|Strong Track Problem|
|In February, 2009 Steve Angst and I sailed the short distance from Hopetown to Great Guana Cay in The Bahamas. The wind was blowing slightly over 15 kts so we decided start out with a reef in the mainsail.|
sailing in the
The new mainsail I purchased from Quantum Sails in 2003 included a Strong Track insert for the existing external track on the main mast. The purpose of the track is provide reduced friction on the sail slides when raising and lowering the sail and also to provide a broader distribution of the load from a fully-battened mainsail. Up until now there had been no problems with this system
other screws are not tapped into the mast, but rather are connected
to a threaded plate on the back of the Strong Track. These
plates were inserted into the existing mast track and the tightening
of the screws should cause the plate to rotate in the track and lock
the Strong Track in place. In the picture on the right you can
see one of these plates has pulled out of the existing track.
There is a second plate at the bottom of the Strong Track that also pulled out of the mast track.
of the Strong Track slides into the existing mast track through the
slide gate shown in the picture on the left.
The bottom foot or two of the track, below the gate is
secured with these machine screws and threaded plates.
The outward force of the reef line had pulled the track away
from the mast. The mystery is what caused the one machine screw to
shear off and the threaded plates to pull out of the mast track.
One possible cause of the problem is the system I used to secure the reef tacks on the mainsail.
gooseneck on Sarah has a conventional set of tack hooks that are
normally used to secure the reef, shown at the bottom of the picture
on the right.
The new mainsail proved to be difficult to secure to these hooks when reefing. The sail is much heavier and stiffer than the previous mainsail. My first solution was to place a short piece of nylon webbing through each reef tack ring with stainless steel coits sewn into each end. With the mainsail lowered the coits could be slipped over the tack hooks and then the halyard tensioned. This worked OK, but it still was tricky to accomplish as one or both of the coits liked to slip off the hooks before the halyard could be tensioned.
After a year of fighting this system I discovered that my Cunningham tackle could be used to secure the reef tacks. Instead of trying to secure the reef tack to the hooks on the boom, I just lowered the mainsail to the point where the reef ring on the sail was about 8”-10” above the boom. Then I slipped the Cunningham hook into the ring and tensioned the tackle to pull the reef tack down to the boom level. This seemed to work very well for over 5 years, included two Atlantic crossings.
The problem may be that this system secured the reef tack vertically, but not fore and aft or side to side. The many miles I sailed Sarah under reefed mainsail may finally caused the mechanical fasteners at the bottom of the track to fail.
looking more closely at the two threaded plates that pulled out of
the mast. The top on is shown in one of the
pictures above. The bottom plate is
shown in the picture on the right. Both of these plates appear
to be drawn tight against the back of the Strong Track, but they
have not rotated such that they would have been locked into the mast
Either the plates rotated over time and came loose from the track or when the strong track was installed these plates never locked into the track. Because the plates are now tight against the Strong Track I don't believe they came loose over time, but were never secured to the mast track.
means the bottom foot or more of the track was secured to the mast
by a single machine screw tapped into the mast wall. Given
that my reef system did not secure the reef tack as solidly as the
reef hooks would have done, the amount of play in the reef tack may
have fatigued this single machine screw and caused it to fail.
The reason this screw is tapped into the mast wall instead of secured with a threaded plate is that there is a second slide gate on the mast track shown in the picture on the left. This undoubtedly was the original gate for the main sail slides when Sarah was first commissioned. The Previous Owner (PO) purchased a fully-battened mainsail sometime in the 1980s and that sail required a different type of track gate which was installed several feet above this gate and is shown in the picture above.
|It appears that the track would have likely held if the two
plates were secured into the mast track. There are a couple
more threaded plates above the point where the track came loose and
they are still secure. So my first action will be to secure
the two plates that came loose into the mast track. Then I
will either drill out screw remnant in the mast and re-tap the whole
for a replacement screw or drill and tape a new hole several inches
from the one that failed.
In order to accomplish those actions I need a relatively calm day to raise the mainsail and possibly drop it on deck. Since Steve and I returned to Marsh Harbor the winds have been blowing 15-20kts.
The other task will be to find a better way to secure the reef tacks. I hate to give up on the Cunningham system because it is so easy and quick. If the Strong Track is properly secured, the small amount of play in the reef tack allowed by the Cunningham tackle may not be important. I'll have to think on this some more after the Strong Track is secured.
|Re-Attaching the Strong Track|
nearly a week the wind finally started to die. Overnight on
Friday, Mar 6 it was actually calm for a few hours. The GRIB
forecasts showed a continuing lightening of the wind on Sunday and
Monday. However I was tired of looking at this problem and
wanted to get started on the repair.
Saturday morning the winds were still light, about 8-10 kts, so I hoisted the mainsail and started work. I decided I would not attempt to replace the broken screw until I dropped the mainsail out of the track, but I could lock the plates into the track with the mainsail fully hoisted. This moved all of the mainsail slides well above the portion of the Strong Track that had come loose.
loosened the screws on the plates so that the plates were at the end
of the screws then pushed the plates into the mast track. With
the plates in the track I tightened the screws and the plates
appeared to have rotated and locked into the mast track.
I pulled and pried on the Strong Track and it did not budge, so it is attached for now.
I still need to replace the broken screw and possibly come up with a different system for reefing the mainsail.
|One good test for the Strong Track attachment was furling the mainsail. The furled sail produces a strong aft pull on the bottom of the Strong Track as can be seen in the pictures near the top of this page. When I dropped and furled the mainsail the Strong Track remained in place.|