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Old 24 June 2014, 19:30   #11
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Originally Posted by Locozodiac View Post
75% of max transom rated is the near cast on stone posted at different boating forums, the same endles theme that AV plate must be even with boat's keel.
So what you are saying is that you will take the "cast in stone from other forums" 75% power to plane as it it's generally accepted? That's fine. I'm not arguing the value or anything else here; I'm just asking where the number came from.

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For me performance is the max out you can take from a given engine/boat setup. That's reving at top wot rpm, being fuel efficient, achieving quick hole shot, fast plane and fun to drive. Describe what's performance for you ?
Sounds reasonable.


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4-Assumed wrong, stated at side of tube, who said anything about back LU ?
Actually, your statement did, which was included in the quote I responded to. Shortened, and requoted:

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drag resistance... is not the same at boat’s side than at flattened out compact water flow passing at speed under keel/boat’s bottom right before hitting lower unit.
I assumed you were saying that leg would see water differently at the back of the boat than at the side. Sorry if I misinterpreted your statement.


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5-We're definitely tuned to other parameters, what's deeper to you probably ain't deeper to me.
Not sure what you're saying here.



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Don't need to run engine at different LU heights untill it fails, by fail you mean kaput ?
I think you missed my point. Your conclusions (the bulleted points you made) are unsupported by your test. They *may* be inferred, but they were not results. Doesn't mean they're wrong; just that you are making conclusions that you have not supported by the test. That was all I was saying.




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So to have a friendly chat on this nice forum, your current boat/engine combo is ....?
Not sure what that has to do with a discussion about performance or how it affects anything we've talked about. But it's a remote steered aluminum hulled RIB, with power t/t.


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better drop your current engine into the blue and get a big fan motor and problem solved.
Yeah, but then we'd get into a discussion about blade shapes, prop/fan diameters and optimum pitch vs rpm.

I'll clarify my position here: I am not saying you're wrong about this; I am just trying to see how you got to the results you got.

jky
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Old 26 June 2014, 11:51   #12
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Jky,

Great difference. that's why your current setup was excluded from this post as clearly stated. The difference is that with TT engines you can adjust trim, engine height faster as opposed to simple tiller engines in which you need to have spot on installations to work as expected and get the max out of each inlatable/engine combo.

Let me tell you that 75% of max rated worked spot on, running full wot rpm with a 18 when my combo needs 30 HP minimum, how's that ?

To fully understand what I'm talking about you should remove your current engine, sit a tiller driven engine with manual trim and experiment each posted point in working order to experiment by yourself what's posted.

It's all related at which LU height you love to have water flow passing by and if that's suits your perfromace best To each his own. For me counting with 2 Tohatsu brand engines it's right under WDP, works fine for me and 250 happy sib/rib/Tohatsu customers.

I assure you that you have not even made ​​the least effort to look back and check what's going at your back transom, you simply trim your engine and voilá, well happy you. We'll agree that a larger HP engine will compensate any lug issues compared to same achieved with portable engines. More HP makes the whole difference, right ?

Happy Boating
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Old 26 June 2014, 16:30   #13
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I used to have a tiller steered, manual tilt boat. I upgraded primarily due to ride comfort on longer runs (though carrying capacity had a lot to do with it as well.)

So yeah, my current boat doesn't apply to your test (as you've made clear), but then again I never said it did. I was simply discussing your test and your findings.

jky
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Old 26 June 2014, 17:33   #14
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Lots of words to read. Little data.
Advice:
Correct neutral trim - check.
Optimal height - check. Then we start to diverge.
You seem to suggest that dropping engine considerably lower, below 1-2 inches below transom, will reduce drag and improve performance. That's a pretty tall order. Little data is provided to prove it.

The water flow this water flow that. Look at the your engine. Good suggestion to keep eye on this. Unfortunately water flow is not a reference point it's something that one eyeballs, interprets, and either like it or not. Some people may not be as "kin" to judging if their water flow is just under WDP or some distance below WDP. There is almost no meaningful way to tell exactly.

AV- plate to transom bottom distance is definite measurement. Every one can replicate that with some effort. Or at least use as starting point. Why can't you simply post (or point to) a picture of perfectly in your opinion height seated boat motor combo. Or at least state the measurement at correct height. This would possibly help other with same motor boat combo. Wouldn't it?

Not withstanding you are suggesting your advice doesn't apply to center console boats you are insisting on chopping transom on exactly that kind of boat with Yamaha engine in the other topic.

2 stroke Tohatsu seem to be peculiar with relatively high water intake. You have to mount those relatively lower in order not to starve cooling system and overheat.
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Old 02 July 2014, 15:53   #15
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Sorry folks, will close this post as posters keeps posting nonsense issues that intended to avoid.

