exhaust gasses outlet for auxiliary diesel engine

[BartW]

I am considering to drive my scuba dive compressor with a small diesel engine, (Kubota OC60, 6HP)
I have room for the compressor +engine in the boat under the bow bed,
Just wondering if it is difficult to install a isolated, flexible ,metal tube, to bring exhaust gasses to the outside,
need to go through the hull somewhere on the side
at 50cm above the water line,
at about 1/3th from the front
(a dry exhaust gasses outlet)
anybody experience with this ?
any advice is welcome,
thanks

 

[Harry25]

Exhaust gasses

Have you thought about using Eberspacher parts. They would do exactly what you want to do. The exhast pipe size on an Eberspacher D2 is 24mm. They have also the skin fitting you will require to go through your moulding. Don't know what exhaust pipe size is on other models or on Webasto, but you could download manuals.

 

[ccscott49]

I am considering to drive my scuba dive compressor with a small diesel engine, (Kubota OC60, 6HP)
I have room for the compressor +engine in the boat under the bow bed,
Just wondering if it is difficult to install a isolated, flexible ,metal tube, to bring exhaust gasses to the outside,
need to go through the hull somewhere on the side
at 50cm above the water line,
at about 1/3th from the front
(a dry exhaust gasses outlet)
anybody experience with this ?
any advice is welcome,
thanks

ASAP supplies have flexible stainless exhaust, but it's not cheap.
You will also need good insulation/lagging around the pipe, also from ASAP.
The exhaust will get hot, you need to consider where to route it.
I have just done the same with an aircooled genny in my lazerette, used the stuff from ASAP with a 1 1./4 bsp, skin fitting.
I would also reccomend, taking the shortest route possible to get the exhaust gasses out.

 

[BartW]

thank you both for the usefull advice !

 

[jfm]

I am considering to drive my scuba dive compressor with a small diesel engine, (Kubota OC60, 6HP)
I have room for the compressor +engine in the boat under the bow bed,
Just wondering if it is difficult to install a isolated, flexible ,metal tube, to bring exhaust gasses to the outside,
need to go through the hull somewhere on the side
at 50cm above the water line,
at about 1/3th from the front
(a dry exhaust gasses outlet)
anybody experience with this ?
any advice is welcome,
thanks

Hmm. Tricky stuff Bart. The exhaust will be very hot becuase it's dry - has no water cooling. I'd expect it is much hotter than Eberspacher exhaust becuase I'd guess the Eber has much spare air in the flow to "dilute" the heat of the diesel combustion. Also you'll need to put a swan neck into the pipe and/or a gizmo to catch water that might get pushed in the pipe, ideally? And all that will get very hot, and the ones in Vetus catalog etc cannot take the heat of dry exhaust.

The other worry is that diesel fuel smells horrid and if you ever have even a slight weeping leak you'll get the terrible smell in the cabin.

What about getting a 6hp genset with proper wet exhaust and fitting that aft, then putting an electric compressor under the bed?

 

[oldsaltoz]

I am considering to drive my scuba dive compressor with a small diesel engine, (Kubota OC60, 6HP)
I have room for the compressor +engine in the boat under the bow bed,
Just wondering if it is difficult to install a isolated, flexible ,metal tube, to bring exhaust gasses to the outside,
need to go through the hull somewhere on the side
at 50cm above the water line,
at about 1/3th from the front
(a dry exhaust gasses outlet)
anybody experience with this ?
any advice is welcome,
thanks

Tried this in the forward cabin on cat, not enough air flow to keep the engine coll enough and the smell of the engine running was not good in that side of the cat.

The exhaust was plumbed in with a short length of flexible stainless that led to a section of thin stainless that was fixed to the inside of the hull, this went straight up to a 180 degree bend and back down to about a foot above the waterline, the pipe then passed through the hull at 45 degrees down and back facing.

The loop up and back was to ensure no water could enter the engine exhaust outlet.

The engine in now stowed in it's own locker and lifted onto the deck when needed, the exhaust is directed down between the hulls by an extention on exhaust pipe, this also reduce the noise.

Hope this helps.

 

[MapisM]

I am considering to drive my scuba dive compressor with a small diesel engine

You're making me curious, which sort of compressor do you have onboard? I've never seen a portable scuba compressor which isn't integrated with either an engine (usually gasoline btw) or an electric motor.
Anyway, I fully agree with the concerns already expressed for the exhaust.
And a diesel engine is the last thing I'd want under my bed anyway.
Crazy as it might sound, I'd rather try to connect the compressor to a main engine...

 

[BartW]

Hmm. Tricky stuff Bart. The exhaust will be very hot becuase it's dry - has no water cooling. I'd expect it is much hotter than Eberspacher exhaust becuase I'd guess the Eber has much spare air in the flow to "dilute" the heat of the diesel combustion. Also you'll need to put a swan neck into the pipe and/or a gizmo to catch water that might get pushed in the pipe, ideally? And all that will get very hot, and the ones in Vetus catalog etc cannot take the heat of dry exhaust.

The other worry is that diesel fuel smells horrid and if you ever have even a slight weeping leak you'll get the terrible smell in the cabin.

