Engine overload

[soldthehouse]

Maybe, I don't run the Ruston very high but that has an 18x19 with a 2-1 box.

Also worth noting... the Dorman box will run in the wrong direction quite happily ie reverse for forward and vice versa

[casper ghost]

Also worth noting... the Dorman box will run in the wrong direction quite happily ie reverse for forward and vice versa

Are you absolutely positive about that? There aren't many manual boxes that will run in reverse happily for any time. I run my PRM in reverse so I could fit my RH prop..

[soldthehouse]

Are you absolutely positive about that? There aren't many manual boxes that will run in reverse happily for any time. I run my PRM in reverse so I could fit my RH prop..

Have you not got a Dorman book, I have a few I'll get one to you if you want it. They are very simple and agricultural and meant for Naval use along with the kitchen rudder set up that was also used.

[casper ghost]

Have you not got a Dorman book, I have a few I'll get one to you if you want it. They are very simple and agricultural and meant for Naval use along with the kitchen rudder set up that was also used.

I grant you the box is massively engineered but the manual specifically states to use a left hand prop.. it also recommends a prop of 16x13 but that is for a 25ft scout boat..

[soldthehouse]

I grant you the box is massively engineered but the manual specifically states to use a left hand prop.. it also recommends a prop of 16x13 but that is for a 25ft scout boat..

Any calculations quoted will be spurious as variations are exponentional I'll jump off the nearest pier if 21x18 isnt correct for your intended boat

Edited January 27, 2011 by soldthehouse

[casper ghost]

Any calculations quoted will be spurious as variations are exponentional I'll jump off the nearest pier if 21x22 isnt correct for your intended boat

Your prop sizes are getting bigger! The nearest pier to me is about 90 miles...

[soldthehouse]

Your prop sizes are getting bigger! The nearest pier to me is about 90 miles...

Its that 4lb... knocked me off my stride

[FadeToScarlet]

Also worth noting... the Dorman box will run in the wrong direction quite happily ie reverse for forward and vice versa

 

Is MoominPapa paying you commission?

[soldthehouse]

Is MoominPapa paying you commission?

Tis a pleasant thought I'll put your "prop"osition to him

[MoominPapa]

Is MoominPapa paying you commission?

Three jelly-babies and pint of Guinness on completed sale?

 

MP.

[soldthehouse]

Three jelly-babies and pint of Guinness on completed sale?

 

MP.

Deal

[mykaskin]

Here is a video of Victoria at speed:

 

 

Is 1000rpm OK on a 1200rpm engine?

 

After seing my mates engine/prop setup in person I do now think it's overprop'd as it doesn't get many revs more than my JP!

 

Mike

[MoominPapa]

Here is a video of Victoria at speed:

Mike,

 

I bet when you were a kid you used to ride your bike with your feet up on the handlebars.......

 

MP.

[mykaskin]

Mike,

 

I bet when you were a kid you used to ride your bike with your feet up on the handlebars.......

 

MP.

 

I was too much of a wimp, and stopped doing no handers when I fell off once over taking someone!

 

Mike

[Proper Job]

Is 1000rpm OK on a 1200rpm engine?

 

After seing my mates engine/prop setup in person I do now think it's overprop'd as it doesn't get many revs more than my JP!

 

Mike

Looks like a good set up to me.

 

Light smoke at 1000 rpm and that turn of speed in deep water. I bet the old JP loved the chance of a good blow out

 

Nothing my JP3 likes better than the chance to run on low comp' at 1000 rpm in deep water. I don't have GPS to know what speed I'm doing but I can give a few cruisers a run for their money on the Thames.

[bargemast]

Hello Mike,

 

if your prop is not 100% right, it must be pretty close as there's no noticeble black smoke coming from the exhaust.

 

Maybe if your stern is slightly deeper in the water it will be a bit more effective as there's still part of your propwash coming up immediatly behind the stern, which is lost power.

 

Peter.

[canaldrifter]

Here is a video of Victoria at speed:

 

 

Is 1000rpm OK on a 1200rpm engine?

 

After seing my mates engine/prop setup in person I do now think it's overprop'd as it doesn't get many revs more than my JP!

 

Mike

 

Call that fast? This is Dreamcatcher at speed on the Weaver.

 

Mind you, a BMC Commander doesn't sound as good... nor does D/C look so good.

 

 

Tone

Edited April 7, 2011 by canaldrifter

[Timleech]

Here is a video of Victoria at speed:

 

 

Is 1000rpm OK on a 1200rpm engine?

 

After seing my mates engine/prop setup in person I do now think it's overprop'd as it doesn't get many revs more than my JP!

 

Mike

 

[pedant]That's not the Weaver, it's the Weston canal [/pedant]

 

You do know there's a speed limit on the Weaver (including said canal)?

(6mph AFAIR but they don't publicise the fact these days).

 

If you're getting no increase of engine speed & no black smoke when you push the throttle lever right back, it suggests to me that there's some sort of fuel stop in place even if you don't have a cold starting pawl. Is there anything at all fixed to the fuel rack at the opposite end to the governor linkage?.

 

Tim

[mykaskin]

[pedant]That's not the Weaver, it's the Weston canal [/pedant]

Yeah I know that... some of it is filmed on the River though!

 

You do know there's a speed limit on the Weaver (including said canal)?

(6mph AFAIR but they don't publicise the fact these days).

