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  #111  
Old 01-27-2008
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Rockter will become famous soon enough
Whe an engine manufacturer does the dynamometer test for a motorcycle, he does not state what size of wheel you have to use with it.

Why do the great Tohatsu not state the engine power against crankshaft rpm? Surely they can find a dynamometer somewhere. That talk about a 2/3 variation in the power output is garbage... notice it is always derated, not uprated. So, a 6 hp motor can drop to 4 hp, but never 8 hp.

They don't have to mention props.

Just publish the power curve.... power with engine rpm.

Chosing the prop would be the owner's problem.

Measuring a bollard pull is not much use. Not too many people tie their boat to the dock, in gear, with the motor running. It frightens the fish.


Rockter.
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  #112  
Old 01-27-2008
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I would have a lot less problem if they had published the power curve that way. However they claim a power output and ship the engine with a standard prop. Then for various boats they give you a choice of about 5 other props. The engine can not meet its max rpm that produces its rated hp with the lowest pitch prop they sell for it.

unless the engine is in neutral.

It's great to claim a certain HP rating in the lab but if it can't meet it under real world conditions doing actual work then the manufacture needs to de-rate the engine regardless of what the federal government says. It would be easy enough and honest enough for the manufacture to state the federal government in bench lab tests rates this engine at 6 hp at the shaft at 6000 rpm. However under actual work conditions due to differences in how 4 stroke engines produce torque this engine has a comparative 2 stroke 4 hp rating.

How hard is that.. truth in advertising

It wouldn't be that hard for the manufacture to publish data on each engine with each prop against a water speed vs engine rpm chart so that people would know that with this engine with the lowest pitch prop if your hull speed is such and such this is how the engine would perform. All it would take is a circular test tank kinda like a lazy river that you can control and measure water flow in and with a set up like that they could even incorporate thrust test equipment into the engine mount they used. Each new model gets thrown on and tested from 0 knots on up with each prop sold for it by the manufacture and the data compiled. I think a world wide manufacture such as tohatsu could easily afford something like this. If I was a manufacture making engines I would require that kind of data just for my internal use as a matter of fact. To my mind the fact that you can not get these kind of performance curves/data is a deliberate choice on tohatsu's and other manufactures' parts. The cost of creating this kind of setup and using it is relatively cheap.

As to the bollard pull..... I agree it is not 100% valid as it doesn't correctly let the prop move through the water. However when done across different engines it does give an apples to apples comparison that i think is very relevant for displacement speed boats. We are talking a difference of 4 to 6.5 knots speed through the water on average from being tied to the dock. Yes this does have a measurable affect on engine rpm...around 500 rpm at 5.5 knots for this engine. This still lacks about 1500 rpm or so of meeting rated rpm.

Maybe if the boat was moving through the water at 20 knots it would make up that other 1500 rpm. How many boats or dingys of any size does this engine push to 20 knots of speed? The engine being able to meet rated rpm at 20 knots of speed is just a wild ass guess of mine but the thought counts. What speed through the water does this engine prop combination have to be moving to allow the engine to get to max rpm? It starts to feel like a chicken and the egg question.

If I had the equipment or could think of a way to arrange it I would rig some kind of scale or meter that would allow me to measure thrust at the engine mount with the engine on the boat in the water as it is moving. Unless someone can give me a simple way to test for this I am thinking it is beyond my capabilities.
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  #113  
Old 01-27-2008
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cardiacpaul is a jewel in the rough cardiacpaul is a jewel in the rough cardiacpaul is a jewel in the rough
I've said this before but I just want to repeat it.

You "did your research", said... " I was semi clueless prior to this episode. I have educated myself a lot during it." know very little about engines (paraphrasing), bought your motor over the internet, then take it to a service center where you don't hear the answer you want, bitch to high heaven to and about about this motor, including how THE SAE and standardized testing has been done for decades.

