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Put throttle into reverse while going fast

Old 05-09-2019, 03:17 PM
  #141  
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I think you got it there. The, “it is impossible,“ line has been followed by plenty of opportunities to explain why, but no explanation has ever been forthcoming except, “only an idiot would believe that.“
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Old 05-09-2019, 03:59 PM
  #142  
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We might need a poll taken. Maybe some of the vote selections could read........


only idiots and liberals would believe it
could only happen if a unicorn was driving
water pumps work in three different directions (in out and boom)
Back splashing water mysteriously makes a connecting rod bend by getting it wet
could never happen south of the equator
all of the above
none of the above



(Where’s the sarcasm emoticon)





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Old 05-09-2019, 06:30 PM
  #143  
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My understanding of engines, is, they turn the vertical drive shaft in only one direction. It don't matter if the boat is going forward or backward, that vertical drive shaft is spinning in only one direction. When you shift, the shift lever slides the clutch dog from either the forward or the reverse gear and the prop shaft goes in the direction of the forward or reverse gear. The vertical drive shaft keeps spinning in the same direction.

My guess is, that when you are running at speed and you suddenly shift from forward to reverse, there is a momentary sudden violent stop of the vertical drive shaft...that energy is transferred to the wildly pounding pistons and the rods get eff'd. That sudden shock at the piston rods and rockers is like a bomb happening in the motor and water gets in the cylinders.

I can't see the engine suddenly changing rotation.

I can't see water back sucking up the prop exhaust...that exhaust is like a jet engine's exhaust in forward or reverse.

Too many people have had the backs of their boats swamped the motor and they didn't ingest water through the breather intakes.

I think most people lose their pinion gear, clutch dog or vertical drive shaft.....if none of those fail at the sudden shift, the engine takes the blow. People are calling it hydrolock because they find water where it ain't supposed to be.
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Old 05-09-2019, 06:48 PM
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Claim............................................. ......Don't give up your desk job.
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Old 05-09-2019, 07:01 PM
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Originally Posted by snagged line View Post
Claim............................................. ......Don't give up your desk job.




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Old 05-09-2019, 07:27 PM
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God I hope that most THT'rs do not vote.
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Old 05-09-2019, 07:47 PM
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Originally Posted by Claim View Post
My understanding of engines, is, they turn the vertical drive shaft in only one direction. It don't matter if the boat is going forward or backward, that vertical drive shaft is spinning in only one direction. When you shift, the shift lever slides the clutch dog from either the forward or the reverse gear and the prop shaft goes in the direction of the forward or reverse gear. The vertical drive shaft keeps spinning in the same direction.

My guess is, that when you are running at speed and you suddenly shift from forward to reverse, there is a momentary sudden violent stop of the vertical drive shaft...that energy is transferred to the wildly pounding pistons and the rods get eff'd. That sudden shock at the piston rods and rockers is like a bomb happening in the motor and water gets in the cylinders.

I can't see the engine suddenly changing rotation.

I can't see water back sucking up the prop exhaust...that exhaust is like a jet engine's exhaust in forward or reverse.

Too many people have had the backs of their boats swamped the motor and they didn't ingest water through the breather intakes.

I think most people lose their pinion gear, clutch dog or vertical drive shaft.....if none of those fail at the sudden shift, the engine takes the blow. People are calling it hydrolock because they find water where it ain't supposed to be.


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Old 05-09-2019, 08:50 PM
  #148  
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If there is no clutch etc and the prop is hard linked to the gears. You are zooming along using 200hp and you cut the engine off. You have say a 2:1 ratio gear box, so lets say the dragging prop only applies 100hp to the drive shaft (i know this is not technically accurate but you get the idea). You now have say 100hp trying to turn that engine. When you use your starter to start the engine it might be say a 1.5hp motor, but has mechanical advantage via the flywheel gearing etc. Maybe say 50:1.. So the starter applies 75hp to the crank and the dragging prop applies 100hp to the crank. Why wont the dragging prop turn the engine? Bang that engine into reverse and why won't it turn the other way? There should be enough force to make it turn. What did I calculate (significantly) wrong?
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Old 05-09-2019, 09:12 PM
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Originally Posted by Jeepman View Post
Just think of all the motors that have been destroyed when being towed in without fuel, or some other reason and by accident was left in gear and the prop was spinning and sucked in water...........
I bet it's similar to the number towed in at greater than hull speed.
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Old 05-09-2019, 09:15 PM
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Originally Posted by acme54321 View Post
Pashaw.....y'all flatter me.

