prop size???

[station tug]

hi, im fitting a lister hrw4 marine engine into my tug..the gearbox is 2-1 reduction.i want it to rev as low as possible when in gear any ideas on what size prop i should use?.the boats quite deep drafted so plenty of room for any prop..iv got a 22" x 21 rh prop but people are telling me its too small???......

[MtB]

hi, im fitting a lister hrw4 marine engine into my tug..the gearbox is 2-1 reduction.i want it to rev as low as possible when in gear any ideas on what size prop i should use?.the boats quite deep drafted so plenty of room for any prop..iv got a 22" x 21 rh prop but people are telling me its too small???......

 

 

Best to ring Crowther Marine and ask them. They'll size it for you on the phone and are they best in the business in my opinion. Plenty of factors they'll ask about are not mentioned in your post. They'll want to know stuff like boat length, weight, draft, engine power, max engine speed, tickover speed and some other things I've forgotten probably too.

 

Be careful of picking a prop that makes the boat go fast at low revs, sometimes you need to go slow too, e.g. passing moored boats, manoeuvring into or through tight spaces spaces, entering locks etc. You need tickover to make the boat go SLOW enough or you'll find you have to constantly engage forward and then neutral to keep the speed down.

 

Mike

[casper ghost]

Hi. We have an HR2 and we fitted a 22x22.5 prop, which we feel is over propped. I expect your prop would be ok on our engine, but i'm far from any sort of expert. You could try it, you can always change it at next backing.

Casp'

[Proper Job]

Try feeding your own data in

 

link

 

It should give you rough idea.

[Speedwheel]

HRW4 - 62hp at 2200 rpm. Is that the right one?

 

22x18 is what I get.

 

Edit, as Tim has done I guessed to boats weight and lenth. 57ft and 15 tonnes.

Edited February 24, 2011 by Speedwheel

[Timleech]

HRW4 - 62hp at 2200 rpm. Is that the right one?

 

22x18 is what I get.

 

If he wants to run a bigger slower prop he could derate it, 45bhp @ 1500 or 36 @ 1200 for instance (based on ratings for the HRW2).

 

Vicprop gives 27.6 x 26.5 for the last of those, as an extreme case (with guesses for boat dimensions).

 

As said already, there's a risk of tickover speed being a bit quick if you go too big.

 

Tim

[paddy r]

I have a HRW2 with 2:1 gear box,prop size 22X13 and Crowther Marine said i was slightly over proped?

[Timleech]

I have a HRW2 with 2:1 gear box,prop size 22X13 and Crowther Marine said i was slightly over proped?

 

Again it depends on the rating. That looks about right for the 29 bhp@ 2000 rpm rating, may be a bit big if you want the full 31 bhp @ 2200.

 

Going to a smaller prop to get the extra few horsepower might not gain you anything other than slightly higher fuel consumption.

 

Tim

[casper ghost]

I have a HRW2 with 2:1 gear box,prop size 22X13 and Crowther Marine said i was slightly over proped?

Hi, that does make our 22x22.5 appear rather big! although Archimedes has a 24x24..

Casp'

[paddy r]

Hi, that does make our 22x22.5 appear rather big! although Archimedes has a 24x24..

Casp'

We still have "prop walk" when mooring next to walls,and i think our's could do with being bigger as when we are on the tidal trent we do seem to be kicking the old girl a little hard.But when we are back on the canals she chugs just fine

I was thinking of 22x16 before i spoke to crowthers?

[tom_c]

if the hrw2 is on a 22x 13 this would give about a 27 x 13 for a hrw4 assuming same reduction ratio and rated speed, hope this helps Tom

[station tug]

HRW4 - 62hp at 2200 rpm. Is that the right one?

 

22x18 is what I get.

 

Edit, as Tim has done I guessed to boats weight and lenth. 57ft and 15 tonnes.

 

hi, my engine is 59hp @ 2200 rpm..the boats 57 ft and roughly 15 tons with the hull and engine the draft is 30" so my prop should be ok.my plan is not to run the boat anywere near 2200rpm.....cheers...

[PaddingtonBear]

If you want to run "as slow as possible".................get a Kelvin or possibly a steam engine, certainly not a modern engine.

[Timleech]

If you want to run "as slow as possible".................get a Kelvin or possibly a steam engine, certainly not a modern engine.

 

The Lister HR isn't particularly modern, some people have started calling them 'classic' etc though I wouldn't quite go that far.

An HRW4 is a very big engine for a narrowboat, it could perfectly well be derated to run a bigger prop and still have power to spare, if that's what the OP wants to do.

 

Tim

[station tug]

If you want to run "as slow as possible".................get a Kelvin or possibly a steam engine, certainly not a modern engine.

 

the engines 40 odd years old so wouldnt really call it modern(havnt found an ecu or egr valve yet) .every engine has been modern at some point in its life and i like the boat im building to be a little differnt to the endless line's of polished kelvins,gardeners and welded on rivets..