Question for experienced Cat drivers
 

After viewing the Outerlimits video it really shows the beginning of the blowover in detail.

I hope all is well with the men involved in the accident and that no more of these accidents happen the rest of the trials.and I don't want to seem cold hearted at all . I am not assuming by any means there was operating error.I am very familiar with how quickly a small quick change of wind can affect you much more when you are traveling at these speeds .

I assume that the beginning of any nose up condition is taken much more seriously than in a Vee bottom because of the increased lift.

It appears that there was about 1 and 1/2 seconds before the nose started to climb and the beginning of the flip began.

My question is can you feel this change in attitude quick enough to get out of the throttles and if you did chop the throttles would it make any difference once the boat has gotten beyond 20 to 30 degrees. It appears once past 30 degrees the flip progresses very quickly.

if any one takes offense to this thread mods please remove it.

you can definitely feel them start to rise (at least in my experience in smaller cats) but at that point and speed its no longer about reaction, its pure physics. When the nose starts to rise its not only being blow back (or slowed actually) by the increase in frontal area but the mass of everything in the bilge continues forward and kind of "flicks" the boat (for lack of a better term)

That makes total sense Dave I left out that part of the Equation of all the weight from the motors being the controlling inertia..when i was thinking about the flip.

I guess you have a 1/2 a second at best when the attitude changes 5 or 10 degrees to chop the throttles to save it?

Would chopping them at that early point make any difference ? Or even at that low level of attack is there simply to much air already in the tunnel that the drag of the decelerated props would have no effect?

Slamming the throttles forward, the torque pushes the bow down.
If a boat it running opened up and trimmed out with no throttle left, there is nothing left to do. If you pull back on the throttles you lose the torque that is pushing you forward and you kite.

never thought of it that way Gino.

So chopping the throttles will just speed up the climb of the bow and the drag of the props have no effect what soever.

Interesting this is why I am asking about cats from you guys that know and run em

Very informative conversation. Thanks for exposing aspects that might not have been considered.

from a fixed frame of reference it visually looks like the nose of a boat is being blown back but at the moment or point of no return in a moving frame of reference i think you'd find the nose of the boat is doing (for arguments sake) 165 and dropping while the stern comes underneath at say 175 with disproportionate deceleration.

just my .02 cents . . . .

Remember having that exact discussion with Brownie a few years back. Sure takes some serious practice and training to get yourself to do that...

Holy Crap I can barely wrap my head around what you are trying to describe Dave.

From here on out no more watching old Two and a Half Men reruns and start watching more Big Bang:D

[QUOTE=glassdave;4176587]

Dave modified your post so I could understand it a little clearer . Is this correct?


from a fixed frame of reference it visually looks like the nose of a boat is being blown back but at the moment or point of no return in a moving frame of reference i think you'd find the nose of the boat is doing 165 and slowing while the stern comes underneath at say 175 with
disproportionate deceleration.because the bulk of the inertia is contained in the stern of the boat.

Math (calc) and physics are actually a hobby of mine :cool: :D but yeah thats another way to put it. Mean 'ol mister gravity always wins though . . . .

So just to RESPLAIN dis to me LUCY

Explain it to me like I am a 6 year old

So once the nose is coming up it is well caught up in the motion of deceleration and no amount of chopping the throttles will make a difference because the drag of the outdrives and props slowing is far to little a braking action to have any effect over the weight and inertia of them and the stern of the boat.

In essence the whole boat is decelerating from the time the nose goes up a little, just the nose is decelerating a little quicker than the stern.

Thus it creates thee illusion that the boat is still under hard acceleration as the nose is continuing to rise.

Which the illusion of continued acceleration may not be an illusion after all because the throttle man may be making a last ditch effort to pour on the coals to get the nose back down.

Also correct?

Forget Big Bang , I am going back to watching Looney Toones:D

With our outboard tunnels, lifting or throttling back it the absolute worst thing a driver can do. When you start to get loose, driving the bow back down is your best chance, trim and throttle are your best friends.

