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#11
posted to rec.boats.cruising,rec.boats.building
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Removing 3 bladed prop on an Alberg 35
On Tue, 14 Aug 2007 13:44:42 -0400, Matt Colie
wrote: Jonathan, This is a very common issue with the long keel boats that have the propeller in an appature. It is a toss up. If the heel casting unscrews, then dropping the rudder is really pretty simple. Take all the head fitting off the rudder, unscrew (2 as I recall) the big screws that hold on the heal casting and down it comes. I actual fact, if you keep track of the shims, pulling a U4 forward an inch and an half is usually just about as hard. The problem if there is one is the exhaust pipe. The hoses and wires will usually pull that far, but if the muffler can't be moved with the engine (some can) then you don't want to mess with that during the season. It may take you out of commission for longer than it is worth. Matt Colie Lifelong Waterman, Licensed Mariner and Perpetual Sailor Jonathan W wrote: I bought an Indigo 3 bladed prop last week for my Alberg 35 with the original Atomic 4, as the existing prop succumbed to electrolysis I went down to the boat yesterday, worried that I might not be able to loosen the old hub's grip on the shaft. It was also a 3 bladed prop. That was actually easy after about 5 minutes with a map gas torch. I seem to have only about an inch of space between the end of the prop shaft and the rudder (post). The hub is about 2-2,5 inches thick. I've tried swinging the rudder from stop to stop, but don't seem to be able to find an angle that will allow the old prop to come off, or, for that matter, a new one to go on. Others must have encountered this problem and found a solution..... At this juncture it seems to me that I either have to dismount the rudder to gain an extra inch or so, or I have to unmount the engine and pull the prop shaft forward a couple of inches (if that's even possible ) I am hoping that I missed something perfectly obvious as I was working late and was tired.... any help appreciated. Thanks, Jonathan Wye There is an Alberg group - google for it -- that has an article about converting to wheel steering that has a pretty comprehensive section on removing the rudder. Bruce in Bangkok (brucepaigeATgmailDOTcom) |
#12
posted to rec.boats.cruising,rec.boats.building
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Removing 3 bladed prop on an Alberg 35
On Mon, 13 Aug 2007 23:00:14 -0400, Jonathan W
wrote: I seem to have only about an inch of space between the end of the prop shaft and the rudder (post). The hub is about 2-2,5 inches thick. I've tried swinging the rudder from stop to stop, but don't seem to be able to find an angle that will allow the old prop to come off, or, for that matter, a new one to go on..... At this juncture it seems to me that I either have to dismount the rudder to gain an extra inch or so, or I have to unmount the engine and pull the prop shaft forward a couple of inches (if that's even possible ) I am hoping that I missed something perfectly obvious as I was working late and was tired.... any help appreciated. ... Jonathan Wye There *IS* the Medieval option. Accomplished with a Sawzall upon the defenseless rudder. Then made good with epoxy/glass, complete with two inch set back for NEXT time :-) Brian Whatcott Altus OK. |
#13
posted to rec.boats.cruising,rec.boats.building
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Removing 3 bladed prop on an Alberg 35
On Wed, 15 Aug 2007 02:45:36 GMT, Brian Whatcott
wrote: On Mon, 13 Aug 2007 23:00:14 -0400, Jonathan W wrote: I seem to have only about an inch of space between the end of the prop shaft and the rudder (post). The hub is about 2-2,5 inches thick. I've tried swinging the rudder from stop to stop, but don't seem to be able to find an angle that will allow the old prop to come off, or, for that matter, a new one to go on..... At this juncture it seems to me that I either have to dismount the rudder to gain an extra inch or so, or I have to unmount the engine and pull the prop shaft forward a couple of inches (if that's even possible ) I am hoping that I missed something perfectly obvious as I was working late and was tired.... any help appreciated. .. Jonathan Wye There *IS* the Medieval option. Accomplished with a Sawzall upon the defenseless rudder. Then made good with epoxy/glass, complete with two inch set back for NEXT time :-) Brian Whatcott Altus OK. That is a point. The User's group listing says that the rudder is solid mahogany.... Bruce in Bangkok (brucepaigeATgmailDOTcom) |
#14
posted to rec.boats.cruising,rec.boats.building
