Best re-power, Westerly Gk29

[Lusco405]

Hi,

Our Westerly Gk 29 has an ageing Lister Petter Ac2w 12hp (when new, reckon a few horses have been let out of the paddock!) that is woefully under powered and will get bogged down at the slightest hint of chop. Her hull speed is 6.9 knots and under engine she can just about make 5.5 in flat water with a 3 bladed propeller. This is taken down to 3.5 knots in a chop and headwind, I'd like and engine that could maintain cruising speed in adverse weather conditions!
I was looking into replacing the engine and came up with the following engines all around 20hp.
I chose engines around the 20hp mark based on manufacturers recommendations of trying to match the hull speed of the yacht.

Yanmar 3 YM 20 (21hp)
Volvo Penta D1-20 (18hp)
Beta 20 (20hp)
Nanni N3.21 (21hp)

Did consider Vetus but they only come in 16hp and 28 hp models.

They all seem remarkably similar, the Nanni and Beta being essentially the same engine, sharing a Kubota block. The Volvo however seems to pack less of a punch than the others in-terms of displacement and Bore x Stroke. I would lean towards the Yanmar due to its refinement and smooth running but have also heard It can have issues with the exhaust elbow.

The Question is, which one would you choose and why?

Thanks for your help.

 

[alahol2]

bump

 

[30boat]

Beta or Nanni.I have the Beta 20 and am very happy with it.The new ones come with the polyvee(spelling?) belts which are very good.The heat exchanger must be cleaned yearly although I haven't done it for over a year and it seems ok.I fitted an expansion tank because the overheating alarm kept going off.20€ for the tank and a few bits like hoses and adapters.No more problems.Beta has their own kit but it's expensive.
Some say the Nanni marinization is better.Both base engines are the same Kubota (very sturdy) unit.The people at Beta are very helpful ,don't know about the Nanni agent.

 

[charles_reed]

Hi,

Our Westerly Gk 29 has an ageing Lister Petter Ac2w 12hp (when new, reckon a few horses have been let out of the paddock!) that is woefully under powered and will get bogged down at the slightest hint of chop. Her hull speed is 6.9 knots and under engine she can just about make 5.5 in flat water with a 3 bladed propeller. This is taken down to 3.5 knots in a chop and headwind, I'd like and engine that could maintain cruising speed in adverse weather conditions!
I was looking into replacing the engine and came up with the following engines all around 20hp.
I chose engines around the 20hp mark based on manufacturers recommendations of trying to match the hull speed of the yacht.

Yanmar 3 YM 20 (21hp)
Volvo Penta D1-20 (18hp)
Beta 20 (20hp)
Nanni N3.21 (21hp)

Did consider Vetus but they only come in 16hp and 28 hp models.

They all seem remarkably similar, the Nanni and Beta being essentially the same engine, sharing a Kubota block. The Volvo however seems to pack less of a punch than the others in-terms of displacement and Bore x Stroke. I would lean towards the Yanmar due to its refinement and smooth running but have also heard It can have issues with the exhaust elbow.

The Question is, which one would you choose and why?

Thanks for your help.

I chose the 3YM20 and, in 2000hrs running, have had little cause for regret:-
Reasons for choice - similar footprint to the 2GM20 (though the bearers had to be extended) - "best" power/weight ratio - Yanmar design superiority over the others. (They're all last-century diesel technology but Yanmar was the least archaic). Finally reutilisation of the 3-blade Autoprop at the limit of its envelope.
Obtaining a reasonable price was a problem, surprisingly I bought in the UK and shipped to Malta to get a reasonable discount - buying direct from Yanmar Europe was an even cheaper alternative.
Cons, rubbish alternator, some cost-cutting in the wiring loom, a very tight squeeze and a mismatch between power/shaft-size, resulting in a weakness at the shaft clamp.
Shaft is 25mm od, clamp slips when you get any fouling and thereafter is a continual problem. That is a perennial Achilles heel of a live-drive, the balance between fail-safe and reliability.

Though the boat is longer, it's considerably lighter and very easily driven - top rpm 3600, 7.8 knots corrected, 1.2 litre/hr @ cruising rpm.
Don't use Yanmar parts (they're only beaten in the chiselling stakes by Volvo), raw waterpump parts direct from Johnson, oil-filter Mazda 323, others from Filters Direct in volume sufficient to get a trade discount.
Beta and Nanni both Kubota - a good enough base motor but heat exchanger problems, especially the Beta.
I wouldn't even consider Volvo - I dislike their marketing philosophy and their flaw-ridden designs.

Exhaust elbow "problems" usually due to maintenance issues and belting the engine - mine cleaned @ 1800 hrs virtually no corrosion and fairly easy to clean off the tar-deposits, mechanically. When it perforates I'll have one made locally in 316L (I'll probably have to source the steel myself through daughter). Nearly all the corrosion is occurring due to carbon-agglomeration at the weld-site, a classic example of slovenly material choice.

 

[Eyore]

Beta or Nanni as they use the Kubota which is brilliant. Beta is British and the guys in Stroud are very helpful and produce a great product. I have had three Betas since 1996 in 3 different boats and never had any issues . Beta then.

 

[Burnham Bob]

Again no experience of the Nanni but my beta has never missed a beat or failed to start. Beta head office are very helpful so I know you won't go wrong with a beta.

 

[typhoonNige]

I had a GK29 some years ago which had a Lombardini 17hp fitted by the previous owner. Never missed a beat in the 4 years of my ownership.

 

[Tranona]

You may want to look at the installation details, particularly access to the service points, controls and exhaust runs. as others have suggested there is little to choose between them technically and the final choice is just as likely to depend on the deal you can get for the whole package. You will almost certainly need to replace the stern gear and exhaust system and may want to do something about electrics, fuel and insulation to get the most out of your new engine.

 

[DavidGrieves]

Hi

I have a GK29 with a Volvo Penta 2002 its 18HP. I know you can't get that model anymore but its 18hp is more than adequate to push it along at 6knts in most conditions.

As already mentioned by others have a look at things like prop shaft size and alignment, exhaust size etc. Might make it easier/cheaper to install.

On a completely different subject, how is your rudder spindle fixed? What prevents the 1/2" s/steel pin from sliding up and coming out of the bottom bracket. If you are just relying on the s/steel pinch clamp below the top rudder fitting I would suggest you fabricate another way of securing it. I drilled a small hole just below the top fitting and inserted an "R" clip, and wired it with monel wire. The rudder pin is an Achilles heel.

Do you want to ask me how I know this?