workout for a compressor but ours will handle it if needed. Some of the others say "30 minutes maximum or one SCUBA tank only and no cascade tanks."
The ALKIN also has a pretty nice fill whip that swivels and has a filling valve that fits BOTH the 300 DIN valve and the standard SCUBA valve. The filling valve has a lever that when open fills your tanks, when you close the valve it releases the pressure in the fitting ONLY so you can start filling your next tank with out having to drain and re pressurise the whole system. They have a lot of nice features but to me the biggest thing is how quiet and smooth they are. (electric models) Our gas motors are as loud as everyone elses motors. Sorry, I will get off of my soap box now.... Curly
As for some of the manufacturors grossly overstaing their performance figures is kind of a pet peeve of mine. One is claiming 4.3** SCFM and actually produces less than 3 CFM and it is a hot fill because the thing is turning 2800 RPM and has very little cooling coils. And to top it off the thing is noisy!
I have measured 6 ALKIN compressors on the same day and they all put out 3.3-3.4 or better actual. At sea level on a fairly dry day they should produce the 3.5 we advertise. Unless you live in Denver Colorado your results will be close to mine. When I tested them we used a 80 cu ft SCUBA tank that was COMPLETLY empty and filled it, we drained the moisture separator as needed which was on a very humid day. If I used the same figures and formula for ** SCFM as some people do then no telling what the ALKIN would put out! If it does not fill an 80 cubic foot tank from completly empty in 18.6 minutes it aint no 4.3 CFM!
I have mesured the air temperature going into the purififer at less than 10* warmer than the intake air. The ALKIN has over 40 feet of Stainless Steel cooling coils and that really helps to draw the moisture out of the air and to give you less of a "Hot Fill" There is some heat created when the tank is being filled and pressurised you certainly do not need to add more heat from the compressor to.
I had one customer tell me he decided to buy a different brand because they put out 4.3** SCFM, I thought boy if he only knew.
I have had atleast two customers that I know of sell their 4.3** SCFM compressor to buy one of the ALKIN's and now they are happy customers. They asked me if I would take them in trade and I just had to say I was not interested in them at all. The ALKIN's are factory approved to run for up to 8 hours straight if needed and fill cascade systems. Sure it is a workout for a compressor but ours will handle it if needed. Some of the others say "30 minutes maximum or one SCUBA tank only and no cascade tanks."
The ALKIN also has a pretty nice fill whip that swivels and has a filling valve that fits BOTH the 300 DIN valve and the standard SCUBA valve. The filling valve has a lever that when open fills your tanks, when you close the valve it releases the pressure in the fitting ONLY so you can start filling your next tank with out having to drain and re pressurise the whole system. They have a lot of nice features but to me the biggest thing is how quiet and smooth they are. (electric models) Our gas motors are as loud as everyone elses motors. Sorry, I will get off of my soap box now.... Curly
pescador775
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Compressor cooling, and hence air cooling, is a function of air flow, oil flow, cylinder and crankcase material, cooling fins, cooling coil design and material, and ambient temp. Oh yes, and the (crucial) number of compression stages. Take for example the Kidde military surplus pump. The entire thing is aluminum. Even the finned cooling coils, of which there are 4 sets with total length of about 5 feet, are aluminum and hard copper construction. The Kidde's expensive finned alloy cooling tubes make maximum available use of space. These cooling coils are about 5-10 times as effective as plain steel or stainless steel tubes per given length of tube. Further cooling takes place in the two condensators. Air discharged at the compressor output pipe is cool to the touch, and this is at 4 cfm+, 72 deg ambient.
It should be explained that the principal factor which causes tank heating, regardless of compressor brand, is air compression in the fill tank, not the temp of air coming from the compressor. The manufacturers do consider it desirable to cool the air flow to keep the cylinder temps reasonable and to enhance the efficiency of the water condensation system. Hence, adequate cooling of the air flow is designed in consistant with costs and available space.
