Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 14-03-2023, 22:25   #1
Registered User
 
tronic72's Avatar

Join Date: Nov 2015
Posts: 152
Which was do they turn ?

Hi,

My motors were removed about 5 years ago and we are preparing the new ones.

One engine spun one way and the other spun the opposite way. I want to make sure the new engines go on the right sides and am making preparations. Can members please confirm which way these propellers spin?

Click image for larger version

Name:	IMG_1678857927.362899.jpg
Views:	64
Size:	460.6 KB
ID:	272805
tronic72 is offline   Reply With Quote
Old 14-03-2023, 22:40   #2
Registered User

Join Date: Nov 2013
Location: Nice, France
Boat: Hunter Marine 38
Posts: 1,338
Re: Which was do they turn ?

Port CCW Starbord Clockwise
sailormed is offline   Reply With Quote
Old 14-03-2023, 23:32   #3
Registered User
 
tronic72's Avatar

Join Date: Nov 2015
Posts: 152
Re: Which was do they turn ?

Quote:
Originally Posted by sailormed View Post
Port CCW Starbord Clockwise
So to confirm, based on what you've said. The "standard" rotating engine which turns counter clockwise would be installed on the Port side (left) and the non-standard rotating engine would be on the Starboard (right side).

Just to be clear the Velvetdrives don't reverse rotation, one engine rotates in a non-standard direction (Clockwise, looking at the flywheel).

Thanks in advance.
tronic72 is offline   Reply With Quote
Old 15-03-2023, 02:07   #4
Registered User

Join Date: Jan 2015
Location: Pittwater NSW Aust.
Boat: Jarkan King 40 12m
Posts: 307
Re: Which was do they turn ?

Looking from the stern forward, on a monohull the top blade of the prop turns outward, on a power cat the top of the blade turns inward. Someone told me why this is so on a cat, but I can't remember why!
Bruce K is offline   Reply With Quote
Old 15-03-2023, 03:02   #5
Moderator

Join Date: Feb 2010
Location: Australia
Posts: 2,155
Which was do they turn ?

Your new engines are contra rotating as were your old engines and the gearboxes are contra rotating velvetdrives. To be absolutely certain the engines go into the correct places you might want to start em up before craning them in to avoid a lot of extra work. Iím curious to know what brand the replacement engines are, initially I thought Detroit diesels but they would probably be too powerful for the Borg Warnerís so are they going to be gasoline engines?
skipperpete is online now   Reply With Quote
Old 15-03-2023, 06:34   #6
Registered User

Join Date: Feb 2009
Posts: 2,390
Re: Which was do they turn ?

The starboard side is standard rotation the portside is reverse rotation
motion30 is offline   Reply With Quote
Old 15-03-2023, 06:42   #7
Registered User

Join Date: Jun 2019
Location: Rochester, NY
Boat: Chris Craft 381 Catalina
Posts: 5,175
Re: Which was do they turn ?

Typically you'd have the standard rotating engine on the port side, reverse rotation on the starboard. That gives outward counter rotation in forward gear (which is what your props are set up for).

However, there's one potential gotcha: The transmissions. If they're Velvet Drives, you need to check the data tags on the transmissions and confirm exactly what model and ratio you have. Most Velvet Drives rotate the output same as input, but there's one ratio that rotates output opposite of input. If you have that ratio, you'll need to swap the engines (reverse rotation on port) to get the correct prop rotation.

Post the Velvet Drive model and ratio here and I'll double-check the book to confirm how they rotate.
rslifkin is offline   Reply With Quote
Old 15-03-2023, 07:35   #8
Registered User

Join Date: May 2015
Location: Muskegon, Mi
Boat: Columbia 36
Posts: 911
Re: Which was do they turn ?

Most all twins are set up with the props "outward turning", or port CCW and starboard CW as viewed from the stern. If you do it the other way the boat will handle weird. Even worse of they both go the same way, the boat won't go in a straight line. Some of the WW2 landing craft did that and the Coxswains hated them. I can see in the photo that the original set up was the standard outward turning. As others have said you do need to know if one or both of your transmissions reverse the rotation. 30 or 40 years ago one of the engines would have turned the other way, but now days not so common. They do the counter rotation in one of the transmissions.
capt jgw is offline   Reply With Quote
Old 15-03-2023, 07:44   #9
Registered User
 
Shrew's Avatar

Join Date: Aug 2010
Posts: 2,813
Re: Which was do they turn ?

