10, 14 or 21hp?

[Seajet]

Jumbleduck,

a chum has a Centaur ( as you say there are important differences, but...) which was fitted with a new Nanni 3 cylinder job just before he got her.

Having covered many miles in an original Volvo equipped Centaur, the difference is astonishing, the Nanni runs like a smooth turbine in comparison.

One thing - it's probably just relevant to my chum's boat, but watch the new installation has a decent exhaust temperature alarm; chum's didn't - guess how we found out and how awkward the timing of that was !

 

[JumbleDuck]

We have a Beta 14 (same base engine as the Nanni) in our heavyweight, long keel 23 footer. It is more than powerful enough. I would guess that 14hp would be sufficient for a 26 footer, 16hp (available from Beta, as mentioned, but not Nanni I think) would be ample, and 21hp a bit over the top.

I seem to recall that the alternator alone will usually take the first one horsepower, so the increase in power over your current engine will be more than the simple proportional increase of bhp.

Many thanks. The 1GM10 has a 35A alternator, so its worst it will be soaking up 35A x 14.6V x something for inefficiency ... yes, close to a horsepower. On longer motoring trips the engine does occasionally slow down very slightly for a bit, then speed up again, which I think is the Adverc doing its stuff. It needs a long trip for the alternator to warm up enough for its internal temperature compensation to reduce the output enough for the Adverc to do anything.

PS: What swayed you away from Beta - PM if potentially libellous.

I hope it's not libellous. Basically they look a bit cheap and cheerful to me, there seem to be lots of issues with heat exchangers and I dislike their reluctance to provide any sort of definitive price list. I do not buying from people whose prices depend on how much they think they can get out of me. Does any reputable manufacturer fit Beta from new or are they only significantly active in the replacement market?

I've the beta 16hp in a 26', 4.5 ton long keel Nic 26. 1800rpm will do around 4.5 knots in calmish conditions & 2200 rpm will do just about 5knt . 2400 rpm will push me through the Portsmouth harbour springs ebb and 6knots comes up around 2800 revs. I've never had it up to it's max revs of 3600.

Many thanks. I paid a pleasant visit to a forumite's Nic 26 in Campbeltown, and we compared 1GM10 experiences. We both get about 5kt flat out ... mine was down to a shade over 4kt at the start of this year's trip but some Italian tuning did wonders for it. On that basis it sounds as if your boat and mine have similar requirements, so 14hp from Nanni should do fine. At the moment I have quite enough power for damn-where's-the-wind auxiliary use, but a tad more would be nice for sod-it-I'm-not-beating-into-this days. 21hp is terribly alluring, but it would be quite a lot more expense and trouble for something which would rarely run above 50% power.

One thing - it's probably just relevant to my chum's boat, but watch the new installation has a decent exhaust temperature alarm; chum's didn't - guess how we found out and how awkward the timing of that was !

'Tis now on the list. Thanks.

 

[BabaYaga]

there seem to be lots of issues with heat exchangers

It could be worth noting that Beta made a redesign of the heat exchanger around 2011/12 that should have solved the earlier problems of tubes getting clogged by zinc anode debris.
There might be other issues, although I have not noticed.

 

[gavin400]

Has anyone re-engined with one of the Chinese MP engines in the smaller sizes 14 - 25hp, or is the cost differential not significant enough?
I know there was a previous thread but I think that was a larger engine around 50hp

 

[PhillM]

Got a beta 14 in a long keel 3 ton mab. Prop in an apature. I cannot use all the power before prop wash starts up too much vibration on the rudder and hull. 10hp would be too little. More than 14 HP would be wasted.

 

[JumbleDuck]

Has anyone re-engined with one of the Chinese MP engines in the smaller sizes 14 - 25hp, or is the cost differential not significant enough?

The price looks pretty good and the agent seems friendly, but I'm worried about service and spare part availability. Kubota bits will be around for decades ...

Miight be worth thinking about. According to the website the range goes 8hp, 10hp, 21hp but according to the price list there is a 14hp in there too. Anyone know if it has just appeared or just disappeared?

Got a beta 14 in a long keel 3 ton mab. Prop in an apature. I cannot use all the power before prop wash starts up too much vibration on the rudder and hull. 10hp would be too little. More than 14 HP would be wasted.

