Dolphin direct drive engine

[wombat88]

I find myself attracted to a small boat with a Dolphin engine. I remember a little about these from my youth but no detail.

For those that don't know they are petrol, two stroke and direct drive. In order to go into reverse the engine must be stopped and started running in the opposite direction.

This is done with a big switch/controller device that does everything in sequence.

So three questions to anyone with first hand experience...

1) Do they have some form of clutch?

2) How long does it take to change direction? In other words can they be used for marina shuffling to and fro or is the change of direction just too slow?

3) From memory the Dolphin was tiny. Would a little Yanmar or something fit in the space?

 

[scottie]

Your memory seems accurate
if you did go ahead I would do what one satisfied owner did and sent the electrics back to dolphin for fettling ever year
the potential for problems and stress rate suggests that other options look attractive

 

[wombat88]

the potential for problems and stress rate suggests that other options look attractive

Hmmm, armchair sailing tends to overlook the obvious! Many thanks for the reality reminder.

 

[scottie]

With regards to clutch I seem to recall a centifugal one
I sailed on a a boat for several years with zero problems but spent several unhappy hours professionally sorting them most problems as I recall we’re down to neglect

 

[KevinV]

I've read up a bit on these - the size, weight and ridiculous simplicity is very appealing for a small boat like mine, though having petrol belowdecks isn't. It's basically the weight of an outboard with the benefit of fitting further forward, and in the dry.
The fact that they've remained largely unchanged for decades and are still in business suggests they're not as bonkers as they seem to those of us used to diesels. If you like the boat then why not ask the owner to demonstrate?

 

[DownWest]

I've read up a bit on these - the size, weight and ridiculous simplicity is very appealing for a small boat like mine, though having petrol belowdecks isn't. It's basically the weight of an outboard with the benefit of fitting further forward, and in the dry.
The fact that they've remained largely unchanged for decades and are still in business suggests they're not as bonkers as they seem to those of us used to diesels. If you like the boat then why not ask the owner to demonstrate?

They changed to gearboxes a while back, probably because of the nervewracking F-R if in tight places, like Marinas. Those hardly existed in their hayday.

 

[Tranona]

Tried one once on a friends boat. The early all electric ones had a Dynastart that was reversible and a control box to stop by earthing the ignition and restart in reverse. Owner said it always worked. Centrifugal clutch and direct dive to a small diameter coarse pitch prop. Later ones had a conventional 2:1 Hurth gearbox.

Small and neat with few bits hanging off. A Beta 14 would be a good replacement but would need a new propeller and modified beds at least.

 

[LittleSister]

There used to be, IIRC, a specialist company down in the West Country which repaired and rebuilt them, and presumably supplied spares. There are so few of those engines remaining in use these days I have some doubt as to whether they would still be in that business.

 

[penfold]

There used to be, IIRC, a specialist company down in the West Country which repaired and rebuilt them, and presumably supplied spares. There are so few of those engines remaining in use these days I have some doubt as to whether they would still be in that business.

Dolphin themselves did that(or a company trading as such) at least up to about 6-7 years ago as I remember perusing their webpage.

 

[DoubleEnder]

I think the company is still around
Dolphin Engines - British made marine auxiliary two stroke engine for leisure and racing yachts
why not give them a call, and get some information from the horse‘s mouth? I believe that over the years they have introduced conventional gearboxes, and modern ignition systems. I have never owned one. But I’ve been on board with one running. They are small and light weight Some people get exercised over keeping petrol on the boat, but many owners have both gas and petrol on board anyway. For a ‘classic’ boat, the great benefit of Dolphin engines is smoothness and lack of vibration, which is much kinder on your rivets. Way less vibration than a 2 cylinder diesel and a world of difference from a single cylinder.
if you like the boat, don’t dismiss the Dolphin.

 

[38mess]

We had one on a yacht we used for racing. Always a bit strange coming into a lock and stopping the engine so we could reverse and stop. Also the cooling water emptied into the cockpit and down the drain holes because the engine was so quiet. I believe they were so light one person could lift it.

 

[jwilson]

I've been on a boat as a passenger that had the stop to reverse Dolphin, and it worked well. Not much slower to go into reverse than a normal FNR gearbox. Apparently some later engines had a conventional gearbox. Very quiet and smooth compared to a diesel. But petrol fuelled, which for some people would be a complete no-no. Though I'm old enough to have sailed boats with various petrol inboards but paraffin stoves instead of the "too dangerous" LPG.

