New Member Compressor Question

[Portager]

Hi;

I am in the process of developing a trawler yacht design for personal use, which we call Portager, and I am looking for recommendations regarding a SCUBA tank compressor. My boat will be professionally designed and built to be a comfortable long range Ocean voyaging boat and trailerable, therefore the name, so we can transport it to our selected cruising grounds. Portager will be 36’ to 48’ long with a 10’ to 12’ beam (yes it requires oversized load permits). I plan to have a compressor on board to fill my SCUBA tanks so I do not need to search out a fill station between dives or fill the bilge with spare tanks.

To reduce cost, space and weight, Portager will not have an AC generator, so I would like to power the compressor using a hydraulic motor and a PTO driven pump on the main engine. Does anyone know of a hydraulic compressor package or will I need to purchase the compressor and motor separately?

Thanks;
Mike

 

[Uncle Pug]

... I don't think you will find a production unit set up that way but it shouldn't be hard to fit a hydraulic motor to a compressor... considerably easier that building the trawler.

 

[Portager]

I think you are probably right, but I would rather take the easy way if there is one.

Assuming I don't find an integrated motor/compressor solution, what compressor would you recommend I use. I prefer small, light weight and low maintenance and since I'll be filling while underway and I won't be going very fast, I don't mind if it takes awhile to fill.

Regards;
Mike

 

[MarcHall]

Hi there

I have a 37 foot sailboat (Crealock 37 "CrazyFish") with a Bauer Junior compressor mounted in a box just forward of the mast.

The compressor has peformed well over the 7 years I have had installed on the boat.

I spent 2 of those years along the Pacific Mexico coast. One thing I would suggest is not to run the compressor off of a hydraulic pump, but it does depend on your overall energy startegy.

On CrazyFish all the electrical needs while at anchor are met by solar panels. The main electrical requirements are refrigeration, lights, music and ham/ssb radios (which includes email at 1200 baud). You will find that the majority of the time if you are cruising you will be sitting at anchor with no need to run the engine to propel the boat. We typically did
1-2 week stays before picking up the anchor and moving to a new spot.

The main diesel is a pretty big engine to run to just run a compressor. However you may be powering your refrigeration and water maker off the main engine and will need to run it a few hours a day anyway, so adding a hydraulic pump to run the compressor might be the way to go. The compressor likes have sufficient air cooling so you need to take that into account if you install it the engine room.

Regards

Marc Hall
www.enjoythedive.com
march@gue.com

 

[Portager]

Thanks for the reply Marc;

You didn’t say which Bauer Junior compressor you are using, but I assume it is the one with a 5 HP Gasoline engine since it would take an amazing alternator and an awesome battery bank to run the 3 HP electrical model long enough to fill a tank.

Portager is a power-boat by design and she will only be equipped with a get home sail, so I’ll need to run the engine to move. In addition, Portager will not have gasoline aboard due to the explosion hazard; therefore, I would need to adapt a diesel engine to a compressor and I would need to run an engine to fill a tank. Since Portager will have a hydraulic pump anyway, I can drive the compressor while underway or when I am running the main to recharge the batteries, make water or provide heating/cooling. Since I will have a variable displacement hydraulic pump, the compressor and alternator speed will be independent of engine speed. The throttle will be computer controlled via pyrometers (exhaust temperature sensors) so the throttle setting will continuously be optimized to the actual load and the engine will usually operate at its optimum point. Boat speed will be controlled by adjusting the pitch of the blades on the controllable pitch propeller.

Portager will be equipped with an equipment compartment separate from the engine “room” to keep the batteries, compressor and alternator out of the engine-room heat-zone. An additional benefit is the engine compartment will be no larger than necessary to enclose the engine, which will make it easier to sound proof.