Ta.

 

[donm]

I am planning to replace my Yanmar 1GM10 this winter. I expect I'll go for a Nanni: the mounts are exactly the same width apart as those on the Yanmar and I don't fancy Beta, for several reasons. A first trawl through the Nanni range suggests that I could fit an N2.10 (479cc, 87kg, 10hp), and N2.14 (479cc, 92kg, 14hp) or perhaps an N3.21 (719cc, 106kg, 21hp) could be squeezed in.

14hp rather than 10hp for another 5kg seems like a no-brainer, but is it worth me investigating the three-cylinder option further, or would that be silly? The boat is 26' LOA, long keel, 4 tons in cruising trim and currently does 5kt under power in calm conditions. Was 23hp overkill for the Centaur?

I have a Beta 20 in my Halmatic 30, which is 5 tonnes plus. Drives a 3 bladed prop very quietly and smoothly down here in the Bristol Channel which has a reputation for tides and sea conditions. In my experience, Beta are very helpful and carry a good stock of spares, if a bit expensive. But if you look around you can get some Kubota spares at lower prices. My engine is about 12 years old and based on my experience, I would fit one again.

 

[JumbleDuck]

I have a Beta 20 in my Halmatic 30, which is 5 tonnes plus. Drives a 3 bladed prop very quietly and smoothly down here in the Bristol Channel which has a reputation for tides and sea conditions. In my experience, Beta are very helpful and carry a good stock of spares, if a bit expensive. But if you look around you can get some Kubota spares at lower prices. My engine is about 12 years old and based on my experience, I would fit one again.

Many thanks ... much appreciated.

 

[LittleSister]

Re the Beta vs. Nanni issue - If you don't want to have a Beta, don't have one: I'll not try to persuade you. But just to let you or anyone else who is considering having one know,
1) I've found Beta staff really helpful and knowledgeable, and spares sent same day, arriving next.
2) I've got ye olde style heat exchanger but never had any problem with it.
3) If I was re-engining a boat I would have no hesitation in fitting a Beta. In fact, it'd be my starting/default choice.

 

[Poecheng]

Re the Beta vs. Nanni issue - If you don't want to have a Beta, don't have one: I'll not try to persuade you. But just to let you or anyone else who is considering having one know,
1) I've found Beta staff really helpful and knowledgeable, and spares sent same day, arriving next.
2) I've got ye olde style heat exchanger but never had any problem with it.
3) If I was re-engining a boat I would have no hesitation in fitting a Beta. In fact, it'd be my starting/default choice.

+1
+1
+1
Don't be put off Beta. I have 20hp and lovely engine. (have had Watermota, IGM10, Thorneycroft HandyBilly, 3GM30, Bukh 36, Bukh 10 and now Beta 20hp)
They are very pleasant and knowledgeable people to deal with

 

[lw395]

Thanks, folks, much appreciated. The boat isn't a Centaur, but close in size and weight. One big difference, which Tranona alludes to, is that the propeller is in a cut out between the stern post and the rudder - she's a double ender - so prop size would be one of the issues to investigate if I went to 21hp. I may well get a Featherstream, but I am a little cautious about having extra moving parts down there, so may just put up with the drag of my current (or a similar) three-bladed fixed prop.

A thought: should I be thinking about a Volvo Penta D1-20? 18hp and three-cylinder smoothness?

It's worth noting that the so-called 'hull speed' of a 'double ender' is slower than that of a transom hulled boat of the same LWL.

If you try driving a canoe stern hull hard under engine, you often find the extra power just sinks the stern and makes a lot of wash.

The flip side of this is that some canoe stern hulls are on the slim side, so drive easily.
So I would avoid comparisons with Centaurs.

Three cylinder smoothness is a good thing IMHO.
But not at any cost.
Also think about mountings and a flex coupling?
Fixed props on a boat that is mostly for sailing? Ideally you'd have a two blader and hide it behind the stern post. A big 3 blader is not something I'd want for the way I like to sail. YMMV.

 

[charles_reed]

I am planning to replace my Yanmar 1GM10 this winter. I expect I'll go for a Nanni: the mounts are exactly the same width apart as those on the Yanmar and I don't fancy Beta, for several reasons. A first trawl through the Nanni range suggests that I could fit an N2.10 (479cc, 87kg, 10hp), and N2.14 (479cc, 92kg, 14hp) or perhaps an N3.21 (719cc, 106kg, 21hp) could be squeezed in.