It should be explained that the principal factor which causes tank heating, regardless of compressor brand, is air compression in the fill tank, not the temp of air coming from the compressor. The manufacturers do consider it desirable to cool the air flow to keep the cylinder temps reasonable and to enhance the efficiency of the water condensation system. Hence, adequate cooling of the air flow is designed in consistant with costs and available space.
The Curly One
Registered
I agree with much of your opinion. Much of the heat is actually the compression of the air in the tank. But if you are putting air that is 40* or more hotter than ambeint air temp you are compounding the problem. A well designed compressor will not add that much heat to the air. The air is heated when ever it is compressed whether it is in the compressor or the tank but a good compressor will remove much of that heat and not just pass it on. I also agree that the aluminum fins wrapped around the tubing helps the tubing cool more effeciently. ALKIN is now using a similar design on their larger compressors to help with the cooling. A simple yet effective way of multiplying the surface area of the cooling coils. Curly
IMHO you can't go wrong with a Bauer. We ran our own sail/dive charter from our 43' sailboat in the Bahamas for a couple of years using a Bauer 8cfm with twin fill whips. Basically, it took us about 10 minutes to fill two tanks from 500 psi.
Our Bauer was gas powered and mounted forward of the main mast. When we did a fill we basically hoisted the snorkel partway up the mast with a halyard in order to prevent any contamination from the motor.
You can certainly get good used Bauers in the FL area for much less than a new unit. However, it's imperative that they were well-maintained. Low hours are also a plus.
Meanwhile, I agree with Pescador: unless you have a big genset onboard, I would NOT go with an electric unit; it just uses waaaaay too much power.
PM me if you want more info.
~SubMariner~
Our Bauer was gas powered and mounted forward of the main mast. When we did a fill we basically hoisted the snorkel partway up the mast with a halyard in order to prevent any contamination from the motor.
You can certainly get good used Bauers in the FL area for much less than a new unit. However, it's imperative that they were well-maintained. Low hours are also a plus.
Meanwhile, I agree with Pescador: unless you have a big genset onboard, I would NOT go with an electric unit; it just uses waaaaay too much power.
PM me if you want more info.
~SubMariner~
pescador775
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I know that some out there have bought military surplus pumps and sometimes I wonder how they made out. Were they put in service or gathering dust?
Before assembling a compressor it is usually necessary to assess and, if necessary, repair the used pump. Here are my experiences with inspection and repair of 4 air force surplus Walter Kidde pumps, model 890228M, all purchased via EBay.
One pump was in excellent condition. Estimated hours, less than 1000. Although looking to be rough and 'beat up' on the exterior, inspection revealed that many parts, including springs and valves, even the head bolts, were new. Since all safety wires were in place it was obvious that this unit had been rebuilt by the military and not put in service. Tests showed outstanding performance. Cosmetic problems on this and other pumps were easy to fix. The cooling fins and cylinder fins are soft aluminum and can be straightened. Usually, a touch up paint job and that part is done.
A second pump had been rebuilt by a private party and showed acceptable performance. No particular repair was needed although some cosmetics were improved.
Number three appeared almost brand new. However, tests indicated problems. Inspection showed that the #3 and #4 plungers were stuck and the first stage intake valve was warped. The valve was replaced and the plungers freed up. There was a large quantity of black 'crud' inside the cylinders and oil tank. This compressor had been fed Anderol 500 by a previous owner and the oil was the cause of the sludge. All was cleaned and the compressor tested. Tests showed more problems. I had missed some sludge somewhere as the third stage filter screen clogged up right away causing the 2nd stage relief to sound off. Also, the third stage plunger was stuck again. During initial inspection and repair I had missed a tiny bit of corrosion on the upper cylinder wall. Scouring with crocus cloth, general cleaning, reassembly and the compressor tested excellent. Estimated hours on this pump, less than 500.
