Vo70

The only time that a boat will launch harder downwind than upwind is when the boat becomes completely airborne off the top of a wave, a 70ft yacht will not do this at 20 knots of boatspeed, the 18ft skiffs are able to do this though they are only 18ft long. I will not dispute that these guys know how to drive a boat downwind (they have 2 of the best skiff sailors in the world as helmsmen).

Because of the difference in boat action (a boat sailing downwind has a tendency to sail nose down where a boat sailing upwind in rough conditions goes very high into the air at the top of a wave before crashing down) over the waves when going downwind compared to upwind there is substantially more load when crashing off big waves upwind, the boat has around twice as far to fall. There is a reason that we don't normally hear of boats breaking up due to pounding in downwind conditions, however when it is upwind conditions they tend to breakup (eg. Skandia and other boats in the Sydney to Hobart yacht race).

 

VO 70 will launch off waves at probably around 10 knots upwind in rough seas, if they are being pushed that hard. Sailors seem to throttle back quicker heading uphill because the unpleasant motion will tell them that the boat is being driven too hard. Downhill, the forces multiply but there are no warning signs until something gives. Sailors will continue pushing the boats at 20+ knots until something breaks. These things dont hit 20+ knots as peak speed, this is what they AVERAGE. It is very easy for them to launch off waves when they get powered up and go flying off at 30+ knots.

 

In order to fully launch (rudders out) which is what puts the excessive load on the boat they have to be doing well and truly in excess of 30, either that or they managed to find a freak wave going in the opposite direction to them (a very steep wave that was travelling upwind), in which case they could do some damage at a lesser speed.

Think about the speed that the boat needs to be doing to fully launch, you need to get 70ft of boat to continue going upwards until the stern of your boat has passed the wave crest, don't forget that during this time the waves are travelling in the same direction as you, so to launch off it you must be travelling at least the speed of the wave quicker than you would need to if it was a stationary wave, perhaps now you are able to see the launching difference between a boat sailing upwind and a boat sailing downwind?

Another way of looking at it, if you have 2 cars colliding, a head on collision has far more impact than 2 cars travelling in the same direction, when travelling in the same direction the speed required for the car behind has to be much higher for there to be anywhere near the same amount of damage as the head on collision (think of each wave as a collision).

 

Van, old buddy old pal... Until you have been out in those conditions, in that part of the world, at those speeds, I think it may be a little specious to posit the forces those boats are seeing and how easy it is to jump waves in them.
I will grant that the 70s seem to be breaking faster than the Open 60s ever have, but then they are a new class.
Be sure that the designers are not happy to see this, and will be thinking hard about why. This is not just some guy in a basement chanting "lighter is faster" to himself, this is a team of experienced folks putting together a boat at the limit of the rule (admittedly) with a great many years of design and engineering between them. In short, a design at the peak of the profession.
Steve

 

Perhaps Bruce Farr has been designing big slow boats for too long.

 

I think we all agree that the crews are a bunch of big kids that drive the boats faster until they break. So you have to design them unbreakable just like other kids toys. The only problem is to figure out the forces. What is the load on the keel when the boat lifts off a 5m wave at 30kn? Do you look into the ABS rules for that? ABS was written for metal structures and they just managed to come up with some rules for composites. I bet the boats are also engineered to a budget and although Mr. Farr has probably quite a bit of money he probably hasn't got enough to fund a major research project to figure out the loads on those boats in extreme conditions. With dodgy loads you can only design a dodgy boat and that's what we've got.

 

Disconnect

I don't agree that the sailors are just big kids pushing until they break something ; I think they are serious ,gutsy sailboat racers who want to win and who believe(d) in their boats!
Somewhere there is a disconnect-between the designer's,engineer's and/or the builder's ,perhaps, but I don't think much of the destruction in the last two or three years can be blamed on the sailors. Boats are simply breaking up; things that shouldn't fail are failing over a wide spectrum of ocean racing-multies and mono's. I've paid attention to these races for years and it seems like the last few years has seen a greater number of structural failures than ever before.
I find it hard to accept that, possibly, the potential performance has outstripped the ability to engineer/build boats that can be driven hard by experienced ,competent sailors-in fact, I just don't believe that. But there damn sure is a serious, life threatening disconnect somewhere.

 

I think you're close. What we're seeing may be what I think of as a tolerance stack. The designs are very close to the edge and small errors/deviations from the design may well put the final structure at risk. In the worst case it could be that normal production tolerances and material variation are big enough to make a design fail. Each part alone barely meets the design spec so a stack of minimum spec parts makes the system or assembly suspect.

I may well be that larger margins of error need to be allowed for in the designs.

Lets hope that the failures remain at the embarrassing level and don't get to the loss of life level.

A fire caused by a loose bolt in a battery compartment? That's just silly. What was a bolt doing loose inside a battery compartment? Who mounts a battery inside a conductive (carbon fibre) box? How much weight was saved over a $20 battery box from XYZ marine?

 

I do tend a bit to agree with Karsten. I was - some years ago, bosun on a large Admirals Cupper with 15 men on board. This was in '88 and in a particular strong gale - Bft 8 to 9 - the guys were still testing the boat till it's limits.
It is just like the F1 driver who is absolutely careless about the technical situation his car is in - as long as he can keep his speed and his time on the track - that's what count.

