Shaft alignment and rudder torque
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Boat Maintenance
Forum Discription: Discuss maintenance of your Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=13715
Printed Date: November-17-2024 at 4:54pm
Topic: Shaft alignment and rudder torque
Posted By: Carl
Subject: Shaft alignment and rudder torque
Date Posted: May-18-2009 at 10:38pm
I aligned the engine to the shaft in my boat recently. The engine wound up all the way to port on the mounts to align properly.
I have also been having trouble adding steering torque by filing my rudder. I'm filing on the port trailing edge of the rudder to add steering torque to port.
I'm wondering if the two could be related.
With the engine to port the shaft is pointing such that the prop is trying to push the stern to port, or into a slight turn to starboard (right).
I want to add left hand torque to my steering, which is opposite of this torque due to mis-alignment of the shaft in the boat.
I checked the shaft going through the bottom of the boat and it is offset to port so needs adjusting anyway.
Just wondering if the alignment could be affecting the steering? Seems as though it could to me.
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Replies:
Posted By: eric lavine
Date Posted: May-18-2009 at 10:51pm
get a good reference point from shaft to chines and measure, how much do you think its off?, look at your strut bushing and respond if its loose on one side and squeezing the other and vica versa on the back side
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"the things you own will start to own you"
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Posted By: 8122pbrainard
Date Posted: May-18-2009 at 10:52pm
Carl,
Is your strut bent?
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Posted By: Fl Inboards
Date Posted: May-18-2009 at 11:26pm
Carl when you aligned your shaft did you pull your shaft packing assembly loose and run it up the shaft to expose where the shaft comes thru the shaft log? This will tell you if you are in the middle of the shaft log or not. I have seen motors that aligned all the way to one side or another and still be in the middle of the shaft log. this is usally because the stringers are not installed in the boat correctly. However I have also seen motors align and be running on the log, if this is the case then something is not straight with the strut.
As for the the rudder torque you are only petting the trailing edge with a file, put it back in the tool box and get out the grinder and grind a nice light straight bevel on the port side trailing edge.
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Hobby Boats can be expensive when the hobbyist is limited on their own skill and expertise.
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Posted By: Carl
Date Posted: May-18-2009 at 11:28pm
I'll measure Wed/Thursday when I go to the lake.
From memory I'd say the shaft enters the bottom of the boat maybe 3/16 to the port side of center. By the time you get to the front of the engine that could double to 3/8 with the extra distance from the strut.
With the coupler unbolted the shaft turns easily, so I don't suspect a problem with the shaft bushings, but I'll check those too.
I don't think the strut is bent. I have had the strut off to replace the bushings. I'm guessing I didn't get it back on in exactly the right orientation.
All that said, could the shaft mis-alignment WRT the boat cause the loss of steering torque I see?
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Posted By: eric lavine
Date Posted: May-18-2009 at 11:41pm
I really dont think so, an 1/4" over at the engine only would cock the prop not even 0.100 the engiine would have to be a couple inches to one side to notice, if at all
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"the things you own will start to own you"
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Posted By: BuffaloBFN
Date Posted: May-19-2009 at 9:59am
I'd loosen the strut up and see if you have some play in the mounting holes. If so, put the engine back in the middle and take a look at the strut.
Also, these stuts get bent and/or twisted pretty easily!
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Posted By: Carl
Date Posted: May-19-2009 at 11:33am
Thats what I was planning to do.
Break the coupler, loosen the packing gland, loosen the strut mounting bolts and center up the shaft where it enters the boat. Tighten strut, adjust the engine mounts, and secure the packing gland.
It needs to be adjusted even if it doesn't affect the steering.
On detecting a bent strut, if the shaft goes into the boat in the right place then I'm assuming the strut isn't bent. Right?
I'll report back with findings.
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Posted By: BuffaloBFN
Date Posted: May-19-2009 at 11:38am
Before you take it apart, turn the rudder straight and sight up the centerline of the boat...rudder to skegs. Where is the driveline in relation to this?
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"It's a Livin' Thing...What a Terrible Thing to Lose" ELO
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Posted By: 8122pbrainard
Date Posted: May-19-2009 at 11:55am
Carl,
The strut could be bent and the shaft still could be centered in the hull hole/shaft log. Do eyeball the centers with the rudder like Greg has suggested.
Have you bedded the base of the strut to the boat with any sealant?
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Posted By: Carl
Date Posted: May-19-2009 at 12:01pm
I cleaned the bed and the base of the strut with acetone, then applied a real light film of sealant before reinstall. Also put a good bit of sealant in each bolt hole to seal out the water.
Is there a good write up on the site for preparing a proper bed for the strut?
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