Offshoreonly.com

Offshoreonly.com (https://www.offshoreonly.com/forums/)
-   Drives and Lower Units (https://www.offshoreonly.com/forums/drives-lower-units-217/)
-   -   Can this break drives? (https://www.offshoreonly.com/forums/drives-lower-units/373492-can-break-drives.html)

resurrected 09-27-2021 06:34 AM

Can this break drives?
 
It was an unusually calm day for Huron a week ago, so my brother wanted to try out his drone (still trying to edit that footage). I mounted a camera on the dash to get some audio to go with the drone footage.
My question is when the prop gets aired out enough to roost and pickup a little RPM but not leave the water completely, how much does this stress the drive?
I have only had this happen once before, these conditions are unusual for here and I was trimmed a little higher than normal, I think because of the green hair and scum on the bottom of the boat from sitting in the water all summer.
Examples are at about 3:11, 3:40 and 3:55
SSMIII drives, 4 blade props and 620HP, running around 85 at peak, I haven't pulled data yet to see what the RPM spike was.



ThisIsLivin 09-27-2021 08:44 AM

I hope not, I run like that a ton.

fossil fuel 09-27-2021 09:37 AM

yes and yes and yes. If you watch race videos when the throttleman is momentarily pulling back the throttles that is to save the drives. anytime the boat launched ideally you want to re enter that water at the same rpm you left the water. This reduces the shock load on the gears. Takes a bit of practice.

Sydwayz 09-27-2021 09:47 AM

Just backing the boat off the trailer can break drives.

So yes, that can break them too. Especially with 5 and 6 blade props. The lower the slip numbers, the more bite, the more shock load on the drive internals.

resurrected 09-27-2021 10:53 AM

Thank you for the responses.
The boat was not really launched in the conventional sense, there was no seat of the pants indication that the drives would be aired out. The waves were 8" to 10" swells with sets in a real tight frequency, and this seems to happen as the boat went over the sets and bridged the trough.

thirdchildhood 09-27-2021 10:55 AM

I do it all the time. No one can be perfect on the throttles.

F-2 Speedy 09-27-2021 11:00 AM

I didnt hear any zinging of the motors so I think your fine, I had way worse than that runnin in the LOTO slop............:D

Griff 09-27-2021 08:36 PM

You prob only have some 200-300 rpm spikes, so I would not be too concerned.
Its when you get the 1000+ rpm spikes and re enter the water at the higher rpm that it gets really hard on drives.

SabrToothSqrl 09-28-2021 09:22 AM

ALL IN PROPS OUT!

is on the back of our shirts for our boat.

It's in/out of the water so often and so fast there's nothing I can do about it. But luckily they are Bravo 1s behind a 350, pushing a 29' boat... so... kinda overkill? Which is good!

resurrected 09-29-2021 06:30 AM

Thank you for the reassurance. I suspected that it was not a huge load on the gears (otherwise I would have stopped after the first one!)
I just installed these drives last spring and they looked like brand new inside and out, and I would like to keep them that way!


All times are GMT -5. The time now is 04:16 AM.


Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.