Don Campbell via Public-List
public-list at lists.alberg30.org
Tue Aug 5 18:17:31 PDT 2014
These things never let go at good places. 3rd lock in the Welland
Canal going down (but have to motor) and motoring across Toronto on
another occasion. I have had way too much experience with them!
The one episode in the canal was worse than what you describe, because
the nut on the end of the transmission shaft let go. That meant the
flange came free and there was no power possible to the prop shaft.
Somehow, I managed to get things to align well enough that the pressure
from the prop and shaft against the transmission shaft was enough to get
me out of the canal and I thought I could sail over to Toronto once in
the lake. Wrong as the wind died and we had to quasi-motor again but did
make it to Toronto and got a temporary fix to get home. Had to rebuild
the tranny after that because all the threads were gone on that shaft.
But in the mean time I noticed the lock bolt on the rear coupler had not
held tightly so looked at that too.This allows a lot of wear on the keys
and so loosens everything. It turns out that there is very little
material in the couplers - both sides of the joint- at the keyway and
they had both cracked on my boat, so they were replaced too. I tried to
get used ones and the only parts I saw were all cracked in the same
place. I suggest you check that too. The chap with the parts had not
seen that crack before I pointed it out and would not buy his bad parts!
Had them custom machined for less than he was asking for the used ones,
- at a small machine shop and he corrected another flaw. I think you
will find that on your couplers the key on the transmission shaft aligns
perfectly with the key on the prop shaft. They ought to be 180º offset
for good shaft balance. And we used more material on the couplers we
made, so they would not crack out again.
The second time I had the bolts unscrew, that was on a trip into 4
foot waves and we had been motoring for about 5 hours. Worst part was
the rudder was holding the prop shaft in and so no steering. Changed to
sail and managed to secure prop shaft to free up rudder. All well except
we landed a bit late for the race we were trying to get to- not for my
boat but crew for another boat. That trip ended in an unusual way too.
1/2 mile from the destination YC we were caught in a thunder storm and
it rained really hard. We were WET! But as is so often the case, there
was no zephyr after the storm, so we tried to drift on left over swell
and managed to get the 1/2 mile, when all wind ceased and we sculled it
to the wharf! I had one bolt sheared and two out and no hard
replacements aboard. Had to go in to Toronto with a borrowed car to get
6 and they were 1/4" too long so had to cut and file to get things good
to go. Once that was done, all good again. I suspect there had been a
bit of wobble in the shaft in the waves and the bolts jarred lose even
with loctite on them.
Check the alignment of the shaft. That is a relatively easy job if
the boat is out of the water or you have SCUBA gear. Sharpen a piece of
wire to a very fine point (coat hanger will do just fine.) Then bend the
wire so that you can tape the wire to the rudder with the point at
either 9:00 or 6:00 on the back end of the propshaft. Rotate the shaft
using the prop with the transmission in neutral. If there is any change
in the position of the wire relative to the shaft, it is not aligned.
Repeat for the other position on the shaft that you did not do first.
Same thing if there is any change in position of the point relative to
the shaft. The 9:00-3:00 axis checks lateral deviation and the 12:00 -
6:00 tests the vertical alignment.
To realign the motor is helps to have the boat out of the water and
two people, one inside and one out. Loosen the mounting bolts or nuts
whichever fits the system in your boat, but do not undo the coupler Move
the motor in such a way as to correct the alignment on the shaft. Have
the person outside check with the wire and a turn. adjust until no
change, wire to shaft. Check the other axis and adjust until no change
wire to shaft. Put the wire on the center of the prop shaft and rotate
again. It should be True with no distortion at all . Tighten the
mounting bolts and check alignment again. Re-adjust if there is
movement. This gives a better measurement than feeler gauges because of
the extra 23" of leverage from the shaft length which magnifies the
0.003" they suggest as reasonable. I have had this system checked with
gauges several times and been within 0.001" every time.
Hope this helps
More information about the Public-List