Volvo new IPS System

[sonarbell]

People have already spotted the major drawback to this system and that is the total loss of the lower leg when coming into contact with a large object when at speed.
Just a thought:: Why not have some form of restraining system like they do in Formula One with the suspension and wheel parts??
Anyone any comments?

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[LeytonC]

<cynical>
Now imagine the volvo board room...
Now image the volvo head guy in tears of joy, during a conversation that goes something like this

'so you have designed a system where the slighest hit makes the main drive unit fall off, and we can charge for a replacement unit' to which the main designer replies 'yes sir, sorry it took 5 years, we had the concept done in 2 months, and the unit designed in 5 months, but the rest of the time went in designing a special coupling that would make the unit fall off 3 days after warrenty ended for no apparent reason - also we have added a special feature, all the shafts bend and ruin the leg just case someone finds it'

</cynical>

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<hr width=100% size=1>Thanks

Leyton

EXTAR Software - Software that works for you
Phone : 07803 139 736

 

[Its_Only_Money]

My idea on another thread was to have a large chain from the lower drive to the transom so that the drive unit wouldn't be lost.....not sure of the forces involved and in any case I would suspect that major components in the upper (ie the bit you'll still have) and the lower (the bit that is on the seabed), would need changing in any case - and that's IF you don't have to fork out for a complete new drive from the engine backwards. After all being "designed to shear off" and "being designed to shear off with no substantive damage to driveline components" aren't necessarily the same thing....


Either that or tie-wrap some sort of locator beacon to the lower drive - even a pinger that can aid location by a diver might be the way to go - but that is only worth doing IF the lower drive is of any use, if Volvo refuse to re-work any drives or it isn't economic to do so then its a lost cause (literally!)

Might be worth Volvo releasing some demo footage from underwater cameras of a drive shearing in action, after all they HAVE done live tests haven't they, this isn't theory/lab speculation as to the shearing properties.....is it????

After all you'd need to be sure that an "uncommanded lower drive separation" doesn't cause a hull breach towards the transom from the drive unit itself....

<hr width=100% size=1>Rgds

Simon
Its Only Money
Fairline Sprint
Solent-based

 

[oldgit]

Ooo Yes,lets add some more techno frippery and extra weight and future maintaince expence to something that did not need to be recobbled up in the first place/forums/images/icons/laugh.gif/forums/images/icons/laugh.gif/forums/images/icons/laugh.gif

<hr width=100% size=1>No good deed ever goes unpunished.

 

[wakeup]

Never mind a chain, why not just have a rear facing hinge so that the leg can give way but you dont loose it or even better can be reset for nowt except praps some prop damage!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!111

<hr width=100% size=1>As independent as resources permit.

 

[Its_Only_Money]

That's a great idea! Maybe it would be better if the drive was transom-mounted to give a better angle of kick-up above the hull bottom. Then again you could improve it by turning the props around to give them protection from the lower drive and skeg. As its a drive mounted right at the stern we could call it the sterndrive - I'm sure it will catch on better than this IPS gimmick.

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I see someone has come up with the idea of a gearbox on the end of conventional shafts to give them duoprops - now that looks fairly sensible, no extra risks of fouling over shafts and duoprop grip on the water (from which I think most of the IPS efficiency advantages come - the remainder come from having the props run in clear water and at a better angle). I guess it will also be possible to have the contra-rotating gearbox in the hull with concentric driveshafts down to the props....

<hr width=100% size=1>Rgds

Simon
Its Only Money
Fairline Sprint
Solent-based

 

[wakeup]

Nooooooone likes a smaaaaaaaaaaaaaaaart arrrrse /forums/images/icons/wink.gif

<hr width=100% size=1>As independent as resources permit.

