QSC 8.3 500 and ZF280-1A Tourque?

[Michael Jungvid]

New here but not to boating and hoping for some help. I am researching my next boat and found a 46″ boat with these engines and gearboxes however looking at the spec sheets the gearbox seems to not handle the max torque of the engine.

I am reading max allowed torque on the gearbox is 1100 Nm and the engine deliver up to 1700 Nm.

Is this as bad as it looks or is there something to this that I am missing?

Topic

[Tony Athens]

Tell the broker to send some really good pictures of the engine, the gear, the exhaust, the aftercooler and everything else in the engine room so I can see what you are dealing with.. Throw in the helm station(s) too..

He needs to earn his keep..

If you are even considering a purchase of a vessel “remotely” without this most basic info (very good pictures of the mechanical equipment and all of the sub-systems) in front of you, then maybe you need to rethink how your are going about the “process” ??..

As to the direct questions, after I “see” what their is to see, I will answer as best I can……………….

I’m a picture guy in case you have not figured that out yet. A dog uses his nose, the forum use its “eyes”..

Tony

[Michael Jungvid]

Turns out I need a bit more help. I was confirming the gearbox type with the broker who checked with the builder and says this particular boat has a Cummins gearbox. I have googled this but don’t find that Cummins do marine gearboxes. He also sent me this for details on the gearbox:

Code article…: 123381 GR CUM QSC8_3-495+2 1 BD DTS

N° moteur 1……….: BD:73087940

N° inverseur 1…….: 20108786

N° hélice 1……….: 660X850LH50

As far as I can tell it does not state what gearbox is in the boat, would you agree?
Also do Cummins do their own marine gearboxes?

The last line would be the props btw.

[Michael Jungvid]

I did not question the info on the D9 reference and was looking for a quick answer to decide if I should walk away from the boat before getting into the “marine age” stuff but now realize it was indeed not the right question so sorry for that and thanks helping me figure it out.
As you say without knowing more about the boat and how it’s propped there is no way to answer my original question properly. I will move on from this trusting that the drive line is appropriate for the boat.
Again thanks for your patience and help.

[Tony Athens]

Michael,

I went thru this 4 times and now must ask–Exactly what help are you looking for or what help do you need ?

We really are here to help..

Why did the gear fail on the Volvo? Was that ever diagnosed as to an actual cause? Most gear failures happen for every reason other than be “over torqued” .. In fact, trying to think of one that was ever diagnosed for that as a failure mode???.

Tony

[Philip]

Keep in mind the torque any engine is rated at is not the limit it can produce. Most diesels can and will produce more than rated torque when overpropped. So going back to basics and making sure your boat is propped under the rated fuel/rpm curve is a must not just for the engine but for the whole propulsion system (engine, mounts, transmission, couplings, shafts, props, etc, etc.).

Phil

[Michael Jungvid]

Thanks Philip for answering my actual question and I understand what you are saying but it is not the help I needed. This will my 14th boat and I have undertaken similar trips in a lot less capable boats multiple times before. I know very well what you all are trying to help me with but It’s not actually helping.
I agree 100% this is not something I should worry about and frankly I did not until another mechanic pointed me to the spec sheets with specific example of this gearbox failing paired with the Volvo Penta D9 500 engine which has a bit less max torque.
Being thorough I wanted to seek confirmation one way or the other. This forum and Tony came highly recommended wrt to the drive line specific to the boat so I reached out.

[Philip]

Michael

First off please don’t take offense in any advice you receive here as everyone’s goal is to educate and help people.

Let me see if I can explain this another way. The questions you are asking are not something you should be concerned about yet the questions you should be concerned about you are not asking. Does that make sense? The last thing you want is a broken boat mid journey with exensive repair bills.

The gearbox will not be affected by your use. However there is a whole lot of stuff that should/needs to be confirmed BEFORE you try and buy/undertake a delivery of this caliber. Items like exhaust design, maintenance history, entire cooling system service, prop loading, electrical condition, fuel filtration, spares, etc, etc, etc.

We can help, I’d suggest starting with what you considering buying, model, serial and cpl numbers, maintenance history and a bunch of pictures. We can give you ideas on pre purchase, post purchase items to address that will make this journey successful. We can go from there.

Hope that helps

Phil

[Michael Jungvid]

I am well aware of all the potential issues buying a used boat and perfectly capable of managing this but that is not what I was asking or hoping to get help with.

Assuming the drive line is properly maintained with less than 200 hours light use will I wear or break the gearbox prematurely running 100 nm per day @ 20 knots for 25 days?

[Rob Schepis]

Tony Athens wrote:

I don’t know how to say this as no matter what I say it will not come out right……………………

Don’t even think about buying a boat like this (?) that you do not “have a clue about”, and then asking it to perform on plane for 25 days at 20 KTS…………………….2500 Miles on plane ???????……………………….

Maybe Rob or Phil can put this into a different perspective..

Tony.

Basically you will be asking EVERYTHING off something you know NOTHING about. Do not misinterpret that comment – I am not saying that you know nothing about boats, but as a new owner you would know nothing as to the REAL history and current state of the engines as to setup, maintenance, reliability, etc etc.

[Michael Jungvid]

You are right it don’t come out right and I assure you I “have a clue” but agreed I skipped a few details on the travel plan but either way it was not the point and not what I wanted to discuss.

The boat should well be able to do 100-200 nautical miles per day and sea state permitting on the plane.

[Tony Athens]

I don’t know how to say this as no matter what I say it will not come out right……………………

Don’t even think about buying a boat like this (?) that you do not “have a clue about”, and then asking it to perform on plane for 25 days at 20 KTS…………………….2500 Miles on plane ???????……………………….

Maybe Rob or Phil can put this into a different perspective..

Tony.

[Michael Jungvid]

Thanks Tony, I figured it was odd for a large manufacturer to fit the “wrong” gearbox.

I read the different usage scenarios and if I buy the boat the delivery trip will potentially be approx. 100 nm per day for 25 days at around 20knots (hopefully). Would this be over stressing the gearbox? If so is there anything I should/could do like change the oil every 50 hours or so?

[Tony Athens]

This is real simple…………………………………….Transmissions ratings have nothing to do with the peak torque rating of the engines………………….. You are trying to read something into sizing transmissions that was never intended by any of transmission manufactures..

NEXT———-The ZF 280A is rated ( marginally though) for the QSC 500 for low annual hour pleasure boat use when supplied as a OEM installation..

Field experience—————Very good gear with a solid long term reputation. Worry not about the gear.. Worry about the maintenance of the engine related to “Marine Age”………

Tony

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