Three Engines Versus Two

[Zorba]

So the humor is out on CSR? Great, let’s make all the postings about boats. You all must be a real hoot at the dock parties.

i hope you know this was a joke. I'm on your side on this.

I gave what i though the asnwer is in the same post. Pods are more effecient with more horsepower.

No fun here...ever. Boating is not pleasure it is business.

 

[hack4alivin]

i hope you know this was a joke. I'm on your side on this.

I gave what i though the asnwer is in the same post. Pods are more effecient with more horsepower.

No fun here...ever. Boating is not pleasure it is business.

My bad…. I thought about that after I posted.

Good grief, it is getting bad when I can’t even recognize the humor! On well, here’s to a better year!:thumbsup:

 

[cpt. sundancer]

I think 3 motors are overkill, 3 motors to maintain, any problems times 3,. just my opinion,but what do i know.I am happy [for now] with a single motor and a 27 ft. boat.the wife wanted a house boat for our next one but now says she wants a larger sea ray:smt038 so 2 motors here i come.

 

[Jackie J V]

I think Pietro nailed the answer - it has to do with getting the necessary HP while using IPS.

My observation is that most manufacturers underpowered their initial IPS boats. A travel companion of mine has a Regal 5260 with IPS and it is clearly underpowered. He hates it when I blow by him in my slow looking bridge boat.

Volvo has been coming out with larger confirgurations, but in the meantime, some manufacturers simply went the route of adding a third engine. Can't be an efficient solution IMHO.

Paul

 

[Henry Boyd]

My bad…. I thought about that after I posted.

Good grief, it is getting bad when I can’t even recognize the humor! On well, here’s to a better year!:thumbsup:

Us northern guys have an excuse we can blame it on the weather and boating withdrawal! :smt101

Henry

 

[fwebster]

When nearly every boating thread is corruped by a feeble attempt to be funny, some of us find it less than enjoyable to participate in what used to be a boating forum. It gets to be like trying to whisper in a hurricane.................



On the IPS question, I don't think this has anything at all to do with weights or engine rpm's. There has been a design limit on pod drives at somewhere near 600-700 hp, depending upon whose drive system you consider. So when 2X that power requirement is exceeded, the only option which retains pod drives is to increase the number of drives. Remember that the power must change direction twice to drive the prop so pod drives have an inherent design disadvantage when compared to an inboard that has no direction changes and a lot fewer gearing and bearing load design issues.

I have read that ZF is working on a higher hp drive that should handle the 800-1200 hp needs, so some day the 3rd engine won't be necessary. That brings up an interesting point relative to the rush to adopt pod drive technology........what happens to the triple drive boat's value when the same hull is available with 2 800hp drives instead of 3 500hp drives?. I suspect it will go south like falling off a cliff.

 

[bmac]

When nearly every boating thread is corruped by a feeble attempt to be funny, some of us find it less than enjoyable to participate in what used to be a boating forum. It gets to be like trying to whisper in a hurricane.................quote]

Great point, Frank. For those of you too new here or for those that may not have noticed.....the responses to boating questions on CSR has also become like the proverbial whisper in a hurricane. I'm all for having a great time joking around but when most of us on here have a real boating question we're really just looking for a real boating answer as I'm sure the OP was on this one. Full disclosure; I've probably been guilty of misplaced or feeble attempts at humor in boating related posts. I will endeavor to keep it in the holding tank ot tiki bar.

And as for the 3 engines vs. 2, Frank as usual has it right. The original pods couldn't handle the output of larger diesels, they still can't but they're better. If I had to bet, ZF's new unit will solve much of that but there will still be an upper limit to the economic application of pods in most pleasure boats beyond 60'. That is just my $.02 as well.

 

[hack4alivin]

And the hits just keep on come’n. Guess I just go back to my pier, we know how to have some fun there.

 

[chuck1]

......
And as for the 3 engines vs. 2, Frank as usual has it right. The original pods couldn't handle the output of larger diesels, they still can't but they're better. If I had to bet, ZF's new unit will solve much of that but there will still be an upper limit to the economic application of pods in most pleasure boats beyond 60'. That is just my $.02 as well.

Okay, dumb question time. How are they getting past the hp/torque limits on the newer ships. It is my understanding that all the newer ships are being fitted with pods not drive/props???

 

[bmac]

Okay, dumb question time. How are they getting past the hp/torque limits on the newer ships. It is my understanding that all the newer ships are being fitted with pods not drive/props???

Not a dumb question, just VERY different animals. It's akin to comparing the reduction gear for my 500 HP diesel to the reduction gears for a ships 20,000 HP propulsion engines (which may be diesel or electric).

 

[bmac]

And the hits just keep on come’n. Guess I just go back to my pier, we know how to have some fun there.

That wasn't directed at anyone in particular and certainly not you, Bill. Don't go back to your pier, I've seen your posts here and at least in my opinion you've contributed to real questions with real answers.

