Vo70

Thanks guit, that was enlightening-still hope Paul and pull it together and that everybody stays fast and safe.

[D'ARTOIS]

I do not understand Russel Bowler's problem with the titanium rods. Of course he is right when he points at the chromed steel rods in modern earthmoving equipment - there titanium is not required and the heavy steel will do just fine.

In a racing yacht however, you will always try to get as minimal weight on board as possible as long as the weights are above the waterline and may influence the CG. In such a case you go for the lighter and stronger stuff - even if triple expensive.
If he is complainig that titanium is not strong enough I am afraid in that case that he doesn't know the metal and the large variety of metal alloys that are available (or not). The corrosion resistance of titanium is second to none of the engineering metals and the metal compositions can be made in such a way that tiatnium is 4 times stronger than stainless by dimension and with only 2/3 of the weight.
If they choose the wrong alloy-type, well that is their problem.

Although titanium is widely used in yachtbuilding, the alloy type that is used
is usually a common type. The special types are not to be found in the commercial market but must be procured through military channels. And than you get to the hot stuff.

[RHough]

Originally Posted by D'ARTOIS

If he is complainig that titanium is not strong enough I am afraid in that case that he doesn't know the metal and the large variety of metal alloys that are available (or not).

I read it as the method, not the material:

"Sailors are not content to use the chromed steel that is the usual
material for the pistons in the hydraulic equipment and demand lighter
materials, notably titanium. "It is not simply the difference in the
metal, but the way that some of these parts are machined," says Bowler,
"it is that that leaves a lot to be desired."

It sounds to me that he's saying that parts got hacked out of chunks of titanium. Poor machining can cause local stresses that make parts fail even if the engineering was good.

The engineer and designer get blamed when the true cause is poor craftsmanship on the shop floor.

[brian eiland]

Originally Posted by RHough

I read it as the method, not the material: It sounds to me that he's saying that parts got hacked out of chunks of titanium. Poor machining can cause local stresses that make parts fail even if the engineering was good....

I think Russell Bowler may be unfairly insinuating that the titanium rams are at fault. Correct me if I'm wrong, but aren't most the failures associated with the supporting structure(s)?

I do think he might be on to something with the idea that the double rams could have something to do with the problem, particularly if these powerful hydraulics were working at odds with one another on certain peak occassions.

[D'ARTOIS]

Somewhere I got to believe that in the VOR boats they use single rams instead of double rams. But that should be an advanatge, not drawback.

If Mr Bowler points to the machining of titanium, I agree with him. W/o the right equipment you cannot machine it. There are special toolings for machining tiitanium and surface treatments for the polishing, that can be done electrolitically or by diamond coating, to give it a superior qualification. I don't believe they have that kind of eqt in the US. Although I am not sure of that.

In any case I know where the problems are; 12 months for designing and buildng those boats is a bit short, to say it nicely. Maybe the 2nd generation will be better, although Mike Sanderson claims that they are strong enough compared by the open 60.

[RHough]

Originally Posted by brian eiland

I think Russell Bowler may be unfairly insinuating that the titanium rams are at fault. Correct me if I'm wrong, but aren't most the failures associated with the supporting structure(s)?

I do think he might be on to something with the idea that the double rams could have something to do with the problem, particularly if these powerful hydraulics were working at odds with one another on certain peak occassions.

A ram failure (as opposed to a ram to keel arm attaching part failure) would be a mistake in grade school arithmetic.

So far:
Movistar; hit something and the support bulkhead buckled.
Pirates; the doors sealing the pivot box failed.
Ericsson; "ram mechanism" failure on both legs.

As I read it, the rule requires two rams. Each capable of controlling the keel.

I don't know what the exact configuration looks like, but it would be easy to end up with a moment at the attachment point between the ram and the ballast pivot. The ram's rod is not likely to bend, the end fitting connecting the ram to the ballast pivot is a likely failure point.

[brian eiland]

Originally Posted by RHough

...I don't know what the exact configuration looks like, but it would be easy to end up with a moment at the attachment point between the ram and the ballast pivot. The ram's rod is not likely to bend, the end fitting connecting the ram to the ballast pivot is a likely failure point.

Courtesy of the Jan issue of the very excellent magazine Yachting World, who I feel would not object to using it in our discussion here ( I highly recommend this mag):

[Vega]

Those were not the only problems with the boats. There were also several structural failures, and one of them happened with only 15 knots of wind.

These boats are certainly stronger than the VOR 60's, but they are also 50% more powerful. It looks to me that the added strength doesn't match the added power. It is to be noted that, till this moment, only the Farr boats have had problems.

[D'ARTOIS]

I will show you here the Canting systems of 1: Mari Cha IV and 2: Genuine Risk; the picture is of the general system

(pitures from Cariboni, Italy)

[usa2]

Those photos are actually of the same boat's hydraulic rams- the 105 foot Kauris III. Mari Cha IV has a single ram, and that has worked well for her. The reason these boats have 2 rams (as required by the volvo rule) is redundancy. If one breaks, the other one can be used to center the keel and then they can pin it. Each ram is capable of moving the keel by itself. Having two rams means you cant accidently overextend one (unless the supporting structure breaks at the wrong moment).

[Vega]

After a lot of uninteresting movies, finally they have posted some entertaining ones.
Take a look at the way Cayard tacks his boat!!!!!


http://es.volvooceanrace.org/mediapl...0-0a603854fccd

http://es.volvooceanrace.org/mediapl...f-abff3ff8dd29

[asathor]

Has anyone calculated the all the forces on these things. It seems to me that as long as they are the seas would push, pull. rotate, twist, shove, suck, bend ..... etc. and not play nice and follow the planes during which the hydraulics strengths lie.

Maybe you have already covered this?

See:
2005ericsson10.jpg
Address:http://www.yachtsandyachting.com/pho...ericsson10.jpg Changed:3:57 AM on Thursday, December 1, 2005

[Shife]

Originally Posted by Vega

Those were not the only problems with the boats. There were also several structural failures, and one of them happened with only 15 knots of wind.

These boats are certainly stronger than the VOR 60's, but they are also 50% more powerful. It looks to me that the added strength doesn't match the added power. It is to be noted that, till this moment, only the Farr boats have had problems.

I think they're all built a little too thin. Remember the steering pedestal getting wiped out by a crewmember on ABN AMRO 1? The hole it left in the deck was pretty impressive.

[usa2]

The steering pedestal incident happened because on ABN AMRO 2 (the first boat built) the structure holding it into the deck was a lot more substantial, and on the second boat(built for the #1 team) someone decided that this was unneeded weight, so the supporting structure was not strong enough.