Globe Drivesaver worked as designed

Somehow, no idea how, a bow line ended up in the prop. Discovered I had no reverse, went back and forth, regained reverse, but port engine hi temp alarm went off. Light goes off and I pulled in remains of 3/4" bow line.
Shaft cutters apparently worked, sort of. Globe Drivesaver now looks like a potato chip. Hate to think of what my transmission would have looked like. Guessing the damper spline would give first.

Diving on the prop tomorrow. New Drivesaver on order.

Kinda depends.


I have had several motors choked off by running aground, heck the assistance boat was choked off probably 50-100 times in the 15 years I ran it. And have seen plenty more.



Borg Warners and Twin Discs...neither ever showed damage.


I wonder what types of incidents does it really take to damage a tranny or what trannys are susceptible?


I have heard of wrapped lines pulling engines off mounts too. Funny how it's not consistent.

psneeld said:

Kinds depends.

I have heard of wrapped lines pulling engines off mounts too. Funny how it's not consistent.

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That happened to a friend of mine on his MT 38. Attempting to grab a mooring at Block Island. Wife had a line set up on the gunnel and it fell overboard. When the boat backed to do a second try for the ball, the line tangled in his prop and pulled the mounts.
He had to get towed back to Mystic.

I wrapped a 5/8 nylon 3 strand slip rope around my prop in my slip long ago.
It yanked boat over hard against a wood piling, and snapped the line and engine was simply idling in gear.

Left over slip rope looked badly frayed where the propr cut it. That was not a new rope, I had used it a long time.

Nothing happened to anything except I had a section of rope around the shaft and prop. I used the boat a few more months and when I hauled, it was like a rope blob. Jammed on so tight I cut it off with a blade.

After that I made sure all line I placed up over the piling tops when I took out boat from slip.

I also learned you cant trust non boating people to know what to do with your lines.
Even though it was my responsibility to check, they just dropped them in the water when we left for the day and I forgot to check the lines.
My friend Rodney who had done that dove under the boat, but it was useless, said he could not stay down to cut the rope off. I mean it was still my fault t happened.

Generally the more of a shock load something gives, the more chance there is of something breaking.



If it just gets loaded up to the point of stalling (especially at idle), it'll likely stall before stuff breaks (even more so with a carbed gas engine that won't throttle up to try to keep idle speed).



If the prop hits something and stops suddenly, there's a much greater chance of something snapping.

I thought the DS was supposed to shatter. That you can drive home.

If that saver had done its advertised job, the shaft would be parted from the output flange. I had that experience recently. The bolts molded into the saver ripped right out of the hard rubber. Looking at the distorted saver suggests to me that something has been bent, either the shaft or the output flange, or both. If it were I, I wouldn't simply replace the saver. I would also have the shaft pulled to check for staightness and realign the engine, in the water.

Replace the saver and use a blank to check for vibration/alignment before you pull everything....no reason to assume something is bent yet

Better idea but what do you mean by a "blank"? A spacer I assume? Sure, install the spacer and check alignment. In any case, that picture sure is disconcerting.

psneeld said:

Replace the saver and use a blank to check for vibration/alignment before you pull everything....no reason to assume something is bent yet

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Diver removed the rest of the line wrapped around the shaft today. Shaft runs true at stuffing box, wobbles at Drivesaver as expected. Would quickly destroy reduction gear bearing and seal if run for any length of time. I will check carefully after installation of new saver.

Shaft cutter (Spurs) stationary cutter ring is gone. Not surprised. It isn't designed to cut through 3/4" line. Something had to give. Interesting comments about what should happen with Drivesaver. I agree, engine would typically stall with rope around shaft without a saver. If rope is wrapped around shaft like an iron band I would expect saver to shear.

In this case I could turn shaft with pipe wrench so decided to use engine to return to marina. Engine got pretty toasty (247 just below injectors, Infrared on Lehman 90, close to head warping range) so shutdown and Seatow put me back into slip. In theory I should have boiled over at 235 and blown a hose. Dash alarm went off at 220 but hard to hear due to engine noise. Will probably install a relay to trigger a high pitched alarm and an LED.

