Best Rib with 150 HP

[Cookee]

Manos - Do I remember you saying that the 150 was tuned to give out a little extra power or is it the standard out of the box 150 that is claimed to do over 60 knots?

[Manos]

Hi Cookee

The 150VMax as you probably know produces 180 bhp and the 200VMax 230bhp.
The 150 VMax as far as I am aware is tuned for F2 racing and as per regulations. I think is similar (or the same) to the UK ones.
The answer is yes but up to the point that is permited for F2 racing.
The racing boat is fast. As you know I have been on it ( actually both the F3 AND F2) in SAfrica last year. I was not looking at the speedo but it felt fast on top of 3 and 5 mtr waves. The F3 with a 90bhp Yam 2-strokes was doing 120kms/hr in the dam
If I rember correctly it was a race last year that it had to do with long distance speed record. I had posted a thread about it.
Any way for some reason one of the fins on the SS prop was snapped. The boat came first after also stopping to inspect the damage mid seas averaging 50 or 55 knots (I think). If you find this thread with photos you will see as I published the report as I had it from the Pilot Dirk Schlechter.
On one of the 700RSRs recreational version we have in Greece we set one notch higher up a 175bhp Evinrude Ram with a 23" pitch SS prop (can't remember what make). The boat from 45-47 knots went to 60-62 knots (I suppose the dials of the Ram are in knots) but we felt it was dangerous for recreational use as the seats are not the bucket type and if you went on a wave at that speed everyone would come off with disasterous results. So we decided to put the engine down again.
When you have the time you are very wellcome to come to Greece and have a ride on the boat. May be this new one we will get some time after Feb next year. The boat IMHO is No1 for RIB racing up to F2. For F1 probably needs a longer hull to get more out of it.
You will be impressed I'm sure.

[Cookee]

Just to clear up 1 point if anyone is confused - the F1 and F2 you regulations you are referring to are South African and bear no resemblance to the class rules in the UK.


In the UK F2 is probably going to be the only class next year and is limited to 200 hp outboard or Yanmar diesels on bigger heavier boats with absolutely no "tuning" allowed other than blueprinting - you cant use anything other than genuine Mercury parts either!
I think you will find that most manufacturers speedos (including but not limited to Searay!) are in MPH although some may be in KPH for foreign markets.

As far as the hull being the best for racing - in which country?

[John Kennett]

Originally Posted by Manos

The 150VMax as you probably know produces 180 bhp

Do you know how they modify it to get that extra 30hp? I don't know much about engine tuning, but a 20% increase sounds pretty impressive (especially as they don't seem to have any major reliability issues with it!)

John

[Manos]

OK I didn't know that I thought since they read from the same rule book that they would have been the same.

OK I understand about the gauges.

The best boat for racing in which country? So far SAfrica. This has been proven time and time agian.
But I'm sure that days will come that it will be used else where.
Is these regs here that make the boat non usable. The hull LOA thing. If nthey just permited boats in F2 with hull LOA 6 mtrs I'm sure that the FALCON would have been here. May be some are affraid, or the bigger boats not sell as well as the smaller ones so they want to advertise them in this way, or ...... Who knows why this regulation had come about

[Manos]

Originally Posted by John Kennett

Do you know how they modify it to get that extra 30hp? I don't know much about engine tuning, but a 20% increase sounds pretty impressive (especially as they don't seem to have any major reliability issues with it!) John

John from what engineers have told me it has to do with the VMax technology(hence the word VMax something like VTec in the Hondas). The VMax series come like that from the factory (i.e. extra 30bhp so they say). I suppose is a marketing thing instead of Yamaha say, Yamaha 180 and Yamaha 230 they say Yamaha 150 VMax and Yamaha 200VMax respectively. If any one knows any more on this subject it would deffinately be of use.

In Greece for example when we inquired to race my recreational Falcon 700RSR with the 200VMax they put me in the 250bhp recreational RIB category rather than the 200 bhp because of the extra 30bhp that the engine produces. That was verified by the scrutineering committee as I made a biog fuss about it. Unfortunately we didn't race due to a serious illness.

I posted today a thread about some parts as we are modifying the 150VMax we have asking a few questions and any advise on that would highly appreciated.

[Cookee]

The minimum length is purely a safety thing - 200 hp on an 18 foot boat might seem normal for some but the organisers have to be responsible for everyones safety, and 10 or 12 miles offshore in a beast like that would be a challenge for anyone!

