Anyone have experience with Shaft Loc?

[Mac2]

I've been debating weather or not to install shaft locks for my twin engines. Two reasons. I don't have electronic fuel injection and I end up cruising at very low rpm's in the ship canal/Seattle area, for hours, several times a year before I'm able to get out in the sound and open it up to burn the carbon out. With the Shaft Loc I could load the one engine to help reduce carbon build up. The second reason would be if I ever decided to make a multi day/week trip (maybe cross an ocean). I'm thinking I would save fuel, rest one engine, and if a engine was having problems, I could shut it down to fix it, or just continue on and not worry about smoking my transmission. Shaft Loc claims they have done studies showing a prop, rotating freely, creates more resistance than a prop that has been locked in place. Shaft Loc was originally designed for sailboats, but they have been installed on all sorts of boats. My questions for the forum is: Does anyone have experience with the Shaft Loc? Does anyone see a negative to installing these (keep

in mind I have put a engine in neutral and my boat tracked straight)?

 

[O C Diver]

For your current situation, I would leave one engine in neutral with maybe 1,000 RPM and run on the other engine. Then switch maybe every 30 minutes. This gives you the ability to immediately access the second engine if the propulsion engine or transmission fails. Certainly wouldn't want to be a close quarters situation with one shaft locked.

Ted

 

[Flatswing]

Perhaps start with your transmission requirements. My ZF manual advises fine to run for a few hrs freewheeling as but one example. At trawler speeds, you don’t need crossovers for the PSS either - the freewheeling side stays at ambient.
Your plan may well be worthwhile if you truly are crossing oceans, but for most of us, the “perils” of several hours at low rpm’s and the “economy“ of locking one shaft that we read about in different forums are perhaps overstated. If you feel it’s important to your cruising style, perhaps a large strap wrench or chain wrench on the coupler might accomplish the same thing?

 

[Mac2]

For your current situation, I would leave one engine in neutral with maybe 1,000 RPM and run on the other engine. Then switch maybe every 30 minutes. This gives you the ability to immediately access the second engine if the propulsion engine or transmission fails. Certainly wouldn't want to be a close quarters situation with one shaft locked.

Ted

They are designed to be disengaged when the engine is put in gear (I think they said you put it it reverse to release the spring loaded locking pin). I've never been able to get a response back from Twin Disc about the free wheeling. The slow cruising I am talking about would not involve any stressful situations. All I would need to do is start the engine, engage reverse for a moment and then I'm back to two engines.

 

[Mac2]

Perhaps start with your transmission requirements. My ZF manual advises fine to run for a few hrs freewheeling as but one example. At trawler speeds, you don’t need crossovers for the PSS either - the freewheeling side stays at ambient.
Your plan may well be worthwhile if you truly are crossing oceans, but for most of us, the “perils” of several hours at low rpm’s and the “economy“ of locking one shaft that we read about in different forums are perhaps overstated. If you feel it’s important to your cruising style, perhaps a large strap wrench or chain wrench on the coupler might accomplish the same thing?

I have the Tides Marine dripless seal that has the crossover for both engines, so the shaft seals will be cooled with one engine running.

 

[cafesport]

I made these when we bought the boat, there are two holes I use to align the locked shaft so that two blades of the propeller aligned vertically behind our skeg. When the shaft is locked the start key is placed in the engine room.


Since you have dripless seals you’ll want to make sure you can isolate the feed water. I know two sister ships that have hydro locked their shut down engine forgetting to do so.

 

[Mac2]

cafesport:
Nice clean setup. Not sure what you mean when you talk about hydro locking the engine and isolating the dripless shaft seal. There is a concern if you have the clam shell strainer on the raw water intake, which could force water into your stopped engine, but I have the sea chest, so not an issue.

 

[Mac2]

Spelled incorrectly: Should be Shaft Lok

 

[Larry M]

I installed one when we had our sailboat. I didn’t have good luck with it. To engage the locking pin, you had to be stopped and the propeller stationary. If the prop was freewheeling and you tried to lock the shaft, the locking pin would get damaged by the rotating ring that it was suppose to lock into. On a sailboat it was a pia. You’re motor sailing and the wind comes up and you want to shut off the engine and lock the prop, you have to stop the shaft from spinning to engage the shaft lok. I ended up removing it and going to a folding prop.

The web site looks the same as it was in the 90s.

Shaft Lok Inc.

The best way to lock the prop!

www.shaftlok.com

 

[Mac2]

I installed one when we had our sailboat. I didn’t have good luck with it. To engage the locking pin, you had to be stopped and the propeller stationary. If the prop was freewheeling and you tried to lock the shaft, the locking pin would get damaged by the rotating ring that it was suppose to lock into. On a sailboat it was a pia. You’re motor sailing and the wind comes up and you want to shut off the engine and lock the prop, you have to stop the shaft from spinning to engage the shaft lok. I ended up removing it and going to a folding prop.

The web site looks the same as it was in the 90s.