This is not a good result. If the shaft wobbled at the saver that means the shaft is bent. You say that the shaft could not be rotated without the use of a pipe wrench. That suggests to me that there was a LOT of binding going on at the transmission because of a bent shaft. I say that because of a very similar experience. Aftercreplacing a blown saver, I started my engine and observed for 10 seconds before running up and shutting down the engine. Plus, you overheated the engine to a dangerous level. As a result, by running the engine you now may have ruined your engine and the transmission. The transmission can be replaced at moderate cost, the engine not so much. I don't get it. Just looking at that damaged assembly one can see that could be something significantly wrong. Question. While running was thectransmission making howling sounds?

Perhaps I am completely wrong here and I apologize if I am way off base but ...

SoWhat said:

Diver removed the rest of the line wrapped around the shaft today. Shaft runs true at stuffing box, wobbles at Drivesaver as expected. Would quickly destroy reduction gear bearing and seal if run for any length of time. I will check carefully after installation of new saver.

Shaft cutter (Spurs) stationary cutter ring is gone. Not surprised. It isn't designed to cut through 3/4" line. Something had to give. Interesting comments about what should happen with Drivesaver. I agree, engine would typically stall with rope around shaft without a saver. If rope is wrapped around shaft like an iron band I would expect saver to shear.

In this case I could turn shaft with pipe wrench so decided to use engine to return to marina. Engine got pretty toasty (247 just below injectors, Infrared on Lehman 90, close to head warping range) so shutdown and Seatow put me back into slip. In theory I should have boiled over at 235 and blown a hose. Dash alarm went off at 220 but hard to hear due to engine noise. Will probably install a relay to trigger a high pitched alarm and an LED.

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I think the jury is still out on this one.

One possibility is that the saver did do its job and the reason that it is buckled is that it bent before the shaft. Why didn't it break? Possibly it was just a fraction of a second from doing that.

Another possibility is that the shaft bent or transmission broke before the shaft saver broke, and so it didn't do its job in protecting the shaft.

Another (seemingly far less likely) possibility is that there was another problem in the system, such as weak struts that bent before the saver or the shaft and messed things up. When I bought my Californian, I had to replace both main struts. One of them was bent from an apparent rope entanglement. It was too sponge like to be worked (it must have had zinc in the "bronze"?), so I replaced both. The shaft was only slightly out of true and there was no damage elsewhere. (I ended up replacing both shafts due to corrosion at the stuffing boxes).

I hope SoWhat (I think the OP) lets us know the end of the story after it unfolds. I'm certainly sorry for the trouble!

catalinajack said:

This is not a good result. If the shaft wobbled at the saver that means the shaft is bent. You say that the shaft could not be rotated without the use of a pipe wrench.

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Pipe wrench was used to determine why engine was overheating. Concluded line was wrapped around shaft due to difficulty turning it. Now that diver has removed the line, shaft turns freely. I ran engine in reverse and forward for a few minutes to determine if any damage was apparent. None noticed.

The transmission was and still is whisper quiet (I rebuilt it with all new bearings) and engine sounds fine. No vibrations or any strange noises. Transmission coupling ran true and engine mounts OK. I didn't want to push things because the out of round drivesaver will trash my rear bearing and seal. Once I replace it I will align couplings to spec and run it at the dock for thorough testing.

I agree with the opinion that the saver was seconds from shearing. Velvet drives are massive and although the spurs didn't cut through they probably abraded the line enough to weaken it. I will update this post when new drivesaver arrives.

Hey SoWhat,

You are actually the first person I know who actually has these. I some questions for you, if you don't mind:

1) If this were a "get home" situation, could one remove the DriveSaver and reattach the shaft to the transmission "in water"? (Assuming one kept the original bolts, etc, even if they aren't used in DriveSaver install).

