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View Full Version : Going into reverse with forwad motion??



RickSE
09-02-2005, 01:34 PM
So what will happen if I throw a Bravo-1 in reverse with forward motion, 30-40 MPH? I'd have to think it would not be good.

Broken parts and maybe water over the back of the boat??

I ask this because last Friday while driving on Powell I turned into an area that looked good on depth. I was running 65MPH about 300 yards off the shore when the water started changing color fast. There was a huge underwater land mass with no where to go so I slowed down, pulled the drive up, kept moving and prayed. Needless to say we made it across without hitting anything but it scared the crap out of me. My depth alarm is set at 3' and went off as we passed over the mass. The thought of stopping the boat went through my head but on a quick judgment I decided to keep moving ahead and trim up. I'm lucky and it could have been ugly since Powell is pretty much all rock with very little sand. This is not the first time this has happened and I need to come up with a game plan if it happens again. Just not sure if I can stop the boat from 60 quick enough.

BTW, I’ve had friends rip out drives completely off their boats at Powell. One was lucky and the input shaft sheared, staying in the gimbal bearing and plugging what could have been a big hole in the back of the boat.

Here's an aerial picture of the butte I ran across, circled in red, which is now under 3' of water.

Despite the scare we had a blast on Powell. This was a quick day trip with my wife and her friend. The girls had a blast since we had no kids along and kept the throttle down. Coming back in we ran close to 50 miles straight at 60-70MPH. What a blast. We were passing people in rough water like they were sittin still and had people on top of house boats cheering us on. This comment from my wife's friend sums it all up and is really what these boats are about.

"I am kinda of an Adrenalin junkie, so going fast on the boat w/the sun on my face, my hair flying, ass lifting a foot off the seat was just what I needed. Soul food."

Everytime they came off the seat in the back I'd hear all kinds of comments and laughing. Sure wish I could ride in the back once in a while. :rolleyes: Time to teach the wife how to drive.

Formula Jr
09-02-2005, 02:07 PM
Powell is unique in its underwater terrian. And its near impossible to follow the old rivers by eye balling it. I had a topo map of the lake while I was there so I could at least have some idea of where the under water hill tops were. As you know thats why the locals drop anchored little milk jugs over the hazards. The only safe way to run Powell fast would be to GPS out your route.

Jamesbon
09-02-2005, 04:45 PM
There's a guy at our marina who has a 29 Formula with twin BBC's, Bravo's and Gaffrig twin stick throttles. At 3500 rpm's and in a panic, he accidently pulled back the shifters into neutral instead of the throttles, heard the engines over rev and slammed them back into gear. He tore up all kinds of stuff in the drives. I'm not exactly sure what he broke, but it cost his insurance company something like 5-6k to fix.

It's a hard call, but sounds like you did the right thing. I've been there before in the Rabco, flying across a shortcut I know in the flats and all of a sudden it looks like it's a foot deep, I immediately start jacking up the trim and jack plate and hope for the best, so far, I've been lucky.

What a beautiful place you have there, Rick. Someday, I'd love to camp out there with my Donzi for a few days....

joseph m. hahnl
09-04-2005, 06:18 PM
[QUOTE=RickSE]So what will happen if I throw a Bravo-1 in reverse with forward motion, 30-40 MPH? I'd have to think it would not be good.

Broken parts and maybe water over the back of the boat??

nothing would happen to the drive as long as it was throttled down.
it's not a car and just because the hull is moving doesn't mean the prop is turning at 40mph. as far as water goes you might get a little no more than when you come off plane. so if you ever have the need to full reverse. you can do it at any time as long as the motor is not at full rpm .single shifter with forward reverse and throttle>


joe

kkriina
09-04-2005, 06:39 PM
You did everything right....You turn off the engines when you skimmed over them?


