Installed or portable in 42' sailboat?

[wwunder]

It sounds like you are going to spend a lot of money on equipment to rig the compressor to run on electricity... Aren't you burning gas or diesel to run the generator??? You still have to make sure that your intake is well clear of exhaust and carry enough fuel to run the thing. Plus you are compounding inefficiencies. Converting mechanical motion to electricity, transformers, frequency drives, and then converting back to mechanical motion involves so many steps with inefficiencies at each one.

What about looking into getting a compressor with a combustion engine that matches the fuel type on board? You can then either run a fuel line to the engine (similar to an outboard motor) or use portable tanks to refill. Run the intake up the mast to a suitable height and start filling tanks.

Also, if that mako compressor of yours is rebranded bauer, it may well be worthwhile fixing it up. Fill it with oil and fire it up it may surprise you, they seem to last forever.

 

[rjack321]

As I see it the Rix has the advantage of not burping out an oily mess every 15 mins and doesn't need a filter stack.

Nooooo. You still need to drain condensed water and you need a filter. It needs to have enough dessicant to dry your gas properly unless you want rusty and/or corroded tanks. You are running a generator nearby. If this is a diesel genset you need AC to remove the exhaust odors. If its a gas generator you need hopcalite to remove CO. You may be anchored near other boats with other exhausts as well.

So the best solution is to get a triplex filter and be done with it.

Both compressors need to be brought on deck to run. Your engine room is going to be too hot and lead to all sorts of problems.

 

[Fishpie]

Wwunder.
There's a permanently fitted Westerbeke 5kw ac diesel generator already onboard with internal 130 gal fuel tank, I don't think there's a "portable" diesel powered compressor that weighs less than 250 lbs that can be stored and moved around on a medium sized sailboat like a Valiant.
My hope is that if I'm running the gen set to charge the house batteries I can also fill a tank or two at the same time.

rjack321
I realize that the Rix has a condensate drain like the Bauer but it will be straight fresh water and not the smelly emulsified oil/water mess that comes out of a regular compressor that has to be collected, stored and disposed of responsibly. I know of several yacht owners running a Rix straight (no filter) and using aluminium cylinders without any problems. I agree that I couldn't use steel tanks. The compressor would be run at anchor with the intake well above and upwind of the generators exhaust. But I would also have to agree with you that proper filtration is a necessity.

 

[CraigAClark]

Thanks again Craig.
Let's see if I am understanding you correctly.
I will be able to run the 115v 2hp version of the Jn II with no mods directly from a 5 kw gen set.
To reliably use the 3hp version (with the higher output) I'd need to use a frequency drive.
There is no way that a 5kw gen set will ever power a 5 hp motor with all the fancy controllers and drives in the world.

This leads me to yet more questions.
Once the compressor is up and running, do you think I will be able to charge the house bank at the same time?
Which would you recommend SA-3 or Jn II?.....not to put you on the spot or anything!
As I see it the Rix has the advantage of not burping out an oily mess every 15 mins and doesn't need a filter stack.

I'm not sure that you will be able to run the 2hp straight up, you would have to try it. I was thinking that you should be able to run the 3hp with the frequency drive, but it will have to be 230VAC.

Craig

 

[Fishpie]

Here's my latest thoughts.
I think I've narrowed the choice down to 2 systems/units.

The number one option would be for an electric SA-3 or Jn II if, and it's a big IF, I will be able to charge the boat batteries at the same time (3 4D AGM's in the house bank plus 2 smaller AGM's for engine and gen set).
If I can't do this I can't really see the point of going the electric route.

Option number two would be for a gas SA-6 with external fuel tank which pumps more than twice the cfm's of the smaller units.
The external tank will allow the unit to be stored below with no gas in the engine. I could use a regular outboard tank with quick disconnect as the fuel tank.
The downside to this is it's 150lbs and 33" by 18" by 19" lump to move around and store.

Craig, I know I'm putting you on the spot again, what do you think?

