Nanni 21hp diesel saildrive

[bushytales]

Hi folks, I’m seeking some sensible comments/experiences on these power plants.
I am considering buying a cat which has these installed with approx 400hrs only on each engine. I have had Nanni engines years back and they proved reliable. However they were shaft driven! Personally I have an aversion to sail drives but as the boat is already equipped with the sail drives I need to find more out, hopefully from this forum. Any comments...positive/negative/personal experiences?
Thank you in advance...jeff

[Ostinato]

I own Nanni engines (29hp).and am quite sure Nanni does not make any sail drives. Instead they use those those made by ZF or Twin Discs. For my size engine they have stopped using ZF and actually make a kit for changing ZF over to Twin Disc (SP60s). I have done that.

In my opinion ZF drives are not built for long hours without extensive servicing. I have discussed with ZF factory reps and have written confirmation of their expected life span. Essentially you can expect 2k hours before needing a major overhaul if they are ZF and their parts are very expensive. Even before then you will be rebuilding or replacing output shafts.

There are one or two threads discussing this in more in detail.

I do not have similar information on SP60s but have reason to be hopeful. Like you however I would prefer a different transmission arrangement.

[bushytales]

Hi Ostinato,thank you for the objective comments re sail drives coupled to Nanni’s.
If they require overhauling at 2k hours, what is required and any idea of costs associated?
Thank you again...Jeff bush

[Ostinato]

I only have limited information on costs. When my drives were at a point that I needed to replace or other wise repair the output shafts (think prop shat) I asked ZF what new shafts would cost. They wanted to sell me the entire leg and an Italian dealer quoted me 4K euros each. When I insisted on replacing just the shaft they quoted 2k each.

They stated the shafts would need to be shimmed to work properly and it was better to replace the entire leg.

When I replaced the ZF drives with SP60s it was obvious the main ZF drive shafts were leaking drive oil into the bell housing. The engines were about 10 years old and had about 2k hours on them so I estimated I would have needed new shaft seals, output shafts and clutches as well as the seals the prevent saltwater from entering the hulls. What that would have totaled I really don’t know but I think I spent about 7k euros on two new drives with two year warranties and the modification kits. I quess-timated that in the end it would be about the same as repairing them and I had new drives.

One more thing to consider is how you will use your engines. I almost always run only one at a time over any kind of distance. So while the total hours I have run may say 2k hours on each engine, the boat may have been underway maybe 3k or 3.5k hours. Does this make sense?

[bushytales]

Many thanks for your objective comments.
Seems as if I need to keep looking. Never had "legs" before - only shafts and/or Yamaha o/B s which were brilliant, easy to service never failed and cheap to run.
Vs your suggestions re costs and fear of major replacements at 2000hrs.
Thanks again...jeff B

[DMR]

I am the second owner of a 38' Cat weighing in at 6 Tonnes powered by 2x21hp Nanni's with Technodrive Saildrives. I find the engines are underpowered and high revving in this application and I would upgrade them if i could afford it. 2x 30hp Yanmar's would be better suited to the task. Getting Nanni parts in Asia is a challenge but the blocks are Kubota's which are also used by Beta Marine and in Fischer Panda Gensets, so that helps sourcing. Any Fischer Panda Mechanic should know their way round the Nanni's.

[Compass790]

I've heard a lotta boatyard complaints about saildrives & stern legs. Great for parts sellers. I haven't owned one but would not buy a vessel with one unless I had a lot more $$$