Since you were traveling at a high rate of speed your boat could easily flipped over if you just shifted into reverse at 65mph. If you are in unknown waters it is best to slow down until you know the area. When i am going idle speed into a marina that im unfimilar with i always trim the drive up just a bit. Or i fallow someone in first, just cause there boat is bigger doesnt mean they use more water. Some 30's use only 3' of water while my 20' monterey uses 3'6" :S




One time, i even called the marina and told them i have never entered in there by boat and was concerned with the bouys and how accurate they are because, when i looked over board i could see large rocks hiding in weeds. So they insured me where to stay and when to make tight turns etc.... But experience does count.


It is better for the hull to hit then the engine because, traveling at 60mph you will most likely get big air and land on the hull rather then leaving your drive down and catch a rock and flip you over.


Sometimes i get so anal, i stop the boat turn off the engine and i will actually swim the boat closer to the beach rather then take a chance.... I guess i just love my baby to much HAHAHAHA. i then anchor and injoy my dad knowing that i will not do damage to anything.

txtaz
09-04-2005, 07:50 PM
[QUOTE=RickSE]
nothing would happen to the drive as long as it was throttled down.
it's not a car and just because the hull is moving doesn't mean the prop is turning at 40mph. as far as water goes you might get a little no more than when you come off plane. so if you ever have the need to full reverse. you can do it at any time as long as the motor is not at full rpm .single shifter with forward reverse and throttle>


joe
I disagree, some of the board members have ripped gears apart going into reverse at speed. I don't appreciate bad advice being given on the board. If you don't know, don't guess.
Wes

JPR
09-04-2005, 07:59 PM
The only way to crash stop full throttle to full reverse is with a variable pitch propeller running on a HUGE driveshaft. If you are not a Navy ship or commercial supply boat, I doubt that is what you have. shut down, drive up, pucker up and hold on!!

joseph m. hahnl
09-05-2005, 09:22 AM
[QUOTE=joseph m. hahnl]
I disagree, some of the board members have ripped gears apart going into reverse at speed. I don't appreciate bad advice being given on the board. If you don't know, don't guess.
Wes


wes: don't get all riled up it is not bad advise. if you under stood how a propellor and out drive actually worked . as i said IT IS NOT A CAR. it has hardly any residual motion on the prop. if you were going to crash into someone or something you had better put it in reverse. . if hitting ground nuetral is allways the best option.
most likely :as in the statement prior he put it in gear with the throttle open.



kkrina: the last thing you want to do is smack the hull it's fiberglass and splinters. ask the guy in the 22 who hit the rock. oh sorry he's dead. killed instantly when the boat split in two.


it sound to me as if there are a lot of dangerous people commenting here .and may be some of you should take a saftey's boaters course.


joe

Mercrewser
09-05-2005, 10:13 AM
I would think if the drive survived going into reverse at speed, with the engine idle, the excessive hydro forces on the propeller would reverse the engine hydrolocking it. Older Volvo pentas had warnings about this in their operating instructions.

There is tons of residual motion, force on the propeller. The hardest thing to do when you have a power failure in an airplane is to slow it down enough to stop the windmilling propeller (which is turning the engine!). This has to be done to reduce drag for a better glide ratio, unless you think you can get the engine running again. This is in air, which is how many times less dense than water?

txtaz
09-05-2005, 10:43 AM
Joe, I'm with Poodle on this one. Go try it and let us know how it worked out for you. The last time I had an outdrive worked on, it was $1600 for a prop shaft, skeg and some prop work. So it's a gamble, but theory to practice is always the best way to "prove" a theory.
Ohh and after 35 years of boating I have a pretty good idea of how an outdrive works.
As far as the notion of "residual motion" on the prop, stick your hand in 40Mph water and let me know how much force is exerted on it. Then imagine your the little drive shaft trying to hold back 3 times that force (3 blades) while the engine, with it's rotating mass, wants you to do even more.
Wes
P.S. If your about to hit something, you shouldn't have been driving the boat in the first place. Prevention is the best medicine. Always be prepared on the water.

