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Old 08-07-2015, 10:53 AM   #41
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Originally Posted by Cottontop View Post
See the chart in post 31.

Got that, assuming it's right to compare something like a D9-500 (~E58K) to an IPS-500 (~E129K)?

But I dunno how to figure in cost of marine gears, shafts, logs/bearings, props, etc. on the standard engines...

-Chris
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Old 08-07-2015, 11:39 AM   #42
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Here's a link to a Finnish accident report involving IPS drives which did not come apart as advertized, resulting in boats sinking very quickly.

http://www.turvallisuustutkinta.fi/m...selostus_2.pdf
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Old 08-07-2015, 12:12 PM   #43
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Here's a link to a Finnish accident report involving IPS drives which did not come apart as advertized, resulting in boats sinking very quickly.
Obviously that can and does happen. Rather rare I believe.
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Old 08-07-2015, 12:35 PM   #44
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We had a pod boat accident here in NC near Beaufort several years ago. Boat wandered out of the channel at speed and hit a gradual slope of a sandbar. The force on the drives was not enough to shear them. But the boat stopped suddenly enough to cause occupants to fly forward, with severe injuries.

Most other types of propulsion present themselves to the bottom with a gradual angle: Skeg keel, sloping prop shafts, etc. In a grounding as boat bottoms, it ramps up and lifts the hull. Deceleration usually not that severe.

I've been involved in several pod failure investigations. Based on this I am no fan.

Downsides:

Fwd facing props subject to easy damage from small floating debris
Damage from grounding more expensive than straight props
Nead to haul for oil change
Some have poor mechanical reliability
Boat is now limited to that propulsion package for life, or heavy mods otherwise
Parts prices through the roof
Underwater exhaust on IPS has some annoying behavior, my feelings only

The speed/efficiency advantage is real, though.

That Finland wreck seems more due to poor glasswork by the builder and not so much due to IPS.
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Old 08-07-2015, 12:45 PM   #45
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Originally Posted by Ski in NC View Post
We had a pod boat accident here in NC near Beaufort several years ago. Boat wandered out of the channel at speed and hit a gradual slope of a sandbar. The force on the drives was not enough to shear them. But the boat stopped suddenly enough to cause occupants to fly forward, with severe injuries.

Most other types of propulsion present themselves to the bottom with a gradual angle: Skeg keel, sloping prop shafts, etc. In a grounding as boat bottoms, it ramps up and lifts the hull. Deceleration usually not that severe.

I've been involved in several pod failure investigations. Based on this I am no fan.

Downsides:

Fwd facing props subject to easy damage from small floating debris
Damage from grounding more expensive than straight props
Nead to haul for oil change
Some have poor mechanical reliability
Boat is now limited to that propulsion package for life, or heavy mods otherwise
Parts prices through the roof
Underwater exhaust on IPS has some annoying behavior, my feelings only

The speed/efficiency advantage is real, though.

That Finland wreck seems more due to poor glasswork by the builder and not so much due to IPS.
Several of your issues you describe are more prevalent with IPS than Zeus, although Zeus has their own set.

First, the grounding issue. Zeus is angled and uses a tunnel, so would be less likely to do the hard stop you describe. Still I can't say they wouldn't do that.

Zeus props are rear facing.

Zeus does not need to be hauled for oil change.

That said, I personally would still choose straight drive over pod on a pleasure boat.
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Old 08-07-2015, 01:03 PM   #46
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Yep, I should have clarified: All the investigations I've been involved in have been IPS.

The other brands have a smaller population, so that is at least one reason.

I think those that use the tunnel have done so to avoid a patent infringement issue, but that is speculation on my part.

The tunnels do have a downside effect on performance.
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Old 08-07-2015, 01:06 PM   #47
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Originally Posted by ranger42c View Post
Got that, assuming it's right to compare something like a D9-500 (~E58K) to an IPS-500 (~E129K)?

But I dunno how to figure in cost of marine gears, shafts, logs/bearings, props, etc. on the standard engines...

