Lower Unit > vrs < Water Flow

[Locozodiac]

AV Plate Foreword :

I have been re reading several engine brands Owner’s Manuals, the general basic installations are imprecise & poor due to being extreme complex. Tohatsu states, “Be sure that the anti ventilation plate of the OB is “below” the water surface when running with throttle wide open.

Yamaha states “The info is intended as a reference only. It’s not possible to provide complete instructions for every precise boat and engine combination. Proper mounting depends in part based on proven experience and the specific engine boat combination.

Both states different AV plate & hull’s bottom distances. None of them states AVP “even” with bottom as a cast on stone universal immovable height in need to be perfectly matched by all. It’s just an assumption everybody is blindly following at boating forums or per word of mouth.

2 examples. Yamaha states 0 to 30 mm, Tohatsu 30 to 50 mm heights, why the difference ? Tohatsu has bit larger lower unit. Those numbers are indicative only, on real world boating will depend entirely on hull’s shape & transom’s height if sitting a Yam or Tohatsu OB.

Nome of them mentions at which lower unit height must water flow be passing when engine is in operation, for what concern us, operation is at plane at speed while sibbing or ribbing.

So based on your particular experience and own frustrated water trials it’s entirely up to you to find at which best height produces a combination of 3 in 1: least lower unit drag resistance, top performance on overall water conditions, and engine efficiency on your setup. If you can achieve those top boating conditions, congrats in advance, you have definitely won the lottery. Meanwhile, back to the water test lab…

[Locozodiac]

This is a long assay, read it carefully to fully undertstand complex ideas, water trials and assorted pictures...

1-Introduction : To achieve the best out of each inflatable/engine setup, all water trials have been done on a 800 Mt rowing water course lab, any errors achieved under dry installation theory set up can be fine tuned later spot on after trial practice ends.

Note : All sib/rib are “standard wooden, alum, flat air decks versions” with tiller driven engines and manual trim. All water trials were done under these Ideal Conditions :

-Flat calm, glassy no wind water conditions.
-Sib/ribs tubes min 3.0 PSI with gauge. Same for keel.
-Tiller driven engine trimed to 90°.
-Max HP engine transom rated for.
-Engine and prop in top running condition at sea level.
- Driver/spotter at throttle, balancer mate up front.
-Fresh high octane fuel.

The story of what’s really happens goes like this :

There’s been lately much controversy talk about Anti Ventilation Plate (AVP) versus Water Deflector Plate (WDP) heights when finally testing boat/engine combo after initial home basic installation.

Everybody knows about AVP, none know what this small metal piece that protrudes is called or even know the great influence this little bug exerts on tlower unit when sib planes at speed over water level.

To understand the general idea of this WDP & AVP >versus <Water Flow (WF) conflict will start from a 0 setup installation will not take into account the height between AVP and lower keel/boat’s bottom when engine is first seated on transom. Will just dismiss this conflictive guy for the time being, in my particular way of seeing things, have done it permanently.

For the theoretical dry water test will use a short shaft transom with a short shaft engine, both sib/engine brand of your particular preference, provided that the engine is max transom rated for, let’s say a 320-350 sib with max 15 HP engine on back.

We’ve taken our sib and now rest at water level at its Natural Floating Position (NFP) each particular sib has his own, have proceeded to mount the engine trimmed to a hole so finally rest at 90°on middle transom. This is the ABC basic installation guideline.

With state of the art balanced sib have gone full grip to WOT now sib is at “perfect plane”. Here’s were tech trouble chimes in, you could have made a perfect transom/height match if happens that transom height was a perfect match with chosen brand engine, but that’s not always 100% so in real world boating.

Driver and passengers fun starts when sib has finally planed out, but before that happens, let’s rewiew some missing tech points I want you to have into account.

[Locozodiac]

2-Glossary : Trim, balance, thrust, lift, density, resistance, are just plain simple words, will see how each one relates and some even between them.

