Bhp?

[philSweet]

Stuck my foot in it again. Lets see if I can sort this out. Gonzo, you are right and I was wrong. I said rated horsepower where I should have said certified horsepower.

In the US, if car mfgs state a hp, it must be something called rated hp which is different.

replace rated hp with certified hp.

[Laranjo123]

Thx everybody i already got the BHP formula....tehehe

[daiquiri]

Originally Posted by Laranjo123

Thx everybody i already got the BHP formula....tehehe

What BHP formula?

[Laranjo123]

BHP = SHP / ng where ng = 98 %

[DCockey]

Originally Posted by gonzo

The rated HP is actual power measured at the wheels in the US. The rated HP hasn't been legal for decades.

Incorrect. Advertised power in the US is power at the end of the engine crankshaft.

The various methods to determine power for auto, tractor, boat, and other engines all determine brake power.

Prior to the 1972 model year the SAE gross power test proceedure was usually used to determine auto engine power. This proceedure resulted in power ratings which were sometimes much greater than what the engine delivered as installed in the vehicle.

Starting with the 1972 model year US manufacturers switched to the SAE net power test proceedures which result in ratings much closer to what the engine produces installed in the vehicle. European manufactuers usually used an equivalent DIN proceedure while Japanese manufactures used the equivalent JSAE proceedure.

In the last five or six years manufactuers have been switching to the SAE certified power test proceedure which is a tighter test proceedure. The ratings for a number of engines went down but some went up when the certified test proceedure was used.

Rated HP just means what the engine is rated at. In some infrequent cases it may be less than what the engine actually delivers.

[MikeJohns]

Originally Posted by Laranjo123

Hello gudday. I've been reading the PNA for about a day ago. I can't find any formula for BHP. My question is is there an exsting formula for BHP because i need to know the formula for BHP..... thank you.

BHP (Or PB) is a common enough term in ship propulsion although there is no formulae for BHP it is a rating . But you arrive at the required BHP working backwards.

Engine
BHP (brake HP)
Gearing
SHP (Shaft HP)
shafting/ bearings
DHP (Delivered HP)
Prop
THP (Thrust HP)
Hull
EHP (Effective HP)

The loss ratio between any of the 3 letter power abreviations is the efficiency of the stage.

Current convention is to remove the Horse "H" and write the abbreviation as: PB,PS,PD,PT,PE

[Laranjo123]

Yes it's true that you can't compute the BHP of the Engine it self. I've read that yesterday. Now my problem is. Where can i find engine with 2900-3000 bhp with 100-200 rpm?....

[MikeJohns]

Originally Posted by Laranjo123

Yes it's true that you can't compute the BHP of the Engine it self. I've read that yesterday. Now my problem is. Where can i find engine with 2900-3000 bhp with 100-200 rpm?....

http://www.rolls-royce.com/marine/pr..._gas/b3240.jsp

[Laranjo123]

Thank you mr MikeJohns...

[Laranjo123]

I have a question. Pd= (Pe x I) / nd
What's the I stands for? The book didn't tell what's that I
Pd= DHP
Pe= EHP
nd = 0.6

[Laranjo123]

Thx for the help all of you.....

[powerabout]

Originally Posted by MikeJohns

http://www.rolls-royce.com/marine/pr..._gas/b3240.jsp

they are medium speed 750 rpm

[MikeJohns]

Originally Posted by powerabout

they are medium speed 750 rpm

700RPM is the engine. Don't forget the reduction gear. The prop speed is presumably the 100 to 200 RPM .

[powerabout]

Sure its just the thread starter that wanted a slow speed engine and I doubt there is one at 5000hp, I would be interested to know if there is one

[rxcomposite]

The second question will be "Where do I get bowthruster?". With no reverse gear, how do you dock?