-Chris
Me neither and would also love to see an "all in" analysis.
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Old 08-07-2015, 01:14 PM   #48
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Great concept for vessels requiring high degree maneuverability, but around here, they're Manatee killers.
No more so than any prop I would think.
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Old 08-07-2015, 01:18 PM   #49
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Originally Posted by Ski in NC View Post

That Finland wreck seems more due to poor glasswork by the builder and not so much due to IPS.
The wreck was due to operator error, the skipper put the boat on the rocks at high speed.

Volvo claims that if you hit something at high speed with the IPS, it will break away, the boat will remain watertight, and all will be well. These particular IPS units did not break away, placing the grounding loads on the hull, which broke. Perhaps it would not of broken had it been better built, or if the IPS units had broken away as advertized.

Its been a while since I read that report but I believe the Finns placed blame on both the builder (Jeanneau) and on Volvo.
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Old 08-07-2015, 01:29 PM   #50
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The wreck was due to operator error, the skipper put the boat on the rocks at high speed.

Volvo claims that if you hit something at high speed with the IPS, it will break away, the boat will remain watertight, and all will be well. These particular IPS units did not break away, placing the grounding loads on the hull, which broke. Perhaps it would not of broken had it been better built, or if the IPS units had broken away as advertized.

Its been a while since I read that report but I believe the Finns placed blame on both the builder (Jeanneau) and on Volvo.
Yep, clearly on the operator for hitting the rocks at speed, sort of goes without saying. But: The glass structure sure did look weak in avoiding the uplift of the drive at the rear of the pod port when contact was made. The question then is once the hull yielded, did that affect the fracture of the fuse link in the drive? The hull yielding reduced the force on the drive.

Similar to a straight drive strut pushing into a hull when grounding, with similar effects. Many boats are weak over the strut pad.

Tad- do you know why Zeus requires the pocket?
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Old 08-07-2015, 02:04 PM   #51
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Originally Posted by Ski in NC View Post

Tad- do you know why Zeus requires the pocket?
AFAIK the pocket for the Zeus is so it can be mounted vertical in a vee bottom. The IPS is set up to swivel so it can be mounted square off the hull bottom.....perhaps part of the patent and thus Zeus had to do something different.....
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Old 08-07-2015, 02:22 PM   #52
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Quote:
Originally Posted by Ski in NC View Post
We had a pod boat accident here in NC near Beaufort several years ago. Boat wandered out of the channel at speed and hit a gradual slope of a sandbar. The force on the drives was not enough to shear them. But the boat stopped suddenly enough to cause occupants to fly forward, with severe injuries.

Most other types of propulsion present themselves to the bottom with a gradual angle: Skeg keel, sloping prop shafts, etc. In a grounding as boat bottoms, it ramps up and lifts the hull. Deceleration usually not that severe.

I've been involved in several pod failure investigations. Based on this I am no fan.

Downsides:

Fwd facing props subject to easy damage from small floating debris
Damage from grounding more expensive than straight props
Nead to haul for oil change
Some have poor mechanical reliability
Boat is now limited to that propulsion package for life, or heavy mods otherwise
Parts prices through the roof
Underwater exhaust on IPS has some annoying behavior, my feelings only

The speed/efficiency advantage is real, though.

That Finland wreck seems more due to poor glasswork by the builder and not so much due to IPS.
I think that grounding was in Gallant Channel by a demo boat. There were some injuries as I remember.
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Old 08-07-2015, 04:20 PM   #53
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I remember the introduction of pods and I was of the opinion they'd never sell, people too set in their ways. I was wrong. However, I think they were wrong on the potential sales. There were many who thought it would dominate a large middle segment of the market, basically all the twin engine boats under 60-70'. A very large number of boat builders (actually 137 per their site) have used them and offer them. However, they're the dominant choice for very few builders.

I don't see what need they fill than either an inboard/outboard or a traditional inboard doesn't. However, they are better at some things, primarily efficiency.
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Old 08-08-2015, 02:15 AM   #54
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The Pod Parted

We run Svitzer's at the Port. They are podded vessels but they are commercial vessels and require a massive amount of manoeuvrability. Not sure it's worth it and a bit wanky on a pleasure craft IYAM.

