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Author Topic: Scale Steering Courses Part 1  (Read 432 times)

GG

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Scale Steering Courses Part 1
« on: December 06, 2019, 05:12:10 PM »

The following is based on something written for my local club's newletter, but might be worthy of wider readership?


The idea was prompted after sailing two of my latest models.  Both were based on US Navy vessels built during WW2 and used single screw and rudder installations. After the usual few minutes checking their handling, I was sailing them in a most comfortable fashion, that is I just thought about what I wanted them to do and. with little if any further conscious effort from me, they did exactly that.  Only, one model was based on the Destroyer Escort warships whilst the other, based on an Aircraft Tender, was almost twice as long and much heavier.


Now, the size of such models does have a significant influence on their maneuvering qualities and yet I was never consciously allowing for this.  So, something in my brain must have been allowing for these differences without much input from me.  No doubt my family could make a few comments at this point!


After a little thought it came to me that this was just like riding a bike, driving a car and similar activities.  Once you have learnt how to do it properly it become "second nature" and you ought to be able carry out the routine actions without needing any conscious pre-planning but of course keeping a lookout for problems that might appear in the near furture .


This lead me to puzzle about what I must be subconsciously allowing for when sailing my models on steering courses.


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GG

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Re: Scale Steering Courses Part 2
« Reply #1 on: December 06, 2019, 05:25:28 PM »

The first thing I must have been allowing for was the difference in the models length.  It's not always appreciated that when turning a displacement hull that the stern swings out of the circle whilst the bows actually swing inwards, Fig 1.


This means that if you start to turn a model whilst it passing between a pair of buoys then, depending on the length of the model, tightness of the turn and buoy spacing, you could easily clout a buoy, Fig 2.


The answer is to try to sail clear of obstacle before attempting to turn.  But you are sometimes placed in the situation where you have to turn early, perhaps to line up with the next obstacle on a fiendish course designers layout?  In this case the best thing to do is sail as close as possible to the inner buoy so that the stern has more room to swing without an embarrassing collision, Fig 3.


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GG

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Re: Scale Steering Courses Part 3
« Reply #2 on: December 06, 2019, 05:49:27 PM »

The previous method works well with a simple pair of buoys but is less useful when faced with the common obstacle of having to "zig-zag" through a line of buoys.  In fact my small Destroyer Escort model could do this quite easily but the Aircraft Tender needs much more room.  The answer is shown in Fig 4, turn the model in the opposite direction on clearing the buoys to allow for the larger turning circle.


This also brings up another point, you should always try to pass through a pair of buoys squarely.  This gives you more clearance and allows for minor sailing errors or any disturbance to the model by wind and/or waves, Fig 5.


With a conventional set-up, that is the propellers and rudders at the stern, you can find yourself in difficulties when faced with turning around in a confined space.  The answer is to sail the bows up to the edge of the obstacle and leave yourself space behind the model.  This allows you room to go astern, when the model probably is less maneuverable, with more safety, Fig 6.


If you develop the trick of reversing the rudder just before the model stops moving astern and "blipping" just the right amount of full ahead, then the model can be made to rotate quite a bit without any significant forwards motion.  With such techniques it is possible to turn a model around in spaces not much larger than itself.


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GG

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Re: Scale Steering Courses Part 1
« Reply #3 on: December 06, 2019, 06:10:41 PM »

Winds might be considered as an enemy when trying to negotiate a steering course, but it is possible to use them to our advantage.  Take the last situation of turning inside an obstacle.  The wind is always going to try and move the model downwind so always start the maneuver by turning into the wind.  Now the wind is going to move the your model in the directions you want it to go, Fig 7.  This method can minimize the chance of the wind pushing the model firmly against the sides of the obstacle, maybe getting stuck there!


However, letting the wind push you into an obstacle can be handy if you have to stop alongside a "Dock".  Given a choice, always dock on the windward side and let the wind do the final part of the maneuver, Fig 8.


Another way to use the wind is when you have wind blowing parallel to the dock, Fig 9.  By using the rudder and propeller thrust to keep the model at a suitable angle to the wind you can sail it to the desired position.  If it's going to undershoot, then increase the power, overshooting then reduce the power, yes a bit like landing an aircraft but turned through 90 degrees!


So, please don't think that success on scale steering courses demands models with multiple props with independent control and a brace of side thrusters. Equally, small models might seem to be able to squeeze through the tightest of gaps more easily, but they can be more readily affected by winds and waves.  Much better to know what your model can do reliably.


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LJ Crew

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Re: Scale Steering Courses Part 1
« Reply #4 on: December 06, 2019, 09:15:25 PM »

Scale all this up a bit, 40ft. by 7ft. Very much the same thing happens. When we have a "novice" steering a narrow boat for the first time I find that the following helps. "Do you drive a car?" "Yes" "Do you reverse it?" "Umm" "Well this is just the same, this is the end you are steering. Get the sharp end where you want it and move the back end to follow it. Simple innit?"
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