Get you home engine, would it work.

[Davy_S]

Not wishing to spoil a thread that was posed on Mobo recently. If you had a small Mobo or yacht and no wind and your engine had broken down, you are a few miles from land. Ok, it could be possible to use a small outboard motor off your dinghy to get you home. If you had a small generator, would it be possible to plug an electric motor into it and fasten a small shaft with prop over the side. Or would a small outboard provide just as much thrust? Say a 2kw genny coupled to a wasing machine motor with a means of welding a shaft and prop to it, then having a means of attaching it to the transom, would it work, or should I go and lie down

 

[maxi77]

On one yacht I carried the dinghy outboard on a transom mount as a get you home and despite being only 3hp it pushed the boat along at nearly 4 kts and still did 2.5 in heavy headwinds so I would go for that option, and have seen a lot of mobos doing it

 

[charles_reed]

Not wishing to spoil a thread that was posed on Mobo recently. If you had a small Mobo or yacht and no wind and your engine had broken down, you are a few miles from land. Ok, it could be possible to use a small outboard motor off your dinghy to get you home. If you had a small generator, would it be possible to plug an electric motor into it and fasten a small shaft with prop over the side. Or would a small outboard provide just as much thrust? Say a 2kw genny coupled to a wasing machine motor with a means of welding a shaft and prop to it, then having a means of attaching it to the transom, would it work, or should I go and lie down

I've used my 3.3/3.5 Mariner/Tohatsu on a number of occasions, usually on the inflatable alongside but on one occasion, tied to the aft boarding ladder.
Don't know about your other queries - they seem more than a little incomprehensibly confused.

 

[RAI]

A 2kW gene output is about 2.7 hp. I would chose the outboard.

 

[Davy_S]

I shall now depart for an Alfa or three, sit by the harbour and watch the arriving boats, whilst pondering my cunning plan further.

 

[Tranona]

Problem with the dinghy outboard is that it is short shaft, so any mounting will be low down on the transom - either a dedicated mount or adapted to a swim platform or ladder. However difficult to operate on a modern high freeboard boat. It will however, give some speed in flat water. As charles says, lashing the dinghy alongside is more effective.

Where mobos have an outboard as an auxiliary get you home it is usually much bigger and dedicated to the job.

 

[mrplastic]

I've often wondered if you could get a couple of decent powered Jet washers, on-board water pump fed with sea water, power it all with a genny and strap the spray heads to the side of the boat! Gotta be good for a couple of knots ;-)

 

[TQA]

If you want to use the dinghy outboard best way is on the dinghy and tie the dinghy to the side of the boat in a 'hip tow'.

Even an egg beater can move a large yacht in reasonable conditions.

I have moved a few boats with a variety of OBs including a Seagull. refilling the tank was a PITA.

 

[maxi77]

If you want to use the dinghy outboard best way is on the dinghy and tie the dinghy to the side of the boat in a 'hip tow'.

Even an egg beater can move a large yacht in reasonable conditions.

I have moved a few boats with a variety of OBs including a Seagull. refilling the tank was a PITA.

The dinghy tow is perhaps OK with a crew and in reasonable weather but when the weather is bad the transom mount is more practical. Worked fine in a 25ft boat but I agree a swim platform type mount may well be required on a bigger boat

 

[Davy_S]

Ok, I am back now, my thirst has been quenched! Observations for the interested, 5 Sunsail bareboats have arrived, 14 Nielson flotilla boats, Sailing holidays are arriving (about 10) as we depart home on our trusty scoot.
Charles, it was a bad description! Imagine an electric outboard motor, remove the battery, keep the shaft and prop, replace the 12v motor with a 240v one, drive it from your generator, would it work better than the normal, clamp the dinghy outboard on the back, would it be more powerful, use less fuel, or a waste of time.

 

[pvb]

Imagine an electric outboard motor, remove the battery, keep the shaft and prop, replace the 12v motor with a 240v one, drive it from your generator, would it work better than the normal, clamp the dinghy outboard on the back, would it be more powerful, use less fuel, or a waste of time.

Most electric outboards have the motor at the bottom of the leg!

 

[rob2]

I have moved a few boats with a variety of OBs including a Seagull. refilling the tank was a PITA.

