More overpropping...

Just read this...thought all the overpropping gurus could have fresh bait.

The only error in the print so far was the plate should have read max rpm as 2700 rpm not 1600.

"I have an absolutely (40 + years) ancient yanmar straight 6 turbo..there are some threads about the boat build and engine already on this board.
Originally the boat propped for a maximum engine speed of 1600 rpm, (Stated on the engine data plate) it will run to 1,700 then smokes.
current prop is 92 cm, (About 3 feet) 3 blades. gear eduction is 3.08.
I have located and refreshen another one of these (IMHO) amazing 40 year old yanmars.
Currently I have 32000 hours on the old lady and she runs great, but clearly she is tired, rod bearings are showing copper...bores are polished.
The plan is to replace to old with the much lower hour engine of the exact same type, bolt in installation.
It would take a month or more to replace the engine with a different make or model with the resources I have where I am. This is the better route for me both in time and economics and the limited skills of the mechanics here on the island."

I think that post is chock full of errors. Can anyone believe that a 1,000 rpm overpropped engine run at near wot at 1,700 rpm could run for 32,000 hours. Or that a 41 lwl wooden hull boat weighs 100,000 lbs, or....

The OP is a nice enough guy. He apparently operates a dive boat in Vietnam where these old engines are ubiquitous but with no provenance.

David

What engine is it? Some old iron can take almost anything as far as loading.

Ski:

Here is the original post on cruisersforum- Way Over Propped but it Works, is it Safe? - Cruisers & Sailing Forums

Eric:

Here is the original thread on cruisersforum- Way Over Propped but it Works, is it Safe? - Cruisers & Sailing Forums

He also posted about identification with some pics at- Identification of Yanmar, Please - Page 2 - Cruisers & Sailing Forums

I can't make much sense about what he is saying. You may be right- old iron can take anything.

David

David thanks for the link. Had a good time reading.

Hello psneed.

Did you get your all encompassing knowledge all on your own ? Or were you able to ask questions as you went along, have books for reference, a marina with a mechanic? I invite you to your nearest third world country, and ask you to try to learn from the locals...There are exactly 6 people on this island except for a handful of westerners who speak even basic English.
Yeah and I know nothing and nobody in this country knows anything, the sparse manuals I have are in Japanese.
So asking questions in the hope of getting some help from self professed experts is reason to cross post for a giggle ? You experts do not even agree !

So here I am fresh bait or you could take a minute to really help.

My copy of 'The propeller handbook" is currently in the ministry of social affairs being scrutinized for subversive material and I may have it from them in a month.

FFS, read my first post...I never wanted to own a boat. I have enough to do, my rental deal fell through...so I had to build one, so I designed it, oversaw the construction and guess what..it runs great and is the best dive boat in the country. I am happy that you could have a chuckle at my expense. I do not think you could have done what I did with the boat, knowing NOTHING at a moments notice on a tight budget with nobody to ask.... And 1 in 100,000 people might just be able to open and run the first western owned business on this island.

Me..I have no idea what the boat should weigh, I clearly expressed that...
so I guess demeaning me for what I do not know makes for great entertainment for you.

Aint no doubt about the fact that it is a 40 year old yanmar with 31,000 on it, turning 1,700 rpm. on a 3.03 reduction
5 + liter after cooled turbo, 155 H.P. ...spinning a 94 cm prop at about 600 rpm.

It was spinning a 1.06 meter ( 40 inches +/-) prop when we got it and I knocked that down because it smoked too easily.
The prop were chosen by the builder based on the engine plate which I have found to be incorrrect, they are often under rated here for tax purposes.
Boat weight is from the builder and I question it.

The engine does not smoke, okay ? (and according to some other self professed experts if it aint broke don`t fix it)....until I wind it up past 1,800 rpm.
To bring this to a conclusion for you.... so you can see that there was a point to my asking... I have another gearbox with a 3.83 reduction and a new 80 cm (32 inches) prop, that should spin it up to 2,800 r.p.m.

The engine was in similar use throughout its previous life..as I am told, provenience is questionable but the business that ran it would have put those hours on it.

psneed, I invite you here to show you how these guys fix this stuff and keep it running for so long, it is shocking, scary but sure as hell works.

Also...If you come here diving, I fully expect you to be a full on expert and know a lot more then I do about diving.

I really hope I have misinterpreted what you said, if not I hope I have put to rest your giggle session.

ti325v said:

Did you get your all encompassing knowledge all on your own ? Or were you able to ask questions as you went along, have books for reference, a marina with a mechanic? I invite you to your nearest third world country, and ask you to try to learn from the locals...There are exactly 6 people on this island except for a handful of westerners who speak even basic English.
Yeah and I know nothing and nobody in this country knows anything, the sparse manuals I have are in Japanese.
So asking questions in the hope of getting some help from self professed experts is reason to cross post for a giggle ? You experts do not even agree !

So here I am fresh bait or you could take a minute to really help.

My copy of 'The propeller handbook" is currently in the ministry of social affairs being scrutinized for subversive material and I may have it from them in a month.

FFS, read my first post...I never wanted to own a boat. I have enough to do, my rental deal fell through...so I had to build one, so I designed it, oversaw the construction and guess what..it runs great and is the best dive boat in the country. I am happy that you could have a chuckle at my expense. I do not think you could have done what I did with the boat, knowing NOTHING at a moments notice on a tight budget with nobody to ask.... And 1 in 100,000 people might just be able to open and run the first western owned business on this island.

