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Sailmonkey · 15-08-2022, 06:05

Quote:

Originally Posted by Gumshoe

Sailmonkey, not being an engineer, I am a little puzzled as to how one engine would bear more load than the other after the RPMs are matched and the clutches are engaged?? The gearbox consists of 3 gears only…one each from the clutches input and a much larger gear in between that connects the two together…this larger gear outputs to the prop shaft…if the only source of loading the engines comes from the single larger prop shaft gear in the center, Leads me to believe the load is equally shared until one engine’s RPM shifts…what is most puzzling is that this system operated successfully for approximately 25 years in the Baltic Sea…The Volvo-Penta tachs are analog with 100 RPM scales so the crew MUST have relied heavily on matching the two EGT gauge readings…I have, in parallel, installed very accurate digital tachs which are a tremendous help but Still need to adjust throttles rather constantly by EGT readings to maintain a balance…

Typically the rpm matching with the throttles is done using a master/slave configuration. But if both engines are hard coupled together, one may be loafing along, while the other provides most of the torque required to turn the shaft. You’ve seen this with the EGT’s, yet the engine speeds were the same.

With the throttles matching the engine RPM, there is no reason for the slave throttle to increase the throttle setting because the slave engine is already turning at the same rate as the master engine.

There may be some software that keeps the throttle position within a certain percentage of the other, but that’s not going to share the load evenly.

Kobelt may have an answer to this that doesn’t cost commercial money, but it’s not a pleasure craft style of installation. My experience with this type of arrangement has been with engines considerably larger than what you’re working with.

Gumshoe · 15-08-2022, 06:31

Sailmonkey, thanks for the input it is definitely helping me understand the issue…you are correct in that the tachs will read the same RPM after clutch engagement occurs…as I discovered during sea trials, I was unable to use them for comparison…in concentrating on my digital tachs I was able to detect a small RPM mismatch…if a electronic throttle system is installed that syncs by RPM comparison rather than by actuator position would not the sync mode constantly attempt to match RPMs effectively even a very small differential say 5-10 RPMs??

Sailmonkey · 15-08-2022, 06:54

Quote:

Originally Posted by Gumshoe

Sailmonkey, thanks for the input it is definitely helping me understand the issue…you are correct in that the tachs will read the same RPM after clutch engagement occurs…as I discovered during sea trials, I was unable to use them for comparison…in concentrating on my digital tachs I was able to detect a small RPM mismatch…if a electronic throttle system is installed that syncs by RPM comparison rather than by actuator position would not the sync mode constantly attempt to match RPMs effectively even a very small differential say 5-10 RPMs??

Your RPM were only different because the gauges were slightly different.

Every synchronizer I’ve ever seen isn’t accurate to 1-2 RPM anyway. Moving a throttle for 5 rpm is almost impossible to achieve too.

Gumshoe · 15-08-2022, 07:10

Sailmonkey…I have actually been considering these same issues and it is pushing me to EGT readings to control RPMs…I will check out Kobelt for solutions…thanks again !!

Gumshoe · 15-08-2022, 12:46

I may be getting closer to a workable solution
https://binsfeld.com/how-to-measure-...existing-shaft

**skipperpete** · 15-08-2022, 18:39

Quote:

Originally Posted by Gumshoe

I may be getting closer to a workable solution
https://binsfeld.com/how-to-measure-...existing-shaft

That solution looks like it has merit but sounds expensive.

goboatingnow · 15-08-2022, 18:47

Quote:

Originally Posted by Gumshoe

I may be getting closer to a workable solution
https://binsfeld.com/how-to-measure-...existing-shaft

can you easily access the individual engine shafts ?

Gumshoe · 16-08-2022, 08:04

goboatingnow…I can but I believe there is limited space to set up the system that is designed for constant monitoring…one of their techs will be calling me in a few days and I expect to have some answers I will post

Sailmonkey · 16-08-2022, 08:55

Quote:

Originally Posted by Gumshoe

goboatingnow…I can but I believe there is limited space to set up the system that is designed for constant monitoring…one of their techs will be calling me in a few days and I expect to have some answers I will post

Do you have any photos of this setup?

Last one I saw was connecting a pair of wartsilla medium speed engines together. Not the most compact thing.

Gumshoe · 16-08-2022, 12:21

Sailmonkey, I do have a number of photos but I am somewhat computer challenged in getting them from my ipad albums into this forum…any suggestions would be helpful…

Sailmonkey · 16-08-2022, 12:24

If you’re using the app, click the plus next to the reply text box, then click the thing that looks like a photo of mountains, you should now have the option to select a photo(s).