[Rhodes22-list] Combination Of Sharp Turn To Port + Single Handed Docking

[Roger Pihlaja]

David,

I pasted your questions in below & added my comments:

"Interestingly, much larger sailboats in the larger slips opposite me (the
ones I back toward as I back out of my slip) seem to have no problem, at
least when I seen them come and go on normal days.  One skipper with two
small sons repeatedly brings his 35-foot sailboat to a dead stop centered in
his slip with no lines whatsoever.  The only differences I can see are:"

"(i)they are headed towards a larger opening"

The degree of difficulty (DoD) of entering a given slip can be thought of in
terms of the ratio of the
slip width/max boat beam.  If your slip is only 10' wide & your R-22 has an
8' beam; then, your
DoD = 10/8 = 1.25   That 35' LOA sailboat probably has a 12' beam.  If his
slip is 50% wider than yours,
or 15'; then your friend faces a challenge of: DoD = 15/12 = 1.25 or
proportionately the same as you.  On the Great Lakes, where boats tend to be
larger, slips in recreational marinas are rarely more than 20' wide.  I know
this max slip dimension from sailing on my friend's 42' sailing catamaran,
which has a 23' beam - we anchor out a lot.  But, on a small inland lake
like yours, a 15' wide slip wouldn't surprise me, especially if the rest of
the marina is laid out small & cramped as per your description.

"(ii) they are turning to starboard, if that makes any difference--is that
what people talk about when they refer
to a right-hand prop?"

Prop side thrust or "prop walk" is caused because the prop is operating in
water that is less dense on the top of the prop vs. the bottom of the prop
because of the weight of the water above the prop. A right handed prop has
the blades arranged such that; when viewed from astern, the prop rotates
clockwise when generating forward thrust.  The density difference of the
water across the vertical diameter of the prop causes a side thrust to be
created.  In the case of a right handed prop, this side thrust is directed
to starboard.  A side thrust to starboard at the stern of the boat causes
the stern of the boat to be pushed to starboard.  Pushing the stern to
starboard causes the boat to rotate about its CR in a counterclockwise
direction - in other words it turns to port.  Large diameter, slow turning
props tend to produce proportionately more side thrust vs. small diameter,
fast turning props.  For a left handed prop, all of the above arguments are
reversed.  In reverse gear, the right handed prop turns counterclockwise,
the stern of the boat is pushed to port, & the boat tends to turn to
starboard.

"(iii) their prop is inboard and at the centerline of their boat, giving
better steering control."

On an R-22, having the prop mounted to port of the boat's centerline
generates a torque about the CR in forward gear that tends to rotate the
boat in a clockwise direction.  In other words, in forward gear, the port
offset location of the prop tends to make the boat turn to starboard.  In
reverse gear, the offset thrust tends to make the boat turn to port.  Note
that this has nothing to do with whether the prop is right handed or left
handed.  This phenomenon is simply a side-effect of mounting the prop off
the boat's centerline.

So why is it so hard to turn sharply to port with a strong wind from astern?
Well, the hull presents much less surface area to the wind when it is
oriented stern-on vs. side-on to the wind.  So, energy is required to turn
the hull from stern to the wind around to side to the wind.  Energy is also
required to hold the hull in the side to the wind orientation as the wind
tends to rotate the hull back to the stern to the wind orientation.  Where
does this energy come from?  There are two potential sources, the kinetic
energy of the boat itself & from the motor.  In a crowded marina situation,
the boat is going to be moving slowly.  So, you don't have very much kinetic
energy to start off with.  But, suppose you start the turn anyway?  As the
boat turns, the viscous drag of the hull in the water + the windage work
together to use up your kinetic energy.  You will likely end up turned
side-to-the-wind, but stopped dead in the water.  When the water stops
flowing across the rudder blade, it stops generating any steering forces.
The wind keeps blowing.  The boat is blown out of control back downwind &
tends to rotate back to the stern-to-the-wind orientation!  So far, these
effects are pretty much the same for a port or a starboard turn.  OK,
suppose we add some power from the port offset mounted prop?  In forward
gear, even with the motor turned full lock to help the port turn, a
substantial fraction of the thrust is acting against the turn.  This is the
difference between a port turn & a starboard turn.  You can't use too much
throttle because a substantial fraction of the thrust is also pushing the
boat forward.  Using too much throttle will result in the boat finishing the
turn & entering the slip going much too fast.  Now, when you put the engine
into reverse & apply full throttle to stop, the prop side thrust tries to
turn you back in the direction you came from.  Arggg!  Overall, this
technique simply has everything working against it.  It's a delicate
balancing act that requires good eye/hand coordination & a good sense of
speed & distance all performed in real time under stress with dire
consequences for failure!

But, if we put the engine into reverse, turn it to full lock in the opposite
direction, & now apply full throttle; everything is different.  With reverse
thrust, the port offset engine location is tending to assist a port turn.
Full reverse throttle will tend to slow the boat down, not speed it up.  So,
you get up a good velocity before starting the turn, use the reverse engine
thrust to spin you around + burn off your speed.  With a little practice,
you will find you can pull a sharp 90 deg turn to port, finishing the turn
with the bow at the entrance to your slip, with the boat moving slowly
forward at just the right speed for docking.  Then, you shift into neutral,
slip your single dock line over a piling or cleat, stop parallel to the
dock, quickly attach your bow line, & then your stern line.  Then, briefly
stop to acknowledge the applause from your fellow boaters!  I know this
technique sounds radical, but I guarantee it really really works.