When sib/engine rests on still water, is that, sib/engine resting on still water, but when sib moves forward propelled by engine at speed the still water has changed its natural condition when passed through hull to become a hardened, compact constant “water flow” exiting under keel/transom to impact lower leg resting at a fixed angle position. There are two “individuals” meeting hard against each other, one is lower unit > the other water flow going < , It’s thrust vs resistance water fight. Imagine all the shot and pull forces going on back there.

You have noticed that once on plane the sib somehow has extended the previous floating height to a higher level, everybody knows it’s a hull related issue, but alone ? definitely not, there’s where our density friend chimes in. Did you know that water is 100 times denser than air, being sea water much denser though, thus creates more drag resistance against a fixed submerged object than same object riding on air if comparing both at same equal speed.

That’s why lower units must ride on water with its 2 planes, vertical (lower unit) and horizontal (AVP) at 90° to achieves the least water drag resistance when moving at plane speed. Imagine the huge lower unit drag resistance achieved when engine doesn’t sit on a straight transom edge or engine has a bent swivel bracket to a side, add AVP not riding parallel to water level. A sib/engine top HP rated will compensate this drag better due to having more HP power than one being underpowered.

When sib rides at speed on water is like riding, sliding over a hard surface, when reaching certain speed the hull will automatically lift up and pull sib out of the water, the time it takes to do so will depend on hull shape, engine power, trim and balance, the faster the lift, the faster the sib will plane out, provided that combo has a healthy and efficient engine & prop, which is a must have. For plane out top efficiency will need 75% minimum of max engine transom rated for.

[Locozodiac]

3-As a test, while sib is at minimum flat plane, extend and sink your finger at passing water next to tube, feel the resistance your finger achieves, plane to ¾ and full throttle, would you say it’s the same resistance on your finger at all 3 tests ? Nope, more speed, more drag resistance, right ?

To quantify drag resistance of a fixed object against water at speed, would you say that a square, round, sharp edge object has same drag resistance ? Defitely not, sharp, round edges which are reffered to as Angle of Atack have their own particular resistance coefficients. Having the sharp edge which cuts WF more efficiently the least drag resistance compared to round ones, right ?

The drag resistance of the 3 mentioned shape forms 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.

Consider, all engine brands are not built same, although being same S, L sizes some have rounded edges, others sharp edges located between WDP and AVP it’s a factory design. A sharp edge as seen before will cut water flow at speed much efficiently and produce least drag resistance on lower unit compared to same round one.

Some heinous examples : 320 sibs with 42 tubes, 380 with 45 tubes, 420 with 50 tubes all being short shafts rated will not float same, larger 420 with 50 tubes will float at a higher water level compared to a 320 with 42 tubes which floats at less level. Short shaft transoms fall in the 15 to 16 inch height category. Long shaft transoms falls in the 18-20 Inche category. As seen tube diam & transom heights will inevitably vary from sib to sib size and brand to brand if comparing 2 same sizes between 2 brands.

Add that same S size engine brands are not built same, there’s slight lower tail heights differences between them, it’s own brand factory design, not a flaw issue. As an example Tohatsu has a sharp lower edge under WDP & AVP as opposed to Suzuki that uses a round edge if comparing 2 long shaft engines between them.

We have reached a trickky conflict between engine/transom to perfectly match each other heights. As own experience, mounted a Yam S 15 HP on well trimed & inflated to perfection 380 sib with 38 cm transom height, performed very well, installed a Tohatsu S 15 HP on same transom after removing the Yam, guess what, horrible performance, so much water splashes over transom that 2 could shower at each side of engine.

What happened, under trial discovered that Tohatsu has bit larger lower unit than Yam, WF was hitting the square edge located right over WDP, raised the transom to 40 cm and voilá, magical superb overall performance. Now WF skims happily under WDP.

[Locozodiac]

4-What has this theory to do with WDP and AVP ? Keep in mind that water flow which has become hardened & compact due to speed will necessarily hit front lower unit at 5 possible heights as seen from rear engine.

At which lower unit height would be ideal for WF to pass by then ? definitely not over WDP no matter which engine brand is it, will experience over or out transom water splashes.

