One of the reasons the Vega prop shaft is offset is that the prop shaft tube has to clear the rudder shaft tube, which is located through the centerline of the boat.
Peter
#1331 'Sin Tacha'
Peter
#1331 'Sin Tacha'
Vega stern tube.
- Thread starter Peter
- Start date
I have a series one vega, and have wondered if boring out the existing
stern tube and replacing with a slightly larger size would be a problem in
hitting the rudder shaft tube-the reason I might want to do it is that the
centered shaft in the tube hits the tube wall due to shaft whip. the
rattling is annoying, and I can see wear marks on the operating sleeve
when the shaft/sleeve is pulled. this would be a question for someone who
has tried...
Ric Eiserling, #935
stern tube and replacing with a slightly larger size would be a problem in
hitting the rudder shaft tube-the reason I might want to do it is that the
centered shaft in the tube hits the tube wall due to shaft whip. the
rattling is annoying, and I can see wear marks on the operating sleeve
when the shaft/sleeve is pulled. this would be a question for someone who
has tried...
Ric Eiserling, #935
Hi Ric,
Do you still have the Albin gas engine or has #935 been converted to Diesel? How about the other end: regular prop or Combi?
When I replaced my cutlass bearing I also replaced the aft motor mounts on the Yanmar Diesel. They had fallen victim to a steady drip of salt water from a leaking exhaust, causing the rubber part to break away from the rusted metal, allowing the shaft to rub on the insides of the shaft tube.
I don't think a larger tube is a good solution. Good motor mounts, a good cutlass bearing, and careful alignment should cure the problem.
Hope this helps!
Peter
#1331 'Sin Tacha'
Do you still have the Albin gas engine or has #935 been converted to Diesel? How about the other end: regular prop or Combi?
When I replaced my cutlass bearing I also replaced the aft motor mounts on the Yanmar Diesel. They had fallen victim to a steady drip of salt water from a leaking exhaust, causing the rubber part to break away from the rusted metal, allowing the shaft to rub on the insides of the shaft tube.
I don't think a larger tube is a good solution. Good motor mounts, a good cutlass bearing, and careful alignment should cure the problem.
Hope this helps!
Peter
#1331 'Sin Tacha'
its the old Albin, with solid mounts, original combi. I've worked on the
combi on three series 2 Vegas and the stern tubes are a larger diameter.
the only other thing I could think of doing would be to try to place some
sort of nylon sleeve part way down the stern tube to keep the rattling
down. it seems no surprise that shaft whip would occur with a small
diameter (inner) shaft and a large 2 bladed prop. alignment is to .003.
Ric
combi on three series 2 Vegas and the stern tubes are a larger diameter.
the only other thing I could think of doing would be to try to place some
sort of nylon sleeve part way down the stern tube to keep the rattling
down. it seems no surprise that shaft whip would occur with a small
diameter (inner) shaft and a large 2 bladed prop. alignment is to .003.
Ric
Hmmmm ... the Series II would be Volvo Diesels, so would jump around more than a gas engine, which is maybe why the tubes are bigger. Hard to say, but if there's something rattling it sounds like something is worn, at one end or the other, causing the rattle. Or maybe something bent?
Peter
#1331 'Sin Tacha'
Peter
#1331 'Sin Tacha'
If there is .003 of misalignment in the coupling its possible that is
not close enough. If the coupling is 4in. in diameter that represents
.009 per foot of shaft length so a four foot shaft would whip about .030
or about 1/32 of an inch. If the shaft is whipping that much it could
be bending a little as well and hitting the sides of the combi tube. Is
the coupling alighned to .003 with the boat in the water ? I would say
that for an engine that does not have rubber mounts and the ablilty to
flex a little the shaft alignment needs to be closer than .003. I have
seen watermen here on the Chesapeake bay work a couple days to get a
shaft lined up within .001. The next question is are you sure it's
within .003 did you align it yourself? IF there was misalignment of the
engine at one time and the shaft was banging the side of the tube, the
shaft even lightly tapping the tube can cause it to take a permanent
bend. The shaft taping or rubbing the tube will cause that side of the
shaft to stretch the effect of one side being even.001 longer than the
other could well be 1/16 of an inch bend. A machine shop can check the
shaft for straightness in just a few minutes and if bent they can
likely straighten it. I doubt your shaft is bent though, I suspect that
it is misaligned with the engine. Boats change shape over time and even
if the shaft was once perfectly alighned. The long term effect of
tightening the rigging can cause a large change in hull shape. A 1/4
inch lifting of the stern by adjusting the rigging can cause a
misalignment problem and this can happen over a period of time. I bet
you're shaft is misaligned more than you think. Doug
not close enough. If the coupling is 4in. in diameter that represents
.009 per foot of shaft length so a four foot shaft would whip about .030
or about 1/32 of an inch. If the shaft is whipping that much it could
be bending a little as well and hitting the sides of the combi tube. Is
the coupling alighned to .003 with the boat in the water ? I would say
that for an engine that does not have rubber mounts and the ablilty to
flex a little the shaft alignment needs to be closer than .003. I have
seen watermen here on the Chesapeake bay work a couple days to get a
shaft lined up within .001. The next question is are you sure it's
within .003 did you align it yourself? IF there was misalignment of the
engine at one time and the shaft was banging the side of the tube, the
shaft even lightly tapping the tube can cause it to take a permanent
bend. The shaft taping or rubbing the tube will cause that side of the
shaft to stretch the effect of one side being even.001 longer than the
other could well be 1/16 of an inch bend. A machine shop can check the
shaft for straightness in just a few minutes and if bent they can
likely straighten it. I doubt your shaft is bent though, I suspect that
it is misaligned with the engine. Boats change shape over time and even
if the shaft was once perfectly alighned. The long term effect of
tightening the rigging can cause a large change in hull shape. A 1/4
inch lifting of the stern by adjusting the rigging can cause a
misalignment problem and this can happen over a period of time. I bet
you're shaft is misaligned more than you think. Doug
With the use of Diesel engines with rubber mounts became a neccesity
because the high compression of a diesel causes the engine to hammer the
heck out of a boat. An advantage for boat builders was that the time
consuming job of aligning a solid mounted engine was shortend considerably.
I delivered a 28ft wooden Sharpie built by a boat builder friend of
mine to the Annapolice Boat show. She had the first diesel engine my
friend had ever put in a boat. The engine, a volvo single cylinder
diesel was installed with solid mounts and she shook nuts and bolts off
of most everything in the boats interior. I cursed diesel engine all the
way up the Bay. We sold her and about a month later I went to New York,
where she was kept, to cut the engine bed down and installed rubber
mounts. I would venture to say that the vibration would have shaken the
boat apart and she would have sunk at some point. Doug
because the high compression of a diesel causes the engine to hammer the
heck out of a boat. An advantage for boat builders was that the time
consuming job of aligning a solid mounted engine was shortend considerably.
I delivered a 28ft wooden Sharpie built by a boat builder friend of
mine to the Annapolice Boat show. She had the first diesel engine my
friend had ever put in a boat. The engine, a volvo single cylinder
diesel was installed with solid mounts and she shook nuts and bolts off
of most everything in the boats interior. I cursed diesel engine all the
way up the Bay. We sold her and about a month later I went to New York,
where she was kept, to cut the engine bed down and installed rubber
mounts. I would venture to say that the vibration would have shaken the
boat apart and she would have sunk at some point. Doug