 

[Its_Only_Money]

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<hr width=100% size=1>Rgds

Simon
Its Only Money
Fairline Sprint
Solent-based

 

[jfm]

Lettem sink

There's no point. If you have a piece of string/chain to hold the drive on, the only benefit is that you dont lose the drive, so maybe you can have it re-attached after repair. But the number of IPS units that will sell versus the number that will be snapped off is a massive multiple, 100,000 to 1 or something. So why add say £50 to the cost of the unit just to save say £3000 very rarely? Much better just to let the damned things sink and buy a new one.

The formula one gizmo is to do with safety, not cost. With theIPS it's safer to let it sink, surely?.

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[Its_Only_Money]

Re: Lettem sink

Assuming it does just "sink", trouble is the rear of the drive is quite sharp/streamlined, assuming you hit something that effectively stops the drive dead but not the boat then the drive could easily rotate and piece the hull, driven up into the hull by whatever you have hit - which is why I'd be very interested to see footage of what does happen in an impact.



<hr width=100% size=1>Rgds

Simon
Its Only Money
Fairline Sprint
Solent-based

 

[Nick_H]

There's no pleasing some people. Diesel costs are going through the roof and Volvo have come up with a system that is significantly more fuel efficient, means we can have smaller lighter engines and still get the same speed, and you've worked out its some great conspiracy to screw us all for more money if we're unlucky enough to hit something in the water or stupid enough to run aground.

<hr width=100% size=1>He who dies with the most toys, wins

 

[Duncan_Hamble]

Re: Lettem sink

So a bit like getting your P bracket pushed through the hull - no different really and not a great risk.

 

[jfm]

Re: Lettem sink

All agreed, but antipierce features need to be designed in. My comment was that there is no need for a restrainer chain/string, which is a quite separate matter from whether the drive can pierce the hull on an inpact

 

[Rxtreme]

Re: Lettem sink

Far too much concern is being put into the lower drive unit shearing off in the event of a crash with an under water object, back in the 1950’s car’s where not designed to crumple on impact in order to absorb the energy, instead the passenger took the brunt of the force and often died The point that I am trying to make is car’s have evolved to better deal with accidents and boats are finally beginning to catch up. As in a car; to trigger the air bags you must have a collision at a speed equal to or greater than the predetermined boundary’s that the air bags are set to go off at, the Volvo IPS follows the same principal. The IPS unit is designed to break away from the boat just before the force is great enough for it to cause damage to the hull that could result in a breach, otherwise the unit will not break away. Just running the boat aground or bumping some submerged object will not cause this unit to break off you must be in a situation where if the unit did not break off you would puncture the hull. I for one would much rather lose a lower drive unit than the entire boat and possibly my life if the boat sank as a result.

Let me give you an example of an actual incident that happened right in my back yard about a month ago. I live on the west coast of Florida where there have been a few Hurricanes’ so we have some sunk boats in our water ways that have not all yet been salvaged. A Tiara 4400 Sovran (with traditional Propulsion) happened to run over a submerged steel hull sail boat at an 18 Knot cruise.

All within a fraction of seconds and with the props still turning, the strut was pushed through the hull on impact while at the same time the turning propeller sawed its way through the hull bottom. With such a large hull breach the boat sunk in a matter of minuets and was totally destroyed the boats’ cost of replacement was 800,000 USD. I strongly believe that had this boat been outfitted with the IPS the out come would have been entirely different, the lower drive would have broken off clean with the hull, and since the boat was moving forward with the props facing forward on impact there would have been no contact of the props with hull. The boat would probably have made it with just the need to replace the Drive unit.

I have also been out on the new Tiara 4000 with the IPS system, and even ran aground while out. The area was unfamiliar and we ran up on a sand bar, the drives did not break off, in fact it felt just like running aground on any other boat only with one exception, because the drive skeg extended below the propellers there was no damage to the props, in fact there was no damage at all! We where pulled off the bar by a local tow boat and went on our way, we ran aground at 27 Knots.

 

[jfm]

Re: Lettem sink

Well said Rxtreme. There has been been much irrational worrying about hitting the bottom with IPS on these forums imho. IPS looks a very fine invention and Volvo deserve praise for it imho