Seeking a new engine.

[Seagreen]

Hello everyone.
I'm considering going up and engine size or so. Currently, I have a Beta 20 pushing a heavy displacement hull (7.5 tons) with a variable pitch propeller, which gives me about 5 kn at 3k revs.

I'm looking for a significant increase in power without going up too much in weight or size, if that is at all possible, with new engines being developed. Any suggestions welcome.

 

[earlybird]

I think that most of the mainstream engines are much of a muchness in terms of weight for a particular power. Lombardini are perhaps amongst the lightest, but not very widely fitted.
The Beta 30 gives you ~50% extra power for 25Kg weight increase, after that it's 4 cylinders and extra length. With a heavy displacement hull, is weight-saving so important?

 

[mogmog2]

Is your Beta 20 knackered, or are you just fed up with the lack of power? I might be interested in it if you go for a replacement.

 

[Seagreen]

My current Beta is by no means knackered, but I am, as you guess, fed up with the lack of power. For a 36' boat at that weight, it really needs more grunt to get in over a choppy fetch. The old engine (10 years but only 250 hours) will certainly be up for sale.

As for the weight saving, its really a question of not having to re-build the engine bay too much. Also, I spent a lot of time and effort moving all the weight (batteries etc) forward to re-trim the hull and improve the sailing qualities, so i'd hate to undo all that effort.

 

[Tranona]

Any of the 30hp engines will be a significant improvement and should allow you to achieve hull speed with the right propeller. As noted only around 35kgs heavier and 50% more power - but still 3 cylinders, not 4. This should give maximum speed in the high 6s and cruise at 5 knots at around 2400rpm.

With a 7 tons+ displacement a 4 cylinder 35 would be better, giving you a reserve, but a big jump in weight and size - over 80kgs heavier, 12cm longer, 6cm wider and 4cm taller. Both this and the 30 require wider spaced bearers as distance between mount centres is 40mm greater.

Think my choice would be the 30hp as the best compromise. The figures above are for Beta or Nanni, but Volvo or Yanmar would be much the same.

 

[Ladybirdgaffcutter]

Some Beta engines have turbo and normal versions of the same engine, you may be able to add extra power off the factory shelf, without faffing too much with mountings, cables etc.

Turbos tend to frighten yachtsmen, but all trucks, most ships and workboats, and many cars get on just fine turbo'd, enjoying the extra power and/or better consumption, and cooler and quieter exhaust.

 

[Tranona]

Some Beta engines have turbo and normal versions of the same engine, you may be able to add extra power off the factory shelf, without faffing too much with mountings, cables etc.

Turbos tend to frighten yachtsmen, but all trucks, most ships and workboats, and many cars get on just fine turbo'd, enjoying the extra power and/or better consumption, and cooler and quieter exhaust.

Afraid not relevant in this HP range - only in the 40hp+. Despite what you say, turbos have a poor reputation on small engines and the only one that has tried it was Volvo with the 2003T which was problematic and soon discontinued.

 

[Ladybirdgaffcutter]

Afraid not relevant in this HP range - only in the 40hp+. Despite what you say, turbos have a poor reputation on small engines and the only one that has tried it was Volvo with the 2003T which was problematic and soon discontinued.

I stand corrected! It seemed like a good idea anyway...

 

[mogmog2]

My current Beta is by no means knackered, but I am, as you guess, fed up with the lack of power. For a 36' boat at that weight, it really needs more grunt to get in over a choppy fetch. The old engine (10 years but only 250 hours) will certainly be up for sale.
.

Seagreen, I would be very interested in your engine then. I am itching to get an engine into my Centaur. Do you have a timescale yet?
Thanks

 

[Seagreen]

Not yet. But provisionally the engine swap will happen in the spring sometime, as part of a far larger refit. There's going to be a great deal to do in short order, and the re-engineing was only discussed as an idea last night. So early days.
I'm quite happy to stick with Beta, as the 30 is only marginally bigger than a 20 (just checked) and so should fit in the existing bay and on the existing bearers without too much grief ensuing.

 

[mogmog2]

Not yet. But provisionally the engine swap will happen in the spring sometime, as part of a far larger refit. There's going to be a great deal to do in short order, and the re-engineing was only discussed as an idea last night. So early days.
I'm quite happy to stick with Beta, as the 30 is only marginally bigger than a 20 (just checked) and so should fit in the existing bay and on the existing bearers without too much grief ensuing.

OK. will pm.

 

[scottie]

Afraid not relevant in this HP range - only in the 40hp+. Despite what you say, turbos have a poor reputation on small engines and the only one that has tried it was Volvo with the 2003T which was problematic and soon discontinued.

2003T was inappropriately supplied to one particular boat builder on a miss understanding of the use of turbocharging
IE it acted like a reserve of power but not to be used under normal use but this meant in practice the engines were never or rarely run at full power this relationship ended in tears and the Japanese smiled all the way to the bank
We used in more appropriate instances I believed it worked well

 

[langstonelayabout]

Seagreen, I would be very interested in your engine then. I am itching to get an engine into my Centaur. Do you have a timescale yet?
Thanks

It’s too big for your Centaur. Buy a Beta 14 for heavens sake.

 

[Tranona]

It’s too big for your Centaur. Buy a Beta 14 for heavens sake.

Bad advice. The 20 is the optimum choice for a Centaur. 14hp is not enough for the displacement to meet today's expectations.

14hp will only achieve 5.6knots but 20hp will get hull speed of 6.5 knots. in the real world that is a big difference, particularly the ability to cruise at much lower RPM as well as having reserve for adverse conditions.

 

[geem]

Always found the rule of thumb 5hp per tonne ( fully loaded) useful and accurate for most monohull applications. I wouldn't size an engine on it but it's a good cross check. If you don't have 5hp per tonne there must be a good reason

 

[seaangler23]

I’ve a bukh 48 in a 36ft 12t yacht and it’s perfect, quiet, economical, pushes well and fairly small as a 3cyl turbo but I wouldn’t fit one, it’s old tech and parts are expensive and hard to get if it does go wrong.

 

[Iliade]

It’s too big for your Centaur. Buy a Beta 14 for heavens sake.

It’s too small for your Centaur. Buy a Beta 30 for heavens sake. ;0)

(A Centaur Owner - I have a VP2003 and it is just about ok)

 

[KellysEye]

I asked a number of engine repair shops in the Caribbean which engine they least had to repair, the unanimous vote was Yanmar.

 

[Lightwave395]

There was a Yanmar 3YM30 with a handful of hours (50 'ish I recall) for sale here on the Island recently - there were two and I bought the other one.
If you might be interested, PM me and I'll try to track down whether it's still available ?

 

[mogmog2]

I asked a number of engine repair shops in the Caribbean which engine they least had to repair, the unanimous vote was Yanmar.

Are there Betas out there in the Carribbean? Presumably they mostly see US makes?