Compressor for now and later?

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jlcnuke

Contributor
Scuba Instructor
Divemaster
Messages
874
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934
Location
acworth ga
# of dives
500 - 999
So, sometime in the next 3-5 years my plan is to buy a sailboat (monohull) in the 38-46' range. Probably a production model like a Jeanneau 469, 439 or equivalent (depending on what's on the market when I go to buy in my price range). At that point I'm 100% certain I want to put a dive compressor on there. Based on my research so far I'm thinking a gas powered MCH-6, Bauer Junior II, or similar model.

In the meantime, with some overtime coming up, I'm thinking it might be a good time to pick up the compressor and use it on dry land for a while to begin with. As such, I have a few questions for anyone knowledgeable on the subject I'm asking about.

1. Any other recommended models for that range of size monohull production sailboats?
2. Any thoughts on future mounting/storage locations? I'm not expecting to have a big engine compartment so lockers or in an enclosure by the mast are thoughts I'm having now? Maybe some sound-proofing thoughts to minimize the chance of bothering others in an anchorage if using it near others?
3. Are there any relatively cost effective options for using it to blend nitrox, deco stages, and/or trimix for the next 3-5 years (clearly I won't have the space to store a ton of O2 or Helium once on the boat, but I have garage space etc. until then)? Assuming I get proper training/understanding of how to do such things safely before attempting obviously.
4. Any other considerations I should take into account based on your experiences?
 
Look at a Rix SA-6, they're oiless and can be mounted in any direction. You'll need to make sure it has adequate air filtration after the compressor to further dry the air.

I don't think any compressor will like being stuffed in a closet, the cooler the better.

I have blended nitrox with mine, not cert. for He yet, so don't have any experience. @Tracy posted that certain mixes of He can actually lower head temps, while others can cook things.

Good luck, I love my little compressor.
 
4 to 6 cfm is awful slow if you have more than one diver.

A membrane system will have good sized footprint even with the bulk of it wall mounted and you'll have to figure out source air options.

I've ran or owned boats with gas , diesel and hydraulically powered compressors and they all have advantages and disadvantages.

I prefer diesel. And 9 to 12 cfm so I could pump 4 tanks in under an hour instead of running it all day to keep up with demand.
 
Yes but for him it will be for two divers if I'm guessing right and a 6 cfm compressor will be fine.
 
Disclaimer: I am not really that knowledgeable on the topic (compressor or boat) and just have a smidgen of an idea (always a dangerous thing), but something you wrote (maybe I misunderstood) has my neck hair raised:
If I were to put a compressor inside my (non-existent) sailboat’s hull, I would make very sure it is anything but gasoline powered. Presuming my main power (other than sail) were to be diesel, I would try hard to keep gas and gas engines (dinghy outboard?) outside of the hull only. I would glamour for a diesel-solar-electrichybrid drive (solar generator, diesel generator, decent battery bank (but not too much because of the diesel genny), e-drive and e-compressor yeah and one of them wind gennys maybe… but one way or another (conventional or very modern) I would not want gas-anything inside of my hull.
 
4 to 6 cfm is awful slow if you have more than one diver.

A membrane system will have good sized footprint even with the bulk of it wall mounted and you'll have to figure out source air options.

I've ran or owned boats with gas , diesel and hydraulically powered compressors and they all have advantages and disadvantages.

I prefer diesel. And 9 to 12 cfm so I could pump 4 tanks in under an hour instead of running it all day to keep up with demand.


6cfm is slow if you fill one tank at a time.
My portable 6cfm Noah Howden has 4 fill whips on it and looking at past records, it filled four 12liter fabers from 100bar to 260bar in 44 minutes. On another occasion it filled two 12 liter and two 15 liter fabers from 50bar to 265bar in 65 minutes with one leaky whip.
Too slow it ain't. ☺
 
6cfm is 6cfm, and it's slow no matter how you try to slice up the time. That's if you can even get 6cfm out of a 6cfm compressor. Welcome to the implacable laws of physics. And I don't want spend an hour charging tanks after every dive.
I've filled probably 20,000 plus onboard and it gets old quick if your spending most of your SI with a compressor running. Even a quiet one. If you ever do have guests, that little compressor will have to run near constantly to keep up.

Enclosures are great for noise control but not access or heat removal, compressing air and running engines generate heat and it has to go somewhere. It's not as bad if the compressor is far away in an auxiliary space on a big vessel, but on small boats the heat can sink into other spaces and it can get stifling hot in the summer, especially if you try to sleep next to a bulkhead near the space.


Tri-mix is hard on a boat because it does require quite a bit of helium. Bring one set of doubles each onboard already filled helps but with 100cuft per set or more a T won't last long even if you boost it to higher pressures before you leave. The good thing about mix is that you can dive a leaner mix on you succeeding dives if they are shallower or your narcosis tolerance is higher. Also diving thirds means the tanks will have a higher amount of residual gas remaining.

As far as gas vs diesel, gas motors are cheap but loud and require far more fuel, I averaged 20 gallons of gas per trip and only 7 using diesel with the same compressor, same hp motor. If you have to use gas, spend money to get a Honda as most of the others are total junk.
 
4 to 6 cfm is awful slow if you have more than one diver.

A membrane system will have good sized footprint even with the bulk of it wall mounted and you'll have to figure out source air options.

I've ran or owned boats with gas , diesel and hydraulically powered compressors and they all have advantages and disadvantages.

I prefer diesel. And 9 to 12 cfm so I could pump 4 tanks in under an hour instead of running it all day to keep up with demand.

There doesn't exist a membrane system that would fit on the size boat I'm looking at as far as I can tell (a 40' monohull once equipped with the necessary things for living aboard, traveling, safety, etc. doesn't have a lot of real estate left over). As such, I'm really only looking at compact options that could be put in a lazarette or *maybe* mounted somehow on the deck.

The demand will generally be whatever tanks I've used, so doing 2-3 tanks in an hour is perfectly fine for what I'm doing. This isn't a charter diving operation or anything like that, simply a liveaboard sailboat for me and maybe a friend or 3 at a time usually. 20-30 minutes per tank isn't a concern for me really.

With very limited battery capacity, and very limited space for a generator, getting a VFD for starting up an electric motor is something I've considered, but based on the feedback I've seen from sailing channels with compressors onboard I'm leaning towards gas.

As for trimix/nitrox, I'm not really considering even trying to do those on the boat, that's 100% for the years until I get the boat.
 
Look at a Rix SA-6, they're oiless and can be mounted in any direction. You'll need to make sure it has adequate air filtration after the compressor to further dry the air.

I don't think any compressor will like being stuffed in a closet, the cooler the better.

I have blended nitrox with mine, not cert. for He yet, so don't have any experience. @Tracy posted that certain mixes of He can actually lower head temps, while others can cook things.

Good luck, I love my little compressor.

I was thinking if in a lazarette then I'd probably pull it out for fills and put it back in after done filling. I know S/V Delos mounted their compressor in their engine compartment, but their boat is quite a bit larger than I'm looking at. They used the remote intake option iirc.
 
There doesn't exist a membrane system that would fit on the size boat I'm looking at as far as I can tell
I have a membrane that is 2 feet long, and includes an 10"x10"x6" box that contains the heater controls, regulator, on/off valve, and the heater. It's a UBS (that are defunct), but that doesn't mean that they aren't there.
 
https://www.shearwater.com/products/teric/

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