Cruisers Forum

Thread Tools Search this Thread Rate Thread Display Modes
Old 14-12-2020, 15:32   #1
Registered User

Join Date: Dec 2020
Posts: 10
Lightbulb Boat Transmissions

Although I have been boating a long time and Enjoy my Sea Ray 30 weekender. I am trying to extend her reach. So on with my question If my prop spins backward with the motors off will that hurt my transmissions. If yes can something be done to prevent the damage.

I am looking into putting a Kite Sail on the front of my boat.
It looks like I can get 5 knots down wind with this rig.

Please any feedback will be appreciated
Hog Wild is offline   Reply With Quote
Old 14-12-2020, 16:03   #2
Certifiable Refitter/Senior Wannbe
Wotname's Avatar

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: C.L.O.D.
Posts: 12,121
Re: Boat Transmissions

It depends on the transmission - some are hurt, others aren't.
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 14-12-2020, 16:19   #3
Senior Cruiser

Cruisers Forum Supporter

Join Date: May 2013
Location: Oregon to Alaska
Boat: Wheeler Shipyard 83' ex USCG
Posts: 2,988
Re: Boat Transmissions

If it a hydraulic transmission, the pump circulates oil that cools the rear bearing. Depending on the speed of the prop, it generates heat. That can damage the rear seal and on some, the bearings and clutch. Check the temp, but also ask the manufacturer.
If it's manual, I've never heard of one being damaged even turning fast.
Lepke is offline   Reply With Quote
Old 14-12-2020, 16:26   #4
Registered User
GrowleyMonster's Avatar

Join Date: Dec 2012
Location: New Orleans
Boat: Bruce Roberts 44 Ofshore
Posts: 2,422
Re: Boat Transmissions

You can simply lock down the shaft with a pipe wrench or a piece of chain if there is any doubt. A more involved remedy would be to install a thrust bearing somewhare along the shaft to transfer all thrust directly to the hull. Some transmissions can safely be placed in neutral with the shaft trailing. The manufacturer should be consulted or if this is not possible, then a competent small boat mechanic.
1979 Bruce Roberts Offshore 44, BRUTE FORCE
GrowleyMonster is online now   Reply With Quote
Old 15-01-2021, 08:30   #5
Registered User

Join Date: Apr 2012
Posts: 2
Re: Boat Transmissions

Wotname is correct. It depends on the transmission, but on some you can stop the shaft from turning my dropping the transmission into reverse.
Krogen42 is offline   Reply With Quote
Old 16-01-2021, 05:00   #6
Registered User
GILow's Avatar

Join Date: Sep 2008
Location: Adelaide, South Australia
Boat: Swanson 42
Posts: 7,368
Re: Boat Transmissions

If in doubt, you can stop the shaft turning with a bit of light line with a loop on one end. Snag one of the coupling bolts with the loop and make the line fast to something strong nearby.

Make the line light enough so that if you forget it or need the engine in a hurry it will snap without doing any damage to the shaft, coupling or bearings.

I used this setup for years without problems. (No longer needed thanks to my feathering kiwiprop.)
On my way at last.
GILow is offline   Reply With Quote

boat, transmission

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
Being slightly over-propped enough to burn up 2 transmissions in 400 hours? sgtPluck Propellers & Drive Systems 16 20-06-2011 20:22
Looking for Opinions on Transmissions SabreKai Engines and Propulsion Systems 0 24-07-2010 09:05
Synthetic oil for diesel/transmissions jdoe71 Engines and Propulsion Systems 35 28-09-2007 21:54
Don't Put ATF in Yanmar KBW10 Transmissions Chief Engineer Propellers & Drive Systems 0 26-08-2007 16:18
Transmissions Brent Swain Engines and Propulsion Systems 0 24-03-2004 14:49

Advertise Here

All times are GMT -7. The time now is 14:27.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.