"HP rating in the lab but if it can't meet it under real world conditions doing actual work then the manufacture needs to de-rate the engine regardless of what the federal government says


Hell, its even the governments fault. Do you have a sweet clue as to how testing is done? My God man, do you understand the term "Brake HP", or how bout "Shaft HP", what about "Flywheel HP", I'm even going to throw in PTO output HP. all different, all NOT REAL WORLD. But, they are standards.


It wouldn't be that hard for the manufacture to publish data on each engine with each prop against a water speed vs engine rpm chart so that people would know that with this engine with the lowest pitch prop if your hull speed is such and such this is how the engine would perform


Your boat is the only boat on the water. How many sailboats would they have to test and publish? How about jon boats, aluminum and fiberglass, wood, composite, fishing boats, inflatables, RIB's, small vee's, small modified vee's, flat bottoms, dingys, life rafts, or anything that flosts that a prospective owner may want to strap it to. What is going to make you happy? ok, i'm bored....

Unless you have access to that top-secret chrome plated "at-the prop that I wanna use on my particular boat dyno" you're SOL.

"I have conducted many empirical tests with equipment I purchased at my cost to test and monitor thrust and rpm."

So, you bought this motor to save a couple of scheckles, eh? hows that workin' for ya?

"Nowhere else have I even found anyone including the manufacture that has tested or published data like this."

and no one will care because you're not all that reliable of a testing lab. Oh, I don't mean that your tests are no good, but what was the ambiant temp that day, relative humidity, water temp, lube oil weight, type and temp, operating temp, the list goes on... (thats why god, the SAE and the gov't made standardized testing.

I'm going to say it again. A little bit of knowledge is a dangerous thing.

You've been turned back by the mfr, the dealer that sold it, the various service centers, even the credit card company told you to take a hike... ever stop to think that maybe it not their fault?

Whiners really piss me off.
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Last edited by cardiacpaul; 01-27-2008 at 01:06 PM.
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  #114  
Old 01-27-2008
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Warning the above post was pointless and my response is also pointless and done for the amusement factor to liven a boring day. So for everyone else there is no need to get worked up one way or the other..

Quote:
Originally Posted by cardiacpaul View Post
I've said this before but I just want to repeat it.

You "did your research", said... " I was semi clueless prior to this episode. I have educated myself a lot during it." know very little about engines (paraphrasing), bought your motor over the internet, then take it to a service center where you don't hear the answer you want, bitch to high heaven to and about about this motor, including how THE SAE and standardized testing has been done for decades.
Yes you have weighed in on the conversation before and your response this time is much like it was last time.. a personal attack. I always love when people attack someone learning something. I was semi clueless about small outboard boat motors in specific and their interactions with prop choice and boat hulls. I am no longer semi clueless. Unlike you who seems to desire me to just accept on faith to what I'm told, I asked for data and documentation. What little I was given did not match real world testing. Most of what I asked about they did not know, or they just didn't bother answering. Unlike a sheep who mostly does what it is told I challenged this by spending many many many hours learning what I did not know. And more hours and resources trying to test what I was told.

Quote:
Originally Posted by cardiacpaul View Post
"HP rating in the lab but if it can't meet it under real world conditions doing actual work then the manufacture needs to de-rate the engine regardless of what the federal government says

Hell, its even the governments fault. Do you have a sweet clue as to how testing is done? My God man, do you understand the term "Brake HP", or how bout "Shaft HP", what about "Flywheel HP", I'm even going to throw in PTO output HP. all different, all NOT REAL WORLD. But, they are standards.
lol... im not the one that brought up the governments less than adequate testing methods. I can see you are going to blame me for it anyways though. I know that there are many different ways to test HP output and at many different points. I would agree with tohatsuguru who works for a dealership that the tests used by the government are not the best tests that could be used. Why do you think there are so many ways for measuring hp in the first place. most of them were developed to give standards for suitability for a specific application. Different tests were designed to test for different jobs.

