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Should I buy a boat with IPS drives?

Discussion in 'General Yachting Discussion' started by Max Waibler, Apr 29, 2020.

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  1. Capt J

    Capt J Senior Member

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    I have run numerous examples of BOTH boats. I was a Captain for Cabo at the time. To me it's a fair example. You're comparing a boat at a given cruise speed so it is apples to apples. People don't want one boat that does 28 knots and another that does 33 knots. It's the fairest comparison you're going to find. Boats are nearly identicle and the numbers I quoted are real world.
  2. mapism

    mapism Senior Member

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    I'm not surprised at all to hear that.
    Just look at the 2009 Motorboating review that you linked:

    "We had the rub rail in the water during initial testing
    ...
    That was when the drives' articulation was 18 degrees.
    It's been dialed back to 17 degrees, but the hull still digs in like a slalom ski..."


    Then the article goes on praising the advantages of tight turning radius and fast maneuverability in a SF boat.
    But the above behavior is firmly among the negatives of any boat in my books, not the other way round.
    And pretending that this is good for fishing sounds like a joke, considering that the side effect could be a crew member thrown overboard!
    Now, that is clearly a pod-driven effect, due to steerable thrust.
    And the boat was Zeus powered, thanks God for that.
    If they would have tested the same setup with IPS instead, I could bet my own boat that they would have had water all the way inside the cockpit, rather than "just" up to the rub rail. :eek:

    All that aside, it was VERY interesting to see the manufacturer's sea trial data with different engines - apropos, thanks for the link!

    There are several considerations that could be done about those numbers, but one is the most relevant, and explains the silly 63 gph number which I already commented in my previous post: the boat tested with MAN R6/800 was clearly underpropped, to the point of making me wonder if they didn't that purposedly, in order to make the Zeus comparison look better.
    In fact, she could have reached a higher top speed, and spinning a lower rpm for any given speed below that.
    This is evident from the numbers, since the boat does not reach 100% load at WOT, even while spinning 2370rpm, which is above the rated 2300.

    Besides, as we all know, the HP prop demand to keep two identical hulls running at the same speed, with the same transmission and with the same displacement, is by definition exactly the same.
    So, it's irrelevant whether the power is provided by a MAN or a Cat engine, and what their max power or torque is. Any powerplant is required to supply the same amount of of power, and therefore burn the same amount of fuel (bar minor efficiency differences).
    Now, it's true that a pair of MAN R6 are about 500lbs heavier the C12s, but that's less than a 2% difference in a 28K lbs boat, which is neither here nor there.
    Not a snowball's chance in hell that such weight difference can account for a 24% higher fuel burn - not even remotely!
    Also because, if anything, the R6 is slightly more efficient than the C12, not the other way round, go figure... o_O
  3. PacBlue

    PacBlue Senior Member

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    It’s an interesting exercise to go through the data, I take away the benefits of pod propulsion are closer to 20% and not the marketing 35% numbers that you see in adds.

    Keep in mind those factory Cabo test numbers could be before final prop selection but they would usually be propped light to give them enough margin, for owners equipment, Tuna towers or enclosed hard tops , higher heat and humidity conditions for Florida and tropical boats.

    The aggressive maneuvering of SF boats is an admired trait in the US, not too many here concerned about it and when it comes down to it, the 800 hp MAN’s are a lot to pack into any 40’ Express or Flybridge (probably a 35’ waterline) but it’s overall performance on the water is second to none in the 40’ class when looking at speed, maneuverability and seakeeping, can’t think of another 40’ SF that I would want. Does it carry some extra hp - no doubt about it.

