appropriate transmission for MTU 2000 M93 12V

[KRMyacht]

Hi everybody,
I am looking for a appropriate transmission shaft and propeller for MTU 2000 M93 12V. I will start to refit 23 meter yacht that has arneson system i will turn it to transmission and shaft system so i will built to machine room from the begining even it will be though...

[Ad Hoc]

You'll need the tank test report to establish what resistance is expect and hence what speed at what displacement. Then you can see if the power of the MTU matches what you 'expect', as the full load speed.

From that and the GA/Lines plan, you can then see what is the maximum diameter prop you can fit, and then work out the gear box ratio, and then once that is selected as the most appropriate, see what diameter shaft satisfies the power/torque.

[FAST FRED]

If you are looking for the Brand of transmission the Twin Disc would be my first choice.

The ZF would work , but are difficult to get worked on , parts are factory , months away .

FF

[KRMyacht]

also owner of the yacht complain about the consumption and high speed because of the surface piercing propeller and arneson machine that way he wants to change propulsion system .in this way he can go wherever he wants with cruise speed and decraese the consumption because now he has to go with max rotation for taking efficiency ..... can u make any suggestion for this process to me? thak you have a good day

Originally Posted by KRMyacht

also owner of the yacht complain about the consumption and high speed because of the surface piercing propeller and arneson machine that way he wants to change propulsion system .in this way he can go wherever he wants with cruise speed and decraese the consumption because now he has to go with max rotation for taking efficiency ..... can u make any suggestion for this process to me? thak you have a good day

In this case the CPP seems to be the logical way. For the lowest cost, you get the highest efficiency at varying speeds and loads, and the best match for a given diameter.

Hundested, Nogva, Helseth, Piening are the brands you should contact.

If a gearbox replacement is required instead of a CPP installation (the latter does not need a gear, except for reduction), then Reintjes is the far better choice than TD. followed by ZF.

Regards
Richard

[FAST FRED]

.. can u make any suggestion for this process to me? thak you have a good day

First you need to discuss with the owner if he can accept the speeds of a displacement boat.

If Long range cruising (In Knots) at about the SQ root of the waterline is OK , the fuel consumption will be 1/10th of the high speed burn . perhaps 1 /20th.

But a 64 ft lwl will cruise at only 8K , and perhaps 10K with 50% higher fuel use.

How slow can you go?

FF

[sbmar.com]

Why not post a few details of exactly what you are thinking about doing.. Pretty sketchy on all..

Rated Engine HP & RPM

Twins or single

All the dimensions of the vessel and maybe a picture ( or a link) so I can see the base design of it?

Good guestimate as to "working weight" of the vessel after it's outfitted as you intend to use it.. Fuel & water loads can play a big part in that number..

Size or diameter of prop you are thinking of using--Thta's where is kinda need to start when selecting a gear and then trying to match that to what you want to extract from the engine HP wise..

Intended speeds--- i.e., are you thinking of trying to use all your HP, or are you thinking 7-12 kts with a permenent "cork under the throttle" ? Could be enormous difference in power train design and cost..

After I get a feel for what you are trying to do, I can offer you some viable alternatives and budgetary $$'s that will accomplish what you want..




Tony

http://www.sbmar.com

[Rik]

Originally Posted by KRMyacht

also owner of the yacht complain about the consumption and high speed because of the surface piercing propeller and arneson machine that way he wants to change propulsion system .in this way he can go wherever he wants with cruise speed and decraese the consumption because now he has to go with max rotation for taking efficiency ..... can u make any suggestion for this process to me? thak you have a good day

Someone is going to be greatly disappointed with this project. Although you have not listed the boat, weight, power, speed, application, etc. the boat is not going to gain mid range speed, top speed nor fuel mileage by switching to a shaft and rudder setup. Quite the opposite.

Someone is leading the customer astray possibly due to lack of knowledge with the current setup, but if the boat is properly geared and has the proper propellers, the efficiency cannot get any better than it currently is and this move is a step backwards.

Rik, It likely will be more efficient at mid-range with a propshaft. Where do you get your information that a surface drive will be more efficient at mid and high RPMs?

[Rik]

Information? Let's start with the fact the boat will loose some 20-30% of its cruise speed and its top speed (assuming both setups were optimal).