The fourth compressor looked a bit rough and dirty but cleaned up nicely. No cylinder fins were bent but the cooling tube fins had to be straightened and painted. Tests indicated excellent air output but blowby was evident so a flow meter was hooked up. Blowby was 0.4 cfm @ 3000 psi and 0.6 cfm @ 3500 psi, clearly out of spec. Inspection showed that the fourth stage was worn slightly. This problem is pending. I have made arrangements to have the fourth stage plunger plated with hard chrome. This will be done by a friend of mine to prevent communications problems. The chrome plating requires a light touch and hand fitting to the cylinder. The allowable clearance is only 0.0003 which is a pretty tight fit and in this case indicates only about 0.0002 needs to built up on the plunger. Generally, if the plunger and cylinder are completely degreased and cleaned it should take about one pound of thumb pressure to insert the plunger. In this case, the plunger would fall from the cylinder when held in the vertical, definitely too loose. I estimate that this pump had 2000 hours on the clock.
I did lots of other stuff, like inspecting oil pumps and checking pressures, replacing soft parts like seals, etc. However, the purpose of this post is to give interested parties a flavor of the experience. I will be around from time to time should questions arise.
Before assembling a compressor it is usually necessary to assess and, if necessary, repair the used pump. Here are my experiences with inspection and repair of 4 air force surplus Walter Kidde pumps, model 890228M, all purchased via EBay.
One pump was in excellent condition. Estimated hours, less than 1000. Although looking to be rough and 'beat up' on the exterior, inspection revealed that many parts, including springs and valves, even the head bolts, were new. Since all safety wires were in place it was obvious that this unit had been rebuilt by the military and not put in service. Tests showed outstanding performance. Cosmetic problems on this and other pumps were easy to fix. The cooling fins and cylinder fins are soft aluminum and can be straightened. Usually, a touch up paint job and that part is done.
A second pump had been rebuilt by a private party and showed acceptable performance. No particular repair was needed although some cosmetics were improved.
Number three appeared almost brand new. However, tests indicated problems. Inspection showed that the #3 and #4 plungers were stuck and the first stage intake valve was warped. The valve was replaced and the plungers freed up. There was a large quantity of black 'crud' inside the cylinders and oil tank. This compressor had been fed Anderol 500 by a previous owner and the oil was the cause of the sludge. All was cleaned and the compressor tested. Tests showed more problems. I had missed some sludge somewhere as the third stage filter screen clogged up right away causing the 2nd stage relief to sound off. Also, the third stage plunger was stuck again. During initial inspection and repair I had missed a tiny bit of corrosion on the upper cylinder wall. Scouring with crocus cloth, general cleaning, reassembly and the compressor tested excellent. Estimated hours on this pump, less than 500.
The fourth compressor looked a bit rough and dirty but cleaned up nicely. No cylinder fins were bent but the cooling tube fins had to be straightened and painted. Tests indicated excellent air output but blowby was evident so a flow meter was hooked up. Blowby was 0.4 cfm @ 3000 psi and 0.6 cfm @ 3500 psi, clearly out of spec. Inspection showed that the fourth stage was worn slightly. This problem is pending. I have made arrangements to have the fourth stage plunger plated with hard chrome. This will be done by a friend of mine to prevent communications problems. The chrome plating requires a light touch and hand fitting to the cylinder. The allowable clearance is only 0.0003 which is a pretty tight fit and in this case indicates only about 0.0002 needs to built up on the plunger. Generally, if the plunger and cylinder are completely degreased and cleaned it should take about one pound of thumb pressure to insert the plunger. In this case, the plunger would fall from the cylinder when held in the vertical, definitely too loose. I estimate that this pump had 2000 hours on the clock.
I did lots of other stuff, like inspecting oil pumps and checking pressures, replacing soft parts like seals, etc. However, the purpose of this post is to give interested parties a flavor of the experience. I will be around from time to time should questions arise.
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