Roger Pihlaja
S/V Dynamic Equilibrium

----- Original Message -----
From: "David Keyes" <dkeyes@houston.rr.com>
To: "The Rhodes 22 mail list" <rhodes22-list@rhodes22.org>
Sent: Sunday, January 12, 2003 12:35 PM
Subject: Re: [Rhodes22-list] Combination Of Sharp Turn To Port +
SingleHandedDocking


> Roger, I will try your single dock line.  But the challenge with a brisk
> wind astern has been even to get that far (to where one is entering the
slip
> between the finger piers), where you could get to the dock line.  I have
to
> think about coming in close on my port side to the sterns of the upwind,
> docked boats just before my slip and fetching the dock line for a pivot
into
> the dock, but this couldn't work single-handed due to the protruding
> outboard motors of the other boats.  I have been coming down the "alley"
> between the adjacent piers with my boat about 2/3 to 3/4 of the way
towards
> the opposite pier to allow for turning room but without my stern getting
too
> close the the sterns of the boats to starboard as I make my turn to port.
>
> As to your question:  Of course the wind is not always that strong.  I
have
> since found out, talking to the marina personnel and some other boat
owners,
> that (virtually) no one goes out on days where there is a strong onshore
> wind (northerly wind--we are on a southern shore), which would be rare in
> the summer but is common in the winter.  They don't go out because of the
> same problem of returning to docks.  But I am going to ask a few of the
> owners who seem to use their boats frequently, year around.
>
> Even on the November day of my docking accident when mine may have been
the
> only boat out, I and my crew of two thought we were successfully turning
> into the slip without incident after a great sail when at the last instant
I
> decided that the wind had caught the bow so that it was going to be pushed
> too hard into the entering edge of the starboard finger pier.  I hit
reverse
> on the engine to soften the blow (and one crew member jumped onto the pier
> at that point) to try to push the boat off, when my motor jammed in
reverse
> and we went rocketing back into the boats in their slips behind me.  (It
was
> when I forced the gear shift into forward just missing a collision with
> those boats but permanently jamming  the gear into forward).
>
>  Interestingly, much larger sailboats in the larger slips opposite me (the
> ones I back toward as I back out of my slip) seem to have no problem, at
> least when I seen them come and go on normal days.  One skipper with two
> small sons repeatedly brings his 35-foot sailboat to a dead stop centered
in
> his slip with no lines whatsoever.  The only differences I can see are (i)
> they are headed towards a larger opening, (ii) they are turning to
starboard
> if that makes any difference--is that what people talk about when they
refer
> to a right-hand prop?, and (iii) their prop is inboard and at the center
> line of their boat, giving better steering control.
>
> Lastly, even on relatively calm days, the approach to the slip requires
> skill, paying complete attention, good anticipation and decisions and
> sometimes a little luck.  Many years ago, I had boats at marinas in lakes
> and bays where this was not the case, within the limits of prudent
> seamanship.  For five years at one lake, I just sailed to the dock with no
> motor at all (boats of 17 and 19 feet).  In Biscayne Bay in Miami, I
docked
> regularly a 34-foot motor sailer in many kinds of weather and never any
> problem.  However, in the present case, for one thing, I usually have to
> start my hard turn to port as if I were going to head into the (already
> occupied) third slip out from me.  If one were driving a car doing this on
> dry land, one would crash into the motor at the back of that boat.  I have
> to "slide" out to starboard during the turn to actually come in,
hopefully,
> right in the middle of my slip without touching anything.  Surprisingly,
> this works at least half the time, and over the past 1-1/2 years until
> November, the rest of the time involved a bump into a fender or the like,
so
> no big deal--at worst a rubbing of the gel coat alongside the white rubber
> strip at the edge of the finger pier, or against the small turning wheel
at
> the entrance to the port finger pier.  But there should be a way to make
> this virtually 100% successful in all but emergency weather conditions and
> where you could even explain to a guest skipper what he or she needs to do
> as the best technique for this particular slip.  My success rate had gone
up
> significantly after the first few months of owning the boat when I started
> the practice of, if needed,  momentarily engaging the engine in forward
> during the turn, with the motor linked to the tiller.  Then, if I weren't
> going to complete the turn in time (i.e., coming in too far too
starboard),
> I would change the tiller/linked motor  steering direction bringing the
> tiller hard to port and momentarily hitting reverse to straighten the boat
> out before proceeding (hopefully) straight into the slip.  This appears to
> have been hard on the engine, as you said in an earlier email.
>
> Roger, I really like your earlier suggestions, which I quote below:
>
> "You might consider finding a different slip for next season. For example,
a
>
> slip right across from you would be better. A tight turn to starboard in
>