joseph m. hahnl
09-05-2005, 01:23 PM
i don't want to argue with you guys about this. and so i will let your argument stand. i don't like nikes so i'm not going to go out and just do it. but in an emergency situation it is the duty and the law that the pilot is to take any means to overt a collision . this means any obstruction. and if your that great of a boater that nothing gets buy you.then my hats off too you. smooth sailing.
but i personally would chance loosing my out drive than the cause of some one loosing there life. "especially my own"

enough said. i'm going back to my corner for a drink of water and wait for the bell to start the next round> ding ding:rlol:


joe

kkriina
09-05-2005, 11:36 PM
i don't want to argue with you guys about this. and so i will let your argument stand. i don't like nikes so i'm not going to go out and just do it. but in an emergency situation it is the duty and the law that the pilot is to take any means to overt a collision . this means any obstruction. and if your that great of a boater that nothing gets buy you.then my hats off too you. smooth sailing.
but i personally would chance loosing my out drive than the cause of some one loosing there life. "especially my own"

enough said. i'm going back to my corner for a drink of water and wait for the bell to start the next round> ding ding:rlol:


joe




Ok say that everything did hold up(lets pretend)




Speed= 65mph?
weight=8,000lbs? Not sure what boat you were in, but considering you were offshore i would have to say a 26'+


Do you get where im going with this?


Even if he did manage to get it in reverse the bow of the boat will sink and since the boat is going 65mph it will probably still hit the rocks anyway and probably make it worse because now the the hull and the drive will hit....


So now only did he/she lose there whole boat, now there were ejected from the boat maybe about 20-30feet in the air. At this time there are probably still travelling at 45mph or so and of course they are wearing a life jacket RIGHT! They will still end up under the water because of the body mass and velocity, lets not forget the rocks for all this sudden reaction!!! So now they come down and land on the rocks that were 4' below the surface.



When you are traveling at 45mph stick your hand overboard and feel the pressure of the water hitting your hand, now imagine your back snapping in multiple places....Now do this at 65mph CRAZY EH!


Thats why when you see a boat crash it just goes in peices.....





Thats like saying:



Your in the middle of winter and hit some ice and think throwing it in reverse will make you stop....It will make it worse, causing your vehicle to be off balance with the mass in the back behind transfered forward and then all of a sudden your going backwords...

joseph m. hahnl
09-06-2005, 05:30 PM
as i said i don't wont to argue the point! and i will agree with, when and only when the prop goes into neutral it will have risidual motion > i stand corrected. and i would'nt doubt master poodle in his wisdom . as he has allways steared me in the right direction.

BUT! i don't have one of those magical donzi's that can maintain 65 mph with out the throttle.as a matter of fact my minx at 58mph i would say it takes no more than .05 seconds to come off plane and be at roughly head way speed." and i won't mind timing it to give you the actual amount of time it takes"
for another thing
as you know it's a jack shaft and when in forward the prop turns what the engine spin no if ands or buts. so at 750 rpm "idle"the prop 1 to 1.5 you seem so good at math you figure it out. i would tend to doubt the bow would go under water as my minx stands straight up in the air coming off plane.

and as you so kindly pointed out about being ejected. that wouldn't of happen if he had slammed into the ground any way right.

oh and it is nothing like slaming it into reverse on ice. it's more like slamming the brakes on rail road tracks and and backing up so the train comming doesn't run you over.

and if it makes every one feel better i agree that rick did the right thing
i too have come into the shallows put the boat in neutral and put my tilt up . and no never at that speed but i generally familiarize my self of the waters i am traveling before i put the hammer down.



thank you please come again whatch your step upon leaving no pictures please:party:

ok now i'm way out of control!!!!! so once again i'll shut up and to leave it at this your all right i'm sorry i didn't know anything about anything.
dam i'm so stupid what was i thinking. man were's my coffee. :shocking:

joe



joe

txtaz
09-06-2005, 05:52 PM
man were's my coffee. :shocking:

joe
Joe, may I recommend a good decaf??? Heheheh, Just teasing ya.
Wes

RickSE
09-06-2005, 06:12 PM
Thanks guys.

