Absolute 50 FLY. (Video)

Blimey, you got it!
How could you guess that, just went for the most stupid you could think of, I suppose...? :D
Actually they claimed both #5 and #6, and neither make any sense imho.
My only (small) doubt is that the boat is not leaning a lot while steering at speed, which is a well known IPS problem - to the point of being scary, particularly with f/b boats.
I wonder if that has anything to see with the triple configuration.
 
I agree Mapis. As I said, the trim does indeed look very nice. I was just pointing out the tilted camera as a fact to keep in mind

Whether that is good design can be debated. I bet the hull is flatter at the bow than an olesinski (whose particular style of hull design causes a couple of degres of upward trim when on the plane. If I'm rright here, it means ability to take a head sea has been traded off for a flatter ride. Perfectly fine for anyone whose list of priorities matches that trade off

I'll go for #5, stability underway, but I don't believe it (any more than I'd believe any of 1-6)
 
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jfm said:
I'll go for #5, stability underway, but I don't believe it (any more than I'd believe any of 1-6)
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Well, obviously, other than 5 & 6, I just made up the other choices (in a sort of inverse laughability ranking, 'cept #7)
Actually #1 is something a builder confirmed me. He told me that for any given performance, the cost of engine+transmission+installation is a tad lower with IPS.
And this, combined with the fact that they can usually "sell" it as a higher value, make it an attractive option from a builder perspective.
This is mainly due to a couple of factors: firstly, it takes less power with IPS to achieve the same performance as shafts. Secondly, the installation is quicker and less critical.
Of course, the other side of the medal is that it takes some investment to properly design a hull for IPS. So, the BEP depends a lot on the number of boats produced/sold.
So, out of the choices I made up, I think that #1 does have (or can have, at least) some sense, though of course you'll never see that advertised in a promo video.
Also #2 wouldn't be completely laughable, in some installations.
 
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jfm said:
Whether that is good design can be debated. I bet the hull is flatter at the bow than an olesinski (whose particular style of hull design causes a couple of degres of upward trim when on the plane. If I'm rright here, it means ability to take a head sea has been traded off for a flatter ride. Perfectly fine for anyone whose list of priorities matches that trade off
[/QUOTE}

This is all wrong the high bow trim in the Olsenski hull started to become more evident since he introduced semi prop tunnels to reduce shaft angle, and increase performance. Add to this a more aft to stern located engines and you have the result.

The old generation Fairline/Princess had deeper Vee to fore about close to 50 deg less to bow of about 15 degrees in the shaft models, and all ride great. These hulls are what gave BO his fame. Fline 36 Sedan, 36 Turbo, 50 are all super sea worthy boats. Princess 45,55 etc
New generation models since early nineties have around 40 deg (standard today) and most of them dont ride so good and suffer head seas over force 4.
When you put those prop tunnels the weight distribution in a hull becomes more probelmatic, reason some builders dont use them on all the models.
Have seen other IPS boats by other builders and half of them dont ride very good. Yes that is a result of hull design and the experience of the builder in the propulsion. They have nine out of ten models with IPS, and soon ten of eleven. I think few today know how to design a hull with IPS as much as Absolute.
Click to expand...
 
jfm said:
Perfectly fine for anyone whose list of priorities matches that trade off
Click to expand...
I forgot to mention: I fully agree with the above.
It's just on the 50', that this trade off seems to have gone too far.
The 58 was much better, frinstance.
 
MapisM said:
Well, obviously, other than 5 & 6, I just made up the other choices (in a sort of inverse laughability ranking, 'cept #7)
Actually #1 is something a builder confirmed me. He told me that for any given performance, the cost of engine+transmission+installation is a tad lower with IPS.
And this, combined with the fact that they can usually "sell" it as a higher value, make it an attractive option from a builder perspective.
This is mainly due to a couple of factors: firstly, it takes less power with IPS to achieve the same performance as shafts. Secondly, the installation is quicker and less critical.
Of course, the other side of the medal is that it takes some investment to properly design a hull for IPS. So, the BEP depends a lot on the number of boats produced/sold.
So, out of the choices I made up, I think that #1 does have (or can have, at least) some sense, though of course you'll never see that advertised in a promo video.
Also #2 wouldn't be completely laughable, in some installations.
Click to expand...

Mapis, ref #1 on your list (lower build cost) i can believe that. At least in simplistic terms: the risk-adjusted cost might be different, becuase making a line of IPS-only boats is a risky strategy for a builder, but there speaks an investment banker type I suppose!

However I'm not sure how lower build cost can be a reason for putting THREE engines in there rather than two :)
 
PowerYachtBlog said:
This is all wrong.
Click to expand...

Whatever. Prop semi tunnels are very common, not at all BO specific, and indeed his tunnels aren't particulary big. But you do I think need to factor in the particular BO hull design feature of creating the forward deep V by taking the keel lower rather than the chine higher. As ever with boats this is a trade off. Makes for nice hull volume for forward accomm, good head sea capability (even if you don't agree, but can we just not bother to argue that please, and agree to differ). But as a matter of geometry it makes the planing surfaces slope down when going from stern to bow, which in turn adds a degree or two of bow lift/trim angle. Trade off as I say; you can choose any hull form you prefer!
 
