Mangusta 72 - Arnesons

Ok, let me try to put this differently.

1) When we did the big trip, the AP was not really needed. We were merely testing systems.
2) I did not experience this type of event in this particular boat. Maybe it doesn't have that issue.
3) If it happens as the other guy said, it should be investigated. Although he put it as a normal thing to happen.
4) We shall see in the future what happens with my boat. I think the Mangusta story is a success case anyway, so the stuff they're made of is good. Anyway, as previously suggested, BCS/Arneson and Simrad are not trademarks of Mangusta. I think, Pershing, Baia, Leopard, Itama, Sunseeker, Jaguar and probably Magnum to name most, all use the same systems. So if there is a hardware issue with this one, the others must have the same type of issues. But I can't see anybody giving out so much info on their boats and attitudes on the web.
5) I think this thread is about the interest in the purchase of a Mangusta 72, and the possible drawbacks of ASDs. So maybe we should not veer away from the subject by dwelling into details that can hardly be scientifically answered at this stage.
Alternatively, if ASDs are a pain, there used to be an AB Yachts with 75 feet. That was called the Follio 72. A nice boat with Hamilton Jets and CAT engines. But a bit older.
Good luck.

We installed a Simrad AP-25 with virtual rru to replace a Robertson that came with the boat originally.

One of the challenges in an autopilot installation on Arneson Drive equipped boats is that there is no easy way to tell an autopilot what the "rudder position" is. The virtual rru eliminates the need for rudder feedback to the pilot, the pilot actually "learns" the characteristics of the boat and gets better and better as time goes on. It did a great job for us at anything above planing speeds, but couldn't hold a line in displacement mode.

With that being said, the only time we used the autopilot was on offshore deliveries to reduce fatigue for the helmsman. The helm was NEVER unmanned, even for a few seconds.

You need a software update for your Simrad.

This was a common problem with Simrad autopilots and had nothing to do with the type of propulsion installed.

Liam, you and Kilbride are verifying what I'm saying. It's not an Arneson issue. It's simply poorly set up or performing Autopilots that need to be fixed or adjusted and adapted properly to the installation.

Anyway, in an attempt to provide the info initially requested by the thread starter, I don't know what issues arise with MANs that power M72s if you sail at 12 or 15 kts for a long while.

As far as keeping a straight line, the M80 does it fine at these speeds as long as you are on it, and if you can adjust the MTUs so as to keep all turbos on, pressures, load and temps within limits, you should be fine for a good while.

I'm not familiar with the ICW. Are there very long no-wake zones ?

On the M80 I guess so, but you can do the adjusting with the foot on the tiller, AP style inputs. I did it standing up on the helm. For close to two hours.

It's an AP20 and J300X junction box. The rest is already mentioned here.