Pod drive????

[Nick14]

I am actually fascinated by this because if you read the Internet everyone hates them. However tons of new boats come with them. So clearly manufacturers believe that their clients want them. No idea which is the correct answer.

FWIW, I've been going back and forth with pod drives for the past year in my ongoing boat search. As others have pointed out, a depressingly large proportion of boats less than 10 years old have pod drives. Used ones seem to be less expensive than boats with straight drives.

I think many manufacturers have gone all-in on pods (such as Sabre) because they are understandably focused on new sales. I don't imagine Sabre or other builders who now only offer pod drives care very much about resale value or what happens years down the road. Their business interests are served by moving as many new boats as they possibly can.

I suspect the manufacturers have learned they can move more boats by offering ease of docking and more interior space. The ease of docking opens up the market to new boat owners, and also to upsell buyers. Someone who might have been comfortable handling a 38-40 ft boat could discover that pods let them dock a 45-50 ft one, thus increasing the sales price and revenues to the builder.

Likewise, many buyers, especially those new to boating, might prioritize interior space over concern about long-term reliability or collision risk.

I suspect the builders have also learned that many boat buyers use their boats as floating condos, more for dockside entertainment with occasional day trips. That may be a bigger market than 'serious' boaters who do long-range cruising.

All of those factors would argue for greater new sales for pods than straight drives.

I've repeatedly tried to talk myself into a pod boat, but just can't do it. Your mileage may vary.

 

[Portage_Bay]

When it comes to Boats ,specifically trawlers ,my motto is simple is better ,they have a cool factor, who doesn’t like cool , I can’t afford cool,I’ve been looking into controllable pitch propeller ,So I can do away with the transmission ,gearbox turns out they recommend keeping the gearbox for the gear reduction, controllable pitch propeller would be pretty simple ,And very useful for other things like fuel economy

Before you head down the conrtollable pitch path towards purchase I recommend some time at the controls of a CP equiped boat. First the gear box is a good idea even if it has no reverse. Otherwise whenever the engine is running the prop is spinning. Finding the sweet spot where there is zero forward or aft thrust is nearly impossible. And you will have some prop walk when the prop is turning, even feathered to zero thrust.

Also there is a delay from forward torque to aft torque when maneuvering in close quarters. Not the instantaneous thrust when you put a traditional gear box in forward or reverse.

You've also got to coniser the seals, moving parts and controls. All together no simpler than a traditional gear box. And in my experience no where near as robust or trouble free.

There are many advantages to CP in the right cirucumstances. I just don't think a typical recreational trawler will see enough benefit from CP to be worth it.

 

[Scooby5959]

Informative and useful

Before you head down the conrtollable pitch path towards purchase I recommend some time at the controls of a CP equiped boat. First the gear box is a good idea even if it has no reverse. Otherwise whenever the engine is running the prop is spinning. Finding the sweet spot where there is zero forward or aft thrust is nearly impossible. And you will have some prop walk when the prop is turning, even feathered to zero thrust.

Also there is a delay from forward torque to aft torque when maneuvering in close quarters. Not the instantaneous thrust when you put a traditional gear box in forward or reverse.

You've also got to coniser the seals, moving parts and controls. All together no simpler than a traditional gear box. And in my experience no where near as robust or trouble free.

There are many advantages to CP in the right cirucumstances. I just don't think a typical recreational trawler will see enough benefit from CP to be worth it.

Thank you for your response .I find it very informative and useful , My interest In Cpp is for fuel economy, I guess this would be what is called thread drift ,However I cannot resist since you seem to be knowledgeable on the subject, I have been doing some research on how to make my boat as fuel efficient as possible, I have a Nordic 26, My subscription to boatdiesel.com has expired ,so I didn’t have access to their calculators , I used beta marine website for these numbers . They tell me the hull speed for my boat is 6 1/2 knots. That requires 10 hp ,if I slow to six knots that would require 4.8 hp a big difference for a half a knot, I have a new Kabota three cylinder the same engine that beta Marine uses for their 25 hp marine application, Looking at the PowerGraph this engine produces 5 hp at a 11 hundred RPMs consuming less than a pint of fuel and hour ,Without getting too far off into the weeds ,I need the ability to get that 5 hp at 1100 RPMs that would require propping the boat for that RPM and not how most boats are prop for Wot . According to the numbers that combination would give me 40 miles to the gallon , seems quite far-fetched , but that’s what the numbers say .as far as being worth the investment probably not , unless I was planning a lot of long distant cruising , in which fuel economy was paramount , This is a subject that would need to be discussed in more detail . a new thread would probably be appropriate