Shaft Lok Inc.

The best way to lock the prop!

www.shaftlok.com

Interesting. Designed for a sailboat, but in reality it would be much easier to engage with a powerboat.

 

[long-cours.62]

We had à system to "lock' our shaft on our Cheoy Lee 53, it was like à car disq, it was locked when the key of the engine was in stop and it open when you start the engine.
Are you sure than à locked propeller do less drag than free one ?
Fre ch désigner Joubert on his motor sailor 'Marguerite' put à...Sandow! Yes like witch one you have on bycicle , can fi d à cheapest way

 

[Larry M]

…Are you sure than à locked propeller do less drag than free one ?…

Some controversy on that. There are people who say lock and probably an equal number who say don’t lock.

When we installed ours, we were doing off shore passages on a sailboat. The off watch berth was ~2 feet from the running gear which was a Borg-Warner. With the prop spinning, the noise and the potential damage to the free wheeling running gear, it made sense to lock the prop.

 

[Xlantic]

Carbon can build up if the engine's operating temperature is not high enough. This can happen when running the engine in neutral for extended periods of time. I would think that running by in gear, even at low RPMs, the operating temperature goes to a normal level and carbon build-up is avoided.

Sport- and commercial-fishing boats troll for hours so it doesn't seem to be a major issue.

If unsure this is the case in the situation you describe I would first invest in EGT gauges to confirm. (If needed, you could consider occasionally deploying a drift sock or a trolling bag to increase RPM while controlling the boat speed.)

As for your second reason, I am also skeptical on the fuel-saving of running on one engine with the other locked. The inefficiencies that running with one prop locked seem so high – turbulence from the locked prop and compensating rudder angle – that I would think outweigh the savings of running on a single engine.

 

[Mac2]

Some controversy on that. There are people who say lock and probably an equal number who say don’t lock.

When we installed ours, we were doing off shore passages on a sailboat. The off watch berth was ~2 feet from the running gear which was a Borg-Warner. With the prop spinning, the noise and the potential damage to the free wheeling running gear, it made sense to lock the prop.

That was actually the motivation behind this invention-the noise of the free wheeling prop.

 

[Mac2]

As far as drag of fixed vs free wheeling prop is going to depend on the boat. A sailboat with a two blade prop that can lock it straight up and down behind the keel will of course have less drag. My 90 boat ton with full skegs in front of the props, will hardly notice weather the props are locked or not. So far I haven’t found a reason (other than they can’t fit or price is stupid) not to install them.

 

[Mac2]

Carbon can build up if the engine's operating temperature is not high enough. This can happen when running the engine in neutral for extended periods of time. I would think that running by in gear, even at low RPMs, the operating temperature goes to a normal level and carbon build-up is avoided.

Sport- and commercial-fishing boats troll for hours so it doesn't seem to be a major issue.

If unsure this is the case in the situation you describe I would first invest in EGT gauges to confirm. (If needed, you could consider occasionally deploying a drift sock or a trolling bag to increase RPM while controlling the boat speed.)

As for your second reason, I am also skeptical on the fuel-saving of running on one engine with the other locked. The inefficiencies that running with one prop locked seem so high – turbulence from the locked prop and compensating rudder angle – that I would think outweigh the savings of running on a single engine.

There have been many articles talking about how damaging underloading a diesel engine is. Specifically non electronic fuel injection engines-mine. There is a 7 knot speed limit in the ship canal. There is no opportunity to speed up to burn off the carbon. I have a triple keel at the stern-my boat does not need rudder compensation on one engine (that I could notice going 7 knots).

 

[Xlantic]

I seldom go faster than 7 knots.

What engines do you have?

 

[Mac2]

Cat 3208 naturals. Temps are perfect when I get up to 1800 rpm or around 8 knots. I end up going less then 7 knots due to traffic, waiting for bridges to open etc.

 

[mvweebles]

Downsides to ShaftLoc? Assuming you have plenty of shaft so it doesn't interfere with log and such, biggest one I can see is it's doubtless an expense and effort to install and secure for something you may occasionally tinker with but never actually need. Sooting is one of those myths that can theoretically happen but never does. Can anyone actually point to a propulsion engine that has been killed because of sooting? As far as saving fuel, ho-hum. Hard to imagine a scenario where running on one engine will save appreciably more than running on two at same speed.

Honestly, I think you're over-thinking this. Just my opinion.

Peter

 

[Mac2]

Downsides to ShaftLoc? Assuming you have plenty of shaft so it doesn't interfere with log and such, biggest one I can see is it's doubtless an expense and effort to install and secure for something you may occasionally tinker with but never actually need. Sooting is one of those myths that can theoretically happen but never does. Can anyone actually point to a propulsion engine that has been killed because of sooting? As far as saving fuel, ho-hum. Hard to imagine a scenario where running on one engine will save appreciably more than running on two at same speed.

Honestly, I think you're over-thinking this. Just my opinion.