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Old 08-08-2015, 08:13 AM   #55
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Will a pod drive rotate a full 360 degrees?
Boattest.com had some info on the Zeus Marine 2800 pod drives and they rotate 180 degrees. Haven't found the radius on the IPS spelled out but it appears to be 120 degrees. Watched a YouTube Volvo IPS video which shows a yacht moving sideways and it was very impressive. I guess if 120 degree radius will move a boat in all directions, that is all that is needed. Sorry, I have never seen pod drives in a real boat except on Yachtworld. To move sideways, two pod drives are required. With a single pod, a bow thruster would be necessary but probably not as effective for sideways motion.
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Old 08-08-2015, 10:30 AM   #56
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My first encounter with pod drives was on a Mikelson 43. The company owner took me out on a cold blustery day to demo the Zeus drives. The wind was up, the harbor was "bumpy" and the boat ran flawlessly. We approached a buoy at 90 degrees to the wind, put the controls in neutral and engaged "Sky Hook." Even though the tidal currents and the wind tried their best to move the boat's bow away from the buoy, it was all in vain. Think about it for a moment...so what's the big deal with that? Well, how about you are single handing and must stop and attend to fenders and lines before docking? Or you are close to a paddy that is holding fish and you don't want to get closer than casting distance? Or you are single handing and in a lock or your slip while readying the boat? There are literally dozens of scenarios where "pods" would come in handy. Yes, they are expensive but so is a Grumman Gulf Stream, my favorite biz jet of all time.
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Old 08-08-2015, 12:53 PM   #57
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My first encounter with pod drives was on a Mikelson 43. The company owner took me out on a cold blustery day to demo the Zeus drives. The wind was up, the harbor was "bumpy" and the boat ran flawlessly. We approached a buoy at 90 degrees to the wind, put the controls in neutral and engaged "Sky Hook." Even though the tidal currents and the wind tried their best to move the boat's bow away from the buoy, it was all in vain. Think about it for a moment...so what's the big deal with that? Well, how about you are single handing and must stop and attend to fenders and lines before docking? Or you are close to a paddy that is holding fish and you don't want to get closer than casting distance? Or you are single handing and in a lock or your slip while readying the boat? There are literally dozens of scenarios where "pods" would come in handy. Yes, they are expensive but so is a Grumman Gulf Stream, my favorite biz jet of all time.
One thing we should think pods for is moving things forward in so many ways. First pods hit the market with joysticks. Now most any boat can have a joystick. First pods hit the market with Dynamic Positioning (such as skyhook). Now there are other dynamic positioning systems being made available. However, I don't think any other system has the simplicity of pods in positioning. The skyhook only has to deal with the two pods. Dynamic positioning on other boats has to typically coordinate between two engines and two or four thrusters.

Places where DPS is extremely helpful. Waiting for bridges or locks. Waiting in line for a fuel dock. Watching a huge event such as fireworks. Macy's 4th of July fireworks, no anchoring and stay in your place. Preparing fenders and lines for docking when single handing.

DPS is important to fishermen to find their perfect spot and stay on top of it.

DPS seems to have even greater potential in the commercial market and in total is expected to be nearly a $1.5 billion market by 2020.
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Old 08-08-2015, 08:30 PM   #58
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I'm holding out for a GB42 with Voth-Schneider cycloydal drive.
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Old 08-08-2015, 09:27 PM   #59
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I'm holding out for a GB42 with Voth-Schneider cycloydal drive.
Those egg beaters are pretty cool.
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Old 08-08-2015, 10:25 PM   #60
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Update from the OP. Yesterday a diver tried to locate the parted pod with no success. He is trying again today. Stay tuned.
With the cost of em... don't they have a signal device built in that can throw traceable e-waves for at least a month? Good God Mon - Pods seem a big income gimmick. By em for great expense. Then, loose em. Then buy em again... over and over. A revolving door system to be sure me matey!
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