 

[rslifkin]

Thank you for your response .I find it very informative and useful , My interest In CCP is for fuel economy, I guess this would be what is called thread drift ,However I cannot resist since you seem to be knowledgeable on the subject, I have been doing some research on how to make my boat as fuel efficient as possible, I have a Nordic 26, My subscription to boatdiesel.com has expired ,so I didn’t have access to their calculators , I used beta marine website for these numbers . They tell me the hull speed for my boat is 6 1/2 knots. That requires 10 hp ,if I slow to six knots that would require 4.8 hp a big difference for a half a knot, I have a new Kabota three cylinder the same engine that beta Marine uses for their 25 hp marine application, Looking at the PowerGraph this engine produces 5 hp at a 11 hundred RPMs consuming less than a pint of fuel and hour ,Without getting too far off into the weeds ,I need the ability to get that 5 hp at 1100 RPMs that would require propping the boat for that RPM and not how most boats are prop for Wot . According to the numbers that combination would give me 40 miles to the gallon , seems quite far-fetched , but that’s what the numbers say .as far as being worth the investment probably not , unless I was planning a lot of long distant cruising , in which fuel economy was paramount , This is a subject that would need to be discussed in more detail . a new thread would probably be appropriate

There are definitely potential gains, but you run into a few concerns: how long would it take for the fuel savings to outweigh the cost of the CPP setup? And even if the engine can make 5hp at 1100 rpm, is it designed to do that continuously? Many engines aren't rated to run at full load all the time, so you might need to be at something like 1400 rpm to continuously produce 5hp with a good engine lifespan.

 

[Portage_Bay]

My interest In Cpp is for fuel economy,....... They tell me the hull speed for my boat is 6 1/2 knots. That requires 10 hp ,if I slow to six knots that would require 4.8 hp a big difference for a half a knot

You hit the nail on the head. That is the primary way to save fuel with most recreational boats. Couple that with rslifkin's question
"how long would it take for the fuel savings to outweigh the cost of the CPP setup?"
and you've got your answer.

Unless you just want CP then by all means go for it.

 

[Andy G]

I have not much more to add to this, except when I mentioned this thread to my good mate who bought a new 46' Cat with pod drives, his reaction was startling.

It been years since i have heard such a string of Anglo Saxon expletives linked together in such an entertaining way. Suffice to say he calls a spade a spade, and this was more of a blunt end shovel response.

The bottom line was he spent over $90K (outside warranty)in the first 18 months on the units.Ended up hating the boat, sold it as soon as he could find a buyer.

 

[twistedtree]

Today, I decide I no longer dislike pods, and actually think they are a good thing for boating. People who would otherwise be a hazard to themselves and others with a conventional boat are able to safely operate their boats with pods - the boat that they would have either way regardless of the drive system. If pods make one less boat a hazard around docks, then I'm all for them.

 

[Art]

Give me keel-protected propeller, shaft and rudder; or give me death.

Mark - IMO - You are 100% correct regarding the most protected u/w drive setup. Include a sturdy grating around front and sides of prop and your type of u/w drive components are basically bullet proof!

 

[Southern Boater]

I have not much more to add to this, except when I mentioned this thread to my good mate who bought a new 46' Cat with pod drives, his reaction was startling.

It been years since i have heard such a string of Anglo Saxon expletives linked together in such an entertaining way. Suffice to say he calls a spade a spade, and this was more of a blunt end shovel response.

The bottom line was he spent over $90K (outside warranty)in the first 18 months on the units.Ended up hating the boat, sold it as soon as he could find a buyer.

The UK/EU motor boat forums appear to have a similar response to pods as your mate Andy, and have done for a long time, and these folks actually like and support Volvo products.
Unreliability and huge servicing costs are the main areas of complaint.

 

[Scooby5959]

Have you seen the size of the hole in the bottom of your boat when you remove one of those things freaking ridiculous

 

[OldDan1943]

What is the pod casing made of?

 

[Art]

Not knowing too much about the physics/design of Arneson "Surface Drives". Do know they were developed/designed by Howard Arneson for very fast boats [100 mph +]

Yet, having seen them up close [I've spoken with Howard in his shop] I can't help but wonder if they might be able to be design modified for use on "trawlers". Factor that Surface Drive apparatus comes relatively straight out transom of boat [rather than under boat like straight drives or fairly deep in water like out drives] it seems that if Surface Drive could be designed to accommodate trawler propulsion needs that they would reduce the current draft depth requirements of trawler in water. And, maybe... these modifieddrives might improve nmpg efficiency???