Hopefully this should help
Attached Thumbnails
Click image for larger version

Name:	rotation.jpg
Views:	21
Size:	9.0 KB
ID:	272822   Click image for larger version

Name:	dual-rotation.jpg
Views:	19
Size:	5.8 KB
ID:	272823  

Shrew is offline   Reply With Quote
Old 15-03-2023, 07:45   #10
Registered User
 
Nicholson58's Avatar

Cruisers Forum Supporter

Join Date: Jan 2011
Location: Caribbean live aboard
Boat: Camper & Nicholson58 Ketch - ROXY Traverse City, Michigan No.668283
Posts: 6,105
Images: 84
Re: Which was do they turn ?

Turn off the fuel. Engage the starter and observe the rotation.
Nicholson58 is offline   Reply With Quote
Old 15-03-2023, 07:49   #11
Registered User

Join Date: Jun 2019
Location: Rochester, NY
Boat: Chris Craft 381 Catalina
Posts: 5,175
Re: Which was do they turn ?

Quote:
Originally Posted by Shrew View Post
Hopefully this should help

That graphic is backwards, at least from an engine perspective. A standard inboard rotates counter-clockwise when looking at the flywheel. Clockwise is counter-rotation. Clockwise is only the standard rotation for an outboard or sterndrive prop, but that is irrelevant to inboard engine rotation.
rslifkin is offline   Reply With Quote
Old 25-03-2023, 18:04   #12
Registered User

Join Date: Aug 2021
Location: PNW
Boat: 35 Ft. cutter, custom
Posts: 1,358
Re: Which was do they turn ?

Quote:
Originally Posted by capt jgw View Post
Most all twins are set up with the props "outward turning", or port CCW and starboard CW as viewed from the stern.
^This.
Whether by engine rotation or the gearbox.
__________________
Beginning to Prepare to Commence
Bowdrie is offline   Reply With Quote
Old 25-03-2023, 18:10   #13
Registered User
 
tronic72's Avatar

Join Date: Nov 2015
Posts: 152
Re: Which was do they turn ?

Quote:
Originally Posted by Nicholson58 View Post
Turn off the fuel. Engage the starter and observe the rotation.
Clearly you didnít read my original post.
tronic72 is offline   Reply With Quote
Old 25-03-2023, 18:11   #14
Registered User
 
tronic72's Avatar

Join Date: Nov 2015
Posts: 152
Re: Which was do they turn ?

Thanks to everyone. Port is counter clockwise and starboard clockwise as per the images posted. Thanks again.
tronic72 is offline   Reply With Quote
Old 25-03-2023, 19:56   #15
Registered User

Join Date: Jan 2022
Posts: 138
Re: Which was do they turn ?

Quote:
Originally Posted by skipperpete View Post
Your new engines are contra rotating as were your old engines and the gearboxes are contra rotating velvetdrives. To be absolutely certain the engines go into the correct places you might want to start em up before craning them in to avoid a lot of extra work. Iím curious to know what brand the replacement engines are, initially I thought Detroit diesels but they would probably be too powerful for the Borg Warnerís so are they going to be gasoline engines?
You don't even have to start them. Simply hook up the power and turn them over for a second and that will tell you which way they rotate.

When you do this make sure they will not start, perhaps by removing the coil wire if they are gas, or by having having the fuel shut off levers in the off position if they are diesel. That last thing you want is a engine purring away on its side in the grass while it jumps around because everyone is too afraid to get close to it.
Sailorman97 is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
What are they, do they relate to mooring? sepharad Anchoring & Mooring 15 04-05-2022 14:10
Will they or Won't they move on? What would you do? TacomaSailor General Sailing Forum 7 02-11-2013 13:48
Is this what They Mean when They Say to Taper the Hole ? off-the-grid Construction, Maintenance & Refit 11 18-05-2010 15:29
They never got over Herreschoff did they? 44'cruisingcat Multihull Sailboats 7 13-11-2007 18:56

Advertise Here


All times are GMT -7. The time now is 01:37.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2023, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2023, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.