[Rhodes22-list] Quick turn instructions

Sat Jan 22 19:56:47 EST 2022

Hi Graham,

After > 44 years of marriage, I can personally attest that yelling at the 1st mate does not generally yield good results!

The beauty of this technique is that you can apply enough engine thrust to really spin the boat around in limited space and even against the wind &/or current.  But, even as you are turning, the boat is slowing down.  You finish the turn going slowly or nearly stopped vs traveling faster than you would be willing to hit the dock using other techniques.  Slow and controlled, lots of time to think - no reason to yell at the 1st mate.  Just warn her to hang on to something or sit down before starting the turn!

Roger Pihlaja
S/V Dynamic Equilibrium

Sent from my iPhone

> On Jan 22, 2022, at 3:20 PM, Graham Stewart <gstewart8 at cogeco.ca> wrote:
> 
> Thanks Roger. 
> 
> I can't wait now to try this  once I launch next Spring. I have little room to maneuver in my little harbor and rocks all around so I really only have one chance to get it right. 
> 
> While I must admit that I have not generally thought in terms of "thrust vectors and torque moment arms" I appreciate the explanation and at least for a fleeting moment thought I understood.
> 
> So far I have depended primarily on shouting at my wife to get into the slip without harm and while that seems to work it has its downsides as well. If I can master your instructions I am sure she will be appreciative as well.
> 
> Graham Stewart
> Agile, Rodes 22, 1976
> Kingston Ontario
> 
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> 
> -----Original Message-----
> From: Rhodes22-list [mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of ROGER PIHLAJA
> Sent: Saturday, January 22, 2022 1:34 PM
> To: The Rhodes 22 Email List
> Subject: Re: [Rhodes22-list] Quick turn instructions
> 
> 
> 
> Sent from my iPhone
> 
>> On Jan 22, 2022, at 12:03 PM, Graham Stewart <gstewart8 at cogeco.ca> wrote:
>> 
>> Roger:
>> 
>> I am trying to use your advice and translate it for my situation where the
>> dock would be on my port and I would tie up on my starboard side once in the
>> slip. 
> Because the boat is only going to side slip a little, for a starboard side tie up, you should start this maneuver about 1/3 boat length later vs a port side tie up.  This will put your starboard side rub rail close to the dock.
>> 
>> I have taken your instructions and stripped them down to the actual steps.
>> I have  added questions in square brackets where I am unsure about your
>> instructions. Would you please look at this and tell me if this sequence is
>> correct? 
>> 
>> Should I be assuming that when you refer to "yaw" you are referring to the
>> boat rotating in place without much forward movement?
> Yaw refers to rotation about the boat’s center of rotation when viewed from above.  Yawing to port implies a counterclockwise ( CCW ) rotation.
>> 
>> Dock on Port side as I approach
>> 
>> a.    Shift the motor into neutral and 
>> b.    turn the motor's tiller all the way the port. [as though I was
>> turning to starboard? Do I let the rudder tiller go free?]
> Yes. You should have your motor mount adjusted so the motor does not rotate when you let go of the motor tiller. 
> 
> It’s a little counter intuitive.  I find it easier to think in terms of thrust vectors and torque moment arms.  In reverse, the motor’s thrust is applied to the transom pushing backwards and sideways towards starboard.  The sideways component of the thrust acts thru the moment arm ( ~12 ft ) from the motor to the boat’s center of rotation to produce a CCW torque. 
> Torque = [Moment Arm]  * [Thrust]
> Because the [Moment Arm] is so long, a relatively small amount of thrust from our tiny outboards can produce a prodigious amount of torque.
> Because the motor is mounted off center, the reverse thrust component also has a small [Moment Arm] ( ~2 ft ) to the center of rotation to produce an additional CCW torque.  These 2 CCW torques are additive, thus making the boat yaw faster in the CCW direction.
>> 
>>   When your bow is even with the end of the finger pier, do the
>> following in quick succession.  
>> 
>> c.    Shift into reverse, apply full throttle, and 
>> d.    put the boat tiller hard over [as though to turn to port?]
>> e.    At about 45 deg of yaw, throttle the motor back to idle and then 
>> f.    shift into neutral.  
>> g.    Straighten out the outboard tiller and the boat tiller.
>> 
>> I will definitely practice this in open water before attempting it in my
>> very restricted docking area.
>> 
>> Thanks for this and any further explanation.
> 