What about getting a 6hp genset with proper wet exhaust and fitting that aft, then putting an electric compressor under the bed?

Yes I agree its tricky,

I have been doing tests with a "Dometic travelpower 3.5KW 230V generator" mounted on the Volvo engine, in addition with a victron 3.5KW invertor but this combination can not deliver the necessary startup currrent for the electric engine (3KW) on the compressor.
not even with the extra power from the 12V battery bank. (power PLUS function on the Victron)
Very soon we will do a test putting 2 x 3.5KW Victron invertors in casacade (with assistance from Victron)
but I hate the idea heaving all these electric high current boxes down in the boat.(1 x travelpower box, 2 x Victron Powerplus invertors)

the genset is not a solution, as there is no room left, and also weight is an issue,
BUT,
I discovered that the engine of the "Whisper" Generator from mastervolt is a Kubota OC60. that one has a heat exchanger for the oil cooling by sea water, but I have seen other applications where this engine is used with its standard "air cooling" (The combustion chamber is oil cooled)
So I am investigating this new plan using that Kubota engine.
The exhaust outlet of the engine would be approx 1m abover the water line,
The distance to the hull is less then 1m,
So when I make a through hull exhaust outlet at 50cm above the water line, I wouldn't need a Goose neck (I think ???)

I have found a solution for the forced ventilation and noise damping of the compressor and engine in that position, remember it is only a 29ft (loa), 26ft (hull) boat.

any advice is welcome, thanks !

 

[BartW]

You're making me curious, which sort of compressor do you have onboard? I've never seen a portable scuba compressor which isn't integrated with either an engine (usually gasoline btw) or an electric motor.
Anyway, I fully agree with the concerns already expressed for the exhaust.
And a diesel engine is the last thing I'd want under my bed anyway.
Crazy as it might sound, I'd rather try to connect the compressor to a main engine...

I have a Bauer Oceanus compressor with a monophase electric engine.
http://www.bauergroup.com/en/produkte/atemluft/mobile_kompressoren/compact_line/oceanus/index.php
(specially made for applications a.o. on a boat; max inclination is 20° and can be used long term)
this compressor is also available with a Honda petrol engine,
but I don't like petrol on the boat (to me even worse then diesel)

have seriously been looking at a PTO solution,
but there is not enough space in the engine room,
could reorganise, battery's and fuel pre-filters, but then everything is even more sqeezed then it is now
and when there is a problem on the engine, it would be a real headache.

thank you for posting.

 

[Bandit]

Serious health risk

Be very careful that there is no way that the compressor will take petrol or diesel exhaust gasses and compress them into the dive bottle, i have read somewhere that this can serious health risks.

 

[MapisM]

I have a Bauer Oceanus compressor with a monophase electric engine.

Aha! I couldn't believe you had a standalone compressor...
You know what, considering all what you said, I'd rather buy a few more spare tanks, and use the compressor with its electric engine while moored at a marina.
I'm assuming that you don't overnight for many days in a row at anchor, considering the size of the boat, but maybe I'm wrong?

 

[BartW]

Aha! I couldn't believe you had a standalone compressor...

in fact I have two, the second is a big poseidon, but that one is not portable,
although it would fit on a boat like yours

You know what, considering all what you said, I'd rather buy a few more spare tanks, and use the compressor with its electric engine while moored at a marina.

thats how we work now,
we usually go out for a day trip with 6 divers, for 2 dives,
the weight of a scuba tank is app. 20 kg,
I would like to avoid some weight and the hassle with 12 tanks on board, also at midday, replacing the 6 empty with 6 full tanks.

furthermore,
carriing these 12 tanks from and to the boat, usually a big distance to the car

and finally,
during the evening somebody has to take care of filling 12 tanks, 15 minutes per tank, while the others are in the restaurant,

I would love the idea of
leaving some tanks at home,
being able to fill tanks while cruising (6 at a time)
and that the tanks can stay on the boat, no carriing any more,

furthermore I like the engineering part of this project
(as long this can be done in a safe way)

 

[ccscott49]

I would reccommend, a 210 amp @12v alternator on one of your main engines and a 5kw inverter. Or 2 x 150 amp x 12v alternators on both engines and a sterling alternator to battery charger with the 5kw inverter. That will do the job for you. I'll take the dometic off your hands!!

 

[BartW]

I would reccommend, a 210 amp @12v alternator on one of your main engines and a 5kw inverter. Or 2 x 150 amp x 12v alternators on both engines and a sterling alternator to battery charger with the 5kw inverter.

hey I have been thinking exactly at this solution,
I can even do the test as I have two Volvo engines with a 12V 140A alternator each, with the two 3.5Kw invertors in cacade. If that works, I was considering adding A 12V 250Balmar alternator to one engine, so that one diesel engine could run the compressor.
My only concern are these extremely high currents comming for several hours from these alternators at 12V.
But you gave me confidence to do the test
(will use VERY thick cables )

I'll take the dometic off your hands

really ? I am willing to sell the unit, it is in perfect shape, and only used for some tests.
You can have it for a reasonable offer. pls send PM