The Whirled At One.

[Geo]

Just to make it clear I have nothing to do with the organisation other than I own two of their propellers on one of my boats and have had no problems with either the props or the organisation. My offer was to try and mediate if all was not well.

 

Regarding the canals use, you will find that the top speed will be a lot lower. The shallowness of the water, the shape of the channel and the closeness of the banks will all decrease the ease with which the boat, particularly a widebeam, move through the water. It tends to get called canal effect. You will find that there will come a point where no matter how much you increase the engine revs there will be no increase in speed, the boat may actually go slower. Reduce the revs and there will be a point at which the boat is happier and the speed is at its maximum for that particular canal and things are smoother.

 

Good boating

[Dalslandia]

I am just guessing but think you have a propeller that absorbe 59.05 % of aviable power.

 

Looking at Beta Marin, there 75 HP @ 2700 and 2:1 gearbox recomend a 20"x14"

at 2500 rpm that will be 15" pitch

 

one inch off the diameter can be replaced with 2.5 inch pitch, so 18"x20, but better with larger blade area/ more blades.

That again make me think you need 5 blades at 18x15, but they naturally cost more/ is harder to make then a 4 blade prop.

 

As I have said earlier, the propeller Moixa, That work just as good in reverse! have some well established good things.

One might be it is thick and good to take the beating from canal litter.

Edited October 19, 2016 by Dalslandia

[MtB]

 

I am now cruising at little over tick over

 

 

In that case I'd be very wary of making any further changes to correct your suspected 'under-propping'.

 

Prop sizing is a compromise of several parameters and while it might be under-propped, correcting that will make the boat go even faster at tickover which paradoxically is a bad thing.

 

A canal boat that won't go very slowly is a pain in the butt to own and use. The last thing you want is a boat that achieves near cruising speed at just tickover. You'll be driven demented the first time you find yourself following a boat that's going slower than you at tickover, having to constantly engage ahead then take it out of gear to slow down. Possibly for miles on end.

Sounds to be as though your blade is now 'just right', if not a bit too long legged.

[Dalslandia]

I was in september, seeing / test drive 2 motorsailer of the same type and same engines, the first was doing some 6.7 kts but later saw the throttle didn't take the pump arm to the stop. it did go slow and nicely with idle rpm and in gear. but didn't note the speed. probably 2-3 kts, I suspect the rev counter showed 2-3 hundred rpm to little.

 

the second was doing 6.99 kts, pump did go to full stop what I saw., but at idle in gear this boat did 4.1 kts, the rev counter was in op. so don't know the rpm. The mechanical log/speed teller, had the needle bent, probably someone used the high pressure washer on the impeller...

must have had the wrong prop on. but this gear box is very nice to slip in and out of gear. no clonk - clonk.

Edited October 19, 2016 by Dalslandia

[j04n]

Just to make it clear I have nothing to do with the organisation other than I own two of their propellers on one of my boats and have had no problems with either the props or the organisation. My offer was to try and mediate if all was not well.

 

Regarding the canals use, you will find that the top speed will be a lot lower. The shallowness of the water, the shape of the channel and the closeness of the banks will all decrease the ease with which the boat, particularly a widebeam, move through the water. It tends to get called canal effect. You will find that there will come a point where no matter how much you increase the engine revs there will be no increase in speed, the boat may actually go slower. Reduce the revs and there will be a point at which the boat is happier and the speed is at its maximum for that particular canal and things are smoother.

 

Good boating

No need to make anything clear! ....... thanks again!

 

I am just guessing but think you have a propeller that absorbe 59.05 % of aviable power.

 

Looking at Beta Marin, there 75 HP @ 2700 and 2:1 gearbox recomend a 20"x14"

at 2500 rpm that will be 15" pitch

 

one inch off the diameter can be replaced with 2.5 inch pitch, so 18"x20, but better with larger blade area/ more blades.

That again make me think you need 5 blades at 18x15, but they naturally cost more/ is harder to make then a 4 blade prop.

 

As I have said earlier, the propeller Moixa, That work just as good in reverse! have some well established good things.

One might be it is thick and good to take the beating from canal litter.

lol! god loves a trier Dalslandia!! ....... I'm going to make do for now, see how she fairs during a 400+ mile round trip early next year and MAY! ....... may come back to you! ......... but wouldnt 5 blades shake the living daylights out of you?

Edited October 19, 2016 by j04n

[j04n]

 

 

In that case I'd be very wary of making any further changes to correct your suspected 'under-propping'.

 

Prop sizing is a compromise of several parameters and while it might be under-propped, correcting that will make the boat go even faster at tickover which paradoxically is a bad thing.

 

A canal boat that won't go very slowly is a pain in the butt to own and use. The last thing you want is a boat that achieves near cruising speed at just tickover. You'll be driven demented the first time you find yourself following a boat that's going slower than you at tickover, having to constantly engage ahead then take it out of gear to slow down. Possibly for miles on end.

Sounds to be as though your blade is now 'just right', if not a bit too long legged.

that would be a first! ........ but totally agree! ....... with my limited experience I believe it to be just right ....... but of course time will tell ...... when I m getting washed out to sea whilst crossing the Wash!

[Dalslandia]

No need to make anything clear! ....... thanks again!

 

lol! god loves a trier Dalslandia!! ....... I'm going to make do for now, see how she fairs during a 400+ mile round trip early next year and MAY! ....... may come back to you! ......... but wouldnt 5 blades shake the living daylights out of you?

 

You don't know how easy it is to make wide belts from others leather a greenie to you.

 

Ps, a five blade will have 5 smaller pulses instead of 3 stronger per turn. 4 might vibrate more then 3 and 5 when 2 blades pass the dead water behind the dead wood at the same time.

 

Good luck with your boating,

if you experience that; "This will go bad!" just aim at something cheap, (Swedish story)

Edited October 19, 2016 by Dalslandia