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How to find the HP of your engine?


BrenMyster

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I was saving him the trouble of turning back the page.

 

A photo of the engine would enable someone on here to say "that's a Widget Mk 2, so it's x hp".

Fair enough.

The OP says that he's visiting the boat later and will let us know the make and model.

Ee, that Widget Mk. 2, now that were an engine...

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Like many boats on there it is probably listed as 999 HP.

 

Wonder what at his insurance company will make of that? smile.png

 

 

Yes amusing if he's beetled off and told them that!

 

On the other hand, maybe no-one there will turn a hair as its' under the arbitrary 1,000hp limit......

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Rule of thumb - assuming it hasn't got a proper engine * is

30ft - 20 Hp

40ft 32 Hp

50 ft 40 Hp

60 and up 50 Hp

(Yes of course there are nay variants)

 

* a proper engine is a great heaving monster all set about with acres of polished copper / brass/ aluminium, so large it has to be in a separate 'room'

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Ah but is that the same as Max Governed speed ?

Probably not.

 

The max governed speed is the max RPM the engine can run at before over rev damage happens.

WOT is fully open 'throttle' ie calling for max power. If the engine is in drive and the propeller matched to the engine, then at WOT the engine should be close to max RPM.

If the prop is too big then the engine at WOT will not achieve max RPM and so not get to max power, likewise if the prop is a bit small then the governor will limit the RPM to a safe level before the engine has achieved it's max power.

 

So if your prop is well matched to your engine then max RPM and max power will be at WOT, but I doubt many boats are perfectly matched.

Edited by Chewbacka
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The max governed speed is the max RPM the engine can achieve.

WOT is fully open 'throttle' ie calling for max power. If the engine is in drive and the propeller matched to the engine, then at WOT the engine should be close to max RPM.

If the prop is too big then the engine at WOT will not achieve max RPM, likewise if the prop is a bit small then the governor will limit the RPM to a safe level before the engine has achieved it's max power.

Even out of gear

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Find out the stroke and bore and no, of cylinders. That will enable you (or someone here who know these things) to calculate the CC.

That is usually good enough for insurance purposes.

My CRT licence renewal form asks for either - CC or BHP.

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Just tell us what engine it is and someone will look it up for you.

 

Or post a photo of it.

Both reasonable questions asked at the outset Mike. I think he's found it on Canalplan and bu§§ered off. I tried Canalplan for him using the boat name he posted under his avatar, but I think he'd used his own name there and has now removed it. We don't even know whether it's a Narrowboat, so it's probably time to down tools pending further OP input.

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Rule of thumb - assuming it hasn't got a proper engine * is

30ft - 20 Hp

40ft 32 Hp

50 ft 40 Hp

60 and up 50 Hp

(Yes of course there are nay variants)

 

* a proper engine is a great heaving monster all set about with acres of polished copper / brass/ aluminium, so large it has to be in a separate 'room'

A proper engine has 'Made in Japan' on it and needs looking at so rarely that I've forgotten where it is!

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post-9340-0-83391100-1487842125_thumb.jpg

 

Liter per HP hour isn't a constant, but vary with the %load, and a small diesel engine use little more then a large engine.

 

.190 to .210 at WOT

but .330 at 10% power, like 4.5 HP of 45 HP ~1.5 L/h

 

that's why a smaller engine will be more economical on fuel in a slow boat, it need to work harder.

say it have a 20 HP engine, using the same 4.5 hp at cruise it will use ,255 l/Hph or 1,15 L/h

Edited by Dalslandia
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We have a barras shire 50hp engine in Nightwatch.

 

No idea how much diesel it uses, but it didn't half move on the Ouse!!

 

We also have a 17" propeller on/under the back end. I sometimes think it's not big enough,as to cruise we have to maintain about 1100 revs.

 

Martyn

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We have a barras shire 50hp engine in Nightwatch.

 

No idea how much diesel it uses, but it didn't half move on the Ouse!!

 

We also have a 17" propeller on/under the back end. I sometimes think it's not big enough,as to cruise we have to maintain about 1100 revs.

 

Martyn

Can the engine achieve maximum revs with a wide open throttle (rack for the pedants)? If it does so easily then you're right :)

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We have a barras shire 50hp engine in Nightwatch.

 

No idea how much diesel it uses, but it didn't half move on the Ouse!!

 

We also have a 17" propeller on/under the back end. I sometimes think it's not big enough,as to cruise we have to maintain about 1100 revs.

 

Martyn

You might or might not need a different propeller, for sure.

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Probably not.

 

The max governed speed is the max RPM the engine can run at before over rev damage happens.

WOT is fully open 'throttle' ie calling for max power. If the engine is in drive and the propeller matched to the engine, then at WOT the engine should be close to max RPM.

If the prop is too big then the engine at WOT will not achieve max RPM and so not get to max power, likewise if the prop is a bit small then the governor will limit the RPM to a safe level before the engine has achieved it's max power.

 

So if your prop is well matched to your engine then max RPM and max power will be at WOT, but I doubt many boats are perfectly matched.

 

Maximum power is not usually produced at maximum RPM in a diesel engine.

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I hope people reading this thread are not zooming up and down the cut at full welly while dipping their fuel tanks! This method is not suitable for any but ocean going vessels and even then it's a daft way to determine your engine power!

 

Reminds me of a student who failed his physics exam. The question he failed was, 'how do you measure the height of a building using a barometer'? He thought this was daft so he wrote that he would drop the barometer off the top and time how long it took to hit the ground. At his resit he said he would use the barometer like a yardstick and measure the inside wall as he climbed the stairs. On his second resit he said he would stand the barometer near the base of the building and use the length of the shadows to calculate the height. Eventullaythe examiner gave in and passed him.

  • Greenie 1
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