Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 30-03-2016, 11:02   #76
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,735
Re: Yanmar V-twin diesel conversion of OMC Saildrive

Quote:
Originally Posted by sgancarz View Post
I know I saw the torque rating on the OMC somewhere, however I can't find it now. But using the formula TORQUE = (HP x 5252) ÷ RPM. ((15 x 5252) ÷ 3750 = 21), the OMC calculates to 21ft/lbs of torque.

Here is a good article that explains this formula and how it is used to calculate HP, as Horsepower is dependent on time. However when trying to calculate TORQUE it does not work quite as well, as torque is independent of time.

Horsepower vs Torque

Great discussion by the way. Made me do some more research and taught me a few things.
You don't need to go through those conversions, and I don't think you have any problem.

Gearboxes care only about torque, and are always rated for a certain amount of torque. I don't think they care about what RPM that torque is delivered at (within their operating ranges of course).

FURTHERMORE, you are looking at MAX horsepower and torque curves, which is not what these engines will do in real use. You should be looking at the propeller curve, which shows how much power is absorbed by the prop at different RPMs.

You simply don't have a problem, if you don't change the propeller. Changing engines does not change the amount of torque absorbed by the prop at any given RPM.

If you do change the propeller, then you just need to mind the maximum torque rating of the gearbox.
__________________

__________________
"Parce que je suis heureux en mer, et peut-ętre pour sauver mon ame. . . "
Dockhead is online now   Reply With Quote
Old 06-04-2016, 21:45   #77
Registered User
 
sgancarz's Avatar

Join Date: May 2014
Location: Racine, WI
Boat: Paceship PY26
Posts: 59
Re: Yanmar V-twin diesel conversion of OMC Saildrive

Last night I test fit the coupling and performed a dry run of the complete shaft alignment proceedure. I then disassembled the coupling to see how easy it would be to change a belt. Sitting on the stand in th garage was not too bad, however I am sure that doing it while laying on my stomach in the lazarette will be a completely different story.

Here is a picture of the Paraflex coupling installed. I still need to complete the pulley to drive the water pump">raw water pump.



Now I am finishing up the painting of the lower unit and will next be permanently installing the Iso-ring on the lower unit with 3M 5200 sealant. At that point the lower unit will be ready for installation. I then need to do a final sanding and paint job on the mount assembly.

Still waiting for warmer weather so that I can finish cleaning and painting the lazarette. Also need to install the thru-hull for the raw water intake and the new fresh water tank.
__________________

__________________
sgancarz is offline   Reply With Quote
Old 04-05-2016, 16:36   #78
Registered User
 
Jesse's Avatar

Join Date: Apr 2008
Location: Oro Bay Puget Sound
Boat: Irwin sloop
Posts: 374
Thumbs up Re: Yanmar V-twin diesel conversion of OMC Saildrive

I just noticed the lower unit is in a flexible mount. I hadn't realized that before. So as power is increased to the propellor the shaft angle will change, which in turn will change the location of the upper end of the shaft proportionally to the amount of power applied. The amount of movement could be small or great depending on the density of the mount. So basically there is a spun shaft on a flexible mount that will change it's angle and center, being driven by a flexibly mounted engine with admitted vibration issues, joined by a very nice coupling that dampens the vibes and accepts misalignment. There will be no middle ground on the results at all, It will be smooth as butter or go to hell in seconds. I'm rooting for smooth but advance the throttle slowly on the first tryout.
__________________
Jesse is offline   Reply With Quote
Old 04-05-2016, 20:05   #79
Registered User
 
deblen's Avatar

Join Date: Oct 2014
Location: Grand Manan,N.B.,Canada N44.40 W66.50
Boat: Mascot 28 pilothouse motorsailer 28ft
Posts: 1,400
Images: 1
Re: Yanmar V-twin diesel conversion of OMC Saildrive

Quote:
Originally Posted by Jesse View Post
I just noticed the lower unit is in a flexible mount. I hadn't realized that before. So as power is increased to the propellor the shaft angle will change, which in turn will change the location of the upper end of the shaft proportionally to the amount of power applied. The amount of movement could be small or great depending on the density of the mount. So basically there is a spun shaft on a flexible mount that will change it's angle and center, being driven by a flexibly mounted engine with admitted vibration issues, joined by a very nice coupling that dampens the vibes and accepts misalignment. There will be no middle ground on the results at all, It will be smooth as butter or go to hell in seconds. I'm rooting for smooth but advance the throttle slowly on the first tryout.
Aha-Ask yourself how a saildrive transmits it's fwd(rev) thrust to the vessel.
or a shaft drive,for that matter. In small hp boats-via the engine mounts.
In hi hp vessels-via a thrust bearing securely fastened to hull & shaft.