Peter

I'll find out the expense, but I'll install myself. I smoked the turbo on my last boat cruising in these conditions-engine ran in the 160s F. Turbo never spun up fully. My engines are naturally aspirated, so not as big of an issue, but still worried about cylinders:
From an article by Steve D'Antonio in passagemaker magazine:

https://www.passagemaker.com/technical/gearhead-chronic-underloading-and-over-cooling.

If I do install, I will add the results to this post.

 

[mvweebles]

Steve D discusses coolant temperature not reaching designed operating temp, usually around 175F-180F (he says 165F-195F which seems wider than I'd expect). He also notes this is much more common in generators which is why I caveated my response with propulsion engines. If you're chronically running under 170F, chances are you have a different problem that a Shaft Loc won't fix, namely the intended usage of your boat is way different than the actual usage.

Peter

 

[Mac2]

Peter: True about intended usage-not a choice of mine. My engines are 210 hp each. I have a hunch that pushing 90 tons with one engine vs two engines will put that single engine in the intended usage range (going 5-7 knots).

 

[mvweebles]

Steve D shows a picture of taking a temp off oil filter which is a good idea.

There are a LOT of 40-50 foot boats built with twin +250hp diesels (many GB 42s built after mid 1980s for example), many with your same 3208s. Given price of diesel, if under loading at 7-kts was a problem, there would be a graveyard of these boats. Maybe it's out there and I just don't see it. But mostly, I think it's a problem that gets too much air time. Always has. There are so many other ways to kill an engine - this just seems like an asterisk.

But if you decide to do it, would definitely be interested in what it takes.

Good luck with whatever you decide.

Peter

 

[Southern Boater]

I've never been able to get a response back from Twin Disc about the free wheeling.

I’ve found the same, been asking on internet forums for years. I’ve got the same engines as yourself, and assume the same Twin Disc 502’s?
I’m over-propped and cruise at 1500 rpm to achieve 8 knots, but engine temps are consistently 170 F (77C) right through the cruising range 1500 - 1800 rpm.
My boat is considerably lighter at 20 - 23 tonnes.

 

[Mac2]

I’ve found the same, been asking on internet forums for years. I’ve got the same engines as yourself, and assume the same Twin Disc 502’s?
I’m over-propped and cruise at 1500 rpm to achieve 8 knots, but engine temps are consistently 170 F (77C) right through the cruising range 1500 - 1800 rpm.
My boat is considerably lighter at 20 - 23 tonnes.

My model is MG 5061: 3 to 1 ratio

 

[Southern Boater]

My model is MG 5061: 3 to 1 ratio

Yours are the raw water cooled versions (I believe), more heavy duty than the 502’s. We are engine coolant cooled, I assume light duty.

 

[Portage_Bay]

In the for what it's worth column I don't think coolant vs raw water cooled has anything to do with light duty vs heavy duty. My previous boat was 502s driven by CAT 3208s coolant cooled. My current boat is 502s driven by Cummins 6BT raw water cooled. Both about the same HP on similar displacement boats. The work boat I used to run was a 530, big heavy duty transmission, driven by a CAT 379 coolant cooled.

Yours are the raw water cooled versions (I believe), more heavy duty than the 502’s. We are engine coolant cooled, I assume light duty.

 

[Mac2]

Got the quote for two Shaft Loks. It will be 4k shipped. About double from what I recall from a couple years ago.
Another thing that could change my mind: I have a hydraulic pump on the starboard engine that runs the stabilizers. If I shut that engine down with the stabilizers in the center position will they stay in that position, or do I need to pin them in place (that would be game set match for me-very difficult to get to the pins)?

 

[marcs]

cafesport:
Nice clean setup. Not sure what you mean when you talk about hydro locking the engine and isolating the dripless shaft seal. There is a concern if you have the clam shell strainer on the raw water intake, which could force water into your stopped engine, but I have the sea chest, so not an issue.

I believe they are specifically talking about crossover water flow so both seals get water even on one engine.

See the Tides manual at https://www.tidesmarine.com/wp-content/uploads/2021/10/water-pick-up.pdf under the crossover section:

Before installing a crossover kit, you must inspect the vessel's raw water exhaust system. DO NO USE A CROSSOVER KIT if the highest point in the exhaust system is above the turn in the exhaust riser. Back-flow could occur while run ning on only one engine causing serious damage to the other engine/turbo.

As long as your installation meets that requirement you shouldn't have to worry.

 

[Southern Boater]

In the for what it's worth column I don't think coolant vs raw water cooled has anything to do with light duty vs heavy duty. My previous boat was 502s driven by CAT 3208s coolant cooled. My current boat is 502s driven by Cummins 6BT raw water cooled. Both about the same HP on similar displacement boats. The work boat I used to run was a 530, big heavy duty transmission, driven by a CAT 379 coolant cooled.

Apologies for thread drift….
Interesting PB, I’m trying to understand the Twin Disc pairing arrangements in relation to with the different HP engines and why the raw verses coolant cooled cooler options, perhaps a different thread!