Quote:
Originally Posted by cardiacpaul View Post
It wouldn't be that hard for the manufacture to publish data on each engine with each prop against a water speed vs engine rpm chart so that people would know that with this engine with the lowest pitch prop if your hull speed is such and such this is how the engine would perform

Your boat is the only boat on the water. How many sailboats would they have to test and publish? How about jon boats, aluminum and fiberglass, wood, composite, fishing boats, inflatables, RIB's, small vee's, small modified vee's, flat bottoms, dingys, life rafts, or anything that flosts that a prospective owner may want to strap it to. What is going to make you happy? ok, i'm bored....
you seem to be easily bored and determined not to get the point.. I have never said they should test an engine on all possible boats it might possibly be used on. That is ridiculous. Hmm maybe thats the point in you trying to say I want that. to make me look ridiculous. lol.... dude.. im human... I can make my self look ridiculous with the best of them... no need to help me.

my post specified a testing setup that would be adequate.. nothing about lots of boats. Just about power/prop interactions with moving water. contrary to your belief motors and props don't know what size the boat they are on is, or how heavy it is. The size of the boat and the resistance it feels does control how fast it will go for a given power but the prop only interacts against the water. It doesn't care if the boat is moving through the water or the water is moving past a stationary boat/prop. Have you ever heard of wind tunnels? Or tank testing boat hulls? same principle.

Quote:
Originally Posted by cardiacpaul View Post
"I have conducted many empirical tests with equipment I purchased at my cost to test and monitor thrust and rpm."
So, you bought this motor to save a couple of scheckles, eh? hows that workin' for ya?
yes i initially purchased this motor from the dealer I did because of the price.. I didn't buy this model to save money. notice the distinction. I bought this model because of the advertised weight/power/fuel economy mix. If I were just going to save money I would have gotten a 2 stroke for a lot less.

and as how it is working for me. Well not to well in some ways but in others quite well.

Like I said before it's been a learning process. I've learned a lot about outboards and props. All valuable information to carry into the future with me that I wouldn't have if I hadn't gone through this.

As to the extra expense of equipment etc.. that I have spent in testing this stuff.. I don't count any of that toward the cost of the engine.. that all gets set to my curiosity account and desire to understand exactly what was happening. I actually have a degree and with it a lot of training in scientific standards. So even if you don't believe in my testing (limited though it might be) I do. I didn't do it for you. I did it for me. I'm perfectly happy to share it with anyone that wants to hear it. They (you) have the right and privilege to not accept it or believe me. I'm cool with that.

Given your adamant stance to not question what people tell you even if they don't give supporting documentation

(here i will take a personal jab.. see im human to)

sigh.. I had a nice personal jab to shoot back at you but when I read it it just seemed too petty, so I'm not even going to bother.

Quote:
Originally Posted by cardiacpaul View Post
"Nowhere else have I even found anyone including the manufacture that has tested or published data like this."

and no one will care because you're not all that reliable of a testing lab. Oh, I don't mean that your tests are no good, but what was the ambiant temp that day, relative humidity, water temp, lube oil weight, type and temp, operating temp, the list goes on... (thats why god, the SAE and the gov't made standardized testing.

I'm going to say it again. A little bit of knowledge is a dangerous thing.
funnily enough I agree with on this one my tests are valid but they are not under controlled enough conditions to be SAE or ISO certified. However they are good enough to give me good solid metrics to measure this engines performance with. Better than anything the manufacture or dealer gave me.

Quote:
Originally Posted by cardiacpaul View Post
You've been turned back by the mfr, the dealer that sold it, the various service centers, even the credit card company told you to take a hike... ever stop to think that maybe it not their fault?
Whiners really piss me off.
you are correct.. they all found in each others favor. The independent source I got to verify my claim was contacted and from what little I can tell pressured to withdraw their support they wouldn't talk about it with me after that. conspiracy? no more than what happens on a regular basis every day around us. The system works best for those with deep pockets. It's funny.. your more pissed off at me for talking about this stuff than I am at people who took me for 1400 dollars for an under powered engine.

lol.. where is the line between whining and a legitimate complaint. I would hate to have you in a position that I would have to bring any kind of legitimate grievance to you.

