Petrol engines on motor boats.

[oldgit]

Two recent examples of petrol powered sports boats around 7 metres in length with 2 berth cabins.
First boat seriously well mantained by the owner and well used on some pretty epic voyages over a couple of years of ownership, skipper dead pleased with the boat.
Then came some mysterious over heating problems , the engine dying and unable to get started again.
Time and money spent and hopefully the problem was sorted, unfortunately it happened again and the boat was sold on.
On the first occassion was off of Southend , the Sheerness lifeboat happened to be out on exercises and towed them back to Queenborough, problem investigated presumed sorted. The adventurous skipper then set off up the Thames the engine failed again, a passing workboat came to their assistance
Moored in Allington Lock and nattering to the skipper of the boat moored behind.
Engine overheated and would not start, he was trying to find somebody who was prepared to look at the problem, was not expecting anybody to be free for a day or two.
Both fairly modern boats powered by Mercruiser V6 engines.
Good idea to ensure that engines are 100% before purchase.

 

[paradave]

Not quite sure on your point there oldgit.

This forum is full of people experiencing problems with all types of engines.
I think the advice to check engines are ok before purchase is a little obvious and I’m not sure how that even applies to your first example.

 

[Clancy Moped]

Sat on the rocky breakwater at Kalamata Marina fishing, this little speed boat rounds the breakwater, it was the kind that was given away on The Generation Game or Bullseye, one blue spark and up it went, it happened so quickly, three blokes in the water one burnt quite badly down one side the others were lucky, the boat drifted onto the rocks and burnt out, no thanks.

 

[Sianna]

Got to remember to run the blowers with a petrol, so it's diesel for me

I know it's been seen many times before but this is how it can go wrong:

 

[Hot Property]

Outboard all the way for me...

Previous boat was 23ft sportscruiser with 200 verado - a supercharged 2.6 litre straight 6. Super quiet and stunning acceleration.

Fresh water flushed after every trip and of course the whole engine (barring the transom bracket) is out of the water so no corrosion.

Fuel cost higher of course, Solent and south coast availability is good. If you spend all year cruising then diesel inboard on shafts is cheaper.

For most recreational boaters 100 hrs is a lot. Berthing costs dwarf my fuel costs.....

Current RIB has 100 Vtec Honda which is powerful, light and efficient. They've made millions of these in the Jazz car so a well developed and reliable engine. Servicing easy and relatively cheap.

So up to around 25ft petrol outboard, over that then diesel shafts - outdrives are indeed the devils spawn....

 

[Momac]

Petrol is very restrictive in terms of range and availability in our area.

But in the right sort of boat and limited requirement on range petrol could make sense.

 

[ChromeDome]

Two recent examples of petrol powered sports boats around 7 metres in length with 2 berth cabins.
First boat seriously well mantained by the owner and well used on some pretty epic voyages over a couple of years of ownership, skipper dead pleased with the boat.
Then came some mysterious over heating problems , the engine dying and unable to get started again.
Time and money spent and hopefully the problem was sorted, unfortunately it happened again and the boat was sold on.
On the first occassion was off of Southend , the Sheerness lifeboat happened to be out on exercises and towed them back to Queenborough, problem investigated presumed sorted. The adventurous skipper then set off up the Thames the engine failed again, a passing workboat came to their assistance
Moored in Allington Lock and nattering to the skipper of the boat moored behind.
Engine overheated and would not start, he was trying to find somebody who was prepared to look at the problem, was not expecting anybody to be free for a day or two.
Both fairly modern boats powered by Mercruiser V6 engines.
Good idea to ensure that engines are 100% before purchase.

Reminds me of the thread about Volvo D3 gremlins. And they are diesels..

