The Whirled At One.

[j04n]

 

As an engineer I learnt many years ago not to listen to sales hype and to do my own research. I have owned boats for something approaching 50 plus years and I don't remember how many props I have put on boats but through research and some expensive research, buying and being wrong, I have learnt a little. One thing is leave room for the prop to shall we say breath, the 15% gap. If you don't things are not as they should be. The other is the need for the power and rpm to be able to turn the prop at the correct speed to develop its thrust, right engine and gearbox. I never ask for a quote from just one place and if there is a major difference in the size and pitch I ask why. I know that in my experience the prop you have bought has some distinct advantages but it will still be of the same order of size etc as a prop from elsewhere to achieve the required on a given boat. I will be interested to know how it performs on the new gearbox. BTW go gentle when you first go astern with it on the 2:1 gbox it has more thrust astern than most other props.

I didnt and I did. Maybe I should have asked 5 times. .......tbh although I am also an Engineer and do take an interest in how things work. As previously pointed out I have no wish to become an expert on all things boating or spend my weekends with my head under the bonnet. I bought a boat to spend my weekends cruising the rivers and canals. I have almost sickened myself during my first year of boating because I have spent far too much time with my head in the Haynes book of boating and scouring the internet for information. I was pleased to find this forum, only recently, so I can stop wasting my time and just rely on you guys who are more interested in tinkering, while I'm out there cruising or in the pub! Thanks for the advise but honestly I have no wish to go flying anywhere. I get into enough trouble on the roads. The river is my release and I am more than happy ambling along. I just felt I was lacking some power on the tidal river on occasions so am looking for that little extra just to keep me out of trouble.

[Geo]

I didnt and I did. Maybe I should have asked 5 times. .......tbh although I am also an Engineer and do take an interest in how things work. As previously pointed out I have no wish to become an expert on all things boating or spend my weekends with my head under the bonnet. I bought a boat to spend my weekends cruising the rivers and canals. I have almost sickened myself during my first year of boating because I have spent far too much time with my head in the Haynes book of boating and scouring the internet for information. I was pleased to find this forum, only recently, so I can stop wasting my time and just rely on you guys who are more interested in tinkering, while I'm out there cruising or in the pub! Thanks for the advise but honestly I have no wish to go flying anywhere. I get into enough trouble on the roads. The river is my release and I am more than happy ambling along. I just felt I was lacking some power on the tidal river on occasions so am looking for that little extra just to keep me out of trouble.

 

I appreciate what you are saying. The trouble on the inland waterway is there seem to be a lot of what call themselves this type of engineer or that type of engineer and very few genuine knowledgeable people and they seem to prey on boaters with little or no knowledge. Does not seem to be as bad in the marine world although not perfect. So knowledge can be a protection even if got from here.

 

Not sure but fingers crossed with a change of gear box that will make things better and your ambling can start with enough to deal with a tidal river at sensible times. There could be times when the flow is too fast for most boats.

 

Have fun and enjoy, and keep the gongoozlers happy because that is of course the only reason people buy boats and use the canals and rivers to entertain the gongoozlers.

[j04n]

Well ....... dare I open this can of worms again!? ....... but as I did promise to report back ...... 2:1 recon gearbox fitted in place of 3:1 and all's good in the world! ........ how wrong could anybody be with their calculations?! Anyway, returning to the positive. It is now clear both gearbox and prop needed to be changed for the best results. The previous owner must have tried to resolve the problem with prop alone hence fitting a 20 x 23 which never really worked but was acceptable on canals and a gearbox ratio change alone would never have worked with said prop. Having now changed both the general consensus is that the boat is still a little under propped, believe it or not, but after living with it for a year with the former set-up I believe the boats performance is certainly the best it has ever been! I am now cruising at little over tick over and can take full advantage of all the sound proofing I installed whilst comfortable in the knowledge there is a little more grunt for those cheeky spring tides. Sure I will not be towing water skiers any time soon but can now live Happily Ever After!!

 

Oh, thats assuming I havent bust the seals on the recon gearbox after stupidly over filling it! ........ I checked and better checked, maybe 6 times, but could not see the oil level on the dipstick until I came back from a test run and found 0.5 litres of gearbox oil in the bottom of the boat. And then proceeded to take out another .5 litres in order to drop it to the max level!

[Dalslandia]

Great, is this with the 18"x16" tree bladed, non twisted blade propeller?

[j04n]

Great, is this with the 18"x16" tree bladed, non twisted blade propeller?

lol! 18" x 15" ....... yep! ...... I was tempted to return it out of badness but couldnt be bothered with the 4 day round trip to dry dock and another £80 dry dock rental.

