Replacement propeller

[Alan de Enfield]

2 minutes ago, B2019 said:

So when I start the engine up and put it in forward drive looking forward as if you are sailing forward the drive shaft turns left ( anti- clockwise) and in reverse it turns the other way (clockwise)

OK, so once you have sorted out your prop-size and pitch, prop supplier, the shaft size and taper, you now know you will need a Left hand Prop.

[B2019]

37 minutes ago, Alan de Enfield said:

OK, so once you have sorted out your prop-size and pitch, prop supplier, the shaft size and taper, you now know you will need a Left hand Prop.

Perfect thanks ?

[Carl123]

22 hours ago, mrsmelly said:

There are different shaft sizes, prop sizes, pitches, left hand, right hand and musnt forget Axiom ?

Hi measure your shaft in side near sturn gland is .it give you a ruff idear it looks like 25mm shaft I could be wrong what size boat is it what type of gear box post a picture of gear box 

2 minutes ago, Carl123 said:

Hi measure your shaft in side near sturn gland is .it give you a ruff idear it looks like 25mm shaft I could be wrong what size boat is it what type of gear box post a picture of gear box

 

[B2019]

16 hours ago, Carl123 said:

Hi measure your shaft in side near sturn gland is .it give you a ruff idear it looks like 25mm shaft I could be wrong what size boat is it what type of gear box post a picture of gear box 

 

Ok thanks. I'm going to do some double check measurements today. Seller is asking about reduction ration? Engine is Saab gg. 

[Alan de Enfield]

Does that prop-shaft look as if it has been slid 'forwards' a few inches - clamp marks on the shaft  near where it is rubbing on the bilge pump hose, or is it bilge pump hose rub marks ?

 

[B2019]

Got some new measurements: 

 

Nut size - 2 cm diameter at beginning

 

Middle of nut - 8cm circumference

 

Beginning of outside shaft- 10cm circumference

 

Drive shaft inside the boat- 10cm circumference

 

Distance between gear box and shaft outlet- 15 inches

 

Distance between drive shaft beginning outside and end outside- 4 inches

 

Distance between beginning of screw and end of screw on drive shaft- 3.5 cm

 

Size in middle between beginningng of sharf on outside and beginning of screw( not the end of screw) 9cm

 

Distance between sharf and top hatch ridge beginning- 8 inches

 

Distance at bottom protective plate to shaft- 7.2 inches. 

 

Company that makes propellers asked me for reduction ration, how do I get this? 

 

Most likely to be a 12 inch left propeller.

 

[Alan de Enfield]

7 minutes ago, B2019 said:

Company that makes propellers asked me for reduction ration, how do I get this? 

It should be on the gearbox (ie 1:1 2:1, 2.5:1, 3:1 etc)

There may be a plate with the details and / or model number.

 

If you cannot find anything on the plate you will need to get someone to turn the engine over for (say) ten-revolutions and see how many revolutions the prop-shaft rotates.

 

If the engine turns over 10 revs and the prop shaft rotates for 5 revolutions then the ratio is 2:1 (two to one)

Edited May 24, 2019 by Alan de Enfield

[Murflynn]

OP seems to be under the misapprehension that the reduction is subject to rationing.   not the case.   

 

if you are specifying a prop you must check the degree of taper by taking exact shaft diameter measurements at the beginning and end of the taper, plus the exact length of the taper.    HINT: you can buy a cheap caliper gauge for a few quid that will give you exact measurements (dimensions to the nearest cm are not good enough). 

[MtB]

I fear the OP is massively underestimating the accuracy needed to measure the prop shaft in order to specify the propeller. Dimensions need measuring to a tenth or a 100th of a millimetre with accurate instruments, not a tape measure. Getting a new prop is likely to run close to four figures once docking costs are factored in. 

 

I strongly recommend getting the stolen prop back....

 

 

[Murflynn]

8 hours ago, Murflynn said:

OP seems to be under the misapprehension that the reduction is subject to rationing.   not the case.   

 

if you are specifying a prop you must check the degree of taper by taking exact shaft diameter measurements at the beginning and end of the taper, plus the exact length of the taper.    HINT: you can buy a cheap caliper gauge for a few quid that will give you exact measurements (dimensions to the nearest cm are not good enough). 

PS : if you are measuring through the weed hatch don't use a digital (electronic) caliper gauge.

[Alan de Enfield]

12 minutes ago, Murflynn said:

PS : if you are measuring through the weed hatch don't use a digital (electronic) caliper gauge.

It does make it difficult to read the numbers.

[B2019]

Spoke to Marine engineer today. Two ways of doing.. easiest is out of the water but there's no boat yards near me that can do it so he told me to speak to T.norris who are specialist's. 

 

Also read engine manual: 

 

Reduction gear ratio is 2:1

 

Propeller torque, cont. Rating, 7,65-7,95 kpm 55-57 ft.lbs

 

Direction of rotation is  left. 

 

Rpm is between 1500 and 1800

 

[Alan de Enfield]

15 minutes ago, B2019 said:

Spoke to Marine engineer today. Two ways of doing.. easiest is out of the water but there's no boat yards near me that can do it so he told me to speak to T.norris who are specialist's. 

 

Also read engine manual: 

 

Reduction gear ratio is 2:1

 

Propeller torque, cont. Rating, 7,65-7,95 kpm 55-57 ft.lbs

 

Direction of rotation is  left. 

 

Rpm is between 1500 and 1800

 

So now you need to know the ACCURATE :

 

Shaft size (probably imperial)

Thread size (take the NUT somewhere and find a bolt to match (it is probably imperial sizing)

Shaft Taper

Is there a key-way in the shaft ? (size)

Is there a hole for a locking pin ?