    But keep in mind we are talking about a boat that was designed before the launch of pods and it is still a retrofit. When you specifically design for pods and get the best of both worlds you can see numbers like this 43 Spencer Express, about 30 knots at 32 gph.

    https://books.google.com/books?id=s...nepage&q=spencer 43 express boat test&f=false
  4. mapism

    mapism Senior Member

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    Yup, I would have understood that.
    I would, if it weren't that the numbers related to the C12 installation are right on the money instead: 2325 rpm WOT, with 100% engines load.
    And aside from the very basic observation that a longer prop on the higher power boat (with exactly the same rated rpm and gear ratio) is a nonsense, a further proof that the R6 boat was underpropped is also in the speeds at any rpm, which are always a bit higher for the C12 boat, in those seatrial sheets... o_O
  5. CaboFly

    CaboFly Member

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    Interesting comparison and I just looked at some of my engine display photos. My 40 Cabo with Man R6's burns 50gph at 30knots. That is right at 1945 to 1950rpm. Looks like the Zeus package would be roughly 8 to 10 gph better. The Zeus reliability and drive maintenance is a bigger drawback IMO than the efficiency gains in real world. Especially considering there is no interior layout gain. Had this allowed Cabo to fit a mid berth bunk on the 40 Express then perhaps I would feel differently. Access in the ER with the R6 is actually pretty good.
  6. olderboater

    olderboater Senior Member

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    The reduced fuel economy varies widely from boat to boat and at different speeds. I've seen data revealing a savings from 10-35%, so a wide range. I have the fuel charts on a Sunseeker Manhattan 65 with 1000 hp MAN's, 1200 hp MAN's and IPS 1200's.

    It's interesting that at slow speed such as 11 knots, the 1200 MAN's and the IPS get nearly identical usage and are around 0.54 nmpg. At the same speed the 1200 MAN's get better fuel economy that the 1000's all the way up the range. For instance, the 1000's get 0.30 nmpg for 24 knots at 2150 RPM, but the 1200's achieve 24 knots at 1850 RPM and get 0.35 nmpg.

    Now then comparing the 1200 MAN's to the IPS, at speed there's a big difference. To achieve 25 knots, the 1200 MAN's turn 1950 RPM and get 0.32 nmpg and the IPS turn 2000 RPM and get 0.47 nmpg. That's a savings of 32% and to achieve 30 knots, the MAN's turn 2300 RPM and get 0.27 nmpg vs. the IPS at 2200 RPM getting 0.44 nmpg, a savings of nearly 39%. In this example the IPS requires 30-35% less fuel at a normal cruise.

    Our conclusion on that boat was that it was underpowered with 1000's. We did try both IPS and 1200 MAN's and decided for the loop there was just too much debris for IPS, especially since it's draft was greater than the MAN's. For all those who mention joysticks, we had joystick on our boat without having IPS.
  7. AMG

    AMG YF Moderator

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    About the heeling with IPS, as I said earlier, Volvo Penta are doing predictions, recommendations and testing of each hull they deliver to. Our boats are doing very close to "true turns" which means you can put a glass on a table and it remains there regardless of speed and radius of the turn. And this is without the use of the interceptors or gyro of course.
  8. PacBlue

    PacBlue Senior Member

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    Good info, that puts it at about 16% - 20%, numbers that I see repeatedly especially for pods that have 600bhp or less.

    Above that bhp, there is an added benefit to the hydrodynamic gains from the pod units versus the stock shaft/strut/rudder set-ups which doesn’t seem to influence as much on the lower bhp side.
  9. NYCAP123

    NYCAP123 Senior Member

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    Joy stick steering is not uncommon with yachts and commercial vessels to control rudders, thrusters or even all (not to mention pod drives) but with IPS it requires a steady hand and attention while cruising because IPS reacts very fast to it. Hence it being easier to steer with the wheel. For docking that joy stick can't be beat.
  10. sgawiser

    sgawiser New Member

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    One key to the IPS system is proper design and setup. Response time to changes with the joystick is adjustable. I have found with the new joystick driving mode that it does take a little getting used to but then it is truly easier to steer than the wheel particularly in rough seas.

    But many of the comments are correct in that the boat really needs to be designed for IPS to get the real advantages.
  11. olderboater

    olderboater Senior Member

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    I also find the criticism of it's steering to be largely unjustified and somewhat a function of age and experience. If you've used a wheel for 40 or 50 years, then adapting to anything different will take some time and effort and you may never feel as comfortable. If you're a video game professional then joystick feels perfect from the outset.
  12. BoulderGT3

    BoulderGT3 Senior Member

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    I owned a Tiara 39' with IPS and took it all through the Bahamas all the time. Much of what the naysayers worried about like ripping a POD off, complexity and so on I think is unfounded. The service is indeed higher and more expensive and I treated the PODS like glass.
    Real world fuel consumption was about 20-30% better but in my experience there is a big BUT. The engines for like performance have lower torque so in rough seas they tend to labor more. Said another way, your mileage will vary based on conditions.

