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Old 07-29-2008, 05:46 PM   #21
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RE: Combined shift and throttle levers?

Like flying a plane, it's not at all complicated to do, but it can be difficult at first for a person to visualize WHAT to do. So the twist-your-butt, drive-the-bulldozer, visualize-parentheses analogies are easy ways to convey to an inexperienced boater what to do with the shifters to maneuver a twin-engine boat around.

You only have two choices in a single engine boat--- forward or backward. You have to know about propwalk and you have to know about rudder function and effectiveness but there's nothing fancy you can do with the shifter.

The butt-bulldozer-parentheses analogies work for a three-engine boat. I don't know what the skippers of triple engine boats today do but the skippers of PT boats in WWII usually had the motor mac in the engine room leave the center engine in neutral or shut it down altogether and they'd do all their close-in maneuvering on the two wing engines only. The drawback there was that the three props on a PT boat all turned the same way and the rudders were so tiny they were all but useless at low or no speed, so the boats didn't have nearly the maneuverability you get with a pair of counter-rotating props.

-- Edited by Marin at 19:53, 2008-07-29
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Old 07-29-2008, 06:26 PM   #22
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RE: Combined shift and throttle levers?

I simply choose to realize and understand the dynamics at work....
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Old 07-30-2008, 04:23 PM   #23
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RE: Combined shift and throttle levers?

Charles wrote: The way I learned was this: Think of the two shift levers as parenthesies as the force of the thrust is in the direction of the parenthesies.
( )

If you want the bow to move to the RIGHT then shift the LEFT engine into FORWARD.
If you want the stern to move to the RIGHT then shift the LEFT engine into REVERSE.

If you want the bow to move to the LEFT then shift the RIGHT engine into FORWARD.
If you want the stern to move to the LEFT then shift the RIGHT engien into REVERSE.

Then he wrote: The parenthesies model works the same on single or double handle installations and any number or engins.

My boat is missing the second shift lever for the parenthesis model to work the same. My single engine turns the back of the boat to starboard every time. If I rev the engine it turns faster, propwalk. So it can't be the same if I don't have two or more engines.

And as Marin points out the PT boats don't maneuver worth crap because of all the props being the same style. A number of the triple screw Chris Crafts were "modified" by taking out the middle engine when one of the outboard ones broke. They sometimes wound up with two engines turning the same direction also. So again the parenthesis maneuver doesn't always work .

So, if one can't learn to mentally translate the shift lever movement into what the boat is going to do accidents will happen. Especially when doing that backing up thing we all get stuck doing every so often. Maybe thinking parenthesis, etc. will help some moving forward. If the person who has to think bulldozer treads when moving forward needs to make a rapid decision in reverse I'm not going to bet that things will go well. It's the think time when a gust blows them out of line that seems to make the difference. Fortunately here in the PNW with no wind and tide that doesn't happen often.

Just my opinion, yours may vary.

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Old 07-30-2008, 07:38 PM   #24
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RE: Combined shift and throttle levers?

Ken--- I agree with everything you said except the think time when using an analogy like bulldozer treads. These analogies work because they elminate the time it takes to reason the situation through. You're simply substituting a process you're totally familar with for one you're not familiar with (yet).

When I was getting used to maneuvering our boat I didn't have to think bulldozer treads and then transfer this to the boat and then manipulate the shift levers accordingly. Maneuvering a bulldozer became automatic to me as a teenager and still is decades later even though I haven't run one since. It's not something I have to think about. So I simply treated the boat as a bulldozer in terms of how to use the shifters to move the back of the boat around or point it in the direction I wanted to go. It took something I didn't know how to do--- maneuver a boat--- and substituted an idential process than I did know how to do--- drive a bulldozer.

The whole thing doesn't work unless the operator is totally familiar with the analogy. I explained the bulldozer analogy to my wife when she was trying to learn to maneuver the boat and got a blank stare. An analogy like this doesn't work if you have to first think about how the analogy works and then think about how to apply it to the boat. But the "rotate your butt" idea was something she didn't have to think about.

Of course if one has any sort of aptitude for operating a boat at all it doesn't take much time before the analolgy is no longer needed. What to do with the boat's shift levers quickly becomes as much second nature as what to do with the clutch levers on a bulldozer (at least on the one I ran in the 1970s-- the new ones use joysticks). But analogies like bulldozers, parentheses, etc. can be very useful in helping a peson overcome their timidity and uncertainty of what to do with the shifters when they are new to twin-engine boats.
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