Adapted for Recreational Use?

If you burn 1000 gallons a year (I don't) it will save you 20.5 gallons per year.

Probably not a great ROI for the recreational user.

Greetings,
Aw rats! Nothing to do with magnets? Aligns fuel molecules? Kills algae (Algae-X)? Cures arthritis? Thanks Mr. ASD. My hopes are quashed...

I thought it was interesting......

Alaskan Sea-Duction said:

I thought it was interesting......

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I think it is. If you can pick up any amount of fuel savings with just a simple solution. Now, would it work the same for a pleasure boat? We don't know that.

Volvo-Penta invented the counter-rotating Duoprop 30 some years ago, so in essence, the improved version was invented first for recreational boats. This is merely the static version of an axial stream straightener.

Yeah, what he said!

"Volvo-Penta invented the counter-rotating Duoprop 30 some years ago,"

C-R props were used aboard military boats during WW1.

What Volvo figured out was how to have an engine installed with minor labor , with little boat skills., and no need for alignment .

From other forums the owners would never again purchase a boat with that system , as it has the longevity of an IO leg.

This isn't the duoprop rehashed though. Principle may be much the same. However, the applications of the duoprop have been limited. It's got all the drawbacks of any inboard/outboard. The approach here is to find a very simple means of gaining a very modest gain in efficiency without major work or cost.

Really to a recreational boater 2.5% is nothing to get excited about. However, if any of us could gain 2.5% at very low cost with virtually no effort and with no negatives, I suspect the vast majority of us would do it. There are very few totally new concepts and sometimes there are the simplest takes off old concepts that turn into something.

Clearly this is aimed at large commercial ships. It may or may not have application for any of us. As to Duoprop, for all it might be, I'm not aware of it on any trawler type boats, I don't have it nor have I ever had it on a boat I've owned. Tell me I have to go to a whole new system, no thanks. Tell me next time I change a prop, I can just change a hub, might just do it.

As to currently available technology for achieving better fuel economy without a sacrifice of performance, the most obvious is Pods. The fuel savings with IPS or Zeus systems compared to conventional inboards is significant. On the other hand the initial cost and the maintenance are negatives. Still it's interesting that most of the boats on this site are in the size range to be perfect for Pod applications, yet they haven't made the trawler world at all. Two reasons. First, this is a market segment somewhat adverse to change. Second, the amount of fuel used for most trawlers and trawler type usages of boats is not significant enough to really justify the upfront cost.

"First, this is a market segment somewhat adverse to change. Second, the amount of fuel used for most trawlers and trawler type usages of boats is not significant enough to really justify the upfront cost."

And most trawler folks would be unhappy eith the replacement cost after a few years.

The pod drive is driven 99% by the ease of low skill labor to stick them in the hole.

FF said:

The pod drive is driven 99% by the ease of low skill labor to stick them in the hole.

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You've lost me FF. IPS, Zeus and clones seem quite the reverse with considerable engineering, electronic and install skills used for the past 8 years or so. Space savings with IPS is dramatic let alone joy stick docking. And, as BB mentions fuel savings to boot.

I have looked at identical vessels with conventional shafts and with IPS. The gained space and better weight placement seems a real plus.

FF said:

The pod drive is driven 99% by the ease of low skill labor to stick them in the hole.

Click to expand...

I can't agree with that. In my opinion there are two drivers to the pod drives. First, is handling. All the docking issues we read constantly about here and elsewhere are tremendously reduced with pods. The joystick controls are remarkable. Now, joysticks are coming into play on non-pods as well that have bow and stern thrusters. But the slow speed handling of pod driven boats is incredible. Second, it's economy. If you've got a 45' Sea Ray or 60' Marquis or even an 80' Delta and you get out and run it fast and often, the fuel savings are sizable. There have been many direct comparisons made. I'll choose one to refer to.

52' Sabre Express. Choices are 2 x 865 hp CAT Shaft drive vs. 2 x 700 hp IPS drives.

Speeds...at WOT, Shaft 30.6 knots, Pod 32.7 knots. At 1800 rpm. Shaft 21.9 knots, Pod 21.7 knots. NMPG at WOT, Shaft 0.40, Pod 0.52. NMPG at 1800 rpm, Shaft 0.51 nmpg, Pod 0.66 nmpg.

Boattest tested a 45' Formula with Pods vs. V-Drives. This was 2 x 575 hp V-drives vs. 2 x 435 hp pods. IPS was 5% faster with 24% less hp. At cruise, the IPS burned 33% less fuel.

In a specific range of boats Pods have some significant advantages. They also do have some disadvantages and outside that targeted range of boats they haven't yet proved practical.

Here's a good example of the limitations of pods. Sea Ray offers Pods on all the Sundancers. However, on their new 59' L to get the desired performance the configuration in which it is sold is triple 600 hp Pods. On the 65' L however they sell that model with twin 1135 hp CAT's. The performance and fuel numbers of those two boats is nearly identical. The issue is that Zeus pods have hp limitations (as do IPS but they go higher), so you start talking triple and quad pods and then they just no longer make sense.

Some things don't scale well, I bet this is one of those items.

Given the shaft RPM and the size of the device it will most likely perform a great bit different on a ship then a device downsized for the average pleasure boat.

Like an anchor most things loose something when scaled a great amount. The savings if any would not be even close to the same.


This item also provides "counter swirls" and is attached to the same shaft as the prop so it is in no way like a Due-Prop.

Imho of course