Arneson Surface Drives

WOW -

 

[rslifkin]

Not knowing too much about the physics/design of Arneson "Surface Drives". Do know they were developed/designed by Howard Arneson for very fast boats [100 mph +]

Yet, having seen them up close [I've spoken with Howard in his shop] I can't help but wonder if they might be able to be design modified for use on "trawlers". Factor that Surface Drive apparatus comes relatively straight out transom of boat [rather than under boat like straight drives or fairly deep in water like out drives] it seems that if Surface Drive could be designed to accommodate trawler propulsion needs that they would reduce the current draft depth requirements of trawler in water. And, maybe... these modifieddrives might improve nmpg efficiency???

I know they've been used on more moderate speed express cruisers. But I'm not sure how well they scale down to the speeds most of us run.

 

[Slowmo]

Pod drives date back into the 70's. I recall Vic Franck in Seattle installing them on multiple new construction boats because it allowed them to install the engines in the rear and avoid a v-drive. The problem is that you have yet another gear set, this one under the water, which requires maintenance. One known problem is potential seal leakage allowing water into the gear set - the pod is like the lower end of a stern drive. The difficulty being under the water is not knowing this happens until its too late. Another unavoidable issue is loss of efficiency. As an engineer I can assure you that each gear train has loss associated. The Pod system requires a pair of gear trains (and associated bearings) to transfer the power down the shaft into the pod and again to turn it 90 degrees for the prop. Even with the most efficient designs you'll see a couple of percent loss greater than a simple shaft. Shafts don't have zero friction but it is much lower than a gear train (assuming proper alignment). The last issue I have with pods is risk of damage.

All that said I don't want to say pods have no place. In high output high speed applications they allow things like counter rotating props on each pod, directable thrust (in some cases), even variable pitch. So if I were building a high speed yacht I'd probably want to use them since they provide some advantages which overcome the negatives. However these advantages don't really play a role that I can see in a trawler type yacht.

 

[BandB]

Everything about Surface Drives is contrary to Trawlering. Designed for top end speed. Difficult to handle at slow speeds. I just found a couple of tests of surface drive boats. Typically same fuel usage in terms of gallons per mile at 12 knots as at 38 or 39 knots. At 8 knots might only use 16 gph. On a 54' Pershing, 0.42 nmpg at 37 knots but only 0.34 nmpg at 10 knots.

 

[Art]

Everything about Surface Drives is contrary to Trawlering. Designed for top end speed. Difficult to handle at slow speeds. I just found a couple of tests of surface drive boats. Typically same fuel usage in terms of gallons per mile at 12 knots as at 38 or 39 knots. At 8 knots might only use 16 gph. On a 54' Pershing, 0.42 nmpg at 37 knots but only 0.34 nmpg at 10 knots.

My intended what-if suggestion was to maybe utilize the general placement location of Surface Drives... but to redesign their thrust parameters... for maybe using them with trawlers. At very least, different props for sure.

It seems clearly obvious that Surface Drive designs which Howard concocted to make turbine powered speed boats go well over 100 mph would not work well for displacement [or any other hull design] trawler.

 

[moparharn]

In regards to reliability mentioned in an earlier post. Actually it was more outright failure and loss of control. Here in the Detroit area there have been documented cases of pod failures on a couple of Tiaras. One of these resulted in a serious impact directly into a seawall as a result of a complete loss of control over the system. Obviously this is not common or there would be no IPS systems sold. Used/early adopter boats might have a greater chance of this kind of failure. I have heard nothing of this in the Zeus model drives. Given the comments regarding the Zeus systems in this thread I would have real concern in considering their purchase. New, used, or otherwise. Operating a conventionally driven boat is for me a good bit of fun. I tend to shun technology and appreciate more of the old school. I could neither afford or appreciate any pod drive system.

 

[OldDan1943]

moparharn, one of those incidents was my bro's boat as he was attempting to enter the GPYC basin. Tiara offered to fix his hull etc. He told them, the boat was in its second season and they would build him a new boat. Tiara reluctantly agreed. This time with the traditional running gear. Now my bro is happy.

 

[moparharn]

Old Dan

I know your brother. He lives a block from me. Our kids were friends through school, and still are. His incident got a ton of talk around here. Tiara is very big in this area. At first most people tried to pin it on operator error. Not one bit. Small world.

 

[OldDan1943]

Old Dan

I know your brother. He lives a block from me. Our kids were friends through school, and still are. His incident got a ton of talk around here. Tiara is very big in this area. At first most people tried to pin it on operator error. Not one bit. Small world.

