?? re Air Cooled engines

[Zane Lewis]

I am interested to know if anybody has experiance with using aircooled engines (Diesel) as axuliarys in yachts.

How have you found it. Noise, heat etc,

How much air does it need for cooling, do you use a forced air blowers etc.

I am working on a modified sharpie design (3 ton) and these have been suggested as an alternitive to an OB in a well. I want to avoid the weight of a standard marine diesel.

Zane

[igatenby]

A lot of small Aussie fishing boats in years gone by used to use air-cooled three cylinder Lister diesels. My understanding was that they were used on boats that put to sea through shallow bars in creeks / rivers so as to avoid sucking up sand with the cooling water.

Fishing boats didn't worry about noise, which will be greater with an air cooled engine and they also mean you have to use a dry stack exhaust.

Ian

[On Vacation]

Here in the shallows of eastern U.S. we use a keel cooler that consists of tubes mounted along the keel area that acts a heat exchanger under water instead of sea water pumps to cool the engine with great success. Many are on standard engines of any make or model.

[SailBoatDude]

I've been a big fan of air cooled power for a long time. They have more noise, but pay off in the systems they don't have to break down, and the heat can be used for other things. Noise can be insulated down to a reasonable level, as can heat.

I still have an air cooled Lister 3 cyl. waiting to go in another boat. It's not for sale, though probable way too big for your 3 ton sharpie

Cooling can be handled by a few different ways, though the manufacture's technique's are usually worked out for you, but fans on the crank, electric or drive belts can do the job.

Weight is an issue with most diesels, but some of the newer designs are much lighter and some automotive applications can stand the conversion and are generally lighter as well.

Each engine has a CFM (cubic feet per minute) requirement for cooling, depending on the application (engine design) The manufacture's spec sheet for the motor will have those cooling inlet and exhaust square inch size minimums in their spec's.

[Zane Lewis]

I guess I was looking at some of the modern light industrial diesels such as the Deutz or Ferrymann etc of about 10-15 hp.
The other options are petrol 4 stroke OB at approx 45kg,
Air cooled deisel at 50kg + gearbox + shaft
Marine water cooled at 90kg + shaft.

The OB is in a well just on the waterline aft which is a large concentration of weight aft and is up high. Inboards are lower and more central but heaveier and the prop's are more exposed.

Thanks for the inputs.

Zane

[On Vacation]

We solve the noise issue with the small air cooled ones in open skiffs by using a Rule live well style pump to exhaust in conjuntion with the exhaust. We encorprate a muffler to discharge overboard. It works pretty good. Those pumps are better than the bilge pumps they make. I will show you the hook up when we finish the one we are working on now.

[Ian McColgin]

Grana has an ancient Deutz. The air exhaust is in the cockpit combing (shortening that cockpit seat) and the muffeler is located inside that ducting but actually exits down by the water line.

It's a little noisy.

Should I retain air cooled through my rebuild, I'm going with a pair of smoke stacks on either side of the proposed pilot house - one to bring air in and one to take hot air and exhaust out. I think if both are sound insulated and high enough, any noise will be shot straight up and should not bother me too much.

Each stack will dead end a bit lower than the ducting leading to the engin compartment. The stacks will be cross connected by drains down there with a just above water line discharge on each side, so rain and snow won't be a hassel.

I've a friend who did something like this except only one stack for hot air and exhaust - intake was from ducts to the bilges - and the actual working stack was removable and only set when the engin was on. Very nice, shippy arrangement except that the stack location made using the mainsail impossible. Didn't bother my friend as he tended to use the motor infrequently.

[Dan McCosh]

There is a cautionary tale oft-repeated in Great Lakes sailing circles about a 45-foot racing sloop owned in the 1960s by a Chevrolet engineer. He replaced an elderly auxiliary engine with an air-cooled engined scrounged from a Corvair. The installation was successful, but required large air vents cut into the transom, with a lever-operated series of flaps that closed off the opening when not being used. A delivery crew taking the boat back from a long-distance race was unfamiliar with the system, left them open in heavy seas and the boat began taking on water. A passing freighter stopped to rescue the crew, but an attempt to tow the boat tore the nose off and it sunk.
Shortly after, Ralph Nader forced the Corvair off the market.

[Thaddeus J. Van Gilder]

my Bristol channel cutter used to have an air cooled Enfield diesel in it.

I was told it worked pretty well.

[Phil Young]

My dad once had an aircooled 1 cyl yanmar in a 23 footer. Vibrated like hell. Made the whole cabin hot. So noisy communication on board was virtually impossible. The exhaust only caught some rags on fire once.

If you go aircooled, get really serious about noise and heat insulation. Around 40 kg's of the lead lined stuff should make it as quiet as water cooled.

Hmmmm.

[Zane Lewis]

30 kg's would suggest that I might as well go water cooled. Most of the air cooled 10kw motors are 40-60kg without a marine gear box. A water cooled diesel with gear box in the same power range is 70 - 90kg. Add the time and hasel and $ to get a suitable reduction / reversing gearbox and going water cooled may not be any more expensive.

Oh well back to the OB in a well again.
At this stage I am going around in circls, OB vs Inboard. Cost vs comfort, Space vs ecconomy
Zane

[Phil Young]

I'd go 4 stroke OB in a well. Quiet, low vibration, not smelly, clean. Fuel economy is irrelevant, how much motoring are you planning?Service costs are far more important-take the OB to the mechanic in your car, vs inboard where the mechanic has to work in your boat. Easy to replace when it breaks. Rig it so it comes right out of the water when not in use, no prop drag, also no corrosion sitting on the mooring. No weed growth on the prop.

[john welsford]

Originally posted by Zane Lewis:
I am interested to know if anybody has experiance with using aircooled engines (Diesel) as axuliarys in yachts.

How have you found it. Noise, heat etc,

How much air does it need for cooling, do you use a forced air blowers etc.

I am working on a modified sharpie design (3 ton) and these have been suggested as an alternitive to an OB in a well. I want to avoid the weight of a standard marine diesel.

ZaneI had a Honda 10hp petrol stationary motor with electric start in a 27 foot IOR racer, she weighed about 2 tons, had quite a lot of windage in her big rig. When I got her she tended to overheat and the cabin was full of fumes and unliveable when the engine was running.
I put a 6inch hose ( airconditioning ducting hose) from the front of the engine box under the main hatch steps to a flange welded to the front of the cooling air shroud. I then sealed all other gaps into the engine box, and ran an 8inch hose from the back of the box into the lazarette under the small aft deck and put a big louvre on the inside face to exit the air. Worked really well after that, gave me about 6 1/2 knots at 2/3 throttle on a 10inch 2 bladed folding prop.
By the way the exhaust was water cooled off a belt driven pump that injected water into a waterlift silencers. Nice and quiet.

JohnWelsford

[Zane Lewis]

Thanks all for your comments
John, good to see you up on this forum. Also appreciate your experiance with air cooled engines as Jack Easton was the only person I know who has put an air cooled petrol into a yacht and I don't know how well it worked.

Yes an OB in well has a lot to recomend itself.
I have done the OB vs inboard in an earlier thread so I won't go there now.
Zane