I crewed to get a Co26 home from Portsmouth to Mill Rythe on Hayling Island using a dinghy alongside with a Seagull. It didn't require anyone in the dinghy once we'd set it up, but I dropped the filler cap overboard whilst refuelling. Being a calm day, we made around 3 knots average for the trip. Test since have proven that the same can be achieved with an inflatable dinghy.

I wouldn't want to have a Heath Robinson contraption to contend with when already frustrated by a breakdown, let alone tripping over it when not in use! I doubt any home built "outboard" would be as reliable or weatherproof as an off-the-shelf version (which can be clamped on the pushpit when not in use).

Rob.

 

[prv]

Most electric outboards have the motor at the bottom of the leg!

So even better, don't start with an electric outboard, start with an old petrol one whose engine is rusted to buggery and being given away.

Pete

 

[25931]

I've used my 3.3/3.5 Mariner/Tohatsu on a number of occasions, usually on the inflatable alongside but on one occasion, tied to the aft boarding ladder.
Don't know about your other queries - they seem more than a little incomprehensibly confused.

Some years ago we moved a 10m Snowgoose more than half the length of the Algarve with 3.3 Mariner on the dinghy which was lashed between the hulls
If you have a mono and normally carry an o/b for the dinghy it might be worth considering fitting a dadicated bracket - more efficient and easier than lashing the dinghy alongside. You'd only try towing once.

 

[Davy_S]

Ok, I can see the merits of a normal outboard motor, I have used one myself in the tideless Ionian. A lot of boats carry a small generator, it could be used to charge your batteries, or to power drills etc, my question was, could it be used to power a get you home system more efficiently, even a diy home built contraption, most generators are governed in their speed, so would probably be more fuel efficient than a revy small outboard motor. It is possible (I Believe) to drive a small hydraulic pump from a generator, that also could be used to drive a propeller. there must be another way of creating a simple get you home system.

 

[pvb]

Ok, I can see the merits of a normal outboard motor, I have used one myself in the tideless Ionian. A lot of boats carry a small generator, it could be used to charge your batteries, or to power drills etc, my question was, could it be used to power a get you home system more efficiently, even a diy home built contraption, most generators are governed in their speed, so would probably be more fuel efficient than a revy small outboard motor. It is possible (I Believe) to drive a small hydraulic pump from a generator, that also could be used to drive a propeller. there must be another way of creating a simple get you home system.

If you're wanting efficiency, surely driving a prop directly by a petrol engine is always going to be more efficient than first converting the engine's output into electricity, then using a motor to drive a prop?

 

[prv]

If you have a mono and normally carry an o/b for the dinghy it might be worth considering fitting a dadicated bracket

I *think* our outboard would clamp onto the lip of the kedge locker in the swim platform, with nothing more than a bit of scrap wood to stop the clamps marking the paint. I should probably get round to trying it some time.

It's only a little 2.2 though, so progress is still going to be pretty limited. And with the throttle out of reach and no neutral or reverse, I'm not sure manoeuvring would be any better than under sail!

Pete

 

[KellysEye]

We used our dinghy and out board to move the boat it was tied fore and aft to the quarter. Five horsepower moved our 12 ton boat fine but it was calm, we only did it to see if we could move the boat if the engine failed. It's definitely checking it works for your weight of boat and dinghy HP.

 

[jon711]

I've often wondered if you could get a couple of decent powered Jet washers, on-board water pump fed with sea water, power it all with a genny and strap the spray heads to the side of the boat! Gotta be good for a couple of knots ;-)

When I worked for a well known pump manufacturer, we did have an inventor approach us with something similar, he had mounted modified pressure washer jets above the waterline, and was able to manouver the boat around the marina using a remote control. He was offering us the marketing rights (He owned the patent). Problem was very weak power (Struggled to overcome a crosswind), and the fact that anybody standing nearby (or on the boat), would get wet, either from a direct hit, or from spray....
It did sound a good idea at first!

Jon

 

[Davy_S]

If you're wanting efficiency, surely driving a prop directly by a petrol engine is always going to be more efficient than first converting the engine's output into electricity, then using a motor to drive a prop?

My thoughts are, a generator runs at slightly above tickover speed, dependant on load, so, we convert the output into kw and use this to drive the prop, the kw tend to remain static output at idle speed, I would have thought that a small outboard motor would consume more fuel. as its output is normally rated at max rpm, a generator runs slower, so burns less fuel.