On the rocks

kenmyfam

Supreme Mariner
Joined
Aug 10, 2006
Messages
14,392
Re: On the rocks

Let's hope he learns from the experience before he kills or injures someone.
 

kyle f

Chief Petty Officer
Joined
Sep 5, 2007
Messages
408
Re: On the rocks

Sorry to say, but no matter what he said... he didn't run that aground while under power.

There is no lower unit damage, props are ok, and both lower units are up in trailering position.

To me, it looks like he beached it and the water levels went down.
 

ShaneCarroll

Chief Petty Officer
Joined
Feb 10, 2009
Messages
639
Re: On the rocks

If he didn't run that aground under power, what happened to the windshield? There is broken glass all over the bow. Well, whether he was under power or not, that sucks. People need to limit themselves of drinking while on boats. I mean, a couple drinks is not that bad, just be responsible. This guy obviously had way too many. Then again, in the dark a completely sober person not familiar with those waters could have done the same thing.
 

TBarCYa

Senior Chief Petty Officer
Joined
Apr 13, 2005
Messages
781
Re: On the rocks

There's a valve in the hydraulics that allow the drives to push up if they strike something to prevent damage to the drives.
 

Aviator5

Chief Petty Officer
Joined
Feb 10, 2009
Messages
431
Re: On the rocks

It is technically impossible to transfer hydraulic fluid that fast to allow drives to come up at that speed.
 

45Auto

Commander
Joined
May 31, 2002
Messages
2,842
Re: On the rocks

You don't think someone could have raised the drives AFTER it had been run aground?? Looks like a pretty soft sandbar (no rocks), doubt if it would have damaged the hydraulics any.
 

GrindKore

Petty Officer 1st Class
Joined
Jun 20, 2008
Messages
211
Re: On the rocks

If you look closer, the skegs appear to be bent. So yes, I think the boat was under power and out-drives were raised after the fact.
 

TBarCYa

Senior Chief Petty Officer
Joined
Apr 13, 2005
Messages
781
Re: On the rocks

It is technically impossible to transfer hydraulic fluid that fast to allow drives to come up at that speed.

Tell that to my alpha1. I've bumped my share of logs while on plane and the drive moves.
 

rusirius

Petty Officer 2nd Class
Joined
Mar 17, 2009
Messages
109
Re: On the rocks

If that so, they would move when you put it in reverce.


Unless the designer / manufacturer was smart enough to think about this before making the boat and decided to disable it with reverse...

Nah... Probably not...:rolleyes:
 

Aviator5

Chief Petty Officer
Joined
Feb 10, 2009
Messages
431
Re: On the rocks

Desighner disabled it electrically, so you can't trim the drive while in reverse, but hydraulic circuit remains the same.
 

Pascal

Petty Officer 1st Class
Joined
Jul 9, 2002
Messages
252
Re: On the rocks

all it takes is a relief valve in the piston to let oil from the rod side back to the piston end of the cylinder. External force on the LU to raise it (like when hitting a log or sand bar) would increase the PSI in the rod side cavity and open the relief valve to let the LU move. It is designed to work that way and work only in one direction.

from the size of the cylinders it looks like it would take less about a pint of oil leaving the rod side to let the LU up all the way and from the looks of the leverage and piston area on the rod side, the instant psi could easy go to over 5000 psi when the leg takes a hit. it needs a path for the oil to go to limit the pressure and keep from breaking and bending things. It wouldn't be supported by oil after the impact and would need a shot of oil to hold it down again.

This exploded view of an alpha one trim cylinder shows what I'm talking about.....

http://www.sterndrive.info/alpha-one/trim_cylinder_layout.html
 

Pascal

Petty Officer 1st Class
Joined
Jul 9, 2002
Messages
252
Re: On the rocks

It is technically impossible to transfer hydraulic fluid that fast to allow drives to come up at that speed.

I guess you have never seen what happens when a hydraulic hose bursts on a raised but mechanically unsupported front end loader........

The oil quantities and the passage sizes are proportional between the two situations. A cup of oil transferred within each cylinder on the boat is enough to allow the out drive's to raise all the way.
 

Aviator5

Chief Petty Officer
Joined
Feb 10, 2009
Messages
431
Re: On the rocks

Than if you go from full forward to full reverse the drive should rise?
 

Pascal

Petty Officer 1st Class
Joined
Jul 9, 2002
Messages
252
Re: On the rocks

Than if you go from full forward to full reverse the drive should rise?

Forces acting in the assembly will dissipate through the path of least resistance. It takes less force to move the boat backwards and/or the force of the prop thrust pulling on the out drive in reverse is limited by the slip in the water so the PSi on the rod side of the cylinder will be less than the designed pressure setting of the shock/relief valve in the cylinder (edit) unless it has an outside mechanical force act on it like the sand bar or it strikes a submerged object while the boat is in motion.
 
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Aviator5

Chief Petty Officer
Joined
Feb 10, 2009
Messages
431
Re: On the rocks

Even if the rod side of cylinder was fully open, so the drive can swing back freely, I don't think it will save it from the impact, cosidering the mass and, therefore, inertia of the drive and speed of the boat.
It is a different story if the line bursts, from the normal operation when the fluid goes thru valves.
 
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