2) I'm assuming that the port and starboard DriverSavers are the same, so one could keep a 3rd one aboard as a spare?

Thanks so very much!

-Greg

SoWhat said:

Somehow, no idea how, a bow line ended up in the prop. Discovered I had no reverse, went back and forth, regained reverse, but port engine hi temp alarm went off. Light goes off and I pulled in remains of 3/4" bow line.
Shaft cutters apparently worked, sort of. Globe Drivesaver now looks like a potato chip. Hate to think of what my transmission would have looked like. Guessing the damper spline would give first.

Diving on the prop tomorrow. New Drivesaver on order.

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Looks like the shaft simply pulled back.

gkesden said:

1) If this were a "get home" situation, could one remove the DriveSaver and reattach the shaft to the transmission "in water"?

Maybe. Depends on how far your prop is from the strut. In my case no. I would have to pull the shaft 1" forward and I have spurs installed so little bare shaft behind strut.

Note that you have to push the shaft back a few inches to install the Allen bolts onto the Transmission coupling. Then pull the shaft coupling tight to the saver and install the hex bolts.

2) I'm assuming that the port and starboard DriverSavers are the same, so one could keep a 3rd one aboard as a spare?

I have 1 1/2" shafts and use 504 savers. They are interchangeable. $300 ea. My spare is Seatow.

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-Gary

Hi Gary,

Thanks so much!

(My questions probably hint at my own estimation of how this will have turned out in the end...)

Thanks again!
-Greg

gkesden said:

Hey SoWhat,

You are actually the first person I know who actually has these. I some questions for you, if you don't mind:

1) If this were a "get home" situation, could one remove the DriveSaver and reattach the shaft to the transmission "in water"? (Assuming one kept the original bolts, etc, even if they aren't used in DriveSaver install).

2) I'm assuming that the port and starboard DriverSavers are the same, so one could keep a 3rd one aboard as a spare?

Thanks so very much!

-Greg

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If you have enough room between the prop and cutlass you could drop the DS out and limp home.

I'm still trying to visualize how these things work...

Let's say I have enough shaft now (I do), I unbolt it, push it back, drop one of these in, and bolt it back up. Now, I've got one of these installed, right? That is all there is to it?

Now, let's say I catch a rope. Ouch! And it deforms or breaks as designed. Supposing nothing bad happens when my engine goes from a cruise load, to a huge load, to no load in seconds (this sounds like a bit of stress on all the important stuff), getting going again seems like it'd be really easy.

Snorkel and cut off rope (easy, right?) Unbolt DriveSaver. Remove it. Slide in a bolt up new drive saver. Or, alternately, just slide shaft forward and bolt up. Rotate shaft with wrench as needed, of course.

So, I guess I am wondering. Even if I didn't have a spare, why would I be limping? Wouldn't I just be good to go?

gkesden said:

I'm still trying to visualize how these things work...

Let's say I have enough shaft now (I do), I unbolt it, push it back, drop one of these in, and bolt it back up. Now, I've got one of these installed, right? That is all there is to it?

Now, let's say I catch a rope. Ouch! And it deforms or breaks as designed. Supposing nothing bad happens when my engine goes from a cruise load, to a huge load, to no load in seconds (this sounds like a bit of stress on all the important stuff), getting going again seems like it'd be really easy.

Snorkel and cut off rope (easy, right?) Unbolt DriveSaver. Remove it. Slide in a bolt up new drive saver. Or, alternately, just slide shaft forward and bolt up. Rotate shaft with wrench as needed, of course.

So, I guess I am wondering. Even if I didn't have a spare, why would I be limping? Wouldn't I just be good to go?

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See installation instructions at https://www.globemarinedirect.com/category-s/184.htm

There are other brands of flexible couplings but Globe came with my boat. If they shear, they are toast. Prop is disconnected and they must be replaced.
If they distort, (as mine did into a potato chip shape) then you might be able to go a short distance at very low speed. The distorted saver will rotate with an oblong motion rather than a circular motion and will ruin transmission thrust bearings and rear seal. Proceed at your own risk.