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Old 05-10-2019, 04:27 AM
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The thing people don't realize is that the prop will freewheel with a ratcheting action if you are running at speed and suddenly shut off the ignition,no problem,the boat just comes to a stop.If you inadvertently shift to reverse at speed,that ratcheting action is reversed,the prop does not freewheel and the prop will turn the motor over backwards.It only takes a revolution or two to suck some water into the cylinders.Water does not compress like air.Hydrolock and bent rods or broken pistons are the result.
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Old 05-10-2019, 04:45 AM
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Originally Posted by staceylynn View Post



Two years ago I shifted from forward to reverse going about 30knots ..... I was trying to avoid hitting a large turtle. Both engines ( Yamaha F250’s ) hydroloc’d, port engine I broke a connecting rod that went through the block. Starboard engine restarted after 10minutes of cranking ( I assume that’s how long it took to get the water out of the cylinders) lost compression in all cylinders , went from 175-180 to all over the place. 65-120.
Fought with the insurance co for two year. Had to hire an attorney. Jerks started out with a settlement offer of $4000 for the one engine with a hole in the block and said the other engine was a maintenance issue. Two years later they paid me $26000 ...attorney fees where $2000

point do a compression check....if they aren’t hitting specs call your insurance agent.

Good luck!
So, you slammed your motors into reverse while going 30 knots and damaged your engines. Then called your insurance company??? Why is your insurance company on the hook for something you caused?
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Old 05-10-2019, 05:04 AM
  #153  
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Originally Posted by tacx View Post
So, you slammed your motors into reverse while going 30 knots and damaged your engines. Then called your insurance company??? Why is your insurance company on the hook for something you caused?
I was driving down the road at 30 mph and swerved to avoid a turtle. I hit a tree. Insurance does not apply since I caused it?
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Old 05-10-2019, 05:32 AM
  #154  
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Originally Posted by tacx View Post
So, you slammed your motors into reverse while going 30 knots and damaged your engines. Then called your insurance company??? Why is your insurance company on the hook for something you caused?
That's actually the definition of insurance, no? If it's someone else's fault you claim on their insurance. Insurance covers the at-fault party.
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Old 05-10-2019, 05:55 AM
  #155  
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Originally Posted by ukadrianj View Post
That's actually the definition of insurance, no? If it's someone else's fault you claim on their insurance. Insurance covers the at-fault party.
Then explain no fault insurance...
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Old 05-10-2019, 05:58 AM
  #156  
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Originally Posted by Claim View Post
My understanding of engines, is, they turn the vertical drive shaft in only one direction. It don't matter if the boat is going forward or backward, that vertical drive shaft is spinning in only one direction. When you shift, the shift lever slides the clutch dog from either the forward or the reverse gear and the prop shaft goes in the direction of the forward or reverse gear. The vertical drive shaft keeps spinning in the same direction.
I don't know why this is so hard for people to understand. Maybe it's the water part that's confusing? Think of a car: if you put it in forward gear then you go forward. Let's say the engine is spinning "+" and the transmission takes that straight through the driveshaft (it has the action of multiplying by direction by 1 = no change), so the wheels turn "+" and you go forward (also "+"). So, normal driving:
.
  • Forward motion: Engine +, transmission 1 = driveshaft +, wheels +, direction +
When you put it in reverse the transmission changes the direction of the driveshaft relative to the engine, so now it has the action "-1" meaning opposite direction, so now you get:
.
  • Reverse motion: Engine +, transmission -1 = driveshaft -, wheels -, direction -
Meaning you end up going in the "-" direction (backwards).