My "opinion" of which you are free to not agree with is that you are just a pissed off kinda guy.


Though I do have to say thank you.. i was spending a boring Sunday, sick at home, and have thoroughly enjoyed picking at your post and replying to it. Normally I would just ignore it but I was bored.

Last edited by audeojude; 01-27-2008 at 04:51 PM.
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  #115  
Old 01-27-2008
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This is not personal., Never has been. Won't be. I don't know you, nor do I care. This is about the decision to buy a motor over the 'net with little knowledge and the resultant whining about the purchase.

"It's funny.. your more pissed off at me for talking about this stuff than I am at people who took me for 1400 dollars for an under powered engine."

No, what chaps me is within the myriad of complaints you have blamed everyone from the dealer to the government for this fiasco, except yourself. YOU made the decision, YOU pulled out your credit card and bought it over the net...

Perhaps, just maybe, I dunno, but if I had no earthly clue as to what I was doing, I'd go to a brick and mortar and ASK!
No, I'm not the owner of a failed store. But I know if i was going to buy a bowling ball, I'd go into a proshop or the lanes... I wouldn't google the hell out of bowling balls and buy one. If I did, and it didn't work for ME, I wouldn't complain that the ball wasn't round, or it was too small, or too heavy. or that I can't get my local proshop to fix it for me.
That, my good man is what you have done.

I'm not pissed off about you talking about this stuff.
What chaps my butt is that you complain about standardized tests that do seem good enough for everyone else in the real world to use and accept.. except you.

What chaps my butt is when you didn't get the answers that you wanted to justify your purpose for the motor its... oh my god, its a conspiracy. Yup, they're all out to screw you out of your 1400.00. They're at the club right now laughing at you, can't you hear them?

"The size of the boat and the resistance it feels does control how fast it will go for a given power but the prop only interacts against the water. It doesn't care if the boat is moving through the water or the water is moving past a stationary boat/prop. Have you ever heard of wind tunnels? Or tank testing boat hulls? same principle."

Unless you've got a Cray, those math calcs based on water molecule size and the deltas that just the tank, hull model and prop config. are going to induce are going to be a bear. I'm not even going to ask your esteemed opinion as to how one would be able to differenciate between the figures for say a motor with a flat bottom before it and a modified vee... 'cuz it would make a difference, in a tank, or on a lake. Maybe we should just use the motor without a hull in front of it and measure the rooster tail. What prop should we use hmmm? face it, your arguments don't wash.

"It wouldn't be that hard for the manufacture to publish data on each engine with each prop against a water speed vs engine rpm chart so that people would know that with this engine with the lowest pitch prop if your hull speed is such and such this is how the engine would perform
"

Oh, I'm going to go way out on a limb here and mention that for the merc 225 outboard, there are no less than 8 prop sizes, 6 of those sizes can be made from 3 different materials. Add in there that there are another 4 companies with both 3 and 4 blade props. Whose do you want to test?

Look around you before you make that kind of statement.
Merc make 30 different outboards, OMC 23, Nissan 13, Suzuki 16.

There is more than one boat, more than a couple of props, more than one motor in the water. Maybe they should just do it for your motor. That wouldn't be too much to ask would it? How many (shudder the thought) power boat companies measure hull speed? the calcs there don't work. I don't even want to start on sterndrives.

As far as questioning, ummm, thats what I do for a living. I accept almost nothing about what I'm told about a boat until I see it with my own eyes.

This is not personal. I am easily bored. Bored with people that no matter what they're told have to find out sometimes the hard way that they are responsible for their own actions.

What really chaps my butt is you're still not all that learned about outboards, and you're STILL wanked off about YOUR decision to purchase this particular motor.

lol.. where is the line between whining and a legitimate complaint. I would hate to have you in a position that I would have to bring any kind of legitimate grievance to you.

