[Rhodes22-list] New Owner Questions ...

Tue Jun 15 09:46:53 EDT 2004

Sheldon,

Question #1:

I am assuming your foresail was reefed to less than 100% in these
conditions.  However, if you are in doubt, if the clew of the foresail
extended aft of the chainplate on the upper sidestays; then, you should
always route the sheets outside of the shrouds.

The only time you will want to route the sheets inboard of the shrouds is
when you are on a point of sail more upwind than a beam reach with the
foresail reefed to less than about 100%.  Please read the jib car tuning
procedure given below.  If this procedure causes the sheet to become fouled
on a lifelife or a shroud & you don't like the resulting sailshape; then,
you should reroute the sheets &/or switch genoa tracks to eliminate the
fouling.

The following article was taken from the Rhodes 22 FAQ website:

http://www.geocities.com/blew_skies/jibcars.html
JIB CAR TUNING PROCEDURE:

The basic method for determining the position for the jib cars is to sight
up the jib sheet & continue the imaginary line past the clew all the way to
the forestay. At the proper jib car position, this imaginary line should
intersect the midpoint on the luff of the sail. As the sail is reefed, the
jib car position will move forward. Shift to the forward track when the rear
track won't give you the proper geometry, usually with a foresail smaller
than about 100%.

The above procedure will give you an approximate jib car position, which can
then be fine tuned thru the use of tell tales. The following procedure can
be used for fine tuning the jib on points of sail from close hauled to a
beam reach. On any point of sail more downwind than a beam reach, you should
just use the above basic procedure since the mode of operation of the sail
changes from behaving like a wing to behaving more like a parachute.

You should have 3 tell tales about 12" back from the luff & equally spaced
down the luff of the sail. Usually, tell tales are installed with a small
window so the sail trimmer can see the tell tale on both sides of the sail
without having to duck their head under the sail. The sail is properly
trimmed when the windward & leeward tell tales at all 3 positions are
streaming backwards. The proper jib car position is determined by either the
jib trimmer pulling in slightly on the jib sheet or the helmsman pinching up
slightly into the wind while watching the behavior of the tell tales. (This
test is done slowly) If the top tell tales flutter before the bottom; then,
the sail shape is twisted too much. You should move the jib car position
forward a few inches. This will alter the geometry of the jib sheet to cause
the line to pull down more on the clew of the sail, increase leech tension,
& reduce twist. If the bottom tell tales flutter 1st; then, the sail needs
more twist & the jib car position should be moved aft a couple of inches.
Note that this effect is subtle & moving the jib car position a few inches
one way or the other is all that is required.

Peter, you should also remember to start your sail trimming with the
headsail, get it close & then trim the mainsail. The two sails will interact
& affect each other's trim settings. So, you have to keep trimming 1st one &
then the other making fine adjustments. Most cruising sailers call the sail
trim good enough after about one repetition of this procedure unless sailing
conditions suddenly change drastically.

Roger Pihlaja
S/V Dynamic Equilibrium
07 Jul 2001

Question #2:

All autopilots contain a built-in magnetic compass & a means of setting a
desired compass heading.  So, the simplest autopilot configuration is not
actually sailing to any definite waypoint.  Instead, the autopilot is merely
reacting to keep the bow of the boat pointed at a set compass heading.  The
control circuitry in most autopilots has adjustable filtering to enable the
response of the autopilot to be fine-tuned for prevailing conditions - i.e.
wave height & direction relative to the point of sail & wind direction.
Many autopilots have an optional input for an apparent wind direction.
Then, the autopilot can maintain a set course relative to the wind
direction - i.e. sail close hauled no matter what the wind direction does.
Finally, some autopilots have a GPS input.  With a GPS input, the autopilot
can actually sail the boat to a defined location on the surface of the
earth.  However, note that the autopilot is not aware of any objects around
it, shallow water, any changes in sail trim required by variations in the
wind speed or direction or course changes.  All the GPS interfaced autopilot
does is keep the bow of the boat pointed at the next waypoint until the
distance between the boat and the waypoint equals zero.  If the input GPS
course takes the boat thru shallow water, over a reef, into a jetty...Oh
well, you get the idea.

We only use our autopilot when we are in open water with a long passage to
make on a single compass heading.  Autopilots do make long passages easier
on the crew & enable singlehanding; but, it is still essential to maintain a
lookout.  We never leave the autopilot driving the boat unattended for very
long.  The Rhodes 22 works very well with an autopilot.  The shoal draft
keel provides a lot of directional stability and the rudder blade is big &
semi-balanced.  In order for the autopilot to work well, the sail plan must
be balanced to provide a nearly neutral helm.  The autopilot has no
knowledge of the oncoming wave patterns &/or wind shifts.  Therefore, it
sails the boat in a reactive mode vs. a proactive mode.  A sharp crew,
actively sailing the boat, will average about 10-15% better speed by taking
advantage of waves & wind shifts.  However, the autopilot does maintain a
set compass course as well as almost any human helmsman.

Roger Pihlaja

S/V Dynamic Equilibrium

----- Original Message -----
From: "Sheldon Green" <sheldongreen at comcast.net>
To: <rhodes22-list at rhodes22.org>
Sent: Monday, June 14, 2004 10:46 PM
Subject: [Rhodes22-list] New Owner Questions ...

> I have a couple of questions for the board...
>
> Question #1:  While sailing this past weekend in relatively high winds
15-20
> knots, I wasn't sure where the Jib lines should be routed... Should the
Jib
> Lines be routed outside or inside the shrouds?  Or when should the Jib
Sheet
> Lines be routed inside vs. outside the shrouds?
>
>
> Question #2:  Is a GPS required to use an Autopilot?  If not, how does the
> Autopilot maintain a specific course?
>
> Love the Rhodes 22!
>
>
> Sheldon Green
> sheldongreen at comcast.net
>
>
> __________________________________________________
> Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list
>
>
>