- Elements of Close Quarters Maneuvering, Part two
In this, the second article in the series on close quarters maneuvering, we will look at the shifter and its role in maneuvering the boat.
Neutral is the preferred gear
As mentioned in article one, 99 percent of the time our primary transmission position is always neutral. How we use the transmission depends on what kind of propulsion system our boat has and the adequacy of the rudder’s size, if there is a rudder at all.
There are two primary propulsion systems used in boats today, fixed and directed. Fixed thrust systems have the propeller in a fixed position. That is, the propeller is rotated on a shaft that is in a fixed position parallel to the centerline of the boat.
The boat relies on a rudder, usually mounted directly behind the propeller, which is turned via the helm. As the rudder passes through the water the water is deflected in the direction of the trailing edge of the rudder. If the rudder is straight (parallel to the boat’s centerline) the boat goes straight. If the rudder is turned to port then the water is deflected to port moving the stern of the boat to starboard.
When the stern pushes to starboard it rotates the bow to port and the boat turns in that direction. Rudder size is critical to how effective the rudder turns the boat. The boat only turns when water flows past the rudder. More water flow…more turn. Single or twin inboard boats including sailboats use this system.
In the other propulsion system, directed thrust, the propeller is rotated from the center-line toward one side or the other. Using this system, the boat is turned by the thrust of the water being directed in a certain direction. That thrust pushes the stern in the opposite direction from which the thrust is directed and that force rotates the bow opposite and the boat turns in the direction of the bow. Single and twin outboard, single or twin stern-drive, and jet drive boats use this type of propulsion system.
The practical difference between these two systems can be summed up as follows:
Directed thrust: The boat can only be turned when the transmission is in forward or reverse. With this system the turn is accomplished by water being trust in the direction the prop is facing. If the transmission is in neutral there is no steerage. Some outboards will have a slight amount of steerage from the water flowing past the lower-unit (the part of the motor that is submerged) but this steerage is minimal. In close quarters the helm must be turn in the desired direction BEFORE the transmission is engaged.
Fixed thrust: The boat can be turned anytime there is water passing by the rudder. Therefore, the transmission position is irrelevant to steerage; however forward or reverse momentum is necessary for the boat to turn. The propeller, when rotating in forward gear throws a constant stream of water directly at the rudder. So, even when the boat is stopped, if the transmission is engaged in forward, there will be immediate steerage. We will use this to our advantage especially on single engine inboard boats. The faster the water passes by the rudder the more steering control the boat will have.
A special note about inboard sailboats
While it is true with all boats that the primary transmission position is neutral, sailboats may require the use of some throttle when maneuvering in close quarters. Sailboats by design have a lot of lateral resistance (it keeps them from blowing sideways as they move forward). For more on this see my article ‘Blowin in the wind, how the wind impacts your boat’.
They are also equipped with relatively small engines, to reduce the weight and because it takes only a little power to move a sailboat, and small propellers to reduce the drag and because they have small engines. All of these things are admirable and desirable traits of sailboats.
They enhance the sailing performance. But they SUCK for close quarters maneuvering. Therefore, it may be necessary to add a little bit of throttle to get the same results as with other boats.
States of momentum
Boats are always in one of three states of momentum. They are building momentum, exhausting momentum, or have no momentum. Furthermore, we can exhaust the boat’s momentum in two ways, actively or passively.
When done actively, a manipulation of the boat’s controls is done, such as moving the shifter from forward to reverse, or turning the helm from starboard to port, or a combination of both. Passively exhausting the momentum is accomplished by using natural means.
For example, if the boat is in forward gear and then shifted to neutral, the drag of the hull in the water will dissipate the forward momentum. Like wise, if the boat is yawing (twisting) to starboard in forward, and the transmission is shifted to neutral the twisting momentum will be exhausted by the required force to move the boat through the water. Got it?
In close quarters maneuvering we really like to passively exhaust the boat’s momentum. The best way to assure that is to always keep the boat needing more momentum, never less. When maneuvering in close quarters, we accomplish that by keeping the boat in neutral most of the time and when in gear, at idle speed. Yes I know that’s not what you’ve witnessed when on the docks or observed when on boats, but it should be.
The slower the approach the better
When approaching a slip the boat should be in neutral, only adding forward or reverse to maintain steerage. For directed thrust boats that means shift into gear to steer and then shift back to neutral. At the slip, as the back and fill turn is made, between each step, pause in neutral and let the momentum nearly exhaust itself before shifting to the other gear. Make sure the helm is turned prior to engaging the transmission to minimize unwanted forward or reverse momentum and maximize the yaw (twisting, for the last time.)
When approaching a dock, side-to (like coming along side a fuel dock), the boat should be under steady power only while a considerable distance from the dock. As the boat approaches from either a thirty-degree angle shallow approach or ninety degree angle steep approach the boat should be in neutral. The goal is to be able to add forward as needed to keep control when close to the dock. If the boat is moving at idle speed the whole way we will build far too much forward momentum and have to exhaust it actively, and that can have unpredictable results.
For example, we are approaching the dock on a shallow approach for a port side-to tie up. All is great except that we are moving to fast because we stayed in idle forward on the approach. We are going to overshoot our target spot. So, what do we do? We add reverse as necessary to stop the boat. YEAH! But the prop walk that we forgot about now slams the stern of the boat into the dock pilings and bends the stern pulpit or breaks the rub-rail. BOO! Had we been in the proper mode of always needing to add more momentum we would not have overshot, would not have needed to add reverse with power, and been able to charter from the company again. Golf anyone?
When executing a steep angle approach to the dock minimal momentum is critical. I have two things to say here. One, never approach the dock faster than you are willing to hit it, and two, you don’t look like an a*&hole until you hit the dock. Slow and steady wins the race. When we are about five feet from the dock we want to shift into reverse and start our rotation. How we rotate is fodder for another article and will be coming soon, but for now we need to rotate. This will be accomplished by forward motion nearly stopping and sideways momentum (yaw) starting. Again, neutral is the gear to be in on this approach. Start the rotation by aiming the gun to which ever side you want to be next to the dock and clutching into reverse idle speed, FOR THREE SECONDS. Now, back to neutral and let the boat’s yawing momentum carry the boat to the dock. Drop the lines onto the pilings, hand out business cards, and make some beer money teaching others to do the same.
There are times in life that you want momentum. Close quarter on a boat isn’t one of them. Go practice, or better yet give me a call and we can work on it together. But for now, I’ve got to run; I hear there’s a boat for sale with only some broken rub-rail and scratches. Maybe I can get it cheap.
See you soon, On the Water…With Captain Frank