Reply
 
Thread Tools Display Modes
 
Old 10-18-2015, 08:42 AM   #1
Senior Member
 
City: Houma, Louisiana
Country: USA
Vessel Name: M/V LUNASEA
Vessel Model: 45ft Bluewater Coastal
Join Date: Aug 2014
Posts: 405
What Gear Ratio Do I Have ?????

How can I tell what the ratios are on velvet drives. When I put port in gear it moves boat more than starboard engine. What I am trying to say is with both in gear boat will turn to port.
__________________
Advertisement

kartracer is offline   Reply With Quote
Old 10-18-2015, 09:19 AM   #2
Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 3,884
If tags are gone or not readable, get a phototach and with engine idling in gear, shoot the engine crank pulley and prop shaft. Divide numbers to get your ratio.

Ask around the dock, many boat owners keep a phototach on board.
__________________

Ski in NC is offline   Reply With Quote
Old 10-18-2015, 09:20 AM   #3
Guru
 
READY2GO's Avatar
 
City: Marathon, Florida
Country: USA
Vessel Name: Walkabout
Vessel Model: 1989 Sea Ray 380 Aft Cabin
Join Date: Jan 2012
Posts: 521
There should be a metal plate on the gear that tells you.
__________________
"Whenever you find yourself on the side of the majority, it is time to pause and reflect." Mark Twain

www.mikeandsharondunsworth.blogspot.com
READY2GO is offline   Reply With Quote
Old 10-18-2015, 09:21 AM   #4
Guru
 
fryedaze's Avatar
 
City: Solomons Island Md
Country: USA
Vessel Name: Fryedaze
Vessel Model: MC 42 (Overseas Ltd) Monk 42
Join Date: Sep 2011
Posts: 1,052
There should be a name plate on the top with the ratio and series numbers. You may have to scape some paint. Not likely that they are different ratios.
Prop condition?
Engine RPM?
__________________
Dave Frye
Fryedaze, MC 42 (Monk 42') 1989 Overseas Co
http://mvfryedaze.blogspot.com/
fryedaze is offline   Reply With Quote
Old 10-18-2015, 09:26 AM   #5
Senior Member
 
City: louisiana
Country: usa
Join Date: Aug 2014
Posts: 207
Hmmm....I would assume your transmissions are the same ratio. Your issue may be slip in the clutch on one tranny or a difference in pitch on one prop. A little time with a non-contact tachometer and a helper will help narrow it down.
rardoin is offline   Reply With Quote
Old 10-18-2015, 10:21 AM   #6
Guru
 
City: gulf coast
Country: pinellas
Join Date: Jun 2014
Posts: 2,199
The above phototach idea answers your question but What WOT will each engine hit? That might give a clue what's going on.


Everything can be weird on a boat but the usual suspect would be a bent or out of spec prop.
Keep it simple and look for the obvious stuff.
bayview is offline   Reply With Quote
Old 10-18-2015, 01:18 PM   #7
Senior Member
 
City: Houma, Louisiana
Country: USA
Vessel Name: M/V LUNASEA
Vessel Model: 45ft Bluewater Coastal
Join Date: Aug 2014
Posts: 405
Thanks Props just out shop but did this before having them redone. Will try phototach
kartracer is offline   Reply With Quote
Old 10-18-2015, 03:20 PM   #8
Guru
 
City: Melbourne, FL
Country: USA
Join Date: Dec 2014
Posts: 918
Quote:
Originally Posted by kartracer View Post
Thanks Props just out shop but did this before having them redone. Will try phototach
You can make a mark on the flywheel and the driveshaft and turn either one a single revolution and see what your ratio is. It is probable that it you can either hand turn the prop shaft by hand with the coupler or a pipe wrench. Since it is a step down transmission, that would be easier than turning the engine over manually. If you want to turn the engine over carefully, (key off, power off, etc.), put a socket and pull handle on the front of the engine crank shaft. Usually there is a nut on the front crank holding the timing wheel / balancer / front pulley on.

Don't make the mistake my Dad made and leave the pull handle on the driveshaft when cranking the engine Big mistake and glad no one got hurt, except the Craftsman pull handle (twisted in a big U shape). No, he wouldn't use their warranty, assuming someone would ask how he screwed it up...

Stu
stubones99 is offline   Reply With Quote
Old 10-18-2015, 03:30 PM   #9
Senior Member
 
capt jerry's Avatar
 
Join Date: Oct 2007
Posts: 321
Quote:
Originally Posted by kartracer View Post
Thanks Props just out shop but did this before having them redone. Will try phototach
some times in the older velvet drives one tranny is 2to1 and the other is 1.9 to one they do that to reverse the rotation when both engines turn the same way. they say that there is a 10% diff . not a big deal
capt jerry is offline   Reply With Quote
Old 10-18-2015, 03:31 PM   #10
Guru
 
C lectric's Avatar
 
City: Somewhere
Country: , Canada
Vessel Name: Island Pride
Vessel Model: Palmer sedan 32'
Join Date: Oct 2007
Posts: 1,870
Quote:
Originally Posted by stubones99 View Post
You can make a mark on the flywheel and the driveshaft and turn either one a single revolution and see what your ratio is. It is probable that it you can either hand turn the prop shaft by hand with the coupler or a pipe wrench. Since it is a step down transmission, that would be easier than turning the engine over manually. If you want to turn the engine over carefully, (key off, power off, etc.), put a socket and pull handle on the front of the engine crank shaft. Usually there is a nut on the front crank holding the timing wheel / balancer / front pulley on.

Don't make the mistake my Dad made and leave the pull handle on the driveshaft when cranking the engine Big mistake and glad no one got hurt, except the Craftsman pull handle (twisted in a big U shape). No, he wouldn't use their warranty, assuming someone would ask how he screwed it up...

Stu


That will not work with a hydraulic gear box. Without the engine running there is no hydraulic pressure to lock the clutches so turning the shaft end or the engine manually will result in no drive through.

Your suggestion would work with the mechanical boxes such as many Hurths where the clutches are locked with a mechanical toggle.

Best bet is per Ski's suggestion.
__________________

C lectric is offline   Reply With Quote
Reply

Thread Tools
Display Modes

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





All times are GMT -5. The time now is 03:31 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012