[Manos]

Yes I suppose there is a point there. But surely if my RIB is sold as 7mtr and has passed as 7mtr why I cannot race it?

If I am mad enough to do it this is my problem and no one elses. We are all adults and take full responssibility for our actions. So why this rule? It didn't appear to be there a few years ago? Wasn't dangerous then?

This rule it does not apply in the Greek RIB races. Boats categories are with bhp and whether they are recraetional or racing. Makes things simple doesn't it? and everybody can have fun.

[John Kennett]

Originally Posted by Manos

The VMax series come like that from the factory (i.e. extra 30bhp so they say). I suppose is a marketing thing instead of Yamaha say, Yamaha 180 and Yamaha 230 they say Yamaha 150 VMax and Yamaha 200VMax respectively.

That's just plain daft. Bigger engines sell for higher prices, so there's no way any manufacturer is going to understate the output of their engines . . .

John

[Manos]

Well may be it is.
However, the 150 and 200 and 250 VMaxes in fact are more expenssive than the 150s and the 200s and the 250s.
So may be the argument that they produce more bhp is correct.
Any way some engineers that I know seem to think that they produce 30bhp more.

[Manos]

Cookee and who ever is intested I just found this thread I was talking about with the broken Falcon prop http://www.rib.net/forum/showthread.php?t=5050Have a look at it if you like

[jwalker]

Originally Posted by John Kennett

..there's no way any manufacturer is going to understate the output of their engines . . .

Yes they do.

[Rogue Wave]

getting back to the original question ....then what about a fantum evo

[John Kennett]

Originally Posted by jwalker

Yes they do.

Who?

[Brian]

Yanmar 300? Actually 315hp??

[Dirk Diggler]

Originally Posted by Brian

Yanmar 300? Actually 315hp??

I've often wondered about that one, it seemed to change overnight. Barrus must have got a new batch of stickers coz as far as I'm aware the motors are the same spec!

[jwalker]

I think it's fairly standard practise, JK. The info. I have is considerably out of date now but I'm sure it'll still be indicative.

These are the results of dyno tests on standard engines:

OMC 150 ..............155 @ 5000
OMC 150GT & XP ...175 @ 5250

Merc 225 ...............225 @ 6000
Merc 200 ...............220 @ 5750
Merc 175 ...............195 @ 5750
Merc 150 ...............165 @ 5750

Yam 225 ................250 @ 5750
Yam 200 ................220 @ 5500
Yam 150 ................160 @ 5250


It certainly accounts for the differing performances of various makes of engine on similar boats. After all, 200hp is 200hp and all boats, if rigged properly, would give the same or, at least, similar top speed with the same engine power.

This, of course, doesn't take into consideration mid range power and, therefore, the actual drivability of a particular boat/engine combination.

----------------

Just as an addition, for information. Except for an increase in engine capacity, the only engine modification which will give increased power over the whole of the rev. range is an increase in compression ratio. Generally, mods give extra power at increased engine revs. Note the word 'generally' because this is not necessarily a fixed rule.

Oh yeh, a higher compression ratio will also give a better fuel consumption. Just though you'd like to know that.

[Jono]

where is "horsepower" measured in these tests, JW, are they crank ratings or prop ratings? If crank, did they establish transmission losses? I notice that Yanmar rate their engine from 250 ish up to 315 depending on inlet temperature. Also they give a continous rating as well. Any idea what the inlet temperature is under normal running conditions installed in a boat?

[jwalker]

The literature refers to an absorption brake powerhead dyno so I guess they are powerhead figures. I believe them to be comparative tests but no indication of air temp or air pressure is given.

Jono, these are all outboard motors, are you referring to a diesel?

Temp in a boat is going to vary with the engine housing design and how much heat is collected by the air passing over various components on its way to the airbox. The engine block temp is going to be very close to the engine water temp. I guess various ancillaries may reach substantially high temps.

[Jono]

Sorry, JW, I should have separated out my post a little better..

Yanmar "315" engine is only rated at 40 C at the injector. I just wanted to know what a standard operating temperature was in this region. I know you have the heat soak effect raising the temperature but you also have the cooling effect of the fuel passing through the injector, so what would the temperature be. it strikes me as a strange way to quantify power rating. I mean, I understand that dirty 'ol diesels ( ) produce their max power when cold, but do they reach 40 C in normal operating conditions?

As for the outboards, if we take transmission losses into account are we more in line with what the engines are "badged" at?