Pod drives for large yachts

2682 hp. 2000 kw.

RR has Mermaid up to 11,000 kw and beyond and HICE up to 18,000 kw. So, no question they could do something nice for recreational vessels.

I didn't know that. I'm wondering why in all this time, more builders haven't used them.

We looked at a manufacturer of normal tunnel thrusters who had through collaboration with another company developed a range of rim drive thrusters.
At the time we were looking I became aware of a recent delivery that was changing from rim drive to conventional thrusters. I made some enquiries and found it was because of some cracks and system failures.
The company we were looking at assured us they had solved all their problems and as such fully expected to be able to charge an eye watering price. Needless to say we did not accept their offer and I have not seen in the press that they are selling thousands of units.

Every model ever shown by anyone at any show has been "well received." I always use to tell the sales guys not to tell me how well the line was received, show me the orders.

Sunseeker is pushing pods. Many of their boats are available with IPS.

As to the larger boats, in many cases they have proven designs that work well for them. Why spend the money to try something different and far more expensive for them? You've also mentioned some that exceed the capabilities of IPS and Zeus and challenge the speed capabilities of some of the other pod systems.

One reason for the slow uptake could be the need to redesign the stern section to enable the use of them and the high level of complication for the operators.

For a fiberglass builder, it's designing and building an entirely new mold. It's more a new model than it is a modification of an existing model. Every design factor changes.

You got me there. I have no experience in building of fiberglass boats, steel and aluminium are what I have spent my career involved with.

The pods don't really make a lot of sense once you have to install more than 2 of them (you lose the fuel savings and then have to maintain 3-4 engines and pods. So that's keeping some of the builders you mentioned from going with them. Also having to completely redesign the hull to accept them is another reason.

KIWI- the pods are actually easier to operate for the operator and can run them just like a shaft boat if you're not comfortable with the pod operation (joystick etc.)

We used to moor next to 'Brittania' that had these fwd drives, she went well for a mid 80's yacht.

I was actually referring to the engineering dept. DE is a much more complex arrgt than a traditional drive line.

The pods (zues and IPS) are more or less glorified stern drives mounted underneath the boat. A lot more electronics, a few more components, definately more maintenance, but not too terribly bad. Generally if you're using them over 50-75 hours a year, the fuel savings more than makes up for the maintenance price (twin zues or IPS).

K1W1 is referring now to the larger pods. The discussion took a twist. We've gone from Volvo to Rolls Royce and they type pods you'd use on a 164' MY.

How a commercial application is working for IPS.

Also do not forget few things about IPS : 1) they are very sensitive, in case of fouling on propellers they can lose more than 5 knots, and even more if the fouling is also on the hull. In the same conditions with shaft you will lose no more than 2 knots. It means they work well only if the hull and the propellers are perfectly clean. 2) if you need to install 3 IPS, it means that the deadrise at stern is basically flat, aka slamming in rough sea.
IPS and POD are basically stern drive. Stern drive can be in general used only until 40 feet since maximum power available is around 400 HP. Over 40 feet POD or IPS.
About consumption, I will say not a big difference with shaft, since you burn 10% less (more or less) with clean hull and prop, but this condition does not last long, unless you use your boat every day or unless every week you jump in the water cleaning your propellers. About maintenance, much more expensive IPS and POD than shaft. About safe navigation.....I let you judge, in my opinion shaft is safer, but someone can have a different opinion. About manouvring , if on shaft you have stern and bow trust there is zero difference.
The only real advantages of POD and IPS are noise reduction and basically no vibration. But you can get the same advantages with waterjets. Waterjets are in my opinion better than ips and pod, also because with waterjets you have nothing under the hull and you can use your boat with no problems also in shallow water. But waterjets are much more expensive than IPS or POD, so rarely a yard is using them ( small medium boats : Hinckley, bigger boats AB yachts and Mangusta ).

If the IPS boat will lose 3 more knots than a shaft boat, it is still faster and using less fuel. About the slamming of a triple IPS, it has to be very rough sea to get the whole boat airborne..? On what boat have you had this experience..?

Fouling will cause exactly the same results to shaft driven yachts to. Fast sportfish and motoryachts need the props clean also. I used to run a 45' cabo with c18's and shafts in Belize. It cruised at 30.8 knots. If the boat wasn't run every 2 weeks and the boat sat for 1 month without a diver....it would barely even get on plane and run 20 knots at 80% load and black smoking like crazy. Growth effects jets and Arneson boats THE WORST. Both have to be squeeky clean to perform. The IPS and shafts about equally. A shaft boat has just as much issues and loses a heck of a lot more speed than you claim.

I've run a 50' MY with pods that only cruises at 21 knots, for 2 years and over 2500NM and it has never lost any speed.

As for Jets I'd never ever own them. On a yacht, there is NOTHING in the stern to make them track straight.....on a 40' in 3-4' seas off the stern they will turn 90 degrees with every wave.....They also lose a ton of speed everytime they go up and down a wave, and you're constantly correcting with steering. At slow speeds they're very inefficient and never track straight. They're 1970's technology that never took off then, and should be left in the 1970s. They're really only efficient at the 1 rpm they're set up for either cruise or WOT, after that they lose huge amounts of efficiency.

I have two questions. First is has Brunswick/Mercury ever done business with MAN? Second is do you really think Cummins would allow that?

It's my understanding that Zeus was owned, not by Mercury alone, but by CMD, Cummins MerCruiser Diesel, which was 50/50 owned. I'm not sure that entity still exists but I'm not aware of anything that has changed the effective ownership of Zeus.