So - and let that be clear - there is some distance between the design team and the drive team.

It should be noted that the first actual big failure was the canting keel. Although lessons were learned in the meantime - the designers still could not cope with the tremendous powers that are liberated on a boat of the size of an open 70 at large in an ocean and 30 knots plus winds.

 

It looks that they are having too much problems in bad (not so bad, if they were not going so fast) but not extreme conditions. These boats should be designed to take more punishment without problems.
I have been in Sansenxo looking at the boats. They look fragile...


"13 November, Sunday morning: in the early hours the first inkling of a problem with one of the Volvo Open 70s became obvious when Paul Cayard’s Pirates of the Caribbean slowed. Then a report was called in to Race Headquarters, recounting they had what the team refers to as, "non-structural damage to the keel resulting in the boat suspending racing." The keel damage is apparently compromising the racing ability of the boat, though not its safety. Falmouth Coastguard MRCC has been informed that the boat was not in danger and was heading for Cascais in Portugal.

Two hours later another call to RHQ confirmed the position shown by the computer tracker that movistar had turned at right angles to the course and was heading towards the coast. The call informed RHQ that the boat had fractured a keel ram shelf, the support that carries the fixed end of one of the massive hydraulic rams that actuate the swinging keel. They were able to carry on sailing for a while, as the Volvo Open 70 rule insists that the keel can be worked with just one of the two rams for safety reasons and that was the situation. Shortly after the original incident, however, the boat reported further problems. This more serious damage caused Bouwe Bekking, movistar’s skipper to report, “The load on the one ram must have been huge, as the main bulkhead buckled badly. No other option than to head to port as it is not safe to carry on.

Chris Bedford, the Volvo Ocean Race met man gives the forecast for the area as follows: “Across the whole area of the fleet the wind will stay at its current levels of 30 to 35 knots from the north, though the Pirates alone, in their more northerly position, may experience some lightening of the wind for a couple of hours imminently. Then the wind will build, possibly reaching 40 knots, with gusts to 50. This will continue through the night until the early hours of Monday morning."

To add to the list of problems, ABN AMRO ONE has reported steering trouble during the night which has caused them to back off, resulting in their team mate ABM AMRO TWO storming away in the lead. .....

Talking to the crews aboard the Volvo Open 70s out in the Atlantic, the common thread running through their reports has been the violent motion and the bashing it gives body and boat.

Steve Hayles, navigator aboard Ericsson puts it succinctly in a typical British understatement, “It was pretty bumpy out there. It was always going to be very fast, but we knew we were reaching and these boats are a real handful in those conditions. ....

Aboard the leader ...ABM AMRO TWO, ...Simon Fisher, the navigator, summarises, “Broke nothing too major, we are largely in one piece. A couple of the bunks were blown out, we had some problems with the wet box for the generator; we were struck by lightning and trawled a spinnaker. We are managing to hold it together and keep the pace on without breaking anything too major, we’re in good shape.” “It was pretty scary the first night, certainly for those who stepped up to have a go on the wheel, water everywhere, couldn’t see much.”

ABN AMRO ONE’s skipper, Mike Sanderson painted the most lurid picture of what was going on, describing the port wheel pedestal being taken out by two crew members when the boat broached as a result of the attachment between the steering and the rudder breaking; and then having to cope with an electrical fire. "

 

I wonder if the problems with these boats are caused by the maximum weight rule?

Perhaps if the designers had more room to move then they could design structures suitable without the fear of the boat being overweight.

 

Mother Nature has not changed her rules. The designers have made the calculations as close to the edge as they dare. The only true uncontrolable variable is the people. Each year they should become more aggressive. That is what the owner is spending all the money for. The captains are expected to give 110%, and they do. Problem is, no boat can be designed to give 110%, and be bought. Owner would say it is overweight and not competitive. --------------------Go back to a cookie cutter class design. Lets put the beef in the boats so they can race again.-----------"How am I going to get a advantage over the other teams."-----------------Same way as now. Buy the best team.------------------ It is only money.------------------Right now a world wide opinion of the boats AND the owners compared to other classes that finish with NO or little damage in the same conditions should make them feel like a bunch of losers. --------------Which is exactly what is happening. --------------I know I cut to the bone, but this garbge has gone on long enough, with no end in site. --------------Time to change ,again.--------------------Next soapbox speaker.

 

Oh yes, 1 more item that needs to be changed. Get rid of any automatic course steering systems. If you want them that bad, we will leave the crews on shore for the races. ----------------------Who needs a human in anything that is automatic.

 

Apparently the damage on Movistar is caused by a collision with an UFO (unidentified floating object). Both the daggerboard and the rudderblade are damaged.

source: http://www.volvooceanrace.com/news/article/20051115/221005/index.aspx

and use an online translator.

 

I don't believe they are allowed in any class at the moment except for the 1 and 2-handed races. Certainly have never been allowed in the Volvo before AFAIK. Anyway, no autopilot is going to be as fast as a human.....
Steve