Yanmar V Volvo

[PowerYachtBlog]

What if it has outdrives..?

Outdrives are okay up till 12 meters, and 9/10 tons. If you do 40/50 hours the saving compared to shafts is felt in fuel consumption not little.
It is obvious that with outdrives yearly maintenance cannot be missed. Oil change in drives, zinc anodes change, bellows every other year etc etc.

The big failure in stern drives from Volvo came with the DPH who improved a lot of stuff from the DPG / E / 290 but forgot all the good stuff the previous generation three decade old stern drive design had.

 

[oldgit]

If you do 40/50 hours the saving compared to shafts is felt in fuel consumption not little.

.....possibly if you spend those 50 hours @ WOT or cruise for the entire time.

In the real world a fair proportion of any boats time will be spent on a combination of merely ticking over on the mooring, manoeuvring into or out of the berth and the long trudge out to where you can actually open up the throttles with clear conscience.This followed by a similar amount of time finding somehere to park at the other end and the amount of time spent getting the anchor to bite.
At 50 hours suspect most of those hours will be multiple quick blasts round to the nearest Cala ?, not long distance trips where the economy just might be worth the extra expence of outdrives.
Perhaps the claimed economy benefits are not quite a great as are claimed for the average boater on her average trip out ?

 

[ari]

Guess ?

I knew you'd come around to them eventually!

 

[PowerYachtBlog]

.....possibly if you spend those 50 hours @ WOT or cruise for the entire time.

In the real world a fair proportion of any boats time will be spent on a combination of merely ticking over on the mooring, manoeuvring into or out of the berth and the long trudge out to where you can actually open up the throttles with clear conscience.This followed by a similar amount of time finding somehere to park at the other end and the amount of time spent getting the anchor to bite.
At 50 hours suspect most of those hours will be multiple quick blasts round to the nearest Cala ?, not long distance trips where the economy just might be worth the extra expence of outdrives.
Perhaps the claimed economy benefits are not quite a great as are claimed for the average boater on her average trip out ?

In the real proportion is done at a fast cruise at planning speed. I do 40 mins trip, 10 is out of marina, 5 to find a mooring possibly less then that.
When you do a cruise the % will turn in large favour to the fast cruise.

Then it is possible you keep your boat in a river or you use it like that, but the majority does not.

 

[petem]

In the real proportion is done at a fast cruise at planning speed. I do 40 mins trip, 10 is out of marina, 5 to find a mooring possibly less then that.
When you do a cruise the % will turn in large favour to the fast cruise.

Then it is possible you keep your boat in a river or you use it like that, but the majority does not.

In the Solent, it is quite rare to have a marina that opens out to the sea. There's normally a river, harbour or other speed restricted area to navigate through first.

 

[Portofino]

There’s no doubt the equivalent size shafty will use more fuel than an outdrive , that’s a given .
But in the bigger scheme of running a 37 ftr / 40 ftr Pershing 37 , Baia B1 , Itama 38/40 the fuel bill merges into the spread sheet .
The columns for a outdrive oil , service , the biannual bellows are always absent, have zero entries.
Ok once every 10-15 y there is an entry in shaft withdrawal, new cutless bearing + rudder stock column , but the sum the outdrive maintenance over this period will far exceeds this .
Bushed props , cone clutches , external rams , internal trim motors + paraphernalia etc etc the list goes on .

Wether that makes up for the extra fuel depends on the hrs .
Yard bills .Given the time a shafty is eminently more DIY erabke .Any fool can scape + paint + use a spanner to bolt an anode on .
While a few on here have developed and nurtured outdrive maintenance, let’s face it he av Joe ain’t gonna be able to do it and require a wallet opening session hiring pros .

Aside the next 10 ft up the number of shafys choise really opens up from 40-50 ft .Ok there are few lingering lightweight outdrive boats with cores hulls , and of course the dangling bit reverses direction and picks up a new title IPS.

It starts to slip in to cubic capacity of the motors differences .
A bigger cubic in capacity motor purring away sub 2000 rpm of the tiny 5.5 L VP IPS - with what ever number Hp it says on the brochure m revving it nuts off at 3500 rpm+ to keep up with the big boys .

Fuel burn is not linear in a boat when planing , the last say 80% load upwards the graph rapidly steepens upwards and any advantage touted is gone fuel burn wise .
Sunseeker dabbled with the Porto 47 , shafts or IPS. Remember it’s a “sports cruiser “ Over 24 knots my mates IPS boat was just guzzling fuel .@ 3200-3400 rpm in season .Note in season .
Anything N of 26 knots it works alarm and force a slow down .

Meanwhile in my boat ( we ran in company) @12.8 L I had to slow down to around 1500 rpm , the turbo spool in no mans land to keep around 24 knots and our consumption would overlap at 60/65 L / side .

So It cost us the same , the same dimension hulls more / less to fuel a trip .

Now yes in a free world i would have eased up my boats cruising speed 28/29 knots sub 80 % load and burned 80L per side .
But same size hull same speed remember .His would no go all day above 26 never mind nearer 30 .
And I was just playing .2000 rpm and it’s 33/34 knots all day albeit over a 100 L per side .

As said on 1 / 2 hr run as if the cost difference of 20 L preside is globally going to make a ripple ?
……………..when you factored in him dropping €4/ €6 K IPS repair bills every season on top of the maintenance.

 

[PowerYachtBlog]

Porto the Portofino 47 with IPS, and 48 and San Remo are bad examples. They are under-powered machines.

Putting two 5.5 litre in a boat weighing over 15 t in running order is next to suicide.
Also for the Portofino 47, that boat and its twenty year old hull was designed to run well with Volvo D9 575hp. The hull was modified for the P48 / SR48 and was IPS esclusive.
btw same goes for the Princess V48/50 and Targa 48 GTO which came after it. Though less bad in the Fl as it had the engines mounted centrally with a jack shaft, and had less weight.
Also unlike the SS and Princess, the Fairline t48 (now T50) was offered from 2018 with Volvo D8 engines, 550hp IPS700 engines.

The IPS with D6 engines are good for boats up to 13 meters in meters and around 13/14 tons in running order weight.
Think the Cranchi 43 Med, Targa 44 GT, Absolute 47, and just managing it with the Azimut 43S. Just to mention some main stream boats.

 

[Momac]

Perhaps the claimed economy benefits are not quite a great as are claimed for the average boater on her average trip out ?

I agree there is nothing in it in real life.

 

[ari]

No one is choosing IPS for fuel savings.

Packaging, first and foremost - try telling the sub 50ft full beam master cabin owner (or perhaps more pertinently his wife) that they need to give that up to accommodate shafts, gearboxes and engines!

Then manoeuvrability. All very well the boating die hards saying 'well you should just learn to drive a shaft drive boat', the fact is that many owners have neither the time nor the inclination. IPS Joystick just makes it so easy. Yes, you can joystick shafts with thrusters now, but it's not as seamless or effective as IPS.

IPS fuel savings, is just a red herring (especially as IPS loses about 10% efficiency the moment the props get even a hint of marine growth on them), great for justification maybe, but no one really cares.