I had a buddy down here in Florida years ago that had a old magnum tunnel with 235 that he was a wildman in. A few years later he bought a wood STV . I guess he had it up around a 100 and it started for the sky and he told me he got out of it quick and the boat slammed back down and pretty much disintegrated

That story always gave me the idea that chopping the throttle may slam you down but would prevent a blowover.

He admitted he was far to inexperienced to be driving it after he crashed it..

try holding a piece of plywood in the back of a truck and let the wind get under it at 50 mph...... now think about 12 pieces of plywood at 180 ...the lift is incredible so..... once down force is gone its a leaf in the wind


i come from a drag boat back ground and it dont take much to make things go wrong .....and it can go wrong real quick .


https://www.youtube.com/watch?v=TKN_0a_NSJA

Be back in 15 minutes gotta run and get some more beer killed the case i started on this morning.

See if the neighbor can drive me in my truck as i been drinkin , Just happen to have a piece of plywood too

Report right back:evilb:

Yea those things are absolutely NUTS.

May as well strap a Titan missile on your azz and hope for the best

how was ur trip ???? lol

Police pulled us over before we got out of the driveway.

I guess the site of a man wearing a childs life jacket with a Hello Kitty helmet on holding a piece of plywood over his head in the back of a picgup truk was suspect.

I call Bullchit. Thats Profiling:D

Anyways found the Rum:drink:

I think the plywood may have won!

Even in Naples thats suspect...

yea who woulda thunk I would stand out like that in this fine community of ours

T2x, I'll bite.
What nonsense. Do you suggest lifting with a ratcheting gearcase is a suitable solution to getting yourself out of a bad situation?

Started out good, thanks for the explanation of things from guys who have done it, I have never drove one and have no idea, only road on 3 in my life

I also think when you get off the throttles the props stop lift the back of the boat as that is what the cleaver props are doing lift the stern so that also make it worse together whit dave s explanation about the mass in the back want to pass the bow you get a disaster .

I like the idea of the spoiler/canard in the front! Most of the really fast tunnel hull jet boats run one!

its really pretty simple airplanes rotate on takeoff but do not flip do to aerodynamic controls a big flap on the nose that could deploy is a split second would stop the upward rotation of the nose or bow we do have the knowledge and technology to stop cats from blowing over period

unsolveable equation there.....

Sure you can make a 200 mph boat more stable, but then you will put more hp in it untill it again becomes unstable

because of the psychological factor. People like us like to be on the edge, if you move the edge farther away, we just go farther to find the edge. A few years ago 200 mph was the edge, Qatar is now knocking on 250. A few years ago a cat going over at 180 was unsurvivable, today they survived. canopies/safety cells have improved but that was 179 not 244.

That all depends on the setup and props. Some props provide stern lift while others provide bow lift.

I can't imagine they had much if any stick left to add additional power to force the bow back down. Looking at the video, it does appear it was trimmed up pretty high, being a Monday morning QB, probably too high. I'm sure it takes a lot of high speed cat experience to learn the feel of what's semi-safe and what's too much. Sadly at those speeds most never get a second chance to learn what 'too much' feels like. This is where having someone with vast amounts of high speed cat experience (like JT) in the boat is priceless.

Sadly all it takes today to get into a 180+ mph cat is a big wallet. Those speeds should be approached very slowly and with a lot of respect for the danger involved. Hopefully Mike makes a full recovery, but I'm sure he'll be a little less aggressive with the trim the next time those speeds are approached in a cat.

The simple fact is these boats have to run on the ragged edge to get the speeds. if you look at the Qatar run that boat is trimmed up also. At some point aero-dynamics take over and boat becomes a wing with no way to control it.

Wannabe

That's why I couldn't understand! I collect bear cans for a hobby!

We been running Cats for a while,decent speeds, when they get high trim down asap, chopping the throttles is worse.... tail drops
Heres the one time we got lucky, Pops a little generous on the up trim, luckily realized and sucked it back in. Little boat, Motion 36

https://www.youtube.com/watch?v=FsdjOdzw7QA

what a coincidence . . . . . i empty 'em for a hobby :drink: