Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 25-05-2015, 08:24   #1
Registered User

Join Date: Jul 2010
Location: Dunedin, Florida
Boat: Compac 23D
Posts: 29
Shaft Alignment Question

Is it possible to check shaft alignment with boat in the water?

BobL
__________________

__________________
BobL is offline   Reply With Quote
Old 25-05-2015, 08:27   #2
Registered User
 
zboss's Avatar

Join Date: Sep 2011
Location: On a boat
Boat: Cabo Rico 38
Posts: 3,425
Re: Shaft Alignment Question

I think that is the preferred method.

I did mine recently and it seemed to work out OK. Its my understanding that you cannot do a proper alignment on the hard because the boat will take on a slightly different shape when its floating. So, you can align all you want on the hard but it won't be correct.
__________________

__________________
zboss is offline   Reply With Quote
Old 25-05-2015, 08:31   #3
Registered User

Join Date: Jul 2010
Location: Dunedin, Florida
Boat: Compac 23D
Posts: 29
Re: Shaft Alignment Question

Thanks for the quick reply. Next question is "how is this done?" I've never aligned a shaft before
__________________
BobL is offline   Reply With Quote
Old 25-05-2015, 08:32   #4
Registered User

Join Date: Jun 2009
Location: still in a roll of fiberglass around Cape Town
Boat: Leopard 40 (new model)
Posts: 1,201
Re: Shaft Alignment Question

Quote:
Originally Posted by BobL View Post
Is it possible to check shaft alignment with boat in the water?

BobL
Sure. When you build a boat or change engine on the hard you do a preliminary alignment out of the water but the one that matters is the one you do in the water. All that said, for the guy or girl doing the alignment the work is the same because all the work is done inside.
__________________
svlamorocha is offline   Reply With Quote
Old 25-05-2015, 08:38   #5
Senior Cruiser
 
skipmac's Avatar

Cruisers Forum Supporter

Join Date: Oct 2007
Location: 29 49.16 N 82 25.82 W
Boat: Pearson 422
Posts: 12,372
Re: Shaft Alignment Question

Checking in the water is the correct method. Out of the water the shape of the hull and thus the alignment will change.

The only way I know to accurately check the alignment is to put a feeler gauge between the two halves of the flange which will involve loosening the bolts and separating the flange. Then put a feeler gauge in the crack at 12, 3, 6 and 9 o'clock. Should be within a few thousandths, 0.05" if I recall but would have to look at my notes to check that.
__________________
The water is always bluer on the other side of the ocean.
skipmac is offline   Reply With Quote
Old 25-05-2015, 08:43   #6
Registered User

Join Date: Jul 2010
Location: Dunedin, Florida
Boat: Compac 23D
Posts: 29
Re: Shaft Alignment Question

I see. How can it be adjusted if its off more than 0.05?
__________________
BobL is offline   Reply With Quote
Old 25-05-2015, 09:44   #7
Senior Cruiser

Cruisers Forum Supporter

Join Date: Mar 2014
Location: Anacortes
Boat: previous - Whitby 42 new - Goldenwave 44
Posts: 1,735
Re: Shaft Alignment Question

On most boats (I am familiar with) you have to adjust the height of the engine/transmission on the motor mounts. This changes the angle of the engine/transmission relative to the prop shaft. You don't adjust the prop shaft itself. It is what it is. But this can be a very challenging job, requiring a good mental ability to imagine the geometry of the engine and the effect of each adjustment to the alignment. And you have to be sure and lock in the adjustment after it is done (and check again).

It can be very tedious with lots of trial and error. But it is doable with patience. Make sure you motor mounts are in good condition while you are at it and replace if shot.

And the prop shaft mounting plate has to be seated right and tight before you start. It has to be dead nuts perpendicular to the prop shaft itself or it will be worse.

You can rough adjust on the hard but the final adjustment should be done in the water as noted.
__________________
exMaggieDrum is offline   Reply With Quote
Old 25-05-2015, 10:24   #8
Registered User

Join Date: Jul 2010
Location: Dunedin, Florida
Boat: Compac 23D
Posts: 29
Re: Shaft Alignment Question

Thanks so much for the great info...I'm going to work on it!
__________________
BobL is offline   Reply With Quote
Old 25-05-2015, 10:32   #9
Senior Cruiser
 
Cheechako's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 19,340
Re: Shaft Alignment Question

Quote:
Originally Posted by BobL View Post
I see. How can it be adjusted if its off more than 0.05?
I think that's a typo... should be maybe .005 (five thousanths) But .010 is fine in my book. it can be tedious. You not only need the gap to be uniform, but the flanges need to be concentric. ie: center of the shaft to be aligned with center of the engine output.
You get there by raising/lowering the engine mounts to get both acceptable. This will require adjusting both fore and aft mounts often. If the gap is not uniform port/starboard, you may have to loosen the mounts and shift the engine... depending on mount type.
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is online now   Reply With Quote
Old 28-05-2015, 03:33   #10
Certifiable Refitter/Senior Wannbe
 
Wotname's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: Van DeStat Super Dogger 31'
Posts: 7,330
Re: Shaft Alignment Question

Quote:
Originally Posted by BobL View Post
I see. How can it be adjusted if its off more than 0.05?
Have a look at this thread, especially the link in post 5.

How to properly align the shaft
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is offline   Reply With Quote
Old 28-05-2015, 22:15   #11
Senior Cruiser

Cruisers Forum Supporter

Join Date: May 2013
Location: Oregon to Alaska
Boat: Wheeler Shipyard 83' ex USCG
Posts: 1,699
Re: Shaft Alignment Question

.002" is correct and achievable, some yards would like you to believe .005 or .010 is ok. Slack the flange bolts. You use any combinations of feeler gauges to measure the difference as you go around the flanges. Turning the shaft shouldn't change where the tightest spot is. Assuming a standard installation: If the tightest spot is on the st'bd side of the flange, either the engine front needs to go to port or the transmission needs to move to st'bd or some combination. It won't be that simple. The tight spot rarely is at the exact top, bottom or sides. Too much misalignment (.005"+) will cause bearing wear, either the stern bearing or the rear transmission bearing. In some older transmissions, internal splines will wear. Sometimes when down inside a silent hull you can hear a thumping sound in a passing boat with a missalignment. It also scares the fish if you're trolling.
__________________

__________________
Lepke is offline   Reply With Quote
Reply

Tags
men

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Need shaft alignment noel32129 Engines and Propulsion Systems 5 11-06-2013 16:18
Engine/Shaft Alignment Tool??? Chuteman Engines and Propulsion Systems 12 31-10-2012 18:25
Aqua Drive and Shaft Alignment wingover Propellers & Drive Systems 12 15-06-2011 16:24
Strut, Shaft, Shaft Log, Engine Alignment KestrelBuck Engines and Propulsion Systems 24 04-04-2011 00:14
Shaft Alignment Problem ? steve77 Engines and Propulsion Systems 27 02-04-2011 15:28



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 11:08.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.