    PODS are great for getting people into boating and they've developed them dramatically since mine.
  13. HTMO9

    HTMO9 Senior Member

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    There seems to be a big difference between this side of the pond (Europe) and the US, especially the south east coast of the USA, as far as Volvo Penta IPS is concerned. The VP service network, the qualification of their (?) service personnel and the availabity of spare parts appear to be much worse than in Europe.

    From what I read on YF about IPS boats and its problems with the pod drives, I would not buy a boat with Volvo IPS for example in FL.

    The IPS system needs a specific hull design for the pod drives. A boat with a hull designed for shaft and wheel / rudder will not perform perfectly and far less efficient with IPS.

    We have two IPS boats in the family. My son in law (a medical doctor, definately not a professional boater) and my oldest daughter own a Prestige 680 with twin IPS 1200 and my oldest son owns a 80+ft Dutch custom built quad IPS boat. Both hulls are designed for IPS only. The Prestige 680 lives on the Weser river above the first lock in sweet water but is operated mostly in the North Sea. The 80+ ft Quad IPS lived the first two seasons in the Baltic Sea but has been relocated as deck load to the Med last year.

    Other than regular maintenance and anual inspections (out of the water), they have not seen any Volvo mechanic. The Prestige 680 gets about 250 hours per season and the quad IPS a little bit more, may be 400 hours. Volvo Penta service in Europe is great, there is always a service station in reach and the mechanics are well trained. Prices are a little bit higher than a VW car shop :) but still reasonable. Both boats are owner operated without crew. Only cleaning and cosmetics are done by local contractors.

    Both boats are on market now. The Prestige 680 will be traded in for a new 680 with a different interior and twin IPS 1350 and the quad IPS will be exchanged with something bigger with surface drives. My son wants to see 40 Kts, which IPS cannot deliver.

    As BoulderGT3 said, IPS pods are great for getting people into boating. And Volvo Penta has definately a problem in the US. But the same seems to be valid for high speed MAN engines in the US. And when reading the numbers posted on YF for service, repair and parts / haul out in the US, I must say, You guys are being ripped off. The only thing which is much more expensive in Europe is fuel. At the moment about 5 US $ per gallon for EN 590 diesel.
    But most German North Sea boaters refuel at the tax and VAT free Island of Helgoland anyhow.
  14. Danvilletim

    Danvilletim Senior Member

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    What’s is the maintenance and other trade offs between surface drive and pods?
  15. HTMO9

    HTMO9 Senior Member

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    My son is very happy with his quad IPS setup. He only wants more speed which the Volvo IPS pods are just not build for. Around 35 Kts seems to be their limit. As far as handling at all speeds, close quarter maneuvering, docking, efficiency and comfort of ride, IMHO nothing can beat IPS in that size, as long as You have a boat that was designed for that system from the beginning and is equipped with interceptor stabis additional.

    For higher speeds, if You do not want conventional shaft and prop, You have only the choice between surface drives and Water jets. Waterjets are awfully inefficient at low speed but work nicely at their design speed. And low speed maneuvering and backing into a slip is no real fun either. With surface drives, You will get most likely the highest speed for a given engine package, depending on the type of surface drives You are choosing.

    My son and I have tested some speed boats in the 80 to 100 ft class with waterjets and Arneson surface drives a few years ago. Also he got addicted to those nice Rooster tails at speed, he bought the quad IPS, as strongly requested by his wife :). She was afraid of that wave pattern and that roaring noise.

    But now he wants to go bigger and faster. With quad IPS 1350, the size limit would be at around 120 to 130 ft and still with max. 35 Kts. Lars Modin has some very nice designs in his portfolio at 105 and 130 ft. I personally think, 35 Kts are more than enough, especially with all the advantages You gain with IPS. I am still trying to talk him into one of those.

