Thanks Dan,
It was a lot of years ago, I was young and somewhat inexperienced. When it was obvious that things were going wrong, there was not much time for adjustments. Had I reduced power early on, things would have played out for the better, I think that's the general agreement.
If a ship was approaching, moving upriver, there might not have been any room for adjusting the ship's position,(I don't remember to that extent). By the time the stern was moving close to his prop, the angle of the tow was great enough that there was no danger of contact and I just have to believe the full power thrust is what kept the stern from being pulled in by his prop suction.
I don't remember if in fact I might have reduced power, but the full power applied came at just the last few seconds.
Dan, I think your comment makes sense in every way and was easy for me to understand.
Thanks everyone for the comments.
Ron
--- In electricboats@yahoogroups.com, danbollinger <no_reply@...> wrote:
>
> I'll add my two cents in my way, but it is similar to what others are saying.
>
> Your title should have been: Water Movement Around TWO Hulls
>
> What happened is that you and the other boat created a very large venturi. When a fluid passes through a venturi its pressure drops relative to what is was before. So, both boats had less water pressure between them than on the other side. This difference applied a force moving both of you together.
>
> For safe passing, the passing ship needed to provide more distance between the hulls to reduce the pressure difference, or you needed to reduce throttle to reduce the energy creating the venturi forces. If I had found myself in this situation I would have backed down instead of increasing throttle, which only made matters worse.
>
> See the image at http://en.wikipedia.org/wiki/Venturi_effect Imagine that the purple pipe is really the Mississippi, and that the "necking" in the pipe is caused by your port side and his starboard side.
>
> For this reasons, refueling at sea is done at reduced throttle and a safe distance requiring heaving a messenger line, usually with a line gun.
>
> --- In electricboats@yahoogroups.com, "Ron" <rlgravel@> wrote:
> >
> > Wow!! so many different things and people that need a response. I have a question about something that happened years ago, knowing what happened and the outcome, I still am not sure what the really correct action should have been. The answer might be a help to anyone active in boating today.
> >
> > The situation took place on the Mississippi river just below New Orleans, I was at the wheel (rudder stick) of a 65' pushboat going downstream pushing two barges (end to end) the river bank on my right, the engines were set at 3/4 throttle. From behind, a freighter (running lite) is moving downstream at a much faster speed, his location seemed to be near the center of the river and as everyone should know it is pretty wide. Signals were made for the passing and as far as I knew everything was fine.
> >
> > As the ship gets closer I notice the space between us starts to narrow, but still no need for worry (so I thought), I give a little right rudder thinking of moving closer to the bank, in a very short time it is obvious the gap is closing (more right rudder). The bow of the ship now about even with me, things are changing fast, so I go to full throttle and hard right rudder, at just a few moments we are at mid ship and I know this is kicking my boat harder towards the ship, but I'm trying to get enough space to allow hard left rudder and not swing the barges into the side of the ship. At what I thought was the right moment (and maybe was) I go to full left rudder, at which point my boat is under the stern of the ship and 10 to 15 feet away from the ships propeller, which is chopping water at about 1/3 above surface. the last image I had of the ship pilot, was him leaning over the bridge rail as far as he could and a real look of concern was easy to see.
> >
> > It was a very close call and I survived as is obvious....the point in relating this event is to draw attention to the massive amount of water that moves, as Chris and a few others have commented, in relation to a hull of any size.
> > The surface in some cases seems to move forward with the vessel while a large amount under water and not visible is being pushed away, which in my mind forms something like a vortice or contrail behind the wing of an airplane. As it seems in my mind, my boat and barges started riding the top of that swirling cone shaped body of water and at some point started being floated or sucked toward the ship.
> >
> > Even in a river as large as the Mississippi, if you are close to the bank you can see water fall and rise as a ship approaches and passes.
> >
> > Other than more space, does anyone have anything to suggest or make comment on that would help someone else keep from falling into a possible similar situation ?
> >
> > Ron
> >
>
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