> this situation is much easier than to port.
>
> "If it were my boat & I were being more cautious, I think I would pull up
to
>
> the end of the finger pier, port side to the pier. I would either put out
>
> fenders on the port side amidships or mount a suitable bumper on the
corner
>
> of my pier. I would loosely tie off amidships & use a bow line to warp the
>
> bow around into the slip. No muss - no fuss."
>
> There is not alot of room to do this at my slip, but it should be
feasible.
> The finger pier at the port is only one foot wide, and their is a long
boat
> with a motor protruding to port.  Likewise there is a boat and protruding
> motor on the starboard side of my slip (mine being the last full one with
a
> finger pier on both sides to make an enclosure), and which of course one
> would not want to "warp around" outside the edge of the slip and into that
> motor.  The slip is 10 feet side.  So what you say should work with a
> practiced technique, and I am going to try it.  Using your single dock
line
> idea  in your article quoted below, this could also be the line that I
fetch
> at the end of the port finger pier.
>
>
> David Keyes
>
>
>
> ----- Original Message -----
> From: "Roger Pihlaja" <cen09402@centurytel.net>
> To: "The Rhodes 22 mail list" <rhodes22-list@rhodes22.org>
> Sent: Sunday, January 12, 2003 5:53 AM
> Subject: [Rhodes22-list] Combination Of Sharp Turn To Port + Single
> HandedDocking
>
>
> > Thank you Steve & Mark!  This was the article on single handed docking I
> was
> > refering to.
> >
> > So, David, what do you think?  Wouldn't executing a sharp 90 deg turn to
> > port & throwing a single dock line over a piling or cleat on the end of
> your
> > finger pier be more graceful & less taxing on your equipment than what
you
> > do now?
> >
> > By the way, if your marina is so tight & the wind blows like you say,
how
> do
> > the boats around you get into their slips?
> >
> > Roger Pihlaja
> > S/V Dynamic Equilibrium
> >
> > ----- Original Message -----
> > From: "Steve Alm" <salm@mn.rr.com>
> > To: <rhodes22-list@rhodes22.org>
> > Sent: Friday, January 10, 2003 5:41 PM
> > Subject: Re: [Rhodes22-list] Single Handed Docking Article
> >
> >
> > > Here it is:
> > >
> > > All boats have a point along both sides, usually just aft of
amidships,
> > > wherein a single dock line will cause the boat to stop parallel to a
> dock.
> > > To find this point, pick a place along the side.  It's helpful to use
> the
> > > sliding cars on the genoa tracks for this purpose.  Attach a mooring
> line
> > to
> > > this point & pull on it from behind.  If the bow pulls towards you
> faster
> > > than the stern, then slide the attachment point aft.  If the stern is
> > > favored, then move the attachment point forward.  When the boat crabs
> > > sideways towards you, then you have found the approximate sweet spot.
> The
> > > actual sweet spot will shift slightly when the boat has forward
> momentum.
> > > However, this approximate location will be sufficiently close to allow
> you
> > > to go out & try to pull up to a dock with a single line.  Try to stop
> the
> > > boat with a single mooring line using your approximate sweet spot.  If
> the
> > > bow or stern tend to crab towards the dock faster, then adjust the
> > position
> > > of the line fore or aft as before & try again.  When you have found
the
> > > correct location, you should at least mark it.  You may even wish to
> > install
> > > permanent mooring cleats there port & starboard.
> > >
> > > With a single mooring line, simply motor up to the dock, slip your
loop
> > over
> > > the piling near the end of the dock, & shift into neutral.  The
mooring
> > line
> > > attached to the sweet spot will snub the boat's forward momentum & the
> > boat
> > > will almost magically "crab" sideways up against the dock.  This
> sideways
> > > crabbing involves a tremendous amount of drag, which uses up the
boat's
> > > forward momentum in a matter of inches, thus making it almost
impossible
> > to
> > > hit the dock.  The boat will stop at a convenient distance away from
the
> > > dock for you to go around attaching your bow & stern lines at your
> > leisure.
> > > Try this technique.  I guarantee it will make you look like a boat
> > handling
> > > genius!
> > >
> > > Roger Pihlaja
> > > S/V Dynamic Equilibrium
> > >
> > > On 1/10/03 12:50 PM, "Roger Pihlaja" <cen09402@centurytel.net> wrote:
> > >
> > > > Hey Everyone,
> > > >
> > > > Did anyone happen to save a copy of an article I wrote several
months
> > ago re a
> > > > foolproof single line docking procedure?  I can't find it in the
> SailNet
> > > > archives or on the FAQ page & I don't know how to search the new
> > archives.
> > > > I'd really rather not retype the whole thing if someone has a copy
> they
> > could
> > > > repost.
> > > >
> > > > I'd like to forward it along to David Keyes.  The combination of the
> > technique
> > > > for making a sharp turn to port which I described in my previous
post
> > along
> > > > with this single line docking technique might work very well in his
> > situation.
> > > >
> > > > Roger Pihlaja
> > > > S/V Dynamic Equilibrium
> > > > _________________________________________________
> > > > Use Rhodes22-list@rhodes22.org, Help? www.rhodes22.org/list
> > >
> > > _________________________________________________
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> > >
> >
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