Prop semi tunnels are very common, not at all BO specific, and indeed his tunnels aren't particulary big.
=Agreed , semi tunnels where invented by Levi in his drive unit and started be used in boats in the eighties.

But you do I think need to factor in the particular BO hull design feature of creating the forward deep V by taking the keel lower rather than the chine higher. As ever with boats this is a trade off. Makes for nice hull volume for forward accomm, good head sea capability (even if you don't agree, but can we just not bother to argue that please, and agree to differ).
=Nope I never said it does not make for a good head sea capability. But when the bow rises to much you loose this for less waterline length while underway. When rising the bow higher most of the times it also makes for a dryier ride too. So as you say in anything there is a tradeoff.

But as a matter of geometry it makes the planing surfaces slope down when going from stern to bow, which in turn adds a degree or two of bow lift/trim angle. Trade off as I say; you can choose any hull form you prefer!
=I like BO hull form and I am a huge fan, the problem remains how much R and D a builder can afford to make on each design. I still think the Fline 36 Turbo was one of his best designs, as was the Fline 50. Both are medium Vee 16 the first and 15 degrees the last.

For me BO's hull shape take a lot from the old David Napier Bertram 54 which is by many standards a benchmark in modified Vee design. The 54 has like 6 degrees angle at low 20 knots speed less to that. Deep Vee aft is 18 degrees. This hull is still used on the 570 Bert with 17 deg and some minor modifications. Many fans of the old 54 will tell you it does not ride as good, mostly because FG moved the fuel tank infront of the engines for better COG and it became a wetter ride.
What i was saying is that a deep fore foot is not an escuse for a high bow ride. Magnum Marine Jim Wynn design have 56 degrees fore foot, and 24 degree aft, and they ride like 3 degrees high about 25 knots with standard line shafts. They ride even better with surface drives....
Now lets keep this thread about Absolute and IPS.
 
You are completely missing the fact that "deep forefoot" and deadrise angle are only part of the story. A 56deg forefoot with a high (Soni Levi) chine is totally different from 56deg with a low (BO) chine . The latter is an excuse/reason for high bow ride; the former isn't. But, whatever, yes, let's stick to Abs and IPS!
 
jfm said:
However I'm not sure how lower build cost can be a reason for putting THREE engines in there rather than two :)
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appart from the reasons that MapisM is sugesting, and are all more or less doubtfull, I still can't understand what are the real reasons to fit three engines in a boat.
Absolute is not the only boat builder who offers three engines

as I see it, the manufacturers reason is that a suitable size twin IPS installation for that boat size is not availabe, (I have to admid that I'm not aware of all available pod drive models at this moment)
and if that is thrue, it just doesn't seem right to fit 3 engines, a lot more disadvantages then advantages, and then I would choose another boat or another brand.
for me I can't understand the "logic" for a three engine installation,
or am I missing something ?
 
BartW said:
for me I can't understand the "logic" for a three engine installation, or am I missing something ?
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Yep, U R... Don't get me started on that! :D
Triple.jpg


Though aside from some very peculiar boats as this one above, I also don't see the point of triples.
I'd just be interested to understand if that has something to see with the better leaning control when steering.
That's the most impressive thing in the previous video.
 
Firefly625 said:
slightly off the point, but IPS and three engines... I guess only the Outer 2 are working when manoeuvring on IPS joystick??
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Good point. In theory, the center one could even get rid of any rotation mechanism, to keep it simpler.
IIRC, that's the setup of the Pershing 115, with a turbine spinning the central, non-steerable waterjet.
No idea if that's actually the case with IPS, though.
 
jfm said:
However I'm not sure how lower build cost can be a reason for putting THREE engines in there rather than two :)
Click to expand...
Can't argue with that! :D
Va sans dire that my comment on costs was related to IPS vs. shafts, rather than triple vs. twins...
 
BartW said:
appart from the reasons that MapisM is sugesting, and are all more or less doubtfull, I still can't understand what are the real reasons to fit three engines in a boat.
Absolute is not the only boat builder who offers three engines

as I see it, the manufacturers reason is that a suitable size twin IPS installation for that boat size is not availabe, (I have to admid that I'm not aware of all available pod drive models at this moment)
and if that is thrue, it just doesn't seem right to fit 3 engines, a lot more disadvantages then advantages, and then I would choose another boat or another brand.
for me I can't understand the "logic" for a three engine installation,
or am I missing something ?
Click to expand...


Three D6's are shorter than two D9's giving more length for accommodation? That's all I can think of unless they're cheaper as well. I always assumed the early triple and quad IPS installations were because you simply couldn't get bigger units but, thinking about it, a quad IPS 600 engine room would be a very short engine space for a claimed 2400 BHP equivalent.

I speak on the basis of absolutely no knowledge whatsoever on the subject though so it's purely supposition on my part (a long way of saying I don't know so I'm guessing).
 
Absolute are doing both the 70 and 64 with twin big IPS third generation of 900hp each.

I think the problem with the Absolute 50 and 56 is that there is a gab between the D6 435hp and D9 670hp used for the IPS900.
An interesting choice would be to use ZF Zeus and their various engine choice but that needs a hull reconfiguration.
One of the few boats i know which is available with both ZF Zeus and IPS is the Atlantis 50x4.
 
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