11
J/105 Tuning Guide
Solutions for today’s sailors
Light Air
In light air the crew should be well forward
and to leeward both upwind and down.
Two crewmembers should be forward of
the shrouds to leeward. Remaining crew
should be up near the shrouds. There
should only be one person in the cockpit
other than the helmsman. In really light
air the main is not trimmed that often
and the helmsman can make small
adjustments. Being to leeward helps heel
the boat increasing helm giving a better
feel and allows for the best pointing and
rudder lift. Being forward allows the bow
to dig in which also helps pointing as well
as reduces wetted surface by getting the
transom out of the water.
Moderate Air
In moderate air the crew can begin to slide
back as they begin to move to weather.
Once anyone goes to weather they should
be stacked just behind the shrouds. At
this point if you have a dedicated main
trimmer, he can slide back to his station
upwind. Downwind as soon as there is
constant adequate pressure on the sheet
and you begin to try to sail low the crew
should move to weather to help rotate the
spinnaker to windward out from behind
the main. This happens at about 10 knots.
There is plenty more coming on downwind
sailing in Part 6, starting on page 21.
Heavy Air
In heavy air the crew should continue to
move aft, especially in waves. If you notice
that your helmsman has to steer a lot to
keep the boat going straight (dialing for
dollars), move aft and as the bow lifts the
boat will track straighter. Since crew weight
is limited the guys who are on the rail need
to hike hard. Remember, sailing is a sport
and it’s a boat not a couch!
Part 6: Downwind Sailing
Sailing the J/105 downwind can be one of
the more difficult things to do well. Paying
small attention to the minor details can
make a huge difference. The key to fast
sailing downwind is good communication
between the trimmer and the helmsman.
The trimmer should constantly be telling
the helmsman how much pressure he has
in the sheet. This will allow the helmsman
to know if he can bear off a little more, but
more importantly when he needs to head
up a little bit to build pressure.
The J/105 has an asymmetric spinnaker set
on a centerline sprit. The goal in downwind
sailing is to maximize downwind VMG. This
is achieved by sailing a wind angle tight
enough to keep speed, but sailing lower
towards the mark whenever possible. The
North Sails asymmetric has been designed
as a running spinnaker for optimum
downwind performance at the apparent
wind angles that produce the best VMG
for the J/105. The sail has been designed
to rotate out to windward to project the
maximum sail area out from behind the
mainsail. Always hoist the sail all the way to
the top. Due to the luff length restriction in
the rules, the tack of the sail is never set all
the way down to the pole. Raising the tack
helps the sail to rotate to windward.
Light Air Sailing (0-9 knots TWS)
In light air, you must sail tighter angles for
best VMG. The tack is set 0.3m-0.6m (1-2’)
off the sprit. The crew should be forward
and to leeward. Keep the crew weight as
low as possible. Steer down in the puffs
until the pressure sheet starts to get light
and then head up slightly. Communication
between the trimmer and the helmsman is
key. Try to find the lowest angle you can sail
before the speed drops. Don’t forget about
the main! Proper mainsail trim is essential
to good speed. The vang should be set so
that the top batten is open by 5 degrees. A
good trick to help acceleration out of the
jibes is for the main trimmer to hold the sail
in a bit after coming out of the jibe. When
the asymmetric is jibed, it needs to
be overtrimmed to make it “pop” through.
When the spinnaker is overtrimmed, it
blows air back into the mainsail relieving
pressure from it. By keeping the main in,