When WF passes through lower unit must necessarily be through WD and AV plates, at speed/plane you will experience 3 possible lower unti heights for WF to pass by which are: Under WDP, between WDP-AVP or above AVP.

When WF exits under boat’s keel/bottom skimming right under WDP, the water that usually swirls/climbs through AVP edge up, will instantly be diverted straight towards middle wake by means of DWP. Will produce a very flat middle wake with no water side splashes on to middle wake.

When WF passes between WDP and AVP water will swirls & climb through rear lower unit coupling under WDP, will produce 2 small side splashes diverting to side of middle wake.

When WF passes skimming above AVP will see more water swirling and climbing real lower unit and hitting more violently lower WDP, will produce bigger water splashes diverting to side of middle wake along complete exposed AVP. That’s with lower legs that counts with sharp edges, round ones will produce bigger side splashes.

When sib/engine combo doesn’t want to plane, what most boaters usually do is play with trim settings to compensate frustrated plane, wrong way to go, as seen before, engine loses best blade grip and prop thrust which is achieved when engine sits at 90°. It’s just a matter or proper inflation, engine/transom height, weight distribution and engine/prop health.

When all factors are correctly dialed, trim should be left untouched at 90º, just fast throttle or wot throttle and out you go for a fast plane.

[Locozodiac]

5-When WF skims under WDP you achieve two main conditions : (1) best prop grip and top prop thrust (2) AVP riding at 180° and maintaining well balanced sib riding along parallel to water level on perfect plane at speed. Also accounts for faster hole shot, best max rpm, best water performance under light to medium choppy, windy, wavy sea conditions, superb tight close turns at slow or higher speeds and overall top engine efficiency.

Consider that what’s light to medium sea conditions here could be a child’s play in UK, USA. So entirely up to you to plane at the speed you like most and feel comfortable with, but taking into consideration water behavior at each one’s location.

As mentioned earlier, AV plate height with respect to keel/boat’s bottom on initial set up is relative as you’re not considering tube diameter, hull shape, transom height, engine brand length for that particular engine/sib brand once sib is running. On the practice, you need to match engine brand to specific sib brand transom height accordingly.

That’s why like going against the current and focus on WDP, that’s the other side of the coin. As you probably know, we sell sibs/ribs/engines locally. Do you think clients will buy from us inflatables with Tohatsu fitted engines that doesn’t work spot on. No way, would you ?

Sea Rider Photo Gallery by Luis Montero at pbase.com

Personally have tested each previous imported new sib/rib model on my water lab to state of the art Tohatsu engine match, then transom height modified at factory to meet those stated conditions. Would be insane modifying each model and quantity locally once arrived.

[Locozodiac]

6-Performed again for second time the wot test with WF skimming right under WDP and skimming right above AVP. The trial skimming right under WDP was much better. Besides faster hole shot with near instant plane, the engine gained + 180 rpm and 1 knot + compared to same test with WF passing right above WP. Both test were done with just driver, tach and GPS on its full lenght water course. Is there any better documented proof than that ?

If you dial that near spot on sweet engine height as seen on this video :

Tohatsu 20hp w/ 3/4" shim and proper trim - YouTube

Will achieve :

-Fast hole shot and instant plane.
-Throttle reduction, fuel comsumption & economy when cruising on plane/speed.
-Top wot rpm engine efficiency.
-Longer engine life.

Add top inflated sib and engine as stated and will achieve a much efficient combo that will work fine in most water conditions. If you are a boater who uses his inflatables as yacht/marinas tenders, who likes pottering around, trolling, going on just displacement speeds or boating miss Daisy, this assay is not for you. It’s intended for those who likes to get the most fun out of their combos, cruise at plane, wot crusing, going off shore to remote places

Will depend entirely on which type of boater you intend to be. It’s up to you...

[Locozodiac]

Prologue:

To simply understand the overall idea and don’t blow your brain out digesting all the complex points that’s been mentioned here, would advise not to take into any consideration sib/engine brand or what has been regularly stated. Simply sit any given engine on any given transom height, go for a wot trail and start from there matching Water Flow to skim under Water Deflector Plate, raise or chop transom down accordingly to achieve that “precise spot on condition” which has proven to work best as opposed to less favorable AVP lower unit height overall performance.

