Advice please, engine issue on sea trial

[Otter]

Sea trial today on a twin engined 1979 trawler motor yacht. Engines are original Ford Sabre (Dorset) normally aspirated 120hp - were 180hp but turbos removed.

Smokey on cold start up - I expected that. No smoke when running warm. But mid way I moved the throttles from idle to full in one movement and the starboard engine blew a cloud of white smoke big enough to obscure us - it smelled of unburnt diesel or at least diesel dumped into the exhaust maybe?

Try as hard as I could I couldn’t replicate this at all on the trial as long as I moved the throttles up relatively slowly.

She’s clearly over propped. At tick over she did 4.5 knots and she’s 32.5 ft lwl. Max revs were about 1700, surely too low?

Any suggestions on what might have caused the huge cloud of smoke? What should the engineer surveyor look for?

Apart from this one incident it behaved impeccably and there’s a superb service record.

Thank you.

 

[Hunterlees]

My Lehman 2712e 80hp did exactly this on its first outing this year, having been laid up all winter -and then has run faultlessly since. I put it down to oil or diesel accumulating in the manifold which is then burnt off as temperature/revs rise.
What is the vessel out on trial?

 

[Otter]

Thanks. Puget Sound 34

 

[harvey38]

Sea trial today on a twin engined 1979 trawler motor yacht. Engines are original Ford Sabre (Dorset) normally aspirated 120hp - were 180hp but turbos removed.

Smokey on cold start up - I expected that. No smoke when running warm. But mid way I moved the throttles from idle to full in one movement and the starboard engine blew a cloud of white smoke big enough to obscure us - it smelled of unburnt diesel or at least diesel dumped into the exhaust maybe?

Try as hard as I could I couldn’t replicate this at all on the trial as long as I moved the throttles up relatively slowly.

She’s clearly over propped. At tick over she did 4.5 knots and she’s 32.5 ft lwl. Max revs were about 1700, surely too low?

Any suggestions on what might have caused the huge cloud of smoke? What should the engineer surveyor look for?

Apart from this one incident it behaved impeccably and there’s a superb service record.

Thank you.

That's what they do.

They rely on air, fuel and so combustion.

No sensors or electronic management so until a stable consumption of air, fuel and temperature, they can be erratic if any of these parameters are quickly changed.

I have a pair of 250hp Sabres, Jurassic but simple

 

[Alicatt]

My old 145hp turbo diesel Perkins do that too, run at idle and then open her up and she delivers her own smoke screen, clears after a minute or so and does not smoke again until a long period of sailing at idle as happens on the canals here.

At idle my boat does about 4.8 knots sog on both engines, and 4.2knots on one engine, boat is a 37ft semi displacement 10ton ocean 37 and has a 10.5m waterline length. Not had her above 1900 - 2000rpm but not much throttle after that she achieved 17knots at that rpm against the slight flow of the canal of about 1 or 2 km/h, the canal we were on is one of the feeds of water to the Albert canal from the Maas.

 

[Paul1962]

Sea trial today on a twin engined 1979 trawler motor yacht. Engines are original Ford Sabre (Dorset) normally aspirated 120hp - were 180hp but turbos removed.

Smokey on cold start up - I expected that. No smoke when running warm. But mid way I moved the throttles from idle to full in one movement and the starboard engine blew a cloud of white smoke big enough to obscure us - it smelled of unburnt diesel or at least diesel dumped into the exhaust maybe?

Try as hard as I could I couldn’t replicate this at all on the trial as long as I moved the throttles up relatively slowly.

She’s clearly over propped. At tick over she did 4.5 knots and she’s 32.5 ft lwl. Max revs were about 1700, surely too low?

Any suggestions on what might have caused the huge cloud of smoke? What should the engineer surveyor look for?

Apart from this one incident it behaved impeccably and there’s a superb service record.

Thank you.

Hi - I thought these engines had a maximum wide open throttle of 2500 rpm

 

[Otter]

Thank you everyone that’s very reassuring!

 

[Otter]

She’s I’m sure she’s over propped.

 

[LittleSister]

Sea trial today on a twin engined 1979 trawler motor yacht. Engines are original Ford Sabre (Dorset) normally aspirated 120hp - were 180hp but turbos removed.

. . .

She’s clearly over propped. At tick over she did 4.5 knots and she’s 32.5 ft lwl. Max revs were about 1700, surely too low?

. . .

Hi - I thought these engines had a maximum wide open throttle of 2500 rpm

Presumably the props were sized to suit the original 180hp motors, and without the turbos there's not the power to achieve max revs with those props. (So the engines won't even be able to deliver the potential 120hp.)

 

[Otter]

Yes it’s effectively running a pair of 80hp engines.

 

[Divemaster1]

Sea trial today on a twin engined 1979 trawler motor yacht. Engines are original Ford Sabre (Dorset) normally aspirated 120hp - were 180hp but turbos removed.

.........................

Any suggestions on what might have caused the huge cloud of smoke? What should the engineer surveyor look for?

Apart from this one incident it behaved impeccably and there’s a superb service record.

Thank you.

Believe that he 180's had an intercooler and a turbocharger ..

You will also probably have the original fuel pump and injectors installed which would be capable of providing all the fuel the 180 hp engine would need. As such and if fuel pump is not not de-rated as well, you will have given the engine (combustion chamber) much more fuel than the engines would be able to burn.... the result would inevitably be loads (excessive amount) of grey smoke which naturally would have given off the distinct smell of unburnt fuel.

At 1700 RPM WOT, I'd suspect original propellors as if she had twin 180's .. so over propped..

 

[Otter]

Believe that he 180's had an intercooler and a turbocharger ..