[Geo]

lol! 18" x 15" ....... yep! ...... I was tempted to return it out of badness but couldnt be bothered with the 4 day round trip to dry dock and another £80 dry dock rental.

 

 

So a good result all round then

[j04n]

I'm happy, but no thanks to you know who! ?

[Dalslandia]

I wild guess from my side, is that you still are under propped, you would need a 20x16 or 18x21 3 blade, or 18x18 4 blade.

 

do you think you got the best propeller?

[j04n]

I wild guess from my side, is that you still are under propped, you would need a 20x16 or 18x21 3 blade, or 18x18 4 blade.

 

do you think you got the best propeller?

Through luck rather than design it works! I don't doubt a little more could be squeezed out of it but I believe I have now the best compromise. The 20 x 16 would be interesting to try but it would limit prop clearance way under recommended and I fear the boat engine would be too laboured on narrow, shallow canals.

[Geo]

I'm happy, but no thanks to you know who!

 

I take it you have a rev count. So what is the max revs at max throttle on the river? in gear

 

What is the engine specified max revs?

Edited October 18, 2016 by Geo

[Dalslandia]

you will see, when you hit the wild open waters, when throttle up, how much throttle you still have when reach red line

[Dalslandia]

it would be a good PR trick to give you a 4 or even 5 bladed prop suited to your engine and 2:1 gear ratio, knowing he miscalculated your 3:1 prop so badly, that would peak his customer service. I know I would

[j04n]

 

I take it you have a rev count. So what is the max revs at max throttle on the river? in gear

 

What is the engine specified max revs?

Maximum recommended engine rpm is 2500 but I have to be careful because maximum throttle will cause it to exceed 2500 rpm...... obviously I don't run at that it was only getting a feel for it after changing the gearbox ratio. Edited October 18, 2016 by j04n

[j04n]

it would be a good PR trick to give you a 4 or even 5 bladed prop suited to your engine and 2:1 gear ratio, knowing he miscalculated your 3:1 prop so badly, that would peak his customer service. I know I would

Any proffesional Supplier might! ? ...... but anyway I couldn't be bothered with the 4 day round trip to dry dock. I'm happy, don't get me wondering!? ?

[Geo]

Maximum recommended engine rpm is 2500 but I have to be careful because maximum throttle will cause it to exceed 2500 rpm...... obviously I don't run at that it was only getting a feel for it after changing the gearbox ratio.

 

So you could get 2500 in gear ahead ?

What was the speed like?

[j04n]

 

So you could get 2500 in gear ahead ?

What was the speed like?

easily! that's why the more experienced than I suggested it was still under propped...... bearing in mind i was only using a cycle GPS in a metal wheelhouse so would question the accuracy, it was bouncing between 5.5 and 6mph upstream. I would guess river flow was no more than 2 mph.

[Dalslandia]

should be possible to do 8,4 mph with 65 HP

[Geo]

Does anyone know the HP at 2500?

 

or the max for this engine?

[j04n]

Does anyone know the HP at 2500?

 

or the max for this engine?

I believe it is 65 hp at 2500 rpm

[Geo]

What is the engine? number of pots

should be possible to do 8,4 mph with 65 HP

 

upstream 5.5/6 mph plus stream my guess she is not far off

[Dalslandia]

The who, that made? the propeller calculations must know,

[Geo]

The who, that made? the propeller calculations must know,

 

Don't want to ask them yet until we have reliable data.

[j04n]

 

Don't want to ask them yet until we have reliable data.

I posted all the reliable data which was supplied before but it was subsequently taken down. I really can't be bothered to go there again unless you have a point?....... however, if it is only for your own learning so the same mistake is not made again forget it. DW made it perfectly clear that he had washed his hands of me and my boat!

[Geo]

I posted all the reliable data which was supplied before but it was subsequently taken down. I really can't be bothered to go there again unless you have a point?....... however, if it is only for your own learning so the same mistake is not made again forget it. DW made it perfectly clear that he had washed his hands of me and my boat!

 

 

If you are happy and comfortable with what you have there, then enjoy.

 

If not I am willing to talk to them but we would have to keep it very calm

Edited October 18, 2016 by Geo

[j04n]

I appreciate the offer, thank you! But honestly, I feel I have a good compromise now. I don't doubt what I am being told about there being more to be had but I suspect it would be marginal and I would be concerned how the boat would handle on narrow, shallow canals which I haven't yet tried.

Edited October 18, 2016 by j04n