Powell has been a tough place to navigate lately. The lake was down 145' in April but picked up 50' over the summer. The main channel is pretty well marked but once you’re off the main channel all bets are off and you're on your own. I have most areas committed to memory but it's been a while since I've been up. That along with the 50' water change threw me for a loop on this one. It's certainly in the memory now, but I'm worried about the next one.

The plan is to have a Garmin GPS plotter w/topo maps by next season. One more trip this weekend and I believe this season is done. :frown:

blackhawk
09-06-2005, 06:50 PM
BUT! i don't have one of those magical donzi's that can maintain 65 mph with out the throttle.as a matter of fact my minx at 58mph i would say it takes no more than .05 seconds to come off plane and be at roughly head way speed." and i won't mind timing it to give you the actual amount of time it takes"

I don't want to jump on you like everyone else here but that statement is crazy! You're saying your boat can go from 58 mph to off plane in .05 seconds? I'd say if you can you indeed have a magical boat!

Offshore racing throttlemen not only let off the throttle in mid air but they also try to maintain the correct prop speed to maintain the current boat speed. In other words, they don't just slam them back, they try to pull them back to the correct position so the props aren't spinning too fast OR TOO SLOW upon re-entry. This is obviously for performance but it is also to not grenade the drive. A prop spinning too slowly is also hard on a drive upon re-entry.

So imagine what would happen going from 65 mph to reverse! My guess is BOOM!!!

joseph m. hahnl
09-06-2005, 07:39 PM
I don't want to jump on you like everyone else here but that statement is crazy! Your saying your boat can go from 58 mph to off plane in .05 seconds? I'd say if you can you indeed have a magical boat!

Offshore racing throttlemen not only let off the throttle in mid air but they also try to maintain the correct prop speed to maintain the current boat speed. In other words, they don't just slam them back, they try to pull them back to the correct position so the props aren't spinning too fast OR TOO SLOW upon re-entry. This is obviously for performance but it is also to not grenade the drive. A prop spinning too slowly is also hard on a drive upon re-entry.

So imagine what would happen going from 65 mph to reverse! My guess is BOOM!!!




yes ! i would think it would be to keep from over reving the motors too.

well yes it is! i sprinkle magic dust all over it and it can defiy gravity. it wasn't crazzy just exaduration. but yah she'll sink down in about 5 seconds flat and i asked my girl and she would say yes 5 seconds pretty quick. so my point is your not going 65 miles per hour at shut down. full shut down is enough to eject a person not seated properly in the boat would you agree. and i know this to be true at half throttle. so your not actually going 65. and i never ever said at any time you could throw it inrevese at 65 mph. what i said was if you throttled back you could put it into reverse. if a boat could maintain the speeds your talking about for any cosiderable distance with out power you wouldn't need a v8 . i could go on for hours and i know none of you will ever understand what i mean."no comprenda" i've been driving boats since i was 8 rs old. and all i can say you drive your way i'll drive mine. think what you want i'll think what i want.

so in conclusion here is the question that you should all ask your selves what is the speed that i feel is safe for me to put my boat in reverse to prevent a collision. and you better think pretty soon cause you never now when jet ski boy might pull his crap in front of you.

JPR
09-06-2005, 10:07 PM
okay, one other little thing. If it is a shallow water thing, you draw the least amount of water at full chat, trimmed out...so maybe you should stay on the throttle and hope...?

Lenny
09-06-2005, 11:46 PM
Rick, Deneen and I want to come down in the X boat and camp for a few. I would LOVE to run that place.