Unlikely you will be able to cut line with a snorkle. Several years ago I hooked a pot warp. Stern was crashing down from 6-8' up. I was under it with a snorkle and a knife trying to saw through the line. Extremely dangerous situation.

I finally hooked line with a grapnel and winched it up so I could saw through it. A line wrapped around your shaft will be like iron. You will need a serrated blade, a utility razor, and a screw driver. If you don't drop anything it will take 30-60 minutes to clear.

Having a spare saver is no help until wrapped line is removed. Having a complete scuba rig onboard would have helped in a remote location but Seatow was 15min away so was best option.

Maybe you would be good to go. But even with the drive saver you may still have some damage to the prop or shaft. But if there is damage it should not be as bad. We have a different version on our boat. They have a couple of metal brackets that are supposed to hold together if the rubber breaks in order to let you limp home. I have a photo of mine but the photo isn’t really good.

Hey SoWhat,

I agree cutting the line off is likely a tough job. Been there. Done that. It wasn't fun -- and conditions were quite good. Also, I cut it off with a hand (not power) saw and knife. The saw helped a lot. My ("Easy right?") comment was very tongue-in-cheek!

But, from those instructions, it does look like nothing else being broken and the rope being cleared, the DriveSaver can be replaced in water, such as at a nearby mooring or transient slip, or protected anchorage, which was my curiosity.

Thanks again, so very much!

-Greg

SoWhat said:

Somehow, no idea how, a bow line ended up in the prop. Discovered I had no reverse, went back and forth, regained reverse, but port engine hi temp alarm went off. Light goes off and I pulled in remains of 3/4" bow line.
Shaft cutters apparently worked, sort of. Globe Drivesaver now looks like a potato chip. Hate to think of what my transmission would have looked like. Guessing the damper spline would give first.

Diving on the prop tomorrow. New Drivesaver on order.

Click to expand...

I would not draw the conclusion that the DS saved the day, if it did it would have sheared completely, just deforming is not likely to have absorbed enough shock to prevent damage to the gear, and I'm not sure this would have damaged the gear.

IMO, products like the DS are a weak link in the drive train, and they make alignment very difficult unless you have a machined shim to insert between the flanges. If you can bring the two coupling halves together without the DS installed, the overhang aft of the Cutless bearing is probably too great (shouldn't be more than 1 to 1.5 shaft diameters), and if you have Spurs then there's no room to bring the coupling faces together. In the event of a DS failure, you should be able to remove it and keep going, that requires either a shim (available from Spurs) or enough clearance to move the shaft coupling forward.

More on couplings https://stevedmarineconsulting.com/wp-content/uploads/2019/06/ShaftCouplings179FINAL-PBB.pdf

Steve DAntonio said:

I would not draw the conclusion that the DS saved the day, if it did it would have sheared completely, just deforming is not likely to have absorbed enough shock to prevent damage to the gear, and I'm not sure this would have damaged the gear.

IMO, products like the DS are a weak link in the drive train, and they make alignment very difficult unless you have a machined shim to insert between the flanges. If you can bring the two coupling halves together without the DS installed, the overhang aft of the Cutless bearing is probably too great (shouldn't be more than 1 to 1.5 shaft diameters), and if you have Spurs then there's no room to bring the coupling faces together. In the event of a DS failure, you should be able to remove it and keep going, that requires either a shim (available from Spurs) or enough clearance to move the shaft coupling forward.

More on couplings https://stevedmarineconsulting.com/wp-content/uploads/2019/06/ShaftCouplings179FINAL-PBB.pdf

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Here is a picture of the machined coupling I obtained from the Spurs company to replace the DriveSavers we had. They machine it to the precise dimensions of their DriveSaver. It can be used to line up the shafts and replace it with a DriveSaver coupling or it can be used to eliminate the coupling. Obviously, I chose to eliminate them. The yard was able to line up one engine within .003 inch, the other to within .005 inch. This is within tolerance of .006 inch for a six-inch flange. Our boat now runs smoooooth after new cutless bearings, shaft straightening, and prop tuning. Couldn't be happier. Steve D. says that it is very difficult to align shafts with the DriveSaver in place. Makes sense with an acceptable tolerance of just .006 inch. Remember, the hard rubber surface of the Drivesaver cannot possibly be as precisely flat as a machined spacer, IMHO.