LOL small world indeed. Dont brag about knowing me. Doug might never talk to you again.

 

[hmason]

1. Friend had boat with pod drives
2. Hit rock and one pod sheared off
3. Called for tow and told reason over VHF
4. Next day diver went to retrieve pod; it was gone
5. Dealer orders new pod; took 6-weeks to receive
6. Dealer’s service department had no clue about how to install new pod
7. Took 3 weeks to get a factory tech to supervise the installation
8. Boating season in New England is lost
9. Bill received for over $30K
10. Battle with insurance company begins
11. Friend buys new boat with conventional drives

True story!

 

[Benthic2]

As much as everyone hates Insurance companies they are pretty good at analyzing data. It would be interesting to find a boat that was offered in a pod and non-pod version and see if the insurance cost is substantially different between the models.

 

[Art]

I recall when pods came out and many raved they would be the NEW thang! That they would become the major propulsion player in the pleasure boating market...

I also recall thinking to myself - Straight drive will eventually win back the pod market share; for several reasons. As it is doing!

That said, I do believe outboards will continue to gain and maintain a sizable market share in the pleasure boat industry. However, for several reasons, I don't personally like outboards on trawler type boats, big sport fishers, large work boats and other types. There are some boat types where I do like outboards.

So... the good ol' straight drive inboard engine still lead the pack for me.

 

[twistedtree]

As much as everyone hates Insurance companies they are pretty good at analyzing data. It would be interesting to find a boat that was offered in a pod and non-pod version and see if the insurance cost is substantially different between the models.

I suspect the claims are lower for pods, simply because there is less opportunity for the inexperienced operator to smash into things, especially in close quarters. For strikes, I expect the occurrence rate is the same regardless of drive type, but I expect the repair cost is higher for pods. But in total, I expect bumper-car smashups are the biggest source of claims.

 

[Tusindtak]

I suspect the claims are lower for pods, simply because there is less opportunity for the inexperienced operator to smash into things, especially in close quarters. For strikes, I expect the occurrence rate is the same regardless of drive type, but I expect the repair cost is higher for pods. But in total, I expect bumper-car smashups are the biggest source of claims.

Just taking delivery this month of new 2022 59’ Zeus pod boat. Paid more than for choice of V-drive shafts.
I plan to put 300 hrs per year on boat and it will not be a dock queen. Florida, ICW and Bahamas use. Scheduled maintenance cost will be higher, but insignificant as percentage of total operating and ownership costs.
Positive Reasons:
1. If MOB is me, wife will be more likely to navigate recovery with pods for enhanced safety.
2. No shaft alignment problems. Read some extensive & painful posts about major time & troubles of misalignment and shaft seals. Integrated design does not have this issue, but I never had this issue in other boats.
3. Zeus props face aft vs. Volvo, as preferred.
4. Boat is effectively equal to 5 ft more of interior space compared with straight drives, adding to less cost & weight from straight shaft equivalent boat’s length.
5. Hard grounding can drive straight shaft running gear into hull or broken shaft and result in sinking. Many stories of pods being sheared off, recovered and quick bolt back on after fixing any resulting damage. Faster repairs, if capable dealer is around, and saving much time waiting for hull repairs is possible. Safer.
6. Fuel efficiency and the correlation to more speed per engine size takes less engine room space. Easier to perform maintenance. Related to #4.
7. Quiet.
8. Exhaust system components are standard built in for all units, underwater and not custom to each boat design.
9. Trim tabs built in.
10. Cummins QSC8.3 are super reliable.

Downside:
1. More expensive initial purchase.
2. Likely more of component changing than working on the broken parts. May be > $’s.
3. Fewer mechanics that are familiar. That can be said for all mechanics and techs now.
4. Maintenance must be maintained. Change seals per schedule or upon grounding.
5. Smaller props are likely less ding resistant from drift in rivers.
6. Electronics everywhere, but that is the current status quo for our times.

Insurance is very reasonable.

Docking is easier, but straight shafts were never a problem either. Will sort of miss the challenge in cross winds.

 

[Scooby5959]

I think we should go back to paddle wheels,Until we can reverse engineer alien technology

 

[Gordon J]

What is the pod casing made of?

Bronze

 

[Gordon J]

Really too bad

If you go to yacht world and look for a Grand Banks heritage 41 in Jesolo Italy, you will see a gorgeous boat with Zeus drives. I think this is the first Bristol boat I have seen. Simply unbelievably well kept and maintained. It is so tempting to throw the dice, but….