Bring one and I'll give it a go. key words... "legitimate grievance"
lets see, the dealers, the service centers, the credit card company... and me... rejected your grievance... hmmm, we must ALL be in cahoots. Next round on me boys, lets spend the profits!
Whiners still piss me off.
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Last edited by cardiacpaul; 01-27-2008 at 08:56 PM.
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  #116  
Old 01-27-2008
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This thread has no moral.

This thread has no end.

This thread only goes to show the folly of men.

Scott,

This has been beat to death at this point and we are back to repeating posts. I can tell you are a bright, articulate guy and I do not detect any malice in your posts. In fact, I think you are a nice guy. You feel you got less than you paid for and that it isn't fair. And I agree. It's not fair that you bought a 6 hp engine to replace a 4hp and it pushes your boat slightly slower. In a perfect world that wouldn't happen. But we all know that this is not a perfect world and that we are not guaranteed a perfect result...At least not in outboards.

So, what are we left with? The engine is not defective. The engine develops 6 hp at it's rated RPM. All outboards are rated the same way. And, all outboards 6 hp and below in the U.S. are four-stroke. And, your screwed. It's no ones fault, but there you are. Due to your application you aren't going to get that perfect result. I don't want to wade back through this mess, but what are we talking here? Something around a .2 difference at hull speed if I remember correctly. Let it go. You got a free prop out of it. I offered you another free one to try. That's 10% of the cost of the engine there alone

Rocter,

Outboards are prop shaft rated due to Federal law. This was done back in the late 80's to standardize outboard hp ratings. At the time, U.S. produced outboards were crankshaft rated and the imports were all prop shaft rated. The Feds felt that it was too confusing to the public to try to determine how much power loss occurred from the transfer of generated hp at the crank to usable hp at the prop shaft so....No more useless crankshaft ratings. This brings up another point which is when someone begins to babble about the torque of their outboard. That's a dead giveaway that they don't have a clue as to what they are talking about as torque by itself is meaningless when determining what an outboard does in the water. I do think that all manufacturers should furnish static measurements of prop shaft hp produced at multiple set RPM's as that could be useful in diagnostic testing.
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Last edited by TohatsuGuru; 01-27-2008 at 10:29 PM. Reason: Just babbling
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  #117  
Old 01-28-2008
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Your right tohatsuguru I'll try and give it a bit of a rest

I will give you a call when I get ready to get my boat back in the water and get one of those props. And honestly I don't expect you to provide one free for the testing.. I will buy it up front in the spirit of curiosity.. no bitching afterwards lol..

Though you don't know how much it means that you would make the offer in the first place.
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  #118  
Old 02-03-2008
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No Justice.

I recommended to a friend of mine who was new to sailing and had bought a 25' sailboat that he get the best and buy a new 9.9 HP Honda. From past experience, having owned at least ten outboards, I thought his chances of success would be much better. The very first time he used it the damn thing quit and the only way he could start it was at full throttle. He called me up and I had to help him get it off the boat so he could get it to the dealer. We could barely get it off the motormount it was so heavy. We went through this experience two or three times because the dealer couldn't figure out what was wrong. Eventually my buddy gave up in disgust and sold the boat. The lesson here is there is no guarantee of success with boats. Failure is the only guarantee. Steve Stuller
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  #119  
Old 04-01-2008
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Smile Under- powered Tohatsu 6 HP

Underpowered Tohatsu 6 HP. I have the same problem. I bought the motor brand new and it runs great. However, a friend with a 2 hp outboard can go faster than me. My dink is 7'11" v-hull airfloor and his is an 8' flat floor. Has anyone come up with a solution? Will a smaller prop do the trick? Is there a carbuerator adjustment?
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  #120  
Old 04-02-2008
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Take it into a dealer and find out what is wrong. There is no 2 hp on the planet that can keep up with a 6....Everything else being equal.
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