Mechanical Clutch Needed To Engage Belt - Powering Compressor Off Boat Motor

[cadmus]

I am looking to power an old Bauer compressor off the front end of a small diesel boat engine. Engine is ~25hp. Rarely is that all needed to propel the boat and often the boat is idling, warming or cooling… perfect time to be filling tanks. I am hoping to find a mechanical clutch system that gradually engages and disengages the compressor without turning off and on the diesel engine.

Compressor, like most, is belt driven. It is easy to add a belt pulley of any size to the front end of the crank shaft of the engine.



-Links or suggestions for any potential clutches are greatly appreciated.
-I would love to see how others are taking power off boat engines to run compressors. And how they engage them. Descriptions or photos are greatly appreciated.

 

[cadmus]

I should have added that:
1- I am looking for a mechanical clutch, not an electromagnetic clutch.
2- I want all controls to me mechanical and manual, nothing electronic. Ideally just a lever on the clutch. But I am still open to any suggestions, I just try to keep everything simple and serviceable by my caveman brain.
3- A diesel engine of 25hp is a far bigger engine than a petrol, but you likely knew that.
4- There is no room onboard for a standalone compressor+motor system. There is no generator to make electricity. There is no hydraulic power either.
5- Yes my location appears as a land locked state but the boat lives in saltwater far from diveshops.

 

[tbone1004]

most scuba compressors do not like variable RPM so you will have to keep that in mind, they can take a very narrow RPM band due to the splash lubrication. Bauers are in the do not like a wide RPM band list. I would strongly recommend hydraulics if you need it to be small and come right off the engine.

 

[rhwestfall]

I thing @100days-a-year was recently discussing the practicality this.....

 

[cadmus]

Thanks Tbone1004.... and acknowledged for sure... It is a low RPM diesel for a slow heavy displacement full keeler sailing vessel which in general does not like variable throttle either and it has a really small range of RPM. But indeed, I agree. And I will design it such that my warm up RPM and max efficiency rpm (the two that i spent 99.5% of my hours at) each have a pulley to match what the compressor needs.

Many here have said the cooling (either large tanks, keel coolers or head exchangers) and reservoirs needed for hydraulic is a large amount of space and a large loss of energy. If they are wrong please tell me what to read up on. Also, it seemed all hydraulic motors I could find had low RPM and high torque so great for a windlass but wasteful to spin a compressor.

 

[Wookie]

I have a mechanical clutch for the engine driven belt drive bilge pump. It’s a Jabsco pump, same impeller as the main engines. The manual clutch is about a grand more than the electro magnetic version.

Jabsco® 6590-0005 - 1380 GPH Manual Clutch Impeller Utility Pump

1380 GPH Manual Clutch Impeller Utility Pump - Part Number 6590-0005 (65900005, JA 6590-0005) by Jabsco. Available in Plumbing Department at www.boatid.com

www.boatid.com

 

[Wookie]

My steering hydraulics drive off of a massive belt driven pump off of the port engine. They are cooled using waste raw water off of the starboard main engine. The heat exchanger is quite small, so I don’t expect that there is a lot of churn in the system. Reservoir is 2 gallons.

My bow thruster hydraulics (since removed) are clutch driven off of the generator, and the oil is not cooled (intermittent use) and the reservoir is massive. About 15 gallons.

On my last boat, the steering pumps were direct drive off of both port and starboard engines, the reservoir was 35 gallons, and the oil was not cooled.

Depending on compressor size and motor HP, you can get away without cooling, but a little cooler isn’t expensive not hard to mount, and eliminating a big hydraulic tank is priceless….

Remember, a hydraulic pump and a hydraulic motor are the same thing….

 

[cadmus]

I thing @100days-a-year was recently discussing the practicality this.....

I noted his post on April 2 2022 and it concurs with what most owners of large motorboats and dive boats do especially those filling tanks each day. He is filling "1500 tanks per year avg". I tried to find his F/V AuntT to see how big she is, maybe he will pop up here. Regardless of vessel size and function I firmly agree with his point on preserving longevity of a primary engine ($$$$). That said. There is no room on my boat for an stand alone system, separate fuel type, jerry cans, etc. SCUBA is not the primary function of the vessel so i am not filling tanks each day, but there is no way to go to dive shops. I am re-powering this year and am buying bigger than typically needed so there will be surplus horsepower and the.
As a small 9000-10000 lbs displacement full keeler I have a great deal of wetted surface so I need to have surplus HP in a storm. But that means 99% of the time i am not heating the engine enough which is bad for a diesel. So I need to balance these all.

Since the compressor appears to only draw 2hp or less, I am considering finding a small diesel engine for the compressor if I can not devise a system that safely draws the needed RPM off the main. Not many efficient 2hp diesels out there.

 

[cadmus]

I have a mechanical clutch for the engine driven belt drive bilge pump. It’s a Jabsco pump, same impeller as the main engines. The manual clutch is about a grand more than the electro magnetic version.

Jabsco® 6590-0005 - 1380 GPH Manual Clutch Impeller Utility Pump

1380 GPH Manual Clutch Impeller Utility Pump - Part Number 6590-0005 (65900005, JA 6590-0005) by Jabsco. Available in Plumbing Department at www.boatid.com

www.boatid.com

GREAT POST. Thanks. I saw those on many fishing boats but never owned one. And yes.... i noticed the high cost. It is a cone clutch. What else has that mechanism?

 

[Wookie]

GREAT POST. Thanks. I saw those on many fishing boats but never owned one. And yes.... i noticed the high cost. It is a cone clutch. What else has that mechanism?

Don’t know, I couldn’t find the clutch alone. Only attached to a Jabsco.

But I’d bet if you haunted places like Sailorman or any of the powerboat scrapyards, you’d find one you could modify. Even if you don’t have the machine shop skills yourself (I don’t either) you could find a hobbyist with a lathe who could build something that would work.

A consideration would be how many HP the clutch can handle. My big belt driven hydraulic pump is about 2.5 HP. When looking at other belt driven applications, it seems that 5 Hp with V-belts is about the limit.