You will also probably have the original fuel pump and injectors installed which would be capable of providing all the fuel the 180 hp engine would need. As such and if fuel pump is not not de-rated as well, you will have given the engine (combustion chamber) much more fuel than the engines would be able to burn.... the result would inevitably be loads (excessive amount) of grey smoke which naturally would have given off the distinct smell of unburnt fuel.

At 1700 RPM WOT, I'd suspect original propellors as if she had twin 180's .. so over propped..

Thank you that’s a clear indication that the pumps would need looking at as well.

 

[Divemaster1]

Thank you that’s a clear indication that the pumps would need looking at as well.

May be easier (and not much more expensive) to fit rebuilt turbochargers on both engines (no need to do anything with the propellors.... With new turbos, the engines would be happy to run at 1500 - 1800 RPM all day long ... if you're happy with the speed of course .. and you'll have the power to push along faster to outrun weather etc., if needed. Also re-sale would be easier if engines are in original configuration..

 

[Flynnbarr]

Yes it’s effectively running a pair of 80hp engines.

All the 34ft trawlers of that era,Chein Hwa…Puget Sound etc usually came with twin 80hp or a single 120hp.
Twin 180hp seems very excessive for what’s basically a 9/10 knot displacement hull……guessing I’d say the turbo’s were taken off as they probably never got going….all you’ll do is burn a lot of fuel and make a lot of wash .

One for sale in Scotland has been re engined with twin Beta 60hp as that’s really all you need.
Nice boats good luck.

 

[Otter]

The one in Scotland is a nice boat. I think twin 60’s are at the margin of adequate, it’s a 11 tonne displacement boat with a huge windage area. I know diesels like to be pushed hard but it bothered me that there wouldn’t be enough in the bank, and it’s an expensive boat. But I agree these twin 120’s are unnecessarily big. Twin 80/90 would be perfect. Trying to push a Puget Sound over the hump would be a great way to burn fuel for no benefit wouldn’t it.
Buying a boat is navigating a complex set of compromises.

 

[Alicatt]

Up to about 7 knots Hunter is quite economical at less than 3 litres per hour, 10knots and you are just making a hole to drain the diesel into, 12knots and you are planing and with 2x 145hp she manages 17knots at 30litres per hour per engine, so far this year since filling the tanks we have done 652km with about 1/4 of a tank being used, tank holds 900 litres.

Speeds here are quite low, all measured in km/h speed over ground our canal is 8km/h which we normally do on one engine at tick over, the bigger canal it's 12km/h so both engines and a little throttle, the Albert Kanaal is 15km/h and depending on flow can be from 900rpm to 1200rpm, sections of the canal are de-resticted and you can push the speed up a bit, it is wide and deep at over 5m in the high speed sections, where our canal is 1.5m to 3m with a nominal 2m depth and full of weed

They say the engines are producing about 20hp each at idle and the difference between one engine propelling the boat and two engines is only about 1km/h

 

[Flynnbarr]

Buying a boat is navigating a complex set of compromises.

Indeed it is!
If your looking at the one in Poole you’d be dodging a major bullet as the teak decks have been removed…

Good friend of mine had a Chein Hwa 34….his teak decks were a major issue and before he knew anything it had rotted a bulkhead as the water always pools about where the stern cabin superstructure is…..the screws in the teak were mild steel !…..was built like a tank though and what if any modern offering has an emergency tiller…..his had single 120hp Ford Lehman and the bow wave was impressive flat out….his nickname for his was Taiwanese takeaway and he did find out that the carvings on the doors in some of them mean something to the team that fitted them out….
I did hear the next owner had to replace the fuel tanks but that’s just the lottery of ownership.
Good luck with it if you proceed

 

[Jim@sea]

I don't think its over propped, I had a motor boat with a single 140 Yanmar, at tick over it would do 4.5 knots, which in a crowded marina seems quite fast, but the boat is designed for the open water.
On one occasion I had a trailer up a slipway waiting for my boat, I had an open cockpit with windows, and it was windy, at tick over the boat was taking me towards the trailer at 4.5 knots and the wind behind me added another 1 knot fortunately my boat had a 9.9 Auxiliary Outboard which I put into reverse so that slowed me down to 3 knots '
You have to do these sort of tricks as I was on my own and no one holding onto the trailer which fortunately was still attached to my 4x4.

 

[Otter]

Indeed it is!
If your looking at the one in Poole you’d be dodging a major bullet as the teak decks have been removed…

Good friend of mine had a Chein Hwa 34….his teak decks were a major issue and before he knew anything it had rotted a bulkhead as the water always pools about where the stern cabin superstructure is…..the screws in the teak were mild steel !…..was built like a tank though and what if any modern offering has an emergency tiller…..his had single 120hp Ford Lehman and the bow wave was impressive flat out….his nickname for his was Taiwanese takeaway and he did find out that the carvings on the doors in some of them mean something to the team that fitted them out….
I did hear the next owner had to replace the fuel tanks but that’s just the lottery of ownership.
Good luck with it if you proceed

Yes it’s the one in Poole and the tanks are Tek Tank replacements but of an earlyish vintage.
The teak decks were removed when the cores were soggy and 15mm ply bonded and glassed into place on top of the GRP deck, effectively raising the deck 20mm. They’re rock solid. I’ve visited two vintage Trawler motor boats now where the teak decks were removed and fake teak slapped on without strengthening the decks. The decks were spongy under foot and so the fake teak caulking had split in places and water was pouring in and out in the splits as you walked around. The silly thing is, before they’d both put the fake teak on, the job was a relatively simple fix, now it’s a nightmare.

Survey is Tuesday

 

[Alicatt]

The teak deck on the cockpit of Hunter was replaced in May 2020, about 2m x 3m of 12mm x 48mm, at the princely sum of €7623 (£6651)