Pod drives

[Latestarter1]

There was a post here regarding a Fairline factory visit and insurance costs regarding pod drives cannot find it now.

I have recently seen three reports on light damage to pod drives, two VP IPS and one Cummins Mercruiser Zeus. In all three cases drives struck underwater obstruction whilst under way, resulting in loss of either one or two propeller blades, on the face of it certainly not catastrophic damage.......

In all cases drives had to be removed and stripped, on the face of it only appeared to be merely prop damage! However on inspection all the drives suffered bent shafts. Overhaul of these units following what appears to be not much more than a serious prop ding can saddle insurance company/owner with a potential bill of over $10,000!

 

[Portofino]

Poking a stick at a Bear

Wonder what the mechanism is? Maybe the vibration from the now eccentric deformed blade (s) damages a seal letting water in ,oil out ?
Or -and the vibration simply knackers the "delicate " internal parts in the leg .

I wonder if the helm can feel any damage ,or just ploughs on = more internal damage ,only to find out real extent later?
Where as ATBE a shaft set up the vibration of a eccentric prop notice able straight away = back off ?

Supposed according to some websites have a 5 year removal+ strip down anyhow if religiously following VP schedule .

Blades all deformed

 

[Anders_P42]

Volvo could have helped prevent collateral damage separating oil systems in lower leg from main gearbox? It seems any significant leak requires full gearbox strip? Do outdrives share oil in lower leg / gearbox?

 

[Oscar24]

Sharks not looking too happy either......

 

[rafiki_]

LS1, we touched on Pod drives at the Fairline factory, and I think we boat owners were unanimously sceptical. What they offer is to free up space for boat show buyers, and offer joystick controls. Of course, conventional shafts can be joystick controlled too, when matched to a decent bowthruster. Can Vee drives offer similar packaging advantages to Pods?

 

[kashurst]

I was coming around to the idea that Pods could be a good thing, until I read some reports on costs to repair them, five year rebuilds and they dont seem to last that long either. Also I think I saw on this forum higher insurance because of them.
So far few new boat tests seem to show a significant fuel saving advantage.
I can see why boat builders like them - no aligning, quieter drive, minimal vibration.
Newby boat owners I'm sure will love the joysticks - but they won't like the service bills or the difficulty finding someone who can really sort out any pod/electronic gremlins. What they will be like when they are 10+ years old ?
Any future boat for me will be very definitely be shafts with minimum electronics. Or I might even go the outboard route.

 

[MapisM]

LS1, we touched on Pod drives at the Fairline factory, and I think we boat owners were unanimously sceptical. What they offer is to free up space for boat show buyers, and offer joystick controls. Of course, conventional shafts can be joystick controlled too, when matched to a decent bowthruster. Can Vee drives offer similar packaging advantages to Pods?

Yes and no, P.

Firstly, re. boats with shafts+b/t, you actually can't move them around in a way comparable to pods, no matter how sophisticated the joystick and the control logic can be.
Have you ever tried a pod powered and joystick-ed boat? That's the only way to immediately see how fast and strong the sideways movements can be (to the point of needing some care in using the joystick).
Which stands to reason of course - there's a big difference between having steerable thrust for the whole propulsion power and using a MUCH less powerful b/t.
This doesn't mean that such pod capability is useful, mind. In fact, imho it isn't, because if there's one thing to avoid while maneuvering, that's speed.
But it's attractive for newbies, because it's the nearest thing to the dream of anyone who can't get his/her head round to the fact that with boats you do something now and the boat follows later - i.e. a boat that reacts almost as immediately as a car!

Secondly, re. V-drives, the space gain allowed by them actually is not so much, in kosher installations.
I mean, if you just place the V-drive very close to the engine, the prop shaft is bound to go through the hull right under the engine sump.
As a consequence, you should either install the engine higher than necessary (not a good idea, obviously), or accept a nightmare accessibility to the shaft seal (an even worse idea). Or compromise somewhere in between.
For this and other reasons, in many installations, the V-drive is significantly forward of the engine, attached to it with a jackshaft - hence taking not much less of e/r space compared to straight shafts.
This way, prop shafts seals remain visible/accessible, still a bit less than with straight shafts of course, but not too bad.
In fact, funnily enough, initially V-drives had nothing to see with space, but were more designed for better performance/balance of fast P boats.
Just think of weight distribution: when choosing whether to place closer to the boat CoG the engines or the fuel tanks, the latter is better in principle, because anything whose weight is a) relevant AND b) variable should be as close as possible to the boat CoG.
Engines are heavy, but their weight is constant, so in a boat where they are placed further astern compared to inline shafts, it's just a matter of designing the hull accordingly.
"Just" not necessarily meaning it's easy, of course...
Besides, for any given engine position, the prop shafts can be installed closer to the keel, because the V-drive, aside from reversing the shaft direction, also shifts its position sideways.