 

[CraigAClark]

Thanks again Craig.
Let's see if I am understanding you correctly.
I will be able to run the 115v 2hp version of the Jn II with no mods directly from a 5 kw gen set.
To reliably use the 3hp version (with the higher output) I'd need to use a frequency drive.
There is no way that a 5kw gen set will ever power a 5 hp motor with all the fancy controllers and drives in the world.

This leads me to yet more questions.
Once the compressor is up and running, do you think I will be able to charge the house bank at the same time?
Which would you recommend SA-3 or Jn II?.....not to put you on the spot or anything!
As I see it the Rix has the advantage of not burping out an oily mess every 15 mins and doesn't need a filter stack.

You would have to see if the load of the charger, combined with the FLA draw of the compressor/frequency drive combo would exceed the power supply load capacity. When you are right at the minimum genset size, sometimes you have to sacrifice having other loads on at the same time, like AC.

You have to be careful with judging whether you need additional filtration or not with a RIX, as the air it produces is only as good as the air it takes in! Filters will often times take care of CO and CO2 that might have been drawn in the intake.

Craig

 

[Scuba Duck]

5 HP = 3.73 KW, so technically the running load of the motor is within the range of the generator. It is the starting load that will cause you problems. Also keep in mind that this 5 HP is the max rating of the motor, a motor that turns against no load draws almost no power at all.

There are a couple neat things you can do with a 3 phase motor and a VFD. We've covered VFD's in this Forum before.

1) soft start, the VFD slowly brings the motor up to the desired speed, this minimizes the current associated with starting the motor. The difference between the speed of the motor and the frequency of the supplied AC is called slip. When you first start a motor, it is not turning, so there is an enormous amount of slip between the motor and bus frequency. This slip is what drives current through the motor, and this current is what provides the power to turn the motor. Most VFD's are programmable so you can ramp up the motor speed over whatever time you want. If you brought the motor up to speed over 15 seconds, there would be essentially no starting surge.

2) You can run the motor at whatever speed you want. If you run the motor at less than 60 hz, it turns slower, does less work, and draws less current. The rate you pump air goes down, but it will still pump to the desired pressure.

Keep in mind that the VFD stuff applies to the motor only, if you have electronic controls, they might not take kindly to a reduced requency.

 

[Fishpie]

Thanks for all the advice everybody.
Here's what I went for.
Rix SA-6 with Subaru/Wisconsin/Robin 7.5hp gas engine with remote fuel tank.
It would have been nice to be able to use an electric powered unit....but only if I could have charged the house battery bank at the same time. I did not have the luxury of being able to try out an electric unit and seeing if it would work.
As to the filter issue, I probably will not use any. I will use an extra long inlet hose (with very secure fittings) with the inlet filter 15' up the mast and up wind of the gas engine. I haven’t filled any tanks yet (in fact I am still waiting on the Rix to be shipped) but will test for moisture by filling an an AL80 a whole bunch of times and then looking inside for condensation.

 

[veriqster]

As to the filter issue, I probably will not use any. I will use an extra long inlet hose (with very secure fittings) with the inlet filter 15' up the mast and up wind of the gas engine. I haven’t filled any tanks yet (in fact I am still waiting on the Rix to be shipped) but will test for moisture by filling an an AL80 a whole bunch of times and then looking inside for condensation.

I hope you NEVER come to regret gambling your life over 8-12 benjamins. Even air that is OK to beathe at the surface can cause unexpected issue at depth, just read some more on these forums.

 

[Fishpie]

I really don't consider it much of a gamble.
Since the Rix is an oilless compressor it is impossible for the compressor itself to produce any CO or CO2.
The only source of contamination is the air drawn from the inlet. The compressor will be used on a sailboat at anchor (remote, probably deserted anchorages). With the inlet 10' to 15' up the mast or forestay
and the petrol engine below and downwind.
As long as there aren't any holes in the inlet hose, its fittings are tight and I don't fill when there is no wind (all simple to check) I think the risk of introducing poison gasses is acceptably remote.