 

[jrudge]

My grand fathers lifelong friend was Ronny Corbett. They blew a petrol engines boat up in San Remo harbour

Petrol is fine but you need to respect it, check it and bilge blow. I have a petrol rib and would be fine with a speed boat but sceptical of something I slept on

 

[ChromeDome]

On this note
Running the engine fan for a few minutes before startup is essential with petrol but do people run their fans with diesel motors in the same way. I don’t see anyone doing this in my marina.

On our twin diesel mobo the engine room fan is powerful (standing on the pontoon, you hear it over the engines idling) and runs constantly from the first turn of a key (pre-heat) until the engines are turned off.

 

[DavidJ]

re @ChromeDome
That’s interesting and it clearly works well for you.
It makes me think that once the engine has started it’s sucking in massive amounts of air and doing the fume clearing quite well.
I‘m thinking two 3.6 litre engines at say 2000rpm is a lot of litres.

 

[julians]

re @ChromeDome
That’s interesting and it clearly works well for you.
It makes me think that once the engine has started it’s sucking in massive amounts of air and doing the fume clearing quite well.
I‘m thinking two 3.6 litre engines at say 2000rpm is a lot of litres.

None of our diesel engined boats have had bilge/engineroom blowers, all our petrol inboard engined boats have had them and we used them every time.

 

[oldgit]

Not quite sure on your point there oldgit.

This forum is full of people experiencing problems with all types of engines.
I think the advice to check engines are ok before purchase is a little obvious and I’m not sure how that even applies to your first example.

A failed attempt to not be too discouraging regards boats powered by petrol engines especially that ubiquitous Mercruiser V6 found in just about everything.
No doubt zillions doing sterling service out there.
Not that exercised about the fuel safety argument but the availabilty of fuel would be a concern.
Diesels are of course not without their little problems, ie. the idler wheels on the compressor clutches on KAD43 which fail.
Recently an idler failed on a boat owned by a club member , fortunately the resulting tangle caused the engine to stall preventing further damage.
Rather than just replace the idler wheel (s), the owner has just fitted brand new VP complete clutch units to both his engines .....just in case.

 

[ChromeDome]

re @ChromeDome
That’s interesting and it clearly works well for you.
It makes me think that once the engine has started it’s sucking in massive amounts of air and doing the fume clearing quite well.
I‘m thinking two 3.6 litre engines at say 2000rpm is a lot of litres.

When a petrol engine use a 15:1 air/fuel ratio (diesels some 25:1 depending on model - some modern lean burners are 70:1), it clearly takes a lot of fresh air to be sucked in. Much less when at idle though, but can do the maths.

Big vents/grilles are needed. On my boat, they are factory fitted and work well.

 

[QBhoy]

They salvaged the remains and did all kinds of investigations. Authorities, insurance companies and more. They found no reason.

Logically, something must have leaked - but no proof of it. The boat was maintained by the book. It's more than 35 years ago now, but it's still with me. My then 5-year-old son was with me, and throwing him into the sea to get him away from the chaos is an image that stays with me for life.

Everyone on board made it, but it's definitely an experience I would have rather not had.

Not known for their marine durability those. Can’t go wrong with a tried and tested GM v6 or v8 short block though. Still countless around, still strong and into their 40’s as for the 3.0 GM. Rough and ready…but the undeniable fact is…that they are by far, the most numerous and successful engine ever put in a boat, last I knew. Totally get the diesel notion too though. Fan of both. Don’t tell anyone I said it out loud…but it’s looking very much like these new mercury 4 strokes are going to leave everything behind. If they haven’t already. I secretly own one currently

 

[Fire99]

There are petrol boats and there are petrol boats.. There is a world of difference between say a modern outboard rib and an old 70s / 80s motorboat with inboard carb fed petrol engines. I've had a variety and my old V8 petrol sterndrive was great but it clearly had been meticulously maintained. That said I did replace the old points ignition for an electronic contactless jobbie and that solved an intermittent stalling issue. But you do need an A1 quality fuel system (tank and lines) and bilge blowers that work. The old issue was that petrol engines need a spark (literally) to fire which isn't too friendly to damp (and often salty) air where as diesels used to be predominantly mechanical and compression driven so were more reliable but these days diesels are virtually as electronically reliant / complex and petrols.
Personally, i'd have a modern petrol outboard boat or even a small petrol sterndrive Inboard but I'd want to make sure I had good fuel availability wherever I intended to use the boat.

