Drive Savers?

[angus99]

Thinking of having them installed on our Lehmans while we’re out for a bottom job. Any thoughts—pro or con? Are any brands considered better than others . . . or to be avoided?

Thanks in advance.

 

[RT Firefly]

Greetings,
Mr. 99. We have them on our boat, twin Lehmans but I have no idea what the make is nor if they work. They are hard plastic and quite rigid. I think there ARE some models which allow for more than the .003" alignment requirements so that might be an advantage IF you're a bit out or if you have a vibration issue. $.02...

 

[menzies]

Sonas has these.

Welcome to Aquadrive

 

[angus99]

Thanks, guys.

RT, I may be mistaken, but think they only “work” when they shatter after you hit something. . Just to add another wrinkle which won’t relate to drive savers, do you get much vibration in the boat when idling?

Menzies, are yours mounted to Lehmans? Do you have the “soft” engine mounts and can you tell if they’re actually reducing vibration?

 

[menzies]

Thanks, guys.

RT, I may be mistaken, but think they only “work” when they shatter after you hit something. . Just to add another wrinkle which won’t relate to drive savers, do you get much vibration in the boat when idling?

Menzies, are yours mounted to Lehmans? Do you have the “soft” engine mounts and can you tell if they’re actually reducing vibration?

No, small Luggers. But I don't believe the powerplant matters.

I can't compare before and after because they were there when we bought the boat. However there is zero noticable vibration.

 

[DDW]

Sonas has these.

Welcome to Aquadrive

The Aquadrive is not a simple retrofit. Drivesavers usually are.

 

[obthomas]

I have drive savers. I put them on. One of my engines had been removed for fuel tank work and when it went back there was some wobble. I adjusted and got rid of the wobble. I added the shaft savers as insurance. They are soft enough to deal with minor misalignment. I consider them flexible couplings. They would be a good addition to any boat.

 

[syjos]

I have a Federal Flexible Coupling on Sandpipers single FL 120.

It made a slight improvement in reducing vibration. Not a huge amount.

New motor mounts reduced the vibration a lot.

The biggest vibration reduction was installing a 200# flywheel.

 

[syjos]

I have a Federal Flexible Coupling on Sandpipers single FL 120.

It made a slight improvement in reducing vibration. Not a huge amount.

New motor mounts reduced the vibration a lot.

The biggest vibration reduction was installing a 200# flywheel.

 

[angus99]

I should have mentioned, I have new motor mounts, but there is significant vibration when the two engines are idling and possibly working against one another. It mostly disappears when I engage the synchronizer, so I’m guessing drive savers wouldn’t have much impact on vibration one way or the other. The engines are due for a valve adjustment and possibly injector service, so maybe that will help with vibration.

 

[SoWhat]

There are a number of prior threads on drivesavers.

I have run over pot warps on boats with and without. Engines stopped in both cases. Drivesaver turned into a potato chip. Maybe a 'soft' stop instead of a 'hard' stop?

I think spurs or some type of skeg extension would provide better protection.

 

[angus99]

I have a Federal Flexible Coupling on Sandpipers single FL 120.

It made a slight improvement in reducing vibration. Not a huge amount.

New motor mounts reduced the vibration a lot.

The biggest vibration reduction was installing a 200# flywheel.

Do these sacrifice themselves, like other drive savers, with heavy impact or are they just to dampen vibration?

 

[angus99]

There are a number of prior threads on drivesavers.

I have run over pot warps on boats with and without. Engines stopped in both cases. Drivesaver turned into a potato chip. Maybe a 'soft' stop instead of a 'hard' stop?

I think spurs or some type of skeg extension would provide better protection.

I have spurs and a full keel that is semi-protective but they didn’t keep me from wrapping a thick mooring pennant around one of the props on our first night with this boat. Stalled out the engine but we were luckily at idle speed.

 

[Nomad Willy]

syjos wrote;
“The biggest vibration reduction was installing a 200# flywheel.“

Some cars could use that treatment.

syjos how did you get a 200lb flywheel? Off the shelf I assume but if you modified a lighter fly (added to it?) or what? If it’s not off the shelf how’d ya get it?

Could be interesting. Like maybe there was a straight eight Lehman.

 

[Comodave]

We have/had them on our boat. I removed one on the port engine last winter when I had the engine out and will remove the starboard one this winter when I have that engine out. They don’t allow a good engine alignment and I don’t trust them if I hit something. YMMV...

 

[psneeld]

I have hit hundreds of things from rocks to logs to sunken boats working commercial salvage boats and think shaft savers are really not needed.

No commercial boat I have ever operated had them....almost all workboats that are in way more danger of hitting things than a recreational vessel.

If you hit something hard, they don't save your props and only maybe your shafts. Who here has had a tranny disabled from hitting something? I will bet some, but not more than half.

At least East Coast cruising....regular river driving, I can't comment on.

 

[DNT99611]

With a drive-saver you may or may not need to cut your drive shaft shorter. You can carry either a spare or a spacer if you need to replace it while traveling.
With an aquadrive you will need to shorten the shaft a bunch, and install a mount to hold all the thrust. The aquadrive will be expensive but they work great. If your shaft is worn and needs to be replaced cutting it for the aquadrive might allow it to be reused and that will offset some of the cost.

 

[angus99]

I have hit hundreds of things from rocks to logs to sunken boats working commercial salvage boats and think shaft savers are really not needed.

No commercial boat I have ever operated had them....almost all workboats that are in way more danger of hitting things than a recreational vessel.