If the boat looses speed at the same rpm level then it loose efficiency at the same time. While there might be many ways to measure efficiency, simply taking into account that the boats distance traveled at a set rpm level will be different between the two propulsion devices, a gain in speed at the set rpm level will also equate to a greater distance traveled at this set rpm level and thus greater efficiency.

The complaint was fuel burn was excessive at the rpm levels. If this boat has electronic motors, the monitors will enable the operator to give the feedback answers, such as % load, Fuel Burn, RPM and Speed.

As I noted, provided the boat is properly gear'd, and properly prop'd for the displacements of the boat, the operator will know this boats fuel burn curve in relation to speed.

The engines will burn a certain amount of fuel per rpm in a given load. So if this boat is loaded 90% at full rpm (with Surface Drives) it will bun X GPH. Likewise if the boat with under water gear is loaded 90% at full rpm it should burn the same GPH. So while the fuel burn will not change in relation to the load and rpm, the distance covered will.

Also, if the boat cruises at X speed @ X rpm with Surface Drives, and X minus speed a the same RPM with underwater gear this results in less distance covered. Likewise, if the under water gear requires X rpm to reach X speed, a Surface Drive application can reach the same speed with less rpm and thus less fuel burn.

Where do you get your information that underwater gear is more efficient than a surface drive?

RIK

"go wherever he wants with cruise speed " was the question! Not max speed.

And of course at lower speed ranges, the conventional prop has advantages. Much more the CPP.

And Marks question was not answered. He asked "more efficient at mid AND high RPMs?"

The surface prop sure is never!

Regards
Richard

[Rik]

Richard, I addressed the "cruise speed". Please re-read my statement.

You are comparing a surface propeller system that has "atypical" slippage of 10% to an underwater gear system that has "atypical" propeller slippage of 25%. How do you calculate the mid range is going to be slower with surface drives?

Please do not attempt to tell us that Surface Drives only work for high speed vessels and suffer across the entire speed spectrum up to that point. You will be sadly mistaken with that argument.

In fact, as I stated, the atypical application with surface drives can reduce the rpm needed to cruise at the same speed the underwater gear reached at a higher rpm. This equates to "LESS FUEL BURNED" at the same speed.

Now, if "KRMyacht" had provided more vital information on this application this would be even easier to prove to you as we possibly have data from under water gear speeds to surface drive speeds.

Just for clarity, your abbreviation of "CPP" is for "constant pitch propeller" or "controllable pitch propeller"?

Originally Posted by Rik

Richard, I addressed the "cruise speed". Please re-read my statement.

You are comparing a surface propeller system that has "atypical" slippage of 10% to an underwater gear system that has "atypical" propeller slippage of 25%. How do you calculate the mid range is going to be slower with surface drives?

Please do not attempt to tell us that Surface Drives only work for high speed vessels and suffer across the entire speed spectrum up to that point. You will be sadly mistaken with that argument.

In fact, as I stated, the atypical application with surface drives can reduce the rpm needed to cruise at the same speed the underwater gear reached at a higher rpm. This equates to "LESS FUEL BURNED" at the same speed.

Now, if "KRMyacht" had provided more vital information on this application this would be even easier to prove to you as we possibly have data from under water gear speeds to surface drive speeds.

Just for clarity, your abbreviation of "CPP" is for "constant pitch propeller" or "controllable pitch propeller"?

I am not sure what we are talking here, but I am sure that I do not go deeper into it. No time to waste with nonsense.
CPP is not my abbreviation, it is the standard one in our industry worldwide!
Look here, you might learn something:
The Controllable Pitch Propeller, a summary.

Regards
Richard

RiK, The problem with surface props is that their thrust does not rise with increased load and dips midspeed, particularly around hump speed. With arnesons, one can adjust the thing down and (wear the CV joint) account for this ( yes, the boat also sits lower in the water at slower speed) but are still not running in its optimum mode.
They are not optimized for this condition and are, in effect, churning butter (frothing) as opposed to the clean flow of a fully submerged prop. The surface prop is designed to run with a layer of entrained air on the forward face, as the prop is slowed, one begins to lose this. There is simply no way that the thing can be as efficient as conventional in this condition. I have been around many surface drives and seen the cruise speed fluctuate and fuel curves turn upward in choppy water when the boats need to slow down. A surface prop is something like 15% less efficient at the speeds we are talking about, as the speed rises, submerged gear starts to cavitate and the drag of their strut, hub and shaft overtake their efficiencies. That is the condition where Surface props shine.
Sorry, you are makin a little butter here yourself.