V P 2003 prop sizing

[[185615]]

Yep that's the one. Helpfully it's not marked with anything use ful!

Its three blades 16 inch diameter and I think it was a 25mm shaft... Inch easily machines to suit taper

I am very interested, happy to make a payment if you wish.
Is 1 " or 25mm standard shaft size? I will be able to check mine when on a drying mooring early July.
Is it anti-clock rotation, and are all VP 2003 the same do you know, it certainly sounds right.

 

[jwfrary]

I am very interested, happy to make a payment if you wish.
Is 1 " or 25mm standard shaft size? I will be able to check mine when on a drying mooring early July.
Is it anti-clock rotation, and are all VP 2003 the same do you know, it certainly sounds right.

Usually vp2003 are LH anticlockwise rotation but you never now it might have a non standard gbox for some reason.

1inch and 25mm are very close together and a pretty common shaft size but never say never.

Either way it's not so hard to alter the taper if needed though it will mean drawing the shaft and taking it to a machine shop, but it's not that onourous.

Sent you a pm give me a call if you like

 

[scottie]

Yep that's the one. Helpfully it's not marked with anything use ful!

Its three blades 16 inch diameter and I think it was a 25mm shaft... Inch easily machines to suit taper

Quick call to venta Marin to see if it can be adapted to suit sail drive spline

 

[Tranona]

Usually vp2003 are LH anticlockwise rotation but you never now it might have a non standard gbox for some reason.

1inch and 25mm are very close together and a pretty common shaft size but never say never.

Either way it's not so hard to alter the taper if needed though it will mean drawing the shaft and taking it to a machine shop, but it's not that onourous.

Sent you a pm give me a call if you like

No it is not. A 25mm has a 1:10 taper and a 1" 1:12. A 1" is 25.4mm so cannot be reduced in size to 25mm.

 

[Sybarite]

It usually stops wherever the engine decides, I know of no known mechanism to stop the prop at a particular point

I would have thought that it would stop where there is the least resistance, ie vertically. (for a two-bladed prop)

 

[Tranona]

Yes of course. 3:1 is a pure guess and may well effect the result.
My boat is a Freedom 35, constructed in UK1987

OK So the prop should be 2 blade 16*11, 3 blade 15*11 - much as I suspected. This assumes a 2.2:1 reduction. A 2.4:1 would mean the shaft runs slower so would swing a larger diameter prop, so 1" larger diameter but same pitch. Shows the importance of getting all the details, particularly gearbox ratio exactly right.

We have 2 Freedoms in our club. One has a Yanmar 29 and the prop is a 15" 3 blade Featherstream. The other, I don't know what engine but has a 2 blade prop. I have seen many Freedoms out of the water over the years and mostly had 2 blade props, probably because as mentioned elsewhere you could stop the shaft rotating with a shaft brake when the blades are vertical and hidden behind the keel. This significantly reduces drag which is good for long distance sailing that these boats were designed for. Bit old fashioned now because you can achieve similar results with a feathering prop as in the Freedom that is in the next berth to me. This one is US built