Maranising an Airhead

[Oggyr80]

Has anybody ever maranised an airhead? ie to put engine into a boat not to put bike into the water.Struggling to find a useful link. Bring on the nay sayers.

 

[Schtum]

Struggling to find a useful link.

Your incorrect spelling of marinised won't be helping there......

However, installing an air-cooled engine in a boat would also require some kind of cooling fan to keep it running at a reasonable temperature.

 

[DrFarkoff]

Marinised

I'd doubt it for salt water there'd be no engine left after a season unless well coated

And how do you intend cooling it??

 

[Shep]

It depends on the type of boat?

I would think keeping it cool would be a big issue, not insurmountable but would need a fair bit of room. Gearbox shouldn't be an problem but you would need a water cooling system/heat exchanger for the gearbox oil if you were using a PRM or similar, whether the engine would produce enough usable torque when matched to a prop i don't know. A heavier flywheel would be a must I would think

The biggest issue apart from the above would be the use of a petrol engine in a boat, something I don't like, cos they tend to smell and have a tendancy to catch fire

it might look good on a Thai 'long tail' type set up though

 

[MattW]

I'd guess the reason you're struggling to find any links is because it's a crazy thing to want to do.

Why on earth would you want to marinise a light alloy air cooled bike engine? It'd dissolve before your very eyes and you'd have to work out some way of cooling it and solve countless other technical issues.

There are much better choices for marine engines (usually those designed for the job).

 

[(RIP) Proff]

It's been done several times, use lateral thinking
Put a airscrew on Beemer, put Beemer on a pontoon and Voila an Airboat

 

[electric_monk]

I have no idea about boats but you get my vote for the "Most confusing spelling of a Thread Title".....

 

[bumpmuncher]

there are plenty of boats with air cooled engines, mostly diesels (lister/petter) the type you used to find on cement mixers dumper trucks of yester year. you would probably have to build a bit of ducting around pots and have a diecent fan blowing cooling air around it. as for the ally problems, i dont know of any outboard engines that arent light ally (mostly jap poo) so either find a suitable paint or just keep a good coat of oily stuff on it .
if you are building one of those thai canoe with fecking great long prop shaft thingy on the back I WANT A GO

 

[(RIP) pastyman]

Or what about those Miami swamp boats with a f....in great prop 2" behind you.
As a matter of interest aluminium is a well known material for building hulls, especially in France, look at the Ovni yachts. Unpainted and untreated, they last for years, dont ask me how.

 

[Miz]

Or what about those Miami swamp boats with a f....in great prop 2" behind you.
As a matter of interest aluminium is a well known material for building hulls, especially in France, look at the Ovni yachts. Unpainted and untreated, they last for years, dont ask me how.

They use a sacrificial anode attached to the hull, that then corrodes and not the boat.

 

[MattW]

there are plenty of boats with air cooled engines, mostly diesels (lister/petter) the type you used to find on cement mixers dumper trucks of yester year. you would probably have to build a bit of ducting around pots and have a diecent fan blowing cooling air around it. as for the ally problems, i dont know of any outboard engines that arent light ally (mostly jap poo) so either find a suitable paint or just keep a good coat of oily stuff on it .
if you are building one of those thai canoe with fecking great long prop shaft thingy on the back I WANT A GO

Yup, but those air cooled engines are nearly always big slow revving iron diesel lumps and were / are designed for the job. I still say that air cooling an airhead (however you coat it) with salty wet air isn't going to do much for its life span. I know most outboard are alloy but they are water cooled (these days) and have proper cathodic protection - even then they need plenty of looking after (if our dive club boats are anything to go by).

And then there's the light flywheel and totally wrong power curve for driving a conventional prop (so, a new cam, ignition system, carbs etc). And you're going to have to find some way to make sure the oil pickup works reliably (or perhaps dry sump it). Etc, etc, etc.

Or what about those Miami swamp boats with a f....in great prop 2" behind you.

Nearly always big block iron V8's with conventional closed circuit cooling systems - when they wear out / die in an explosion of pistons and bits of crank case (a fairly regular occurrence), they just go to a scrapper and get another . Swamp boats also require completely different power characteristics as they are driving a big fan in air.

As a matter of interest aluminium is a well known material for building hulls, especially in France, look at the Ovni yachts. Unpainted and untreated, they last for years, dont ask me how.

I know, I used to have one (not a yacht, a little motor boat) - as others have said, it depends on good cathodic protection systems - stray current from engine electrics also kills them fast if you aren't careful.

I still say if you were going to choose an engine to marinise a (comparatively) high revving, low torque, air cooled alloy motorbike engine would be well down the list. There's a good reason that information is hard to find - if it were easy / a good idea, someone would have done it / written about it - penny pinching boaters are always looking at innovative solutions.

If I had an airhead engine (which I'll eventually have), I'd want it attached to the rest of an airhead so I could use it as God intended

Now, if you were talking about using one in an aircraft.....

 

[Sylvester]

Am I allowed to ask why? FFS!

 

[Beemerboff]

I bought a complete K bike front end on Ebay - cheap and local.

When I picked it up the guy showed me the rest of the bike - neatly mounted in a aluminum boat and according to the owner performing well.

He had mounted most of the bike including the frame, tank and radiator, and had a heavy duty car type electric thermo fan in front of the radiator.

 

[Eldergrim]

Kitchen corner

Thought you might be wanting to soak it over night in a Spicey Cajun Sauce!!

 

[Keith Chapman]

there are plenty of boats with air cooled engines, mostly diesels (lister/petter) the type you used to find on cement mixers dumper trucks of yester year.

Those old diesel lumps normaly have an outer flywheel which has vanes that blow air onto the engine as cooling.

He had mounted most of the bike including the frame, tank and radiator,.

Your clue there is Radiator the K lumps are water cooled.

 

[(RIP) pastyman]

Yes I suppose a water cooled K brick would work ok but would still suffer from corrosion problems.could paintit I suppose. would need a marine gearbox so all in all not worth the ewffort..

By the way BM do a marine deisel so if you really want one.......

 

[(RIP) Proff]

Yes I suppose a water cooled K brick would work ok but would still suffer from corrosion problems.could paintit I suppose. would need a marine gearbox so all in all not worth the ewffort..

By the way BM do a marine deisel so if you really want one.......

Easy way round,
Closed circuit cooling with cooling water being keel or swim, cooled by heat exchanger
no need for nasty salt or polluted river water to sully BMW's brick

 

[MartinL]

Tie a rope 'round it and use it as an anchor?

 

[Oggyr80]

It's a floater

http://www.youtube.com/watch?v=o5yb3-ZETAY