/ Len
__________________
My personal experience & humble opinions-feel free to ignore both
deblen is offline   Reply With Quote
Old 04-05-2016, 21:12   #80
Registered User
 
sgancarz's Avatar

Join Date: May 2014
Location: Racine, WI
Boat: Paceship PY26
Posts: 59
Re: Yanmar V-twin diesel conversion of OMC Saildrive

Quote:
Originally Posted by Jesse View Post
I just noticed the lower unit is in a flexible mount. I hadn't realized that before. So as power is increased to the propellor the shaft angle will change, which in turn will change the location of the upper end of the shaft proportionally to the amount of power applied. The amount of movement could be small or great depending on the density of the mount. So basically there is a spun shaft on a flexible mount that will change it's angle and center, being driven by a flexibly mounted engine with admitted vibration issues, joined by a very nice coupling that dampens the vibes and accepts misalignment. There will be no middle ground on the results at all, It will be smooth as butter or go to hell in seconds. I'm rooting for smooth but advance the throttle slowly on the first tryout.
This has been a concern of mine since the beginning. I originally wanted to mount the engine directly to the top of the drive leg, but not sure the Iso-Ring could handle the weight and additional torque of the diesel. So I opted for the current configuration.

With the addition of the Para-flex coupling, I think I am going to be ok. The Para-flex can handle up to 4 degrees and 1/8" of misalignment. The Iso-Ring seems to be pretty rigid, so not sure there will be much movement there, but once I get it mounted in the boat I plan on taking some measurements of the actual movement.

The plan is to mount a dial indicator on the mounting base and push and pull on the lower unit to see how much movement I actually get at the end of the input shaft.
__________________
sgancarz is offline   Reply With Quote
Old 06-05-2016, 13:46   #81
Registered User
 
Jesse's Avatar

Join Date: Apr 2008
Location: Oro Bay Puget Sound
Boat: Irwin sloop
Posts: 374
Re: Yanmar V-twin diesel conversion of OMC Saildrive

The plan with the dial indicator should tell a lot. Can the ISO-RING be compressed at all? That might offer some adjustment in its rigidity.
__________________
Jesse is offline   Reply With Quote
Old 06-05-2016, 16:21   #82
Registered User
 
sgancarz's Avatar

Join Date: May 2014
Location: Racine, WI
Boat: Paceship PY26
Posts: 59
Re: Yanmar V-twin diesel conversion of OMC Saildrive

Quote:
Originally Posted by Jesse View Post
The plan with the dial indicator should tell a lot. Can the ISO-RING be compressed at all? That might offer some adjustment in its rigidity.
The Iso-Ring does compress between two halves of the lower unit and is also secured in place/sealed with 3M 5200. But as far as compressing it more that is not possible. It appears quite rigid the way it is, but then again I don't have a lot of leverage with it not being installed.

Maybe someone with previous OMC Saildrive experience could chime in on how much movement they have experienced?
__________________
sgancarz is offline   Reply With Quote
Old 17-05-2016, 16:56   #83
Registered User
 
malbert73's Avatar

Join Date: Jun 2008
Boat: Tartan 40
Posts: 1,032
Re: Yanmar V-twin diesel conversion of OMC Saildrive

How did this work?


Sent from my iPhone using Cruisers Sailing Forum
__________________
malbert73 is offline   Reply With Quote
Old 17-05-2016, 21:14   #84
Registered User
 
sgancarz's Avatar

Join Date: May 2014
Location: Racine, WI
Boat: Paceship PY26
Posts: 59
Re: Yanmar V-twin diesel conversion of OMC Saildrive

Actually still a work in progress. I am however, getting close. I hope to have the lower unit in by next week. Lots of moving pieces with this project. Lots of parts to source with lots of trial and error. Lately my nemesis has been the drive pulley for the raw water pump. On my third attempt and looks like I am going to have to do some machining to get this one to finally work.

The weather has not cooperated much this year either. Temps have been up an down here. Also had to take a week off for a much needed vacation.

Hopefully will get a chance to get some work done on it this weekend. I will try and post an update early next week.
__________________
sgancarz is offline   Reply With Quote
Old 27-05-2016, 22:51   #85
Registered User
 
sgancarz's Avatar

Join Date: May 2014
Location: Racine, WI
Boat: Paceship PY26
Posts: 59
Re: Yanmar V-twin diesel conversion of OMC Saildrive

Well the lower unit is finally in. I splash the boat first thing tomorrow morning. Still quite a punch list left before I can install the engine. But, hopefully there are no leaks tomorrow. Here are some pics of the lower unit installed and ready for the water.