When Sweet Transon Height Spot has been reached, you can go from there maximizing your rpm wot numbers playing with prop pitches to optimize your inflatable/engine combo for your particular recreational needs and wishes, not before.

To finish, will say that if in need to raise by any means or chop transom down accordingly to match what have been stated here, it’s your personal issue not mine. The Sweet Spot is only achievable under trial and error on ideal water conditions by simply start “looking” what’s going on at back transom’s party.

When asked arlier, once AVP was seated even or slight under keel/boat’s bottom what were you trying to achieve or if water flow was of any importance to you before sib was tested on water, nobody responded.

This concludes that both WDP & WF villains are in nobody’s dictionary, give too much importance to AVP height as have been long time stated worldwide, but nobody states what will you accomplish with that setting.

What’s written on engine owner’s manual delivered with each new engine is completely vague and bland. To me its Limbo time, as a dog roaming the neighborhood.

Now that important tech points you didn’t care or knew about has been easily explained here in simple writing & illustrated details that makes any boating day a big difference, are you thinking same as before or are we on same page ?

Important notice : This is a “standard” sib/rib assay, so not to fly over the Cuckoo’s nest in pure theoretical assumptions and out of this world strange comparisons, the following setups will not apply nor have been taken into the least consideration when writing this assay : Being way underpowered from max transom rated for, Zodiac with speed tubes, V deep inflatable keel decks, Thundercat type with speed tubes, double hull sibs or center console driven sibs/ribs with electric trim, tilt.

Anyway so not to lose heart, all general tech points can be applied to all those nice mentioned toys, a matter to try them out correctly under trial and error and check which ones dials best to them. That's all Folks, hasta la vista baby, enjoy your boating days and Good Luck!!

PD: Would like to maintain this assay as impeccable as possible so not to go off topic, if any point is not clear simply inquire about what you don’t understand about it.

Happy Boating

[jyasaki]

Couple of notes/questions:

Post #3

Imagine the huge lower unit drag resistance achieved when engine doesn’t sit on a straight transom edge or engine has a bent swivel bracket to a side, add AVP not riding parallel to water level.

I read this as "motor is not vertical in the water". That would not increase drag aside from the slight length increase (assuming the motor reaches the same depth as a plumb installation.) Drag is caused by the interference of the object (the LU in this case) to the passage of the surrounding environment (water in this case); since the only change is the vertical angle of the object, and not it's presented cross section, there should be no increase in drag.

If you are talking about a LU that is not tracking straight, well, it's a tiller steered motor we're discussing, so that would imply a turn.

Post #3

For plane out top efficiency will need 75% minimum of max engine transom rated for.

Where did this number come from?

AFAIK, plate max hp figures are chosen by the manufacturer based on safety and liability, and not necessarily on performance. The max suggested hp thing may be a good suggestion or it may be quite conservative, depending on the manufacturer. Since the number is sort of arbitrary, I'm unclear on how you can assign a number to that.


Post #4

The drag resistance of the 3 mentioned shape forms 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.

Yes, it is. Assuming the water at the side is traveling past the LU at the same speed as behind the hull, with the same LU immersion depth, the drag will be the same. Water is not compressible, so the amount of water passing will be the same, the speed is the same, and the cross section is the same, therefore the same amount of drag created.


Post #7

Will achieve :

-Fast hole shot and instant plane.
-Throttle reduction, fuel comsumption & economy when cruising on plane/speed.
-Top wot rpm engine efficiency.
-Longer engine life.

I'll give you the first one, as you tested that. Are the other conclusions based on numbers from your tests? With the motor deeper in the water, you were able to maintain a given speed with less throttle (and conversely achieve a higher speed at WOT)? Did you actually compare fuel consumption at the different heights for a given distance? Did you run both height settings until the motors failed?

I'm impressed with your tests, but these claims are a bit beyond what the tests support (unless you're holding numbers back.) If they are your hypotheses, fine, but state that they are your beliefs rather than a test result.

