[Public-List] Bolts

Don Campbell via Public-List public-list at lists.alberg30.org
Tue Aug 5 18:17:31 PDT 2014

Hi Matthew:
     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

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