Has anyone come up with a better system for cleating the adjustment
line so that it can easily be handled from the helmsperson's
The backstay acts as a "turnbuckle" for the forestay and to shift the
balance of the rig forward/aft (as in lee/weather helm). In theory,
it should be tight for close-hauled and loosened as you fall off the
wind, helping jib sail shape. In practice, I am not racing the boat
and can see little change in the jib sail shape. It could also be a
factor of the furling system (very stiff). When the wind kicks up,
I find the 175% jib will overwhelm the main. Then I use the IMF and
the jib furler to balance the boat and just leave the adjuster tight.
I might change my opinion if I switch to the Harken 00 system for the
jib (its plastic foil should be softer).
I run my backstay adjuster line through the hole in the port transom
cleat, back up and wrap on the port aft main cleat. Plan to use a
turning block on a lanyard sometime, but works as is...
s/v "Sailsman's Bounty" 1984,
I have a 95 Rhodes. Installed a simple backstay adjuster this year
that works well. Bought a fiddle block with cam cleat (about $30)
and installed it on the current backstay just below the traveler.
Installed by cutting the aft stay line and installing pulley at one
end. Installed fiddle block on other cut end. You run a line through
the fiddle block and pulley. Adds a 2:1 purchase and very easy to
adjust. I let tension off when at slip. Also added a bungee cord to
hold the fiddle block so it is not loose when I slack the line. This
setup works very well. I do not tighten much more than did before,
but sure is easier.
06 Jul 1998
I mounted mine on the top narrow edge of the transom, to starboard.
Seems to work real well for us, although I rarely adjust it underway.
It is bad enough leaning over the transom to: A) raise the swim
ladder B) Raise/lower the motor (GB's newer style motor mount is
going on next winter) C) Installing the motor freshwater flushing
muffs, a real pain in the ass due to the new Yamaha prop being too
big in diameter for my old bucket flushing method.
I mounted a Harken #144 swiveling base with #150 CAM-MATIC cam cleat,
#137 eyestrap, #071 stand-up spring, and a 2.25" dia. block just in
front of the starboard side backstay chainplate. The standard
backstay adjuster line will thread up to this assembly like it was
designed to be there. Thru-bolt the Harken swivel base to the gunnel
with silicone RTV, four #10-24UNC X 1" stainless steel flat head
machine screws and use a #10 stainless steel fender washer under each
nut as a backing plate.
Before drilling any holes, thread up the backstay adjuster line and
experiment with the position of the swiveling base. You will find
there is a sweet spot just in front of the chainplate where the line
will run fairly into the block without chafing on the backstay or
blocking the boarding ladder. Don't use the smaller Harken #205
swiveling base because the base is right near the boarding ladder &
sooner or later, someone is bound to step on the swiveling arm. The
Harken 144's swiveling arm can stand up to being stepped on and the
The swiveling arm on the Harken 144 makes trimming the backstay
adjuster very easy from either side of the cockpit. Be sure to mount
the swiveling base so that the arc of the arm's movement won't allow
the adjuster line to flop overboard. I marked my backstay adjuster
line at 6" intervals with colored magic marker so I can reproduce the
In order for the backstay adjuster to be able to cause any noticeable
difference in lee or weather helm, you need to have the rest of the
rig set-up properly. With only the slack taken out of the backstay
tension, the inner (lower) shrouds have to be set quite tight. The
outer (upper) shrouds just need to have the slack taken up. Sight up
the mast and be certain the mast is not bent or leaning side-to-side
or bent fore-and-aft.
The mast should have a slight aft rake to it, about 2 deg max. Now
when you tighten up the backstay, the forward lower shrouds will
restrain the middle of the mast. The head of the mast will be pulled
aft. This will simultaneously take up slack in the forestay and
induce a slight bend in the mast. (Note: NOT recommended with IMF
Tightening up the forestay is desirable for genoa sail shape when
beating to weather. If your mainsail is properly cut and not blown
out from old age, the mast bend will cause the mainsail shape to
flatten out into an aerodynamic shape that is better for high winds
and beating to weather. You will also move the sail plan's center of
effort aft, thus inducing weather helm.
This is an inexpensive modification that works so effortlessly that
Stan ought to consider it as a factory option. My backstay adjuster
has been absolutely bullet proof for 10 hard sailing seasons.
S/V Dynamic Equilibrium
07 Jul 98
Thanks for your detailed description. Sounds like a good solution.
Did you have any trouble getting to the back ends of the through-
bolts? Seems like a long narrow reach. Can you get them from inside
Your mention of IMF mains got me thinking, since that's what we have.
Maybe with the furling tube adding stiffness to the spar, I won't be
able to induce much bend anyway, so prudence on cranking down the
backstay is probably wise. It's also likely to have some ill effect
on the performance of the furler, if the IMF furling tube isn't
straight. My new forestay has a turnbuckle (required by the CDI
furler), so I can do more adjusting there.