If you hit something hard, they don't save your props and only maybe your shafts. Who here has had a tranny disabled from hitting something? I will bet some, but not more than half.

At least East Coast cruising....regular river driving, I can't comment on.

Thanks, Scott. Still pondering this.

Good to hear your experience but I’m guessing most commercial boats have bigger maintenance budgets than mine. Also, I’m wondering if tranny damage is always instantly apparent?

 

[angus99]

We have/had them on our boat. I removed one on the port engine last winter when I had the engine out and will remove the starboard one this winter when I have that engine out. They don’t allow a good engine alignment and I don’t trust them if I hit something. YMMV...

Generic drive savers or Syjos’s flexible couplings in post 9?

 

[Comodave]

When I removed the drive savers I had to get a spcaer made to fill the gap. I got it from Spurs, not cheap though. But the shafts are not long enough without the savers.

 

[syjos]

syjos wrote;
“The biggest vibration reduction was installing a 200# flywheel.“

Some cars could use that treatment.

syjos how did you get a 200lb flywheel? Off the shelf I assume but if you modified a lighter fly (added to it?) or what? If it’s not off the shelf how’d ya get it?

Could be interesting. Like maybe there was a straight eight Lehman.

I bought the 200# flywheel and bellhousing adapter 20 years ago. It was a Lehman accessory kit available into the late 90's. It is featured in the original Lehman catalog.

I bought the last three kits that were available. Installed one on Sandpiper and sold the other two to clients.

It required the shaft to be shortened and the rear motor mount moved aft. The other option would be to move the engine forward.

It reduced vibration significantly but the idle speed still needs to be 600 to 700 rpm.

I replaced the motor mounts first, which helped reduce vibration at idle a bit. The 200# flywheel was next and the combination of the two was the trick.

The Federal Flexible coupling was installed to mitigate "rumble" while at crusing speed. The rumble was caused be either hull flex or engine movement in a sea. The cause was not pinpointed but the rumble is a lot less with the flex coupling.

The Federal coupling does not protect drivechain from hitting something with the prop.

 

[syjos]

Do these sacrifice themselves, like other drive savers, with heavy impact or are they just to dampen vibration?

Just to dampen drive chain "rumble" from hull flex or engine movement.

Federal Flexible Couplings

https://federalmarinetransmissions.com/contact.html




.

 

[catalinajack]

And in my opinion they are nothing but trouble. According to Steve D'Antonio, he has never seen a DriveSaver save anything. Plus, they make it very difficult to do engine alignments with confidence that a sufficient level of precision has been reached.

Now, here is why I removed them and installed spacers made by the Spurs folks. Two years ago I nosed into a sandbar. I tried to back off. As the boat began to break free I applied morempower. No big deal, right? Oh, but it was a big deal. DriveSavers have a torque rating. That extra power ripped the bolts right out of the hard plastic thus parting the shaft from the transmission. We had to run 40 miles on one engine to Fort Myers. We pulled into Legacy Harbor Marina in the dark on Christmas Eve. I HATE drivesavers. By the way, I lost the saver on the other side in the sixth stair-step lock in Ottawa.

Ian, I know that you are doing drive-line work. When that DriveSaver failed on Christmas Eve, I later motored 25 more miles on one engine down to GULF marine Ways in Fort Myers Beach. The good folks there pulled my shafts, replaced the cutless baerings, sent the shafts out to check for trueness - they were not and they were straightened, Spurs machined spacers installed, engines realigned. All runs so smoothly compared to before. Don't do it. If you decide to do so, I have a nearly new DriveSaver on the shaft I will sell you for a really cheap price but I will say unequivocably that I wouldn't install them even if I got them brand new for free.

I have drive savers. I put them on. One of my engines had been removed for fuel tank work and when it went back there was some wobble. I adjusted and got rid of the wobble. I added the shaft savers as insurance. They are soft enough to deal with minor misalignment. I consider them flexible couplings. They would be a good addition to any boat.

 

[psneeld]

Thanks, Scott. Still pondering this.

Good to hear your experience but I’m guessing most commercial boats have bigger maintenance budgets than mine. Also, I’m wondering if tranny damage is always instantly apparent?

Actually not, some small businessmen spend way less than many here.

They just don't listen to boating rags or worry worts on the internet

 

[syjos]

The Federal Flexible Coupling:

Replaces shaft coupling - no need to shorten shaft

Handles angular and parallel misalignment

Neoprene absorbs torque and thrust loads

Neoprene inserts are replaceable

Dampens oscillating shaft vibration and rumble

 

[catalinajack]

New motor mounts? Have you aligned the engines after installation? I would think this needs to be done.

I should have mentioned, I have new motor mounts, but there is significant vibration when the two engines are idling and possibly working against one another. It mostly disappears when I engage the synchronizer, so I’m guessing drive savers wouldn’t have much impact on vibration one way or the other. The engines are due for a valve adjustment and possibly injector service, so maybe that will help with vibration.

 

[catalinajack]

Here are two pictures. One is the fractured DriveSaver I mentioned in an earlier post. The other is with the Spurs spacer in place.

 

[angus99]

New motor mounts? Have you aligned the engines after installation? I would think this needs to be done.

Yes, the motor mounts were installed three years ago and the engines/shafts have been aligned twice since then; once after I hit a submerged object.

 

[High Wire]

If you have them, carry a spare.

 

[timb]

If you have them, carry a spare.

ok another spare I need . I wonder if I can find a cheap one . with only one engine I'm going to be stuck if it breaks. I guess I could pull it and make a spacer to take it's place.