Also I obtained a NOS OMC folding prop earlier this month on ebay. This is a great addition to the project.



__________________
sgancarz is offline   Reply With Quote
Old 28-05-2016, 05:23   #86
Registered User
 
deblen's Avatar

Join Date: Oct 2014
Location: Grand Manan,N.B.,Canada N44.40 W66.50
Boat: Mascot 28 pilothouse motorsailer 28ft
Posts: 1,400
Images: 1
Re: Yanmar V-twin diesel conversion of OMC Saildrive

Quote:
Originally Posted by sgancarz View Post
Well the lower unit is finally in. I splash the boat first thing tomorrow morning. Still quite a punch list left before I can install the engine. But, hopefully there are no leaks tomorrow. Here are some pics of the lower unit installed and ready for the water.

Also I obtained a NOS OMC folding prop earlier this month on ebay. This is a great addition to the project.



Nice workmanship!

It appears that the Iso-ring hull seal carries the full weight & torque of the engine.
In a normal horizontal engine/saildrive setup,the engine would be on 4 engine to hull mounts.
Perhaps you will need 4 more mounts between your adapter & the hull?

Cheers/ Len
__________________
My personal experience & humble opinions-feel free to ignore both
deblen is offline   Reply With Quote
Old 28-05-2016, 06:00   #87
Registered User
 
sgancarz's Avatar

Join Date: May 2014
Location: Racine, WI
Boat: Paceship PY26
Posts: 59
Re: Yanmar V-twin diesel conversion of OMC Saildrive

Actually the Iso Ring will only be carrying the weight of the lower unit. The adapter sits on top of the original mounting plate which mounts to the fiberglass foundation that is molded into the Hull. The engine will then be supported on the four mounts atop the adapter.

The engine only weighs 120 pounds, so really don't need the heavy stringers normally associated with a big cast iron diesel.
__________________
sgancarz is offline   Reply With Quote
Old 28-05-2016, 08:37   #88
Registered User
 
deblen's Avatar

Join Date: Oct 2014
Location: Grand Manan,N.B.,Canada N44.40 W66.50
Boat: Mascot 28 pilothouse motorsailer 28ft
Posts: 1,400
Images: 1
Re: Yanmar V-twin diesel conversion of OMC Saildrive

Quote:
Originally Posted by sgancarz View Post
Actually the Iso Ring will only be carrying the weight of the lower unit. The adapter sits on top of the original mounting plate which mounts to the fiberglass foundation that is molded into the Hull. The engine will then be supported on the four mounts atop the adapter.

The engine only weighs 120 pounds, so really don't need the heavy stringers normally associated with a big cast iron diesel.
Gotcha! / Len
__________________
My personal experience & humble opinions-feel free to ignore both
deblen is offline   Reply With Quote
Old 28-05-2016, 15:36   #89
Registered User

Join Date: Feb 2013
Location: WY / Currently in Hayes VA on the Chesapeake
Boat: Ocean Alexander, Ocean 44
Posts: 922
Re: Yanmar V-twin diesel conversion of OMC Saildrive

Is one end of the U shaped mount made out of flat plate going to be boxed? We had a mount for made like that for a garage door operator and had much trouble until the designers stiffened the structure . I really think you need something in addition to the vertical plates for stiffness .
__________________
darylat8750 is offline   Reply With Quote
Old 28-05-2016, 15:37   #90
Registered User
 
Terra Nova's Avatar

Join Date: Apr 2007
Location: Marina del Rey, California
Boat: Freya 39 cutter- Terra Nova
Posts: 3,645
Re: Yanmar V-twin diesel conversion of OMC Saildrive

It must be boxed.
__________________

__________________
1st rule of yachting: When a collision is unavoidable, aim for something cheap.
"whatever spare parts you bring, you'll never need"--goboatingnow
"Id rather drown than have computers take over my life."--d design
Terra Nova is offline   Reply With Quote
Reply

Tags
diesel, omc, sail, saildrive, yanmar

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
OMC Saildrive ? goofy57 Monohull Sailboats 3 06-08-2016 21:12
OMC Zephyr Saildrive _floater_ Propellers & Drive Systems 12 18-09-2015 06:09
Conversion of Saildrive to hybrid diesel electric mstrebe Monohull Sailboats 1 30-03-2015 02:05
Winterizing an OMC Saildrive and engine JimJohnston Engines and Propulsion Systems 0 04-11-2014 09:18
Twin Gas vs Single or Twin Diesel Banjohans Engines and Propulsion Systems 4 04-10-2011 11:50



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 19:50.


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.