Jky, in order to prove what the entire post was all about, you need to come down here and test any of my boats/engines combo you like. The post was based on plain practice, not plain theories which you love to endorse without the minimum tech support. What seems to work allright on the theory, will not always work same on the practice. That's how men flew.

Sibrider, will not waste my precious boating time discusssing, arguing whatever you want to call it with you. Your boating theories, comprehention and skills are of such extremely poor level that probably will errase my fingerprints answering bumb posts specially ones coming from boaters who can't see far beyond its own nose You really should be knitting, not boating...

Bottomline : Test what's posted as indicated and reach a tech conclusion by yourself not other's conclusions. As stated before Yam recommends siitng lower unit at a height that produces the least water drag resistance on tail which are only achievable at 2 points, water deflector and anti ventilation plate. Go for the one that suits your boating needs the best and voilá....

Happy Boating
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Old 02 July 2014, 17:06   #16
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Jky, in order to prove what the entire post was all about, you need to come down here and test any of my boats/engines combo you like.
Doesn't that defeat the whole point of a treatise to inform others of a new way of looking at this?



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Your boating theories, comprehention and skills are of such extremely poor level that probably will errase my fingerprints answering bumb posts specially ones coming from boaters who can't see far beyond its own nose You really should be knitting, not boating...
...Aaaand we've reached that point again.


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Old 07 July 2014, 11:57   #17
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Doesn't that defeat the whole point of a treatise to inform others of a new way of looking at this?
Being a skeptical boater and having a proper answer for each one of my replies, you are the indicated who should come down here to have a close look under real water tests and not under themes that don't correspond over the net as this will turn in an endless tech discussion.

What bothers me is the amount of time invested in research, documentation, writing, posting pictures and then Sibrider comes along saying : Lots of words to read. Little data and then advising as an expert with themes that doesn't correspond as he has a different type of inflatable which by BTW was exclusded form this post too. If he's so lacy to read the entire post completely to fully understand it, that's his personal theme.

With this proven assay I'm just stating tech issues which nobody cares about, have not been aware of its existance before nor will find searching the net or even written on any inflatable & engine owner's manual brand. So if you want to follow these simple and spot on guidelines for top sib/engine performance as suggeested be my guests, if not continue with your boating life as usual...

Happy Boating
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Old 08 July 2014, 13:05   #18
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Originally Posted by Locozodiac View Post
What bothers me is the amount of time invested in research, documentation, writing, posting pictures and then Sibrider comes along saying : Lots of words to read. Little data and then advising as an expert with themes that doesn't correspond as he has a different type of inflatable which by BTW was exclusded form this post too. If he's so lacy to read the entire post completely to fully understand it, that's his personal theme.

With this proven assay I'm just stating tech issues which nobody cares about, have not been aware of its existance before nor will find searching the net or even written on any inflatable & engine owner's manual brand. So if you want to follow these simple and spot on guidelines for top sib/engine performance as suggeested be my guests, if not continue with your boating life as usual...

Happy Boating
Loco you are certainly assured of your expertise but understanding of what proven means in tech article seem to escape your mind. Post some numbers such as this height produced such RPM and speed, this height such and such, and so on. Reader then can easily do their own conclusion without shoving it down their throat. Single identifying picture of "ideally" height seated engine motor would do too. With all the research put into this issue that's too much to ask for I guess.

It's a big claim that no one in entire world knows, writes, thinks, takes interest about of LU flows. Guess LU shape of modern outboards were created randomly out of the blue without engineers thinking about it. Not to mention having motor at 90 degrees to water level is covered in every book/outboard manual if you actually read those. You recently started as you mentioned. You might discover lots of interesting info.
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Old 08 July 2014, 14:20   #19
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Gee, really don't undertsnad you at all, the info you request is of no interest to you having a different sib than most of us, right. Will content you, next time before posting nonsense issues of yours check closely at what's posted.

Post 6, second pic right below 1, will that answer your original inquiry ? Would you like to know which fuel brand was used during the tests too ?

With respect to LU water flows will agree with you, you know why ? that's because that info is written in nowhere land and that ideal height must be guessed by each one, even you. I already found ideal mine and that's posted on nowhere world, but sharing it with forum members selflessly

Don't tell me that 100% of boaters have their engines sitting at 90°, if engine dosen't work right the first thing they do is trimming engine out of 90°, will include you. I happen to have and read different engine owner's manuals brands, strictly from A to Z.

If with time, go to the other side of the pond and check : Engine/Transom Heigh and have a look, check what most engine brands poorly and confusing states regarding setup installations...

Happy Boating
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Old 09 July 2014, 03:38   #20
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So this is the best performing setup with least drag. Is it? Must be southern hemisphere thing. It's all upside down there anyway. That's best explanation I can come up with. As my experience is opposite.
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