14hp rather than 10hp for another 5kg seems like a no-brainer, but is it worth me investigating the three-cylinder option further, or would that be silly? The boat is 26' LOA, long keel, 4 tons in cruising trim and currently does 5kt under power in calm conditions. Was 23hp overkill for the Centaur?

A 3 cylinder vertical is about x2 as well balanced as a vertical twin. (I'll refer you to Ricardo for the math).
Running a more powerful engine, @ lower RPM has proved considerably more economical (2GM20 to 3YM20).
However you may need to consider the cost of new sterngear - in my case the Autoprop worked with both outputs.
The 2GM just gave 6.5 knots flat out - the 3YM 7.5 knots @ 3600rpm. These speeds are dictated by more by LWL not just power output.
The Volvo 23 hp fitted to the Centaur, had more to do with purchasing and stock economies than with naval architectural considerations.

 

[Iliade]

The manoeuvring capabilities of the MB2B engined Centaur was a joy while it lasted though: 0 to ~6kt in seconds. Jeremy Clarkson would be pleased and it was great for getting into my cross-current pier mooring without ramming the boat moored ahead.

 

[JumbleDuck]

A 3 cylinder vertical is about x2 as well balanced as a vertical twin. (I'll refer you to Ricardo for the math).

Anyone know whether the Kubota base two-cylinder engine is 360^o, 270^o or 180^o? The problem with a straight twin is that you either get reasonable balance or you get an even firing order, but not both.

 

[LittleSister]

Anyone know whether the Kubota base two-cylinder engine is 360^o, 270^o or 180^o? The problem with a straight twin is that you either get reasonable balance or you get an even firing order, but not both.

I believe it is 360 degrees (like the vast bulk of parallel twins), i.e. the pistons go up and down together, firing alternatively, resulting in even firing.

As I said before, it's really not a vibratory engine, and we've never felt (!) its vibration as a problem or nuisance.

 

[CAPTAIN FANTASTIC]

In my opinion, I would base my decision on frequency and sea conditions. How often I will be using the engine for motor sailing and how exposed the local sea area is. In the main, I would prefer a larger engine (21 hp) so that I can operate it at reduced rpm to obtain the optimum torque, (presumably that the 14 hp engine would be developing its peak torque at a higher rpm than the 21 hp); the extra hp would be useful for when going against tide and wind.

 

[lw395]

In my opinion, I would base my decision on frequency and sea conditions. How often I will be using the engine for motor sailing and how exposed the local sea area is. In the main, I would prefer a larger engine (21 hp) so that I can operate it at reduced rpm to obtain the optimum torque, (presumably that the 14 hp engine would be developing its peak torque at a higher rpm than the 21 hp); the extra hp would be useful for when going against tide and wind.

Not sure how that would be affected by being limited on prop size.
If you can't convert the torque into thrust.....

 

[lw395]

A 3 cylinder vertical is about x2 as well balanced as a vertical twin. (I'll refer you to Ricardo for the math).
....

I might refer you to any number of Triumph and BSA owners for the reality....

 

[lw395]

...Running a more powerful engine, @ lower RPM has proved considerably more economical (2GM20 to 3YM20).
.....

But don't forget that lower cruising rpm means a higher 'dead slow ahead' speed. Probably not an issue for most of us?

 

[earlybird]

Anyone know whether the Kubota base two-cylinder engine is 360^o, 270^o or 180^o? The problem with a straight twin is that you either get reasonable balance or you get an even firing order, but not both.

I believe that the Kubota twin engine used by Beta for their 10 and 14 is 180 deg. ie uneven firing. Presumably the Nanni is the same.
I had a Yanmar 2GM20, also 180 deg. but I never noticed the uneven firing effect, but it certainly jumped around at lowish revs, the balance wasn't anything to write home about.
Digressing slightly, doesn't the Bukh twin design have a geared balance shaft? but I don't know if that's a 180 or 360 deg. layout?
The heavier flywheels on small diesels compared with 'bike vertical twins probably make the uneven firing less of an issue.