Me..I have no idea what the boat should weigh, I clearly expressed that...
so I guess demeaning me for what I do not know makes for great entertainment for you.

Aint no doubt about the fact that it is a 40 year old yanmar with 31,000 on it, turning 1,700 rpm. on a 3.03 reduction
5 + liter after cooled turbo, 155 H.P. ...spinning a 94 cm prop at about 600 rpm.

It was spinning a 1.06 meter ( 40 inches +/-) prop when we got it and I knocked that down because it smoked too easily.
The prop were chosen by the builder based on the engine plate which I have found to be incorrrect, they are often under rated here for tax purposes.
Boat weight is from the builder and I question it.

The engine does not smoke, okay ? (and according to some other self professed experts if it aint broke don`t fix it)....until I wind it up past 1,800 rpm.
To bring this to a conclusion for you.... so you can see that there was a point to my asking... I have another gearbox with a 3.83 reduction and a new 80 cm (32 inches) prop, that should spin it up to 2,800 r.p.m.

The engine was in similar use throughout its previous life..as I am told, provenience is questionable but the business that ran it would have put those hours on it.

psneed, I invite you here to show you how these guys fix this stuff and keep it running for so long, it is shocking, scary but sure as hell works.

Also...If you come here diving, I fully expect you to be a full on expert and know a lot more then I do about diving.

I really hope I have misinterpreted what you said, if not I hope I have put to rest your giggle session.

Click to expand...

We take for granted in this country the ease with which we can get expert advise and service and I have the greatest respect for folks like you who make it all work in those parts of the world where simple things are real tough to do. Sorry you encountered arrogance in response to your question.

ti325v said:

Did you get your all encompassing knowledge all on your own ? Or were you able to ask questions as you went along, have books for reference, a marina with a mechanic? I invite you to your nearest third world country, and ask you to try to learn from the locals...There are exactly 6 people on this island except for a handful of westerners who speak even basic English.
Yeah and I know nothing and nobody in this country knows anything, the sparse manuals I have are in Japanese.
So asking questions in the hope of getting some help from self professed experts is reason to cross post for a giggle ? You experts do not even agree !

So here I am fresh bait or you could take a minute to really help.

My copy of 'The propeller handbook" is currently in the ministry of social affairs being scrutinized for subversive material and I may have it from them in a month.

FFS, read my first post...I never wanted to own a boat. I have enough to do, my rental deal fell through...so I had to build one, so I designed it, oversaw the construction and guess what..it runs great and is the best dive boat in the country. I am happy that you could have a chuckle at my expense. I do not think you could have done what I did with the boat, knowing NOTHING at a moments notice on a tight budget with nobody to ask.... And 1 in 100,000 people might just be able to open and run the first western owned business on this island.

Me..I have no idea what the boat should weigh, I clearly expressed that...
so I guess demeaning me for what I do not know makes for great entertainment for you.

Aint no doubt about the fact that it is a 40 year old yanmar with 31,000 on it, turning 1,700 rpm. on a 3.03 reduction
5 + liter after cooled turbo, 155 H.P. ...spinning a 94 cm prop at about 600 rpm.

It was spinning a 1.06 meter ( 40 inches +/-) prop when we got it and I knocked that down because it smoked too easily.
The prop were chosen by the builder based on the engine plate which I have found to be incorrrect, they are often under rated here for tax purposes.
Boat weight is from the builder and I question it.

The engine does not smoke, okay ? (and according to some other self professed experts if it aint broke don`t fix it)....until I wind it up past 1,800 rpm.
To bring this to a conclusion for you.... so you can see that there was a point to my asking... I have another gearbox with a 3.83 reduction and a new 80 cm (32 inches) prop, that should spin it up to 2,800 r.p.m.

The engine was in similar use throughout its previous life..as I am told, provenience is questionable but the business that ran it would have put those hours on it.

psneed, I invite you here to show you how these guys fix this stuff and keep it running for so long, it is shocking, scary but sure as hell works.

Also...If you come here diving, I fully expect you to be a full on expert and know a lot more then I do about diving.

I really hope I have misinterpreted what you said, if not I hope I have put to rest your giggle session.

Click to expand...

You did misinterpret....I was pointing out that "USA style boating" is insanely overthought and I often use examples of "less than perfect boat show" mentality to show that boats will often work and work well with just a few tidbits here and there, never even designed for the task.

Go here if you want to lean more about my philosophy...using one thread to see what a person is made of is like using one sentence in a book if you are not careful.

http://www.trawlerforum.com/forums/s3/bad-irresponsible-boaters-16230.html

I think perhaps the plate on the engine might be correct , 2700rpm is high for 40 year old diesels.

The 5 GPH burn would be perhaps 80 hp so realistic for a 155hp rated engine at cruise RPM..

AS the engine was run close to overloading >black smoke< but not overloaded the operation at higher HP at modest RPM is as close to ideal as can be found , both for fuel burn and engine life.

Drop the newer one in , go for a ride and observe if/where black smoke begins and pull back about 10% or so.

Gotcha, glad you were not taking the p*ss, infact this post has brought me a great reply from morrisey over on cruisers forum.