Re-powering - Beta Vs Nanni

[Chris in Tassie]

Hi people,

Hoping someone can assist me with my re-powering dilemma.

The Perkins 4.108 in my Robb 35 met a watery death and I'm now on the re-powering journey.*

It is a full keel 6.7 tonne sloop on teak. Built by Cheoy Lee in HK in 62.

I have knocked out Volvo and Yanmar (the latter simply because the agents haven't come back to me).

I'm drawn to the simplicity of the Kubota based engines, namely The UK's Beta and France's Nanni.

I've been advised the Beta 43 is a great switch for the 4.108, while Nanni recommended their N4.38.

Both engines have their pluses and minuses. The nanni is based on the 1500 Kubota, weighing 154kg, while the Beta is on the 2000 Kubota and weighs in at 240kg.

The Beta has a lot more overall torque, but the Nanni seems to carry its torque peak across more of its rpm range.

Plenty of people have offered advice on the marinisation of each engine, with some saying the Beta uses better components, namely the heat exchanger. The Beta also has a heavier flywheel etc. While Nanni*talk about their in-engine coatings etc that*they say reduce noise and vibration etc.

Nanni offers a 3 year parts and labour warranty, while Beta offer the same, plus extend their warranty to five years (tapered) and include a self service provision.

I'm line ball on both engines, but can't have both! So would appreciate*any advice and guidance that might assist me in making a*decision

Cheers, Chris*

[Searles]

Have repowered a robb 35 in Adelaide not a cheoy lee ,but an lionclass built in 1967 in Huon pine with mahogany cabin and teak decks a beautiful classic yacht ,still with a spruce mast clear finished ,re powered from a Volvo penta M D 2 B t0 a 3 cyl fresh watered cooled Nannie’s diesel with a 2/1 g box , 28 hp at 3000 rpm ,plenty of power plus an easy fit .⛵️⚓️

[Searles]

Ps remember the small prop apature 15 inch prop about the max .⛵️⚓️

[stormalong]

Can't comment on Nanni. I replaced my boats Perkins 4-108 with a Beta 50 in 2003. Still have the boat and still happy with the install. Kubota parts are available everywhere. The 4-108 was underpowerd for my 44 footer and the extra HP was needed.

The Beta 43 is the same engine block with a smaller cylinder bore. I worked directly with the factory, I was wintering in England at the time. I had a few customizations done to make it more serviceable. My boat has a V drive transmission so the engine is backwards compared to most installations.

One of the best things that Beta can do for you is custom engine mounts to match your existing engine beds. That greatly reduces install time. I did the work myself and it took about a week.

[Chris in Tassie]

Thanks Searles, that is good advice

[LittleWing77]

Here's a couple of threads you may find useful, Chris:

Beta Engine - Good/Bad for Repower?
https://www.cruisersforum.com/forums...er-218646.html

Opinion on Nanni Engines?
https://www.cruisersforum.com/forums...es-256690.html

[Searles]

Just remember it’s not the so called horse power but how you use it , r p m and torque is what turns the prop ,often a smaller engine geared at 3/1 will do a better job than a larger motor at2/1 ,just horses for courses, ⛵️⚓️

[mfw]

If you are in tassi, I would suggest to speak with David Duffen, d man.
Prince of Wales bay clean lift .
I have a beta 60.

[Jim Cate]

Just remember it’s not the so called horse power but how you use it , r p m and torque is what turns the prop

Actually one formula for calculating horsepower is Horsepower = Torque x RPM / 5,252.

That is to say that it is indeed horsepower that turns the prop.

Jim

[Bowdrie]

Torque is not dependent on time, whereas HP cannot exist without movement during a time frame.
You can use a wrench to push/pull on a frozen bolt and apply a large amount of torque, but if the bolt doesn't turn you've developed no power.
Kind of like the road crew guys who lean on their shovels all day, lots of effort, no work accomplished.
A steam piston engine and an electric motor develop maximum torque at zero RPM, but no HP is developed until they start rotating.
The constant of 5252 indicates that no matter the HP or torque rating the curves of each will cross at that RPM, (if the engine will reach that speed).
Internal combustion, (infernal combustion?) engines generally obtain max torque at the RPM at which they have the greatest volumetric efficiency.
Roughly speaking:
Torque= How big a diameter/pitch prop can you swing.
HP= How fast can you turn it.

[deblen]

Originally Posted by Searles

Ps remember the small prop apature 15 inch prop about the max .⛵️⚓️

That small prop aperture is the limiting factor on max "usable" power.IMHO


My 28 HP VP 2003 turns a 3 blade fixed 17"D x 14" P thru a 2.5 reduction.
I am guessing that the same 28-30 HP & 2.5 reduction would probably require a 3 blade 15" Pitch if diam. was limited to 15".



Is he going to re-use existing shaft & prop?


Cheers/Len

[Solty]

Look at these from Sydney
Witchards Marine - inboard diesel engine manufacturers for yacht or motor boat - WM Diesel.

[Gerben SYD]

Originally Posted by Solty

Look at these from Sydney
Witchards Marine - inboard diesel engine manufacturers for yacht or motor boat - WM Diesel.

Thanks, I did not know about this outfit, and they are up the road from me!

[Munoz]

The 1500cc Kubota is the one to get, ask beta for a quote on the 35 and/or the 38
Might be worth paying a 5-10% premium over Nanni or WM, but not more

[Uncle Bob]

Originally Posted by Munoz

The 1500cc Kubota is the one to get, ask beta for a quote on the 35 and/or the 38
Might be worth paying a 5-10% premium over Nanni or WM, but not more

Hi, as the owner of a WM Kubota based diesel I can unreservedly say that the marinisation is superior to the equivalent Beta, based on observation of three Beta marinisation fails.