One last ramble. The marinas I have spoken to use regular pump E10 petrol. A lot of petrol powered boats won't like it. So I think it is worth doing a little homework on your prospective engine and modern fuel, whether it'll need an additive etc. Just a thought.

 

[ChromeDome]

Our marina now sell GTL Diesel and E5 100 octane petrol only. Not cheap by any means as the marina at all times use a markup to cover cost of running the pumps w/card payment etc.

I see still more owner with jerrycans.

 

[scottie]

There are petrol boats and there are petrol boats.. There is a world of difference between say a modern outboard rib and an old 70s / 80s motorboat with inboard carb fed petrol engines. I've had a variety and my old V8 petrol sterndrive was great but it clearly had been meticulously maintained. That said I did replace the old points ignition for an electronic contactless jobbie and that solved an intermittent stalling issue. But you do need an A1 quality fuel system (tank and lines) and bilge blowers that work. The old issue was that petrol engines need a spark (literally) to fire which isn't too friendly to damp (and often salty) air where as diesels used to be predominantly mechanical and compression driven so were more reliable but these days diesels are virtually as electronically reliant / complex and petrols.
Personally, i'd have a modern petrol outboard boat or even a small petrol sterndrive Inboard but I'd want to make sure I had good fuel availability wherever I intended to use the boat.

One last ramble. The marinas I have spoken to use regular pump E10 petrol. A lot of petrol powered boats won't like it. So I think it is worth doing a little homework on your prospective engine and modern fuel, whether it'll need an additive etc. Just a thought.

I find the using jobbie strange as in my area it is what you might refer to as feces so not exactly a recommendation

 

[Fire99]

I find the using jobbie strange as in my area it is what you might refer to as feces so not exactly a recommendation

Probably not the biggest issue on earth...

In my area, Jobbie, Malarkey, oojamaflip, yoke, thingymabob etc etc.. will all do without causing a ruffle of feathers.

 

[QBhoy]

Two recent examples of petrol powered sports boats around 7 metres in length with 2 berth cabins.
First boat seriously well mantained by the owner and well used on some pretty epic voyages over a couple of years of ownership, skipper dead pleased with the boat.
Then came some mysterious over heating problems , the engine dying and unable to get started again.
Time and money spent and hopefully the problem was sorted, unfortunately it happened again and the boat was sold on.
On the first occassion was off of Southend , the Sheerness lifeboat happened to be out on exercises and towed them back to Queenborough, problem investigated presumed sorted. The adventurous skipper then set off up the Thames the engine failed again, a passing workboat came to their assistance
Moored in Allington Lock and nattering to the skipper of the boat moored behind.
Engine overheated and would not start, he was trying to find somebody who was prepared to look at the problem, was not expecting anybody to be free for a day or two.
Both fairly modern boats powered by Mercruiser V6 engines.
Good idea to ensure that engines are 100% before purchase.

Sounds like horrid effort or lack of, in terms of maintenance. It takes serious neglect to break a 4.3 GM. The 3.7 disaster of a thing though…sounds more like the very thing they are famous for perhaps. Anyone who does the very basics in maintenance on these fairly frequently, will know how robust they are. So cheap to own too.

 

[Ribtecer]

I have a 7m rib with a 150hp diesel Cummins inboard, running thru a mercruiser Alpha one leg.

It's a great set up, I like my spanners and took the engine out to deal with a few little minor issues, but in general its been great and uses very little fuel. I love it.

All boats have niggles, most can be ironed out with proper maintenance.

I love my boat, its a keeper