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Removing 3 bladed prop on an Alberg 35
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#15
posted to rec.boats.cruising,rec.boats.building
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Removing 3 bladed prop on an Alberg 35
On Aug 15, 4:40 am, wrote:
On Wed, 15 Aug 2007 02:45:36 GMT, Brian Whatcott wrote: On Mon, 13 Aug 2007 23:00:14 -0400, Jonathan W wrote: I seem to have only about an inch of space between the end of the prop shaft and the rudder (post). The hub is about 2-2,5 inches thick. I've tried swinging the rudder from stop to stop, but don't seem to be able to find an angle that will allow the old prop to come off, or, for that matter, a new one to go on..... At this juncture it seems to me that I either have to dismount the rudder to gain an extra inch or so, or I have to unmount the engine and pull the prop shaft forward a couple of inches (if that's even possible ) I am hoping that I missed something perfectly obvious as I was working late and was tired.... any help appreciated. .. Jonathan Wye There *IS* the Medieval option. Accomplished with a Sawzall upon the defenseless rudder. Then made good with epoxy/glass, complete with two inch set back for NEXT time :-) Brian Whatcott Altus OK. That is a point. The User's group listing says that the rudder is solid mahogany.... Bruce in Bangkok (brucepaigeATgmailDOTcom) I will defend my suggestion although it sounds impractical for the Alberg. A coupler properly made, probably from SS about 1" ID larger than the shaft with deep holes drilled and then milled to size will be as well balanced as the original. A few barnacles on a prop would produce a far greater imbalance. I have been amazed at how my 3 bladed prop does not shake even though it gets covered with barnacles. I hit a mast from a dismasted Laser this past year and made a huge ding in one blade and it still turns smoothly. This causes me to believe that it is alignment, not balance that is most critical and a well made coupler would maintain that alignment. Besides, you can always re-align the shaft (fairly easy on my S2). |
#16
posted to rec.boats.cruising,rec.boats.building
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Removing 3 bladed prop on an Alberg 35
On Thu, 16 Aug 2007 09:59:09 -0700, Frogwatch
wrote: There *IS* the Medieval option. Accomplished with a Sawzall upon the defenseless rudder. Then made good with epoxy/glass, complete with two inch set back for NEXT time :-) Brian Whatcott Altus OK. That is a point. The User's group listing says that the rudder is solid mahogany.... Bruce in Bangkok (brucepaigeATgmailDOTcom) I will defend my suggestion although it sounds impractical for the Alberg. A coupler properly made, probably from SS about 1" ID larger than the shaft with deep holes drilled and then milled to size will be as well balanced as the original. If what you want is to get in the water, thirty minutes with a rasp and sandpaper might do it. No sawzall needed. Or is it covered with glass? Casady |
#17
posted to rec.boats.cruising,rec.boats.building
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Removing 3 bladed prop on an Alberg 35
On Thu, 16 Aug 2007 09:59:09 -0700, Frogwatch
wrote: I will defend my suggestion although it sounds impractical for the Alberg. A coupler properly made, probably from SS about 1" ID larger than the shaft with deep holes drilled and then milled to size will be as well balanced as the original. A few barnacles on a prop would produce a far greater imbalance. I have been amazed at how my 3 bladed prop does not shake even though it gets covered with barnacles. I hit a mast from a dismasted Laser this past year and made a huge ding in one blade and it still turns smoothly. This causes me to believe that it is alignment, not balance that is most critical and a well made coupler would maintain that alignment. Besides, you can always re-align the shaft (fairly easy on my S2). Here's a little engineering insight. If a drive shaft is lightened by drilling out an axial hole whose diameter is one half the outer diameter - the shaft's strength in torque is reduced by 5% and its weight is reduced by 25% This is important in aircraft construction. So as applied to cutting and shutting a propellor shaft, if its diameter is x, and it is cut then bridged with a coupler, the coupler's diameter ought to be just over twice the shaft's diameter, to bridge across the gap. As to passing the torque into and out of the coupler - the ideal connection is splines, the more the merrier, within reason. But this is unlikely to be an option. Another option, much simpler to arrange, is two well-fitted bolt holes at right angles to each other, at one shaft diameter back