As an example, a LU with less surface area (meaning less in the water) will have a lower overall induced drag at a given speed, right? So max engine efficiency will be attained with the least amount of LU in the water that allows for the prop to cleanly drive water. Overall performance will suffer (meaning ventilation in turns or waves), but efficiency will still be higher in smooth calm water while traveling straight.

Which brings us back to the point of contention in the prior AVP/water flow post: Setup will be a compromise between efficiency (less created drag) and performance (ventilation, for the most part.)

But your results are interesting, and probably bear some looking at.

Thanks for the report.

jky

[Locozodiac]

JKY,

Some acclaration regarding my questioned points :

3-As established exprofeso well in advance it's a tiller driven manual trim engine. 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. OK, let's find a culprit for that.

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 ?

Personally have taken the max out engine performance powering a rib that's rated for 40 with min 30 HP with just a 18 HP. Don't need a 30, with just 18 performs top for my boating needs.

4-Assumed wrong, stated at side of tube, who said anything about back LU ?

5-We're definitely tuned to other parameters, what's deeper to you probably ain't deeper to me. See it my way, nobody at least down here is cracy enough to run wot for extended time periods when 95 octane fuel costs on average US $ 5.65 for a 3.78 Ltr to a gallon. If my engine powers my boat more efficiently, needs to be throttle less than same boat with less efficient exact same engine, both going at same speed right.

Don't need to run engine at different LU heights untill it fails, by fail you mean kaput ? I'm most pleased with my LU sittting at a height where water skims and engages right under WDP. Why keep looking for the 3 feet cat ? What perfectly matched on an ideal rowing course works top at open waters too.

How much more drag will you achieve running LU with water flow passing through WDP or AVP, just bit slight more, as long WF is efficiently cut at lower edge that runs WDP downward to AVP, what's the big deal. You are skipping one issue that's, if having a higher water bed level as in posted pic, prop will bite and grip much efficiently onto WF and thus compensating the sligh more drag while running engine sitting at a higher position, get it ?

You definitely have been lightly reading the whole post, it's all related to tiller driven, manual trim engines powering sib/ribs with up to 40 HP initial installations. So to have a friendly chat on this nice forum, your current boat/engine combo is ....?

Let's not get too extremely picky if at lower unit water, boils, bubbles, sparks, gets fined or stops for a coffee break. There's extreme forces going on fighting at back transom, the whole idea is to minimize, appease them and live with it, if you are in pursuit of dismissing them forever, better drop your current engine into the blue and get a big fan motor and problem solved.

As stated earlier on the AV foreword, it's just a matter to pick the engine height that works best for your particular setup, just giving an overall idea of what works top for me and other sibbers, ribbers that have tried it worldwide and boating happily ever since.

We're not going to argue or quarrel about if water flow must pass along under WDP or AVP, on a short shaft engine it's only 10 cm difference, and that's definitely the boating difference. Lower unit will always produce drag resistance, the least the better specially if under powered.

The issue with plain theories is that not always turns out as expected under trial and practice. You know why ? Nobody looks what's happening at back transom, it's the only way to correctly match water flow to pass under your preffered lower unit height. Seems, everyone enjoys wild guessing, assumes, asks at the forums endlessly. To each his own...

I'm not going to delve deeper on this post. If what's written works top for any one that wants to try it out, be my guest, If not keep rigging your boat engine combo as you been doing so, if works superb for you congrats in advance.

Bottomline, my results are not a matter of having a look at them, sorry, must be water tested under trial and error.

Happy Boating

[jyasaki]

Originally Posted by Locozodiac

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.

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.

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:

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.

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.

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.

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.

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

[Locozodiac]

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

[jyasaki]

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

[SIBRider]

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.

[Locozodiac]

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

[jyasaki]

Originally Posted by Locozodiac

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?

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.


jky

[Locozodiac]

Originally Posted by jyasaki

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

[SIBRider]

Originally Posted by Locozodiac

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.

[Locozodiac]

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

[SIBRider]

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.