Now think about jump starting: you are basically reversing the energy flow - pushing the car to turn the wheels to make the engine spin. So, if you put a car in forward gear (transmission 1) and push it forwards you get:
.
  • Normal jump starting: direction +, wheels +, driveshaft + transmission 1 = engine +
Now put the car in reverse and push it forward, so it's the same but the transmission is now -1. What happens to the engine?
.
  • F'd up jump starting: direction +, wheels +, driveshaft +, transmission -1 = engine -
What? Engine "-"?!! Yes, it turns backwards. You put a -1 operator between the driveshaft and the engine (via the transmission) so now the engine HAS to spin the opposite direction from the driveshaft. Push a car forwards while in reverse gear, or backwards while in forwards gear, and the result is the same: the engine spins backwards.

Same for boats: just replace "wheels" with "prop". Put it in reverse and drag it forwards fast enough and the prop spins the engine backwards. Now your power head which used to be an air pump pulling air from the carb and pushing it out through the exhaust turns into a reverse air pump, pulling air through the exhaust and pushing it out through the carb.

But oh dear: that's not how boat exhausts work: they don't terminate in air but in water, so your power head is now a great big water pump pulling in sea water and trying to push it out the carbs. It doesn't need to spin many times to get a little water in the cylinder, and when you stop a boat and it swamps, there's a whole lot of water backed-up in the exhaust to get yanked into the cylinder - the engine barely has to purge any captured air in the exhaust before it primes itself. And how much does the engine have to turn? Not even a revolution: if you pull one piston down hard enough with a swamped exhaust full of water you might pull in a mouthful of water. And how much does it take to hydrolock one cylinder? Oh, about a mouthful.

So it's not so hard to believe, right?
.
  • Engines just run backwards if you force them against the transmission - that's mechanical
  • When running backwards an engine pulls whatever is in the exhaust into the engine
  • In a crash stop the exhaust swamps and so what's getting pulled in is water
  • The engine doesn't have to turn much to pull water in: just one down stroke of one cylinder
  • A small amount of water in one cylinder means a hydro locked engine. You don't need a ton of water in all cylinders after many revolutions of the engine: just a little water in one cylinder after a partial revolution.
Sow now does that seem so hard to believe? To me it sounds all but inevitable.
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Old 05-10-2019, 06:00 AM
  #157  
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Originally Posted by muskamoot View Post
Then explain no fault insurance...
Happy to: no fault insurance means that you (the insured) are covered regardless of fault. You screw up: you are covered. Someone else screws up and causes a loss to you: you are also covered.
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Old 05-10-2019, 09:05 AM
  #158  
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Originally Posted by muskamoot View Post
The thing people don't realize is that the prop will freewheel with a ratcheting action if you are running at speed and suddenly shut off the ignition,no problem,the boat just comes to a stop.If you inadvertently shift to reverse at speed,that ratcheting action is reversed,the prop does not freewheel and the prop will turn the motor over backwards.It only takes a revolution or two to suck some water into the cylinders.Water does not compress like air.Hydrolock and bent rods or broken pistons are the result.
It depends on your motor. My Merc 60 ratcheted when you turned the motor off in "forward". My F-70 doesn't.
That is why I say simply turning the engine off in gear may be as effective in slowing down at cruise speed as trying to put it in reverse.
The thing people miss is they assume the engine stalled. If it is still putting out 100 HP or so either the prop will cavitate or you will break something in the drive train. I am still not sure how you transit from forward to reverse without holding your finger on the lockout. It should stop in neutral and lock. Maybe we just need better trigger discipline. This isn't supposed to be like Lenny on Law and order with your finger on the trigger all the time
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Old 05-10-2019, 09:06 AM
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Though we don’t have it here in N.H, our neighbors in MA have it.

My understanding is no matter who’s to blame the costs related to an occurrence is split down the middle between both insured parties.


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Old 05-10-2019, 10:22 AM
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My fishing partner was turning 4500 when he hit a discarded net, unmarked. Engine shut down immediately in mid cycle. Two cylinders had exhaust valves stuck partially open. His wake caught up and forced water up the exhaust ports into the two cylinders. He needed a tow and a rebuild. That is a real world example I saw. Now i’ll Wait for the brain trust to tell me it couldn’t happen.
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