    D105 Carbon.jpg

    X130,40m.png
    We do not prefer the Arneson drives. My son has some jetty neighbours in the Med with Arneson drives (Pershing). They are either not used at all or have a lot of trouble with their propulsion train. But with 4 non steerable surface drives like the Levi drives or the Q-SPD drives, the props ventilated with the exhaust gasses, one could go up to 165 ft LoA. With quad MTU 16V2000 M96L and 4 Q-SPD drives even a Mangusta 165 E could easily make 40 Kts cruise.

    IMG_2308-2-e1494646855993.jpg

    fig4.JPG

    IMG_2388-1-e1555365468107.jpg
    These are pictures of smaller variants but bigger ones are available on request for up to 3.000 HP each. I am sure those drives are far less trouble prone, cause less maintenance and are even cheaper to buy than Arneson drives.

    With the Corona travel restrictions, I have most likely some more weeks to convince him. I would like to hear the opinion of Lars about IPS in general and especially about a larger IPS boat with quad IPS 1350 versus
    one with surface drives, versus conventionell shaft and wheel.

    HTMO
  16. AMG

    AMG YF Moderator

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    Hello my friend,

    First, with IPS/1350 they have props for speeds up to 42 knots. With the D8/800 the limit is 40 knots and with the D6 range up to IPS/650 you today have props for speeds up to 50 knots!

    The 105' boat with quad 1350 was intended to be built in carbon fiber as our other large boats and with the same approximate performance of top speed near 40 knots and cruising 30+.

    At the same time as I did this design, Volvo Penta presented a hybrid solution, with integrated electric motors, why the project was waiting for more info. Since then this hybrid has vanished from their map and we don´t know if it ever will be launched or be replaced with a new concept. Whatever, a semi electric drive would be the perfect combination for the IPS drives. Especially compared to water jets or surface drives.

    Conventional shafts are of course a good solution on displacement and semi displacement yachts, but not that efficient compared to IPS between 20 and 30 knots cruising speed. As always the decision must include your personal preferences on speed, vs range and cost...
  17. HTMO9

    HTMO9 Senior Member

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    Hello Lars,

    Great info Lars. My Volvo IPS knowledge seems to be not up to date then. Your connection to the Volvo guys is definately much better than ours as normal mortal end users. When talking to VP Germany in Kiel, they only told us to talk to the boat manufacturer for more details.

    I will tell my son in law about the higher speed props for his new Prestige 680. His dealer did not say anything about them. He probably did not know either.

    The 105 quad IPS is a perfect design Lars. Will Delta Power Boats still build it?

    What kind of propulsion did You plan for the 130?

    HTMO
  18. AMG

    AMG YF Moderator

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    The 130 was intended for pods or shafts, but just semi displacement with cruising about 12-14 knots, a floating beach house.

    The 105 could be built by Delta Powerboats if we could sell a few before making moulds, but we are not actively marketing it now.

    Instead we are making moulds for a big catamaran that can be ordered in different lengths, from about 24 up to 40 meters with the same beam of 13,6 meters. The first built should have IPS...

    /L
  19. Capt J

    Capt J Senior Member

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    Surface drives are high maintenance as well as pods, compared to shafts. Surface drives tend to be the most efficient at putting HP to the water (lowest amount of slippage). If the props on a surface drive boat aren't crystal clean the boat will not usually get on plane (like if you have 7 barnacles on them). Surface drives are very hard on the engines when shifting and at slow speeds as you're running twice as much prop as they're propped for. Generally WOT only half the prop is in the water and that is what it is pitched for. You also have seals that go bad for all of the rams mainly from not being used every week or two from growth, steering rams, trim rams etc. And, usually every 2-4 years you have the props checked, reconditioned, tweaked. I'm not familiar with the other brands everyone posted, only Arneson.

    AMG- are the carbon fiber hulls noisy at cruise? I was only on a 65' SF cold molded carbon fiber hull and the boat was noisier than hell at cruise. It sounded like the entire boat was coming apart as the Carbon fiber transmitted all of the noise. Yet the boat is now 30 years old and still running around at 32 knots cruise.
    Last edited: May 25, 2020
  20. AMG

    AMG YF Moderator

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    Our boats are infused with divinycell core and an average sound level from our measuring is around 7o db(A) in all planing speeds. Like in a modern car, you talk without raising your voice.