So long as it is HOT and SUNNY :D

(P.S.) I need a Bravo anyway ;)

RickSE
09-07-2005, 12:48 PM
Lenny & Deneen,
Come on down. I'd certainly meet you there. It's an awesome lake with so many places to explore. Typical season is May-Sept but can be pushed to April-October. Late summer is the best with warm water and cooler air temps. Two weeks ago there was not a cloud in the sky, 80 deg. water and air temps in the mid 90's. We ran over 100 miles in one day. Let me know if you’re coming down. Bring Blueliner and Thriller with you.

Trim up and keep moving is a good option, but it still depends on the situation. In this case I had slowed to about 35-40 by the time I passed over the hazard. This unfortunately dropped me down deeper in the water but I certainly don't want to hit something at a high rate of speed. It's pretty easy to see underwater stuff on Powell until the sun and waves cover up the obvious signs. Again a GPS should help.

joseph m. hahnl
09-07-2005, 07:42 PM
rick. things are pretty shallow up here too. the lake i run is about a foot shallower than normal. a a few people smacked their props off . i was driving by the souhegan river wich at times has some pretty serious rapids. it looked about a foot deep by 2 ft wide like you could jump across it.

joe

BaldEagle
09-07-2005, 08:00 PM
Very interesting theories and comments. My first thought was why be flying into an unknown. In the manual from my cruiser with inboard twin Cat TA diesels, it says in an emergengy to avoid collision, the shifters can be reversed while at cruising rpm. It doesn't say the gear will still be in one piece afterward. In my own case I don't go into the proverbial unchartered waters without caution. A lot of the time I'm not the only one in the boat.

I'll match my craziness/safety record with anyone out there but calculated risk is not the same as blind risk. If I am going 65 in my 18C and I am faced with a decision of going into the rocks or reversing thrust, theres a good chance I'm gonna lose. If nothing else I like my boat too much to do that.
BE

RickSE
09-12-2005, 10:21 PM
Got an email this morning from a buddy on the lake. He said a 50' houseboat ran aground this weekend on the same spot I crossed. Said it took 3 tow boats to get the boat off the rocks. See I'm not the only one. This spot is right in the middle of a huge bay that is bigger than most lakes. There will be others hitting it if the National Parks doesn't mark it soon.

goatee
09-13-2005, 12:20 AM
i have done it, (full reverse from full forward)
but only i was in a jet boat. get this................

guy was sitting in the front with his back to me. handle on either side ,(was holding both)

ever see wile E coyote go through a wall? his shape torn through that same wall?
ok, same thing... i watched a literal "wall" of water come from behind this guy.
(towards me) hit him,,, and leave his imprint, (head, arms,neck, torso, you name it) as it crashed down on all of us.
yes we were bailing after that.

but it was so fun!!!!!

Ramman
09-13-2005, 02:23 AM
Ok i can answer all your questions and comments. I had a guy on a damn waverunner hit me a few weeks ago, I was at WOT around 60 mph and he broad sided me and got sucked under the front of the boat when I let off the gas. I had no option or choices but to throw the boat in reverse at about 25-30 mph, I would have ran him clean over if I had not. Boat was in neutral and coasting to a stop at 25-30 mph and I threw it in reverse at idle, the boats fine. I drove it home after the incident and have used it twice afterwards. Yes the front end did come down alot, but no water entered. The bravo drives are tough pieces of machinery, used be surprised what they can take. Now Im not saying that at 65 mph u can throw a boat in reverse, ud be dead the boat would run you over.

RickSE
09-13-2005, 12:12 PM
Randy, Your situation sounds a lot like mine. By the time I had to make a decision I had slowed to the 30-40 MPH range. Sounds like you were able to put the brakes on pretty quick and get the boat stopped or at least significantly slowed down.

Team Hula Girl
09-19-2005, 08:38 PM
Does anybody care about what would happen when you have outboards instead of I/O's? Especially the new Verados?

J Mitchell