 

Yeah I know that too... only 0.7 mph over - surely they can't expect exact speed! :-)

 

If you're getting no increase of engine speed & no black smoke when you push the throttle lever right back, it suggests to me that there's some sort of fuel stop in place even if you don't have a cold starting pawl. Is there anything at all fixed to the fuel rack at the opposite end to the governor linkage?.

 

Tim

 

I'm getting no increase of engine speed, but a lot more black smoke does ensue. In fact you can't really hear it on the video thre is a noticeable change in sound when you are there. That lever is attached direct to the fuel pump, so nothing is stopping it - and no there isn't anything on the end of the rack. I'm not sure about the design of the fuel pump, it could be that the last bit doesn't add much more fuel - but it does make more smoke, so it must be putting more in!

 

Now to supercharge it! What did I do with my hairdryer...

 

Thanks,

 

Mike

[Timleech]

Yeah I know that... some of it is filmed on the River though!

 

 

 

Yeah I know that too... only 0.7 mph over - surely they can't expect exact speed! :-)

 

I think some of the boaters who go on the Weaver now think it must be 4mph

 

 

 

I'm getting no increase of engine speed, but a lot more black smoke does ensue. In fact you can't really hear it on the video thre is a noticeable change in sound when you are there. That lever is attached direct to the fuel pump, so nothing is stopping it - and no there isn't anything on the end of the rack. I'm not sure about the design of the fuel pump, it could be that the last bit doesn't add much more fuel - but it does make more smoke, so it must be putting more in!

 

Now to supercharge it! What did I do with my hairdryer...

 

Thanks,

 

Mike

 

OK, your blade must be a bit on the big side. That said, early JPs were only rated for 1000 rpm, and your boat seems to go pretty well, so maybe not something over which to loose too much sleep

 

Tim

Edited April 7, 2011 by Timleech

[mykaskin]

 

OK, your blade must be a bit on the big side. That said, early JPs were only rated for 1000 rpm, and your boat seems to go pretty well, so maybe not something over which to loose too much sleep

 

Tim

 

I don't think I'll loose too much sleep over it. On the cut it's better to be over prop'd a little, slower nicer sound.

 

Oh, and I found a nice little video which shows the fuel rack nicely that for some reason I didn't upload when I did it. Just processing now:

 

 

Mike

[by'eck]

I don't think I'll loose too much sleep over it. On the cut it's better to be over prop'd a little, slower nicer sound.

 

Oh, and I found a nice little video which shows the fuel rack nicely that for some reason I didn't upload when I did it. Just processing now:

 

 

Mike

 

Hey that's the sweetest sounding JP2 I've heard Mike. Almost like a 2LW at the exhaust end

 

Just interested in your reasoning for fitting 28 x 16" prop although I don't know your gearbox reduction. Have read that "square" props give a lot of prop walk although something approaching square seems to be more common.

 

Other reason I ask is shortly taking possession of a rebuilt JP2M with 2:1 PRM260 to be fitted in a Steve Hudson 60 foot shell he starts work on next month. I want engine to be propped such that the full 1200 rpm is attainable from it on rivers.

 

Reading between the lines a 28" prop seems a tad on the large size for this & was thinking maybe 24" x 22". Would prefer smaller diameter anyway as don't want blades too close to surface leading to lost thrust.

 

Would welcome your or any others suggestions.

Edited April 8, 2011 by richardhula

[mykaskin]

Hey that's the sweetest sounding JP2 I've heard Mike. Almost like a 2LW at the exhaust end

 

Wash your mouth out!

 

 

Just interested in your reasoning for fitting 28 x 16" prop although I don't know your gearbox reduction. Have read that "square" props give a lot of prop walk although something approaching square seems to be more common.

 

The larger the prop the last losses there are, so I went for the maximum size that is practical on a narrowboat - any bigger you start to get it near the bottom and edges. You then match the pitch to the available torque of the engine. The gearbox is a 2:1 "3R".

 

The advantage of going big, with a shallow pitch is the reduction in the paddle wheel effect (I believe prop walk is a different effect where the prop is at an angle to the water surface... but stand to be corrected). High pitch, especially over square props should in theory suffer from prop walk far more.

 

 

Other reason I ask is shortly taking possession of a rebuilt JP2M with 2:1 PRM260 to be fitted in a Steve Hudson 60 foot shell he starts work on next month. I want engine to be propped such that the full 1200 rpm is attainable from it on rivers.

 

Reading between the lines a 28" prop seems a tad on the large size for this & was thinking maybe 24" x 22". Would prefer smaller diameter anyway as don't want blades too close to surface leading to lost thrust.

 

Would welcome your or any others suggestions.

 

If I was buying again, I would be tempted to go for a 27 x 16, though I do like the low revs I use on the canal. To drop that down to 24" would make the pitch in the order of 22, so I think you are about right with that.

 

More JP porn here:

 

 

Cheers,

 

Mike

[by'eck]

Thanks for advice & porn Mike. I'll never mention that other make again

 

BTW looked up prop walk & paddle wheel effect - the Wicki says they are the same but vary according to boat geometry, boat speed/direction, prop direction & depth of water.

 

I know my sailboat from standstill would pirouette anti-clockwise all day at any revs or rudder angle in reverse unless you started at minimum, waited to get on a little way & counteracted with rudder or bowthruster.

 

Not sure if you have it sorted but wonder if this pic helps your cause.

 

Edited April 10, 2011 by richardhula

[mykaskin]

 

Not sure if you have it sorted but wonder if this pic helps your cause.

 

 

Hi, Thanks for that. It's surprising just how much rack movement it takes off. Will have to have a play.

 

Mike