Your recommendations for adjusting the upper and lower shrouds will
be very helpful, too. Thanks again.
07 Jul 1998
The Harken 144 swiveling base is mounted on the starboard side gunnel
just in front of the backstay chainplate. The job will require 2
people, one down in the lazarette to hold the wrench and a helper up
topside to turn the screwdriver. However, the gunnel is wide enough
to easily reach up there with a wrench. You were probably thinking
the swiveling base mounted on the top of the transom, which would be
a very long narrow reach to get at the thru-bolts on the backside.
It turns out the top of the transom isn't wide enough to mount the
My roller furler has a turnbuckle as well. This forestay turnbuckle
is used to adjust the static rake of the mast when there is no
backstay tension. For a conventional mainsail, the proper mast rake
is about 2 deg to the rear. I don't know what an IMF mainsail
requires for mast rake. You may have to experiment with mast rake
until you get neutral helm. You may find the best you can do is have
a slight lee helm in light air building up to neutral helm in a
moderate breeze & then weather helm in heavy air. With an IMF
mainsail, I would adjust the forward lower shrouds somewhat looser.
Then, increasing backstay tension would simply increase the rearward
rake of the mast without bending the mast. This would get you the
forestay tension you need to be able to point to windward. The
chances are your IMF mainsail isn't designed to respond to mast bend
anyway. Remember, I have a fully battened conventional mainsail & I
specified my mast bend parameters to the sailmaker when I ordered the
sail. I would imagine bending an IMF mast & then operating the
furling mechanism might cause the mainsail to chafe inside the mast &
put a lot of stress on the furling mechanism's bearings. Is an IMF
mast much stiffer than a conventional mast? I've never seen one off
the boat. How much heavier is an IMF mast?
S/V Dynamic Equilibrium
08 Jul 98
Had the IMF apart 2 weeks ago. Any rake would be bad news, since the
mainsail is wrapping around a tube with roller/spacers top and bottom.
If the tube changes distances to the mast wall I do not think the sail
would go in (i.e. the whole thing would jam up). The IMF is about two
inches more fore/aft and about Ĺ to 1-inch greater in width, than
other masts on boats that size. Itís very stiff, but I have never
seen the GB standard mast.
The OD of the forestay wire & the rigidity of the headsail foil have very
little to do with forestay sag. Forestay sag is primarily controlled by the
amount of backstay tension + some secondary & tertiary effects caused by
other details related to the way the standing rigging is setup. The use of
3/16" OD wire for the forestay permits the backstay adjuster to be really
cranked down hard with no fear of forestay wire stretch or fatigue cycling.
The use of the larger diameter wire also introduces an additional safety
factor to compensate for corrosion, mechanical damage, etc.
I have my backstay adjuster setup on a Harken 144 swivel base, 150 Cam-Matic
cleat, 071 stand-up spring, & 001 single 2.25" block mounted on the
starboard side gunnel right at the transom. Backstay tension is quickly
adjusted by pulling on the backstay control line thru the Cam-Matic cleat.
The 144 swivel base & 150 Cam-Matic cleat allow the backstay tension to be
adjusted from virtually any helm position. I used the 144 swivel base
because the backstay adjuster is right near the boarding ladder where it
might be accidentally stepped on. The large 144 swivel base is rigid enough
to step on without damage, while the smaller Harken swivel bases can't take
such abuse. The backstay adjuster control line is striped every 2" so that
the backstay tension is reproducible.
My standing rigging is setup such that increasing the backstay tension
simultaneously reduces headstay sag & bends the mast for flattening the
mainsail. Both actions are desirable for sail shaping in heavy air. I have
a fully battened conventional mainsail, which is cut very roachy & is
designed to respond to mast bend by flattening. I use only one mainsail,
but it has 2 jiffy reef points. Needless to say, backstay tension is one of
the most important sail shaping controls on Dynamic Equilibrium.
Good grief! I just gave away a couple more racing secrets! Hopefully, no
one else is listening.
I guess I don't understand your question re noticing any difference when the
sail is fully extended given the weight. The only fully nylon sails are
spinnakers. Did you mean, have I ever noticed a difference in light air
behavior between a Dacron genoa & my Cruise-Lam genoa? If that's your
question, the answer is the bi-radial Cruise-Lam genoa has a better sail
shape under all conditions vs. the standard Dacron genoa. In heavy air, the
Cruise-Lam + bi-radial construction genoa's sail shape is much better as the
standard Dacron + cross-cut construction genoa becomes hopelessly distorted.
The secret of Cruise-Lam's longevity is the Dacron outer skins. The Dacron
provides chafe, UV, fatigue resistance, & environmental pollution
protection. The reinforcing Kevlar scrims & Mylar film core are buried
inside the composite sandwich & are thus protected from the harsh outside
world. Unprotected Kevlar & Mylar would be expected to only last one season
or less in the marine environment.
S/V Dynamic Equilibrium
12 Jan 2002