 

[Southpaw II]

Commercial Tow Boats (Tugs) typically have Z-Drives. These are large props surrounded by a cone that rotates 360 degrees. Additionally, they have flanking rudders.
I have a friend that works the Mississippi river and captains a 180' x 54' tow boat. This boat has total 8,400 hp with 3 engines. He pushes 30 barges back and forth from New Orleans to St. Louis.

 

[hack4alivin]

That wasn't directed at anyone in particular and certainly not you, Bill. Don't go back to your pier, I've seen your posts here and at least in my opinion you've contributed to real questions with real answers.

Sorry Brain, but I have been a little testy today. I found out this morning that one of my boating friends at our marina was diagnosed with cancer over the holidays. Bummed me out and makes me realize that boating is supposed to be about fun, so I should enjoy every minute of it, even if it is only on a website.

Now back to the thread.

 

[highslice]

When nearly every boating thread is corruped by a feeble attempt to be funny, some of us find it less than enjoyable to participate in what used to be a boating forum. It gets to be like trying to whisper in a hurricane.................



On the IPS question, I don't think this has anything at all to do with weights or engine rpm's. There has been a design limit on pod drives at somewhere near 600-700 hp, depending upon whose drive system you consider. So when 2X that power requirement is exceeded, the only option which retains pod drives is to increase the number of drives. Remember that the power must change direction twice to drive the prop so pod drives have an inherent design disadvantage when compared to an inboard that has no direction changes and a lot fewer gearing and bearing load design issues.

I have read that ZF is working on a higher hp drive that should handle the 800-1200 hp needs, so some day the 3rd engine won't be necessary. That brings up an interesting point relative to the rush to adopt pod drive technology........what happens to the triple drive boat's value when the same hull is available with 2 800hp drives instead of 3 500hp drives?. I suspect it will go south like falling off a cliff.

Interesting. The article I read never mentioned HP limits on the drives. But that's not too surprising, no boating magazines are critical anymore, Volvo's PR department probably wrote the article. Thanks, Frank, that makes sense.

Okay, dumb question time. How are they getting past the hp/torque limits on the newer ships. It is my understanding that all the newer ships are being fitted with pods not drive/props???

The larger pod drives showing up on the huge ships, that I am familiar with, are actually huge electric motors mounted in the pods. The engines (diesel or gas turbines) actually just run generators to power the electric motors. It is much the same way a railroad locomotive is powered: diesel over electric - lots of torque is required to start a mile long train moving down the tracks.:wow:

 

[Pietro]

With Volvo the limit was not actually on the pods, but on the engines...Volvo does not manufacture high power units as Cat or Man, but the novelty of IPS was just too tempting...

 

[Rebounder]

Geez guys, it seems everyone is really sensitive!!! Yeah, I know, I only have a handful of posts, who am I? However, if you go back through the thread, no one is out of bounds, it all seems in line to me, just saying!!!

Let the “who the Hell does this guy think he is” comments begin. Good God!

 

[bmac]

Sorry Brain, but I have been a little testy today. I found out this morning that one of my boating friends at our marina was diagnosed with cancer over the holidays. Bummed me out and makes me realize that boating is supposed to be about fun, so I should enjoy every minute of it, even if it is only on a website.

Now back to the thread.

We all have those days, Bill, no problem. Unfortunately I am all too familiar with Cancer as that disease has ravaged my family for years. When my father died of Pancreatic Cancer at the age of 59 it opened my eyes to my own mortality. Although he left my mother financially secure he worked his whole life, never fully enjoying the fruits of his labor. That's why 6 months after his death I went out and bought my first boatn('03 320DA). His premature death showed me that, as you said, we should enjoy every minute of it (paraphrasing here). It also taught me that you can't take it with you so you might as well spend some of it while you're here and boating is the best way I can think of doing that. Here's to a happy and healthy New Year to all!!!:smt038

 

[Pietro]

We all have those days, Bill, no problem. Unfortunately I am all too familiar with Cancer as that disease has ravaged my family for years. When my father died of Pancreatic Cancer at the age of 59 it opened my eyes to my own mortality. Although he left my mother financially secure he worked his whole life, never fully enjoying the fruits of his labor. That's why 6 months after his death I went out and bought my first boatn('03 320DA). His premature death showed me that, as you said, we should enjoy every minute of it (paraphrasing here). It also taught me that you can't take it with you so you might as well spend some of it while you're here and boating is the best way I can think of doing that. Here's to a happy and healthy New Year to all!!!:smt038

Nice words Brian...I've been through too as I've lost my mother way too soon... boating is for me one of the means of cheating mortality and the strongest way to create unforgettable memories.

Happy new year to all :smt038

 

[katricol]

Pietro...me too. Lets have a good "new" year !!! Ric

 

[Henry Boyd]

I can't post now, got to go to dinner. But I sent an email last night to a friend in Singapore who is in the ship management business and got a lot of interesting info about ship pods. Tim is right on the ABB Azipods are diesel electric (nobody but the Navy can afford steam turbines these days) with power delivered to the Props at levels of 26 MW about 35,000 HP! If any one is interested I'll post more of what he sent me later.

Henry