By the way, I hate DriveSavers. What caused me to replace them was this. I ran up on a sandbar at low tide at the exit from an anchorage. Nothing behind me so I tried to back off. The boat started to move so I gave it more throttle. Well, the DriveSaver fractured on one side. Here's what you need to know. They are rated for a maximum torque. I obviously exceeded that torque and you know the rest of the story, well, not the whole story. I suspect that when the shaft parted from the flange that it whipped around and got bent. No way of knowing for certain. Some folks swear that they eliminate the last vestiges of a vibration. Perhaps, but my assessment is that vibrations should be able to be eliminated without "artificial assistance". If it were I, I would get the spacer from Spurs and off the DriveSaver. However, if you really, really want to keep the Drivesaver, I have a brand new #504 in my spares inventory that is useless to me.

3/4" - wow! Watched Towboat pull a 40' Sea Ray into the slings in 2017. Two 2" gas pumps running on the swim deck pouring water like mad. Out of the water stbd strut had been yanked out of the hull leaving a 16x6" tear in the bottom.
He wrapped a mid ship line. It wasn't 3/4", but smaller.

Driver Saver seems like snake oil. I got a 1/2" nylon line from a mooring buoy system level-wound between my stbd prop hub and the aft strut (two struts per shaft) which pulled the prop aft and the strut forward while bending three motor mounts on the FL 120/Borg Warner combination. Why the wooden hull strakes did not fracture and just sink the boat right there, I do not know. Snorkel and hacksaw required to cut the steel-hard nylon clear. All my car jacks and some short lengths of chain were required to lift the engine a few inches and replace the mounts. Shaft was hard to turn, but not bent. A haul out later on reseated and aligned the strut. The tranny? No problem. Still didn't see need for a DS.

It appears from the picture that the wrapped line forced the shaft away from the transmission, causing the plastic drive saver to dis-taught.

I picked up some discarded ground line in the Rupert harbour at low tide (very strong line used in long line commercial fishing). It wrapped my prop while the engine was idling in reverse (to cool my freezer pipes).

The engine was a 210hp V8 Cat. The drive shaver shattered but not before the stuffing box was ripped out. Obviously it was not a simple matter of joining the couplings back together with the original bolts, which I still had on board, and sailing away. Was towed to a ship yard. My pumps kept up control till I was lift out the following morning.

Maybe the drive saver saved some additional damage as the shaft was not bent? No way of knowing though? I suspect the shaft whipped before the drive savor shattered which was why the stuffing box was ripped out?

I bought a new drive savor but never did install it.

I think in a 2 or 3 cylinder engine, a line around the shaft will stall the engine.
In a 4 cylinder (such my P90 lehman with 1 3/4" shaft) the drivesaver distorted.
6 and 8 cyl engines are more powerful so the torsion and shear forces at work are much greater thus tearing out mounts and stuffing boxes before the drivesaver breaks apart.

The limited anecdotal data would seem to indicate that Globe's claims that drivesaver will save your transmission and engine might be a bit misleading. If your boat sinks because your struts or shaft log tears out then your engine is not going to be saved. It will sink along with the rest of the boat.

In my case, PO installed them and I will keep them. I have everything back together but need to buy a dial indicator to measure TIR. I didn't notice any new vibrations or thumping but with Lehman soft mounts it's hard to tell.

I know a lot of boats wih big block gas or 300+hp Diesels that have choked motors without doing damage.


Especially from just lines wrapping.


Not saying it won't happen...just that it doesn't automatically mean it will cause damage.