Out of curiosity, what did the FL folks think of V-drives

 

[rafiki_]

Interesting P. We didn't really discuss Vee drives at F/L. Lots of other things to cover. Will discuss with their Eng Director in the future.

 

[Latestarter1]

Interesting P. We didn't really discuss Vee drives at F/L. Lots of other things to cover. Will discuss with their Eng Director in the future.

I have done two boats with V drives, one remote using MPM the other used ZF, both worked well in service however the setting and lining up time is just what builders hate and completely the opposite from installing a pod.

Going back to pods simply striking say a waterlogged pallet will bend or take a blade off, however it seems that propeller shaft also bends with very little impact, and this applies to both IPS and Zeus. Apparently there have been a raft of design changes on both types of pod in an attempt to beef the shaft up.

The repair practice is different for both types, V.P. offer no parts but supply an exchange unit at around $10,500 on a long lead time and although Zeus can be repaired, few trained dealers who can actually obtain the expensive special tools as well as poisonous parts prices which usually ends up costing the same as IPS.

Cummins offer very effective engine thruster joystick integration package using same algorithms as Zeus, however some dumb marketing clown decided to choose a crummy make of thruster as a dancing partner ensuring that no right minded person would specify it!

 

[Wavey]

I'm by no means an engineering expert but the emerging reports now pods have been around for a while seem to bear out all the concerns about them. To the point where, if I was in the market for a new boat, anything with pods just wouldn't be on my short list.

Maybe it's just me but with boats I much prefer simplicity and ease of maintenance and am more than happy to accept all the compromises that go with that. Also, as kashurst mentioned, I do question how easy it's going to be be to sell on pod driven boats when they're 10+ years old.

 

[rafiki_]

Fully concur with residual and maintenance concerns. However I can see the showroom attraction of the additional space freed up, and the ease of mooring during a demo run. A new boater may not be aware of the growing dangers lurking beneath!

 

[MapisM]

A new boater may not be aware of the growing dangers lurking beneath!

Joystick wow factor is a KSF with newbies for good.
I'm not sure the pod cons can be swept under the carpet in the internet days, though.
Inexperienced as any newbie can be, if he/she is smart enough to be able to buy such expensive toy, more than likely is also able to do his/her homework and take an informed decision...?

 

[rafiki_]

Joystick wow factor is a KSF with newbies for good.
I'm not sure the pod cons can be swept under the carpet in the internet days, though.
Inexperienced as any newbie can be, if he/she is smart enough to be able to buy such expensive toy, more than likely is also able to do his/her homework and take an informed decision...?

I'm sure a salesman would have the right patter to allay any fears.................

 

[MapisM]

Possibly, but as much as I agreed that IPS is more attractive for newbies, I'm far from thinking that newbies=stupid.
You don't make a small fortune in this millenium without being able to separate the wheat from the chaff...

 

[Wavey]

Not saying they're stupid but newbies with that sort of money to spend are unlikely to have a manufacturing/engineering background. More likely service industry orientated.

Would they necessarily consider the engineering side when faced with a beautifully fitted boat, handles so easily you can almost tie it in knots, goes like a rocket, dealing with a very knowledgeable and convincing salesperson, and perhaps most importantly the whole package is offered by a very prestigious and well respected manufacturer. I'm willing to bet many wouldn't.

 

[aquatom]

In my experience the people who buy boats around that size never really keep them long enough to have to worry about any future problems.
Having said that we look after around 10 boats with IPS from smaller targa 44's up to larger predators and can't remember having any major issues with any of them.