 

[Rich T]

I find myself attracted to a small boat with a Dolphin engine. I remember a little about these from my youth but no detail.

For those that don't know they are petrol, two stroke and direct drive. In order to go into reverse the engine must be stopped and started running in the opposite direction.

This is done with a big switch/controller device that does everything in sequence.

So three questions to anyone with first hand experience...

1) Do they have some form of clutch?

2) How long does it take to change direction? In other words can they be used for marina shuffling to and fro or is the change of direction just too slow?

3) From memory the Dolphin was tiny. Would a little Yanmar or something fit in the space?

I had a Dolphin in a Folkboat for several years. Pre conventional gearbox so electrical FNR. Simple three way switch and start button. Boat was in a marina and provided you allowed a bit more time to go F/R it was no problem. If a little quick with the changeover it backfired slightly and blew a perfect smoke ring out of the exhaust ! Two batteries automatically in series to give 24v when stating ensured a good kick for the Dynostart starter. Automatically switched back to 12v once running. Never gave any trouble, great wee engine, smooth, light and simple.
Richard

 

[wombat88]

Hardly a bad word for an engine...not bad going, I need to research more and talk to the manufacturers regarding ongoing spares supply if needed.

 

[scottie]

The are a marmite experience I believe !

 

[jlavery]

We had one in our 1961 SCOD, albeit with a gearbox.

Generally pretty reliable.

Be careful if considering replacing with a diesel. Almost any diesel will be heavier and upset the balance of the boat. Also a Dolphin is so small, a diesel may not fit in the original space without significant modifications.

 

[Tranona]

Not sure the weight difference would make any difference to a boat like a SCOD (or many of the other older style boats that Dolphins tend to be fitted in). Compared with a Beta 10 it is 35kg for the gearbox model and 45kg for a direct drive. About 10kg less for a 1GM. Physical size may be an issue, mainly under the beds as the Dolphin does not have a sump, but length and height with gearbox not so different. Biggest problem when replacing a direct drive is likely to be propeller diameter and therefore tip clearance. Direct drive is a 9 or 10" diameter , gearbox (2:1) 12 or 13".

 

[Keith 66]

I fitted a reconditioned one in our old Anderson 22, Reason was my wife hates outboards in wells & im not keen either. The engine was the same weight as a 6hp outboard & was mounted fwd under the companionway step giving better balance than an outboard & less drag, excellent access & very quiet, For a boat that size it was ideal, the power curve & fuel consumption graph lines crossed at a shade over half throttle which gave 6hp & 10 miles range on one gallon of fuel. At that throttle setting the boat was doing just over 6 knots ie max hull speed. Opening the throttle further just cused her to squat but barely increased the speed. They are smooth & quiet & the feeling is of having a turbine under the deck.
Manouvering in confined spaces was never a problem & in 6 years the engine never let us down, Cracking engines that beat outboards hands down. Interestingly quite a few members of our club had them & the only ones that ever gave trouble were the gearbox models with electronic ignition!, Moral of the story is if it works well dont fix it!

 

[DownWest]

I fitted a reconditioned one in our old Anderson 22, Reason was my wife hates outboards in wells & im not keen either. The engine was the same weight as a 6hp outboard & was mounted fwd under the companionway step giving better balance than an outboard & less drag, excellent access & very quiet, For a boat that size it was ideal, the power curve & fuel consumption graph lines crossed at a shade over half throttle which gave 6hp & 10 miles range on one gallon of fuel. At that throttle setting the boat was doing just over 6 knots ie max hull speed. Opening the throttle further just cused her to squat but barely increased the speed. They are smooth & quiet & the feeling is of having a turbine under the deck.
Manouvering in confined spaces was never a problem & in 6 years the engine never let us down, Cracking engines that beat outboards hands down. Interestingly quite a few members of our club had them & the only ones that ever gave trouble were the gearbox models with electronic ignition!, Moral of the story is if it works well dont fix it!

Keith, what is the oil mix for them?
When I think my preferred o/b is a Yam 3.5 aircooled 2T from 1980, a 2T inboard doesn't sound so bad....

 

[wombat88]

For those who haven't seen it:

Dolphin Engines - British made marine auxiliary two stroke engine for leisure and racing yachts

On one page a mixture of 40:1 is mentioned, don't know if this is for all Dolphins or just the later ones.