[MtB]

15 minutes ago, Alan de Enfield said:

Is there a hole for a locking pin ?

 

Irrelevant.

 

Even if there is, the chances of it being in the right place for a new propeller and nut are vanishingly small, so a new hole will have to be drilled. A challenging task with the boat in the water. 

 

 

 

 

[B2019]

Perfect thanks for your help. I will find those measurements over the coming days. 

CRT local officer said to me he's extended my stay by 7 days to rectify the problem. Yeah right! I've got contacted boat movers in the area and out if area but they won't be able to move to boat for another 4 weeks and over . If I get the correct propeller it will take at least 2 weeks to come. Move it around with a stick?

[MtB]

1 minute ago, B2019 said:

Move it around with a stick?

 

No, move it around with a rope!

 

Pretend you are the horse...

[Tony Brooks]

2 hours ago, Mike the Boilerman said:

 

No, move it around with a rope!

 

Pretend you are the horse...

 

Only if you have a steerer and a puller.

 

Take a long stern line from back to more or less the font of the boat and the bow line at about 90 degrees to the boat to the bank. Hold both lines.

 

Pull on the stern line and the bow will try to sheer out into the canal, control this with the bow line. You will be able to get the boat to move parallel to the bank a few feet out.

 

If you try with just a bow line you will be forever trying to push the front out.

 

 

[Murflynn]

7 minutes ago, Tony Brooks said:

 

Only if you have a steerer and a puller.

 

Take a long stern line from back to more or less the font of the boat and the bow line at about 90 degrees to the boat to the bank. Hold both lines.

 

Pull on the stern line and the bow will try to sheer out into the canal, control this with the bow line. You will be able to get the boat to move parallel to the bank a few feet out.

 

If you try with just a bow line you will be forever trying to push the front out.

 

 

if you follow these instructions properly you will never ever need a propeller again.   

[RLWP]

Curiously CRT have come across 'my engine doesn't work, I can't move' before. It doesn't wash with them so expect trouble 

 

Richard 

[MtB]

3 minutes ago, RLWP said:

Curiously CRT have come across 'my engine doesn't work, I can't move' before. It doesn't wash with them so expect trouble 

 

Richard 

 

Wearing my cynical hat, I'm beginning to doubt the whole "someone stole my prop with the boat in the water" thing.

 

Whenever I need to get a prop off it usually involves a long lever to get the nut undone, liberal application of blowlamp(s) along with two people with a hammer each trying to achieve simultaneous blows on each side of the boss. 

 

Wearing my less cynical hat, I wonder if the prop was ever on the boat when possession was handed over. They whole thing seems faintly odd to me.

 

  

[B2019]

I mean would it be easier just to get an outboard and stick that on for now?

[Murflynn]

Just now, B2019 said:

I mean would it be easier just to get an outboard and stick that on for now?

yes

[B2019]

19 minutes ago, Mike the Boilerman said:

 

Wearing my cynical hat, I'm beginning to doubt the whole "someone stole my prop with the boat in the water" thing.

 

Whenever I need to get a prop off it usually involves a long lever to get the nut undone, liberal application of blowlamp(s) along with two people with a hammer each trying to achieve simultaneous blows on each side of the boss. 

 

Wearing my less cynical hat, I wonder if the prop was ever on the boat when possession was handed over. They whole thing seems faintly odd to me.

 

  

It was on the boat as I moved it around 1.5 miles and checked propeller after.. it was still there when I left it. I came back and gone. 

[Bee]

What I would do. (and have done)  See if you can draw the shaft out. Can you lift the rudder out of its cup at the bottom? do so and shove it sideways. Does it unbolt from the tiller just under the counter? Is it possible to pull the shaft OUT?  lift the engine and pull the shaft IN? If you can get the shaft out and bung a piece of tapered wood in the stern gland then you can take the shaft to a good industrial fixings supplier, find a nut,  fit a key (carefully, it might be TOO HIGH and prevent the prop fitting properly on the taper and need filing down),  (My present boat has a Whitworth thread on a second hand shaft) Fit the propeller, tighten it all down, drill the nut and shaft and put a good STAINLESS steel splitpin in it. Refit it underwater with prop attached or unfitted if you cant get it past the rudder, re- assemble till the splitpin aligns and the job is done. Wedge the bung in place with a bit of wood rammed up against something solid to stop it popping in and sinking the boat. To find a propeller look in E Bay or ring round boatyards and Midland Chandlers, they sometimes have second hand ones. I've got a suitable one but its right hand. Good luck

[B2019]

4 minutes ago, Bee said:

What I would do. (and have done)  See if you can draw the shaft out. Can you lift the rudder out of its cup at the bottom? do so and shove it sideways. Does it unbolt from the tiller just under the counter? Is it possible to pull the shaft OUT?  lift the engine and pull the shaft IN? If you can get the shaft out and bung a piece of tapered wood in the stern gland then you can take the shaft to a good industrial fixings supplier, find a nut,  fit a key (carefully, it might be TOO HIGH and prevent the prop fitting properly on the taper and need filing down),  (My present boat has a Whitworth thread on a second hand shaft) Fit the propeller, tighten it all down, drill the nut and shaft and put a good STAINLESS steel splitpin in it. Refit it underwater with prop attached or unfitted if you cant get it past the rudder, re- assemble till the splitpin aligns and the job is done. Wedge the bung in place with a bit of wood rammed up against something solid to stop it popping in and sinking the boat. To find a propeller look in E Bay or ring round boatyards and Midland Chandlers, they sometimes have second hand ones. I've got a suitable one but its right hand. Good luck

Many thanks Bee. I saw someone taking out the shaft on YouTube and I reckon I can but I spoke to engineer today and they said it was a bit risky to take shaft out in water but might be the quickest and beat bet.