Volvo IPS - CMD Zeus

Now that's something new to me. Thanks for the education K1W1.

Those Voith-Schneider cycloidal drives are quite successful as I understand it.

As far as damage to ANY propulsion system other than jets....DON"T HIT THE BOTTOM...it can be expensive

You are right, and with jets you should not even be near the bottom...

The "True Pod" discussion

Well K1W1, I have to say that link was clever.
But I am afraid you still don't really win the argument in the long run (with me you do), as Mercury, CMD and the press are not about to stop calling them POD DRIVES. Volvo Penta went with Inboard Performance System (the IPS thing), maybe they are not the best at marketing? But again, you have my respect on this issue. You and Marmot can hail a victory I suppose. At least I won't call them POD drives in this forum.
The sterndrive comparison Marmot I would not agree with at all. There are no U-joints surrounded by rubber bellows, no aluminum, no rubber hubs and now plenty of torque and horsepower can be applied. The underwater exhaust, low noise and low vibration characteristics however are similar. I know I never had to scrub the transom anymore after a long days run on an IPS powered vessel, so I was pleased.

This is what we need folks, better yachts with better performance, better fuel economy, lower noise, less emissions and easier handling/docking. Can we agree on that?

I feel you need to rethink this Marmot. There are some really talented people working on these new propulsion systems. If you look at some efficiency gains and improvements the IPS (with countless magazine reviews and sea trial statistics) and the what they say about ZEUS so far, that this is in fact an improvement over traditional inboard shaft propulsion in planning yachts in the range of 35-75 feet. If you want some pictures of inboard boats with struts pulled out, washed up on shore in pieces or whatever, I think we can find more than a few to send you. Give this stuff a chance will you?

I never said it was useless or didn't work, but I strongly suggest that the marketing hype far exceeds the real performance gains and costs above that of a conventional outdrive. The risk of hull damage and increased drive damage beyond that of an outboard or I/O in a similar grounding outweighs any slight performance increase in my opinion. The marketing department doesn't talk about cost/benefit ratios for these things does it?

Sure you can provide thousands of bent shaft pics, there have been millions upon millions of them running around over the past century or more so the opportunity to acquire a damage history is rather large.

I say marketing trumped engineering because they have usurped a term that describes a particular form of propulsor in order to form a public image that distances these drives from what they really are, an I/O that drives through a hole in the bottom and doesn't offer the hope of salvation in a hard grounding the same way a transom mounted I/O does. They are only sold in pairs because they are trying to sell a control system.

Given the location and operating environment of the type of boats in which these drives are installed, I predict many more horror stories related to what otherwise would have been far less damaging groundings or encounters with crab pots and such. As an engineer I look at cost vs benefit vs risk. I don't see any good numbers in this application.

Marmot, the IPS is for boats that otherwise have shafts and rudders. They are not competing with outdrives, which by the way can also have joystick steering.

The range of engines provided are mainly too powerful for any of the Aquamatic drives and the IPS II and coming IPS III will be sold for yachts up to about 100 feet. They are sold in twin, triple or quadruple configurations, but you can probably have just one as well, but then there is not much advantage over a center mounted shaft and rudder.

Fair enough regarding the use on larger planing boats. But, in that application they are competing with surface piercing drives and jets, either of which offer outstanding high speed performance with far less risk of hull or drive damage.

In the context of 100 foot planing hulls, efficiency is a non-sequitur so claiming higher efficiency in that application is kind of amusing.

Not when you translate it into range.

You figure those boats will do a lot of long range cruising?

They are made for speed, not for tankering enough fuel to get anywhere.

That is where designers (stylists) get it so wrong. They forget or don't know that weight is the antithesis of speed and "high performance" for the kind of boats that would use this kind of drive. If they want speed they can't tanker a large load of fuel, high power burns a lot of fuel so the range must be short. If they want range and speed those drives can't deliver enough power to do both without using herds of engines and lower units. The boat would look like a sea urchin and the drag would be all out of proportion.

There are lighter more efficient means to power a 100 foot hull at high speeds than with 4 or 6 engines and drives sticking out all over the bottom.

Repeat after me: cost benefit cost benefit

You are welcome to show the better options, I will soon design a fast 75-footer...

[Marmot, the IPS is for boats that otherwise have shafts and rudders. They are not competing with outdrives, which by the way can also have joystick steering.)


I have a listing on an Island Pilot 395, a fast trawler type of small boat with Volvo diesels and outdrives. This boat is smaller than most of my listings, but I thought it would make a great boat for use in the Bahamas, the Florida Keys, the west coast of Florida or anywhere else with a lot of skinny water. This model was first built with outdrives and then with IPS, and can be purchased either way. Only a 3'2" draft, and if you run into a 3' spot, the outdrive can tilt up, a big advantage over the IPS.

Two or three years ago a boat of this size with outdrives would be very difficult to sell, but with all the press on IPS, the outdrives look better. I have described in the listing that the Volvo duo prop outdrives are the PRECURSER to the IPS, the technology is not really too far different.

You are right in the timeline, but as I said, IPS is not to replace outdrives. Boats where you have both as an option, usually sell more outdrives. They give you a better speed/mileage and also have props for higher speeds.

We have used Aquamatic on all boats up to 40 feet, with top speeds near 50 knots. On our new 54´we will try IPS in twin and triple installations, but the props are only allowing a top speed of 43 knots. Perhaps Cat/Zeus have faster options but I have not found out yet.

Whatever, there are no standard outdrives that can take the torque of a 575 hp diesel as far as I know.

http://www.thrustmastertexas.com/products/propulsionUnits.html

Most members know I like IPS but we are now doing a major rebuild of a very early installation.

The seals had let go and salt water was left to sit in the drive while the boat was for sale. Volvo are covering the costs and these are riseing very fast.

Each part of the rebuild we delve deeper into the drive, the more corrosion we have found. Pitting has traveled right up to the main ring, thus everything except the shafts and outerbody have to be changed.

This all may sound major money but I've ordered the following yesterday

1 X Gearbox for a Sidepower 55 bowthruster £430

1 X Gearbox for a Bukh 20hp sailboat engine £910

1 X Gearbox for a Volvo 122D , get this, £8750 without oil cooler

(Not sure what the rate of $ exchange is today, about 1 to 1.46 I think)

The IPS is now sounding not too bad against that little lot, costwise, for a rebuild. £3000 for a complete job. The costs with a DPH is not that much lower and more often (bi-annually sometimes).

As AMG says, how else do you put 500hp down without shafts?

As a small aside, Sidepower are now offering a sternthruster that sits between DPH drives, that should help a bit on larger boats.

You can probably sell the TBODs (ThruBottomOutDrives) to someone who can justify it just because no one else on his block has one.

But if you are really asking for better options for a 75 foot fast boat, you have already been shown them ... jet drives for a fast boat or surface piercing drives for a really fast boat.

Now you are welcome to show us how you can get enough power to move a 75 foot boat "fast" using TBODs without installing a half dozen of the silly things.

Of course it doesn't cost a stylist anything to "design" a whole herd of powerplants into a computer rendering but some poor schmuck has to pay the lifecycle costs of the hardware.

Repeat after me: cost benefit ... cost benefit ... cost benefit

OK, but people are not buying them because of several reasons. But anyone who has tried an IPS-boat want to have it, especially women like them.

Last but not least, a boat designer have to create a boat that sells. If it is not working or not selling, I am out of job.

I have to give you full marks for honesty.

Both you and the future (probably short term) owner are the victims of marketing hype.

I hope to install twin or triple IPS III with D13:s of 1.200 hp each or so...? That would move my new hull pretty fast.