 

[Art]

Just taking delivery this month of new 2022 59’ Zeus pod boat. Paid more than for choice of V-drive shafts.
I plan to put 300 hrs per year on boat and it will not be a dock queen. Florida, ICW and Bahamas use. Scheduled maintenance cost will be higher, but insignificant as percentage of total operating and ownership costs.
Positive Reasons:
1. If MOB is me, wife will be more likely to navigate recovery with pods for enhanced safety.
2. No shaft alignment problems. Read some extensive & painful posts about major time & troubles of misalignment and shaft seals. Integrated design does not have this issue, but I never had this issue in other boats.
3. Zeus props face aft vs. Volvo, as preferred.
4. Boat is effectively equal to 5 ft more of interior space compared with straight drives, adding to less cost & weight from straight shaft equivalent boat’s length.
5. Hard grounding can drive straight shaft running gear into hull or broken shaft and result in sinking. Many stories of pods being sheared off, recovered and quick bolt back on after fixing any resulting damage. Faster repairs, if capable dealer is around, and saving much time waiting for hull repairs is possible. Safer.
6. Fuel efficiency and the correlation to more speed per engine size takes less engine room space. Easier to perform maintenance. Related to #4.
7. Quiet.
8. Exhaust system components are standard built in for all units, underwater and not custom to each boat design.
9. Trim tabs built in.
10. Cummins QSC8.3 are super reliable.

Downside:
1. More expensive initial purchase.
2. Likely more of component changing than working on the broken parts. May be > $’s.
3. Fewer mechanics that are familiar. That can be said for all mechanics and techs now.
4. Maintenance must be maintained. Change seals per schedule or upon grounding.
5. Smaller props are likely less ding resistant from drift in rivers.
6. Electronics everywhere, but that is the current status quo for our times.

Insurance is very reasonable.

Docking is easier, but straight shafts were never a problem either. Will sort of miss the challenge in cross winds.

Hi Tus - Welcome to TF!

Thank you for that straight-on honest appraisable. You will be a valuable contributor on TF.

You and wife enjoy your new boat. Try NOT to become the MOB just to test your wife's skills with Zeus!

And, please provide photos!!

Art

 

[Cruzer]

To add some additional perspective, for whatever it’s worth in this discussion… Our last boat, which we purchased new, was a 47 footer with Zeus pods tied to Cummins QSB 5.9’s. Our overall experience with the pods was excellent - we truly loved having them. We had no unusual mechanical issues and were quite impressed with their performance through the 4 ½ yeas we owned that boat. We were seasonal weekend/vacation boaters in the northeast throughout that time with just a few hundred hours of use per season. We did take delivery in Florida and enjoyed her there in our first winter before the boat was delivered to NY for us. She cruised comfortably at 26 knots all day long burning a relatively miserly 37 gallons per hour. The Zeus pods lived up to all the hype… exceptional close quarters maneuvering, terrific fuel efficiency, diminished sound levels and the awesomeness of dynamic positioning. We also found Zeus' proprietary autopilot system to be excellent.

Daily checks had several additional tasks and regular maintenance was certainly more expensive (perhaps by around 50% though I can’t immediately recall). The one intangible that we didn’t anticipate… we, like many boaters, always left the dock with a certain amount of anxiety expecting that something would go wrong. While that has thankfully eased over the years (though we think a bit of that is healthy), there was always a good deal more of the “hopefully nothing will go wrong” feeling with the pods than what we have now with straight shafts. That certainly came from the added overall complexity as well as the number of sensors that could potentially fail and throw a trip-altering code because that’s what happens sometimes. So we felt the increase in those odds. While our experience did not bear out the added anxiety, it was just something we could never fully shake. Maybe that’s just us.

For the kind of cruising we now do (up and down the east coast, Bahamas) we are much more comfortable with traditional propulsion. We still have oft-maligned fly-by-wire shift and throttle technology (we love it) but are much more comfortable with the ease with which we can generally service things ourselves or much more easily find qualified techs. And we certainly have much less of the aforementioned anxiety. If our cruising was more localized to areas with good service options and we were OK with the potential for long periods of downtime that often seem to come with pod issues, we might consider them again. We had a preference for Zeus over IPS but also would be more likely to favor the Volvo system due to its seemingly more ubiquitous support and longevity. We have a few friends who had IPS and they’ve all had issues from modest to bad. And they have each bought subsequent IPS-driven boats. Incidentally, pod driven boats that use jackshafts to connect the engines to the pods can most certainly have a shaft come out of alignment. Friends of ours with IPS are dealing with that right now.

Someone had mentioned that they believed Prestige was IPS only. FWIW, we checked out their 550 when it was first released and it was offered with Zeus drives.