> Because the motor is mounted off center to port on the transom, there is a noticeable difference in the maximum yaw rate ( ie deg yaw/sec ) that can be achieved in each direction.  When yawing to port ( CCW rotation ), the reverse thrust component aids the rotation, thus increasing the maximum yaw rate.  Conversely, when yawing to starboard ( CW rotation ), the reverse thrust component acts in opposition to the rotation, thus reducing the available torque and limiting the maximum yaw rate.  It’s not a huge difference.  But it’s noticeable enough that you should practice this maneuver in both directions.  In either direction, you can still spin your Rhodes around in either direction faster with this technique than any other.  It’s just slightly slower yawing to starboard vs port.
> 
> Hopefully this helps Graham.
> 
> Roger Pihlaja
> S/V Dynamic Equilibrium 
>> 
>> Graham Stewart
>> Agile, Rodes 22, 1976
>> Kingston Ontario
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> -----Original Message-----
>> From: Rhodes22-list [mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of
>> ROGER PIHLAJA
>> Sent: Friday, January 21, 2022 10:06 AM
>> To: The Rhodes 22 Email List
>> Subject: Re: [Rhodes22-list] Quick turn instructions
>> 
>> Bob & Jeff,
>> 
>> The fastest way to make your Rhodes 22 turn a corner under power does not
>> involve the tiller-outboard connecting linkage.
>> 
>> Assume you want to make a hard turn to port in the minimum possible area.
>> You setup by motoring along  slowly, say 2-3 knots, just enough speed to
>> maintain rudder steering control.  Put the desired slip about 1 boat length
>> away to port.  Assume you are going for a port side docking against a finger
>> pier.  Shift the motor into neutral and turn the motor's tiller all the way
>> the port.  When your bow is even with the end of the finger pier, do the
>> following in quick succession.  Shift into reverse, apply full throttle, and
>> put the boat tiller hard over.  Hang on to something!  The boat will yaw 90
>> deg to port in about 1 sec!  It will simultaneously slow down, side slip
>> about 1/3 boat length to starboard, and drift forward about ¾ boat length.
>> At about 45 deg of yaw, throttle the motor back to idle and then shift into
>> neutral.  Straighten out the outboard tiller and the boat tiller.  The
>> boat's rotational inertia will complete the 90 deg of yaw.  Note, the hull
>> and shoal draft keel produce a lot of drag vs. yawing.  The boat will use up
>> it's rotational inertia very quickly.  With a little bit of practice, you
>> will end up virtually stopped at the entrance to the slip, with your bow
>> pointed into the slip, and about 12 inches of clearance between your port
>> side rub rail and the pier.  Now shift into forward and idle into your slip.
>> For a starboard quick turn, simply turn the motor tiller to starboard before
>> shifting into reverse.
>> 
>> This technique is also very useful to force the bow to yaw into strong cross
>> wind &/or cross current.  It's also very useful for a stern to docking.
>> 
>> It's best to practice this maneuver in open water a few time before
>> attempting it in a crowded marina.  You will be impressed with how much
>> faster the boat will yaw when the motor is simultaneously applying sideways
>> and reverse thrust to the transom.  Obviously, the tiller-outboard
>> connecting linkage cannot be connected to execute this maneuver.
>> 
>> Try this technique, it will make you look like a docking genius!
>> 
>> Roger Pihlaja
>> S/V Dynamic Equilibrium
>> 
>> Sent from Mail<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgo.microsoft.com%2Ffwlink%2F%3FLinkId%3D550986&data=04%7C01%7C%7Ccd612eb57a4b499101d308d9dde4ab41%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637784796482119068%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=pH28wz9AZD7woR1buLRVEai0hSzuUDQA9cNdl3siEG8%3D&reserved=0> for Windows
>> 
>> From: Bob Garrant<mailto:bgarrant at gmail.com>
>> Sent: Friday, January 21, 2022 5:43 AM
>> To: The Rhodes 22 Email List<mailto:rhodes22-list at rhodes22.org>
>> Subject: Re: [Rhodes22-list] Tiller-Outboard Interconnect question
>> 
>> That's what I'm looking for. My slip is in a corner so i only have 90° To
>> maneuver in rather than 180°. So every little bit helps.
>> I appreciate all the guidance from those way more experienced than I am
>> with this vessel.
>> Bob
>> 
>>> On Fri, Jan 21, 2022 at 7:10 AM Jeff Smith Photo <jeffsmithphoto at gmail.com>
>>> wrote:
>>> 
>>> I use the connection to my Yamaha 8 only when approching the mooring or
>>> dock.  It enables me to make a tighter more controlled turn.
>>> 
>>> Best Regards
>>> Jeff Smith
>>> 
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> 