[Rhodes22-list] Combination Of Sharp Turn To Port + SingleHanded
Docking
Saroj
saroj@pathfind.net
Mon, 13 Jan 2003 18:03:27 -0500
I used this approach when I first got my boat. I posted it at one time, but
not sure if it is me you are referring to.
Saroj
----- Original Message -----
From: "Steve Alm" <salm@mn.rr.com>
To: <rhodes22-list@rhodes22.org>
Sent: Monday, January 13, 2003 5:56 PM
Subject: Re: [Rhodes22-list] Combination Of Sharp Turn To Port +
SingleHanded Docking
> David,
> Some one here on the list (I forgot who) posted this idea: Create a sort
of
> safety net at your slip for when you're coming in too fast. Fix a
permanent
> line from the left front corner of your slip to the right side of the slip
> about half a boat length back. Then another line just the opposite, from
> the right front corner to the left side. This makes the lines cross and
> form a "V" several feet out from the middle of your finger peer in your
> slip. Then you can come in a little faster (without losing steerage) and
> use the "V" to "catch" you and stop you from hitting the dock.
> Slim
>
> On 1/13/03 7:44 AM, "Roger Pihlaja" <cen09402@centurytel.net> wrote:
>
> > 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
> >>>>
> >>>> _________________________________________________
> >>>> Use Rhodes22-list@rhodes22.org, Help? www.rhodes22.org/list
> >>>>
> >>>
> >>> _________________________________________________
> >>> Use Rhodes22-list@rhodes22.org, Help? www.rhodes22.org/list
> >>
> >> _________________________________________________
> >> Use Rhodes22-list@rhodes22.org, Help? www.rhodes22.org/list
> >>
> >
> > _________________________________________________
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>
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