Azimut 68 vs Ferretti 72

[Deleted User YDKXO]

IPS experience- 25 knot— 10 l/Nm fully loaded 84 foot flybridge

Which boat?

 

[NYboater]

Delta 8

Which boat?

Delta 88

 

[Deleted User YDKXO]

Delta 88

Not sure an all carbon fibre boat is a fair comparison

 

[NYboater]

Not sure an all carbon fibre boat is a fair comparison

I think the comparison is reasonably fair for IPS versus shaft flybridge boat performance since all 3; the Azi, Ferretti and Delta are about the same unladen weight.

 

[vas]

would the 12-15ft longer hull of the Delta give an advantage though?
It would for sure on hull speed, no idea if that also helps in planning performance, anyone?

 

[Bouba]

There’s got to be a difference. I come across huge wakes as some boats can only plough through the water on plane while others leave barely a ripple

 

[Portofino]

There’s got to be a difference. I come across huge wakes as some boats can only plough through the water on plane while others leave barely a ripple

Yes sone hulls are more efficient at different speeds , which will have a knock on effect with the amount of Hp and thus fuel burn to push it along for a given speed .
The flatter Lower dead rise tend to lift more than the deeper dead rise .So reduce drag
Having said that , depends on the speed ranges you are in .In this case up to 25 knots or around low twenties .
If you can get it nearer 30 / 35 unlikely with a 22 M FB then subtle lifting strips can actually create more lift and reduce the wetted area and the drag , the fuel burn / distance improves .You end up on a plateau of efficiency.The L/ hr increases slightly, but run time for a trip decreases so going faster say 27 knots to 30 knots uses the same vol of fuel .
Once on this plateau created by the second stage of lift by subtle hull tweaks , you may as well let rip .
The whole engine package , propping , weight , drag ( or lift ) , hull shape can be married together .

The ones you see creating the biggest wake I suspect are the semi displacement hulls operating at the top of there speed range .
They lack either the hp to go fast enough to lift the thing up enough so you see the “ plough “ and wake .Also the shape of the hull lacks the lifting tweaks like a hard chine or multiple wide lifting strips incorporated into the design of the spray rails .There’s not enough Hp to lift it out high enough or it can not lift so it just divides up tge water = huge wake .

As said a deeper V at speed will push huge vols of water to the side so fast that as it rips along , when it returns the water rolls it’s self into a kinda mini rooster tail as each side collides in the centre .The payback is it takes a lot of Hp to displace a lot of water quickly so the boat can move through it fast ,
So theses Uber efficiency hulls like the delta 88 will be flat tea tray types .Couple in light weight and some lift features then the Hp requirements drop along with the fuel burn , Flatter aft sections are more agreeable with IPS set ups as well .
But as you know theory is one thing practice another ,All I have said is easily undone in the med with fouling , props / sterngear as well as hull .
Agree with Mike for a 22/24 M FB 4 cabin boat fuel burn relative to each other would not figure in the decision .

With seasonal fouling I would be seeking out the larger engined version tbh ,You know a 1550 over a 1200 or what ever .
On the basis I would prefer one running at a lower % load for a given speed and fouling .It might even overall end up buying less fuel in a typical season .
Certainly I would be peed off if the stern gear needed constant “diver “ attention because the Hp is on “the edge “ in real world boating.

 

[MapisM]

I think the comparison is reasonably fair for IPS versus shaft flybridge boat performance since all 3; the Azi, Ferretti and Delta are about the same unladen weight.

If weight would be all it takes to make a fair comparison, some lorries are even heavier, and they burn much less fuel.
At Delta, they deliberately decided to go for a totally IPS-driven design of their hulls, rather than a sea-driven design as most other builders do - or at least some sort of compromise.
The result, which speaks for itself, is below.

Then again, maybe Delta was right and all others were wrong.
But they aren't the new kid on the block anymore, and if nobody copied their concept yet, there must be some reasons, I guess...

 

[MapisM]

84 foot flybridge

BTW, you're actually talking of a 79 feet boat.
Calling her an 84' (let alone an 88') doesn't make her any larger.
Just saying...

 

[NYboater]

If weight would be all it takes to make a fair comparison, some lorries are even heavier, and they burn much less fuel.
At Delta, they deliberately decided to go for a totally IPS-driven design of their hulls, rather than a sea-driven design as most other builders do - or at least some sort of compromise.
The result, which speaks for itself, is below.

Then again, maybe Delta was right and all others were wrong.
But they aren't the new kid on the block anymore, and if nobody copied their concept yet, there must be some reasons, I guess...

You may be correct but I believe the picture is of a Delta 54 hull. Only providing our experience with over 22,000NM in the past 4 years.

 

[NYboater]

BTW, you're actually talking of a 79 feet boat.
Calling her an 84' (let alone an 88') doesn't make her any larger.
Just saying...

Agreed. Actual molded waterline length is 23.90m. Length from bow including swim platform is 25.84m or 84 feet.

 

[MapisM]

You may be correct but I believe the picture is of a Delta 54 hull.
Only providing our experience with over 22,000NM in the past 4 years.

Correct, the pic was of a 54, but I think the design principles are similar throughout the whole range.
Congratulations for the miles crunching, that's indeed impressive!
I guess you must have found some rough staff, occasionally.
Are you happy about how she handled that - possibly also compared to more traditional hulls of similar size?

 

[Hurricane]

IPS experience- 25 knot— 10 l/Nm fully loaded 84 foot flybridge

I'm confused - did you mean 64 footer?
I didn't think that Volvo made the bigger engines - let alone IPS of that size.
Anyway, have you seen what happens when barnacles get into an IPS drive?
I wouldn't be seen dead in an IPS boat so it doesn't matter how efficient they are.
IPS will always cost you more in the end.

 

[Alicatt]

What about the likes of the Sunseeker Predator 80?
3 1200hp diesels to surface drives giving a cruise speed of 30kt and top end of 40kt

Just a random one I picked off the interwebs, I remember the Predator 80 being unveiled and being a boat that I would like to own but a good bit out of my price range
https://www.yachtworld.co.uk/boats/1999/sunseeker-predator-80-3592127/
or
80 Sunseeker Predator 1997 | HMY Yachts

 

[NYboater]

I'm confused - did you mean 64 footer?
I didn't think that Volvo made the bigger engines - let alone IPS of that size.
Anyway, have you seen what happens when barnacles get into an IPS drive?
I wouldn't be seen dead in an IPS boat so it doesn't matter how efficient they are.
IPS will always cost you more in the end.

84 feet LOA. Triple IPS 1200’s (900hp). As for IPS costing more in the end, you may be correct but we save E15,000 a year on fuel. Barnacles haven’t been an issue yet, but in full disclosure we lost a steering seal 2 months ago. Volvo covered on their extended warranty (5 years) but it was a P!TA.

 

[NYboater]

Correct, the pic was of a 54, but I think the design principles are similar throughout the whole range.
Congratulations for the miles crunching, that's indeed impressive!
I guess you must have found some rough staff, occasionally.
Are you happy about how she handled that - possibly also compared to more traditional hulls of similar size?

Sorry, I have almost no experience on similar size traditional hull boat- only sea trials on calm days?