 

[PowerYachtBlog]

As far as I know Fairline never touched with V-drives, on the other hand Sunseeker did it many times over and over. 52 Caribean / 53 Manhattan / 54 Manhattan series comes to mind.
I think Sunseeker in most cases did it for space, in some cases the CoG was good see boat above, in others it is bad, see 44 Camargue/ 46 Portofino series. Also being underpowered boats never helped them much.

Ferretti has been going with this since the 80s and they did it for CoG, and sometimes with impressive result.
I will say this the old Ferrettu 57 build between 1998 to 2002 has among the best CoGs ever, even compared to boat with straight line shafts. On plane always straight as the horizon and low and high end speeds and with both Cats or Man 800s or 1000hp units.

I think the trick is how much you put into the study of a hull with a certain type of drives, and where you are putting your engines.
In cases by Sunseeker build in the 90s for example you can see that this IMO looked as coming as an after thought, and you can look at the addition of hull extension to understand this on the models quoted above.
Also when I spoke to knowledgeable engineers about this in late 90s, they strictly advised that going with aft positioned engines, tunnel drives, and low angle shafts (12 or less) equals entrance planning speeds over 17/18 knots, and bow high ride at any given speeds. Also a deeper V aft in between the tunnels did not help create down lift at low pl speeds, hence same problems in also some mid mounted engines cruisers.
Hull making, engine position is a bit of a science, it is obvious that a good hull designer will give you the correct spot and all, but sometimes builders do tend to move things around after to deliver the bigger bedroom.

Returning to this post i.e Pods it is impressive one thing how the ZF (Zeus) pods are much better product then the Volvo units, and yet the later are dominating the market 8 to 2. It is pure marketing skills I guess, in selling what does not exist.
They are better not because of my paranoia of looking aft, but when you look deep also on the important hull design side with ZF being very friendly to nearly any type of Vee shape, with the IPS needing to go fairly flat from midships (-20) to aft preferred angle being around (-12).

 

[MapisM]

I will say this the old Ferrettu 57 build between 1998 to 2002 has among the best CoGs ever, even compared to boat with straight line shafts. On plane always straight as the horizon and low and high end speeds and with both Cats or Man 800s or 1000hp units.

W, what's your take on the even older 165 and 175 (the first being actually very close in size to the 57, and the latter a fair bit larger/beamier), both on V drives?
Talking of my other thread on older boats being built better, by now I could write pages about the things I liked better on the 165/175 vs. the 57......

 

[Latestarter1]

I'm by no means an engineering expert but the emerging reports now pods have been around for a while seem to bear out all the concerns about them. To the point where, if I was in the market for a new boat, anything with pods just wouldn't be on my short list.

Maybe it's just me but with boats I much prefer simplicity and ease of maintenance and am more than happy to accept all the compromises that go with that. Also, as kashurst mentioned, I do question how easy it's going to be be to sell on pod driven boats when they're 10+ years old.

I thought Zeus the number of shaft supersessions and housings was bonkers, however if you look at the number of IPS lower unit part numbers which are now obsolete..................Begs the question, do V.P. take a discontinued leg back as good core against current production exchange unit. I would certainly want a certified V.P dealer to give me the facts in writing, $10,000 PLUS a non return surcharge is certainly worth investigation.

 

[volvopaul]

I thought Zeus the number of shaft supersessions and housings was bonkers, however if you look at the number of IPS lower unit part numbers which are now obsolete..................Begs the question, do V.P. take a discontinued leg back as good core against current production exchange unit. I would certainly want a certified V.P dealer to give me the facts in writing, $10,000 PLUS a non return surcharge is certainly worth investigation.

Early IPS suffered problems with worn out slipping clutches , net result a case full of brass filings that create the vicious circle as it blocked the oil pump inlet strainer , the more you use it the worse it gets then you faces 10k rebuild bill.
Some mods took place , better filtration and updated relief valve to combat the problem. Remember it's still a glorified out drive with two contra rotating shafts with seals that leak.
You then get water in the drive and as its a uniform lube system it wears out the clutches when it has to use emulsified oil, pump pressure drops etc, getting the picture now?
Personally I'd never go there but many do and get bit , as ever the VP parts market booms.
Nothing much wrong with the boats there in.
I'm not sure I agreed with the fuel figures either but then again you won't find the same hull with a shaft, IPS or drive to test.
The only true way to give 100% accuracy would be to do that.