from the cut, and the other at two diameters back if possible. This is likely to be weaker than the original torque capability. There is another option, which will be familiar to you from examining an old style (English) bike pedal crank. A flat is worked on the shaft, and the pedal crank has a hole to pass the shaft. But it also has a hole at right angles to the shaft through which a cotter bolt with a tapered flat passes to bear on the main shaft's flat. The cotter, when bolted tight, eliminates slippng between the two pieces, so a wear point is eliminated. If an eccentric hole can be drilled in the coupler, so a cotter bolt can bear on the shaft, it would stop relative motion. But there are many other ways you could concieve of connecting a shaft into and out of a coupler, I'm sure. Brian Whatcott Altus OK |
#18
posted to rec.boats.cruising,rec.boats.building
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Removing 3 bladed prop on an Alberg 35
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#19
posted to rec.boats.cruising,rec.boats.building
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Removing 3 bladed prop on an Alberg 35
On Fri, 17 Aug 2007 02:13:06 GMT, Brian Whatcott
wrote: There is another option, which will be familiar to you from examining an old style (English) bike pedal crank. I had one like that, back in 1960. Loathed those cotters. And they were tacky. Oh, so British. Then there was the cotterless cranks with insufficient room for a standard bolt. Head was too big. I got one from the Datsun dealer that fit. Casady |
#20
posted to rec.boats.cruising,rec.boats.building
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Removing 3 bladed prop on an Alberg 35
On Fri, 17 Aug 2007 02:13:06 GMT, Brian Whatcott
wrote: On Thu, 16 Aug 2007 09:59:09 -0700, Frogwatch wrote: I will defend my suggestion although it sounds impractical for the Alberg. A coupler properly made, probably from SS about 1" ID larger than the shaft with deep holes drilled and then milled to size will be as well balanced as the original. A few barnacles on a prop would produce a far greater imbalance. I have been amazed at how my 3 bladed prop does not shake even though it gets covered with barnacles. I hit a mast from a dismasted Laser this past year and made a huge ding in one blade and it still turns smoothly. This causes me to believe that it is alignment, not balance that is most critical and a well made coupler would maintain that alignment. Besides, you can always re-align the shaft (fairly easy on my S2). Here's a little engineering insight. If a drive shaft is lightened by drilling out an axial hole whose diameter is one half the outer diameter - the shaft's strength in torque is reduced by 5% and its weight is reduced by 25% This is important in aircraft construction. So as applied to cutting and shutting a propellor shaft, if its diameter is x, and it is cut then bridged with a coupler, the coupler's diameter ought to be just over twice the shaft's diameter, to bridge across the gap. As to passing the torque into and out of the coupler - the ideal connection is splines, the more the merrier, within reason. But this is unlikely to be an option. Another option, much simpler to arrange, is two well-fitted bolt holes at right angles to each other, at one shaft diameter back from the cut, and the other at two diameters back if possible. This is likely to be weaker than the original torque capability. There is another option, which will be familiar to you from examining an old style (English) bike pedal crank. A flat is worked on the shaft, and the pedal crank has a hole to pass the shaft. But it also has a hole at right angles to the shaft through which a cotter bolt with a tapered flat passes to bear on the main shaft's flat. The cotter, when bolted tight, eliminates slippng between the two pieces, so a wear point is eliminated. If an eccentric hole can be drilled in the coupler, so a cotter bolt can bear on the shaft, it would stop relative motion. But there are many other ways you could concieve of connecting a shaft into and out of a coupler, I'm sure. Brian Whatcott Altus OK I think the point you are missing is that although a coupling may very well cope with the torque there just isn't any room to fit a coupling of the type you describe at either the propeller or the engine end. One might possibly use a larger cutlass bearing running on the O.D. of the coupling but that would just add complications to a system that should be as sim0le as possible. The most logical answer is(1) remove the rudder, or (2) saw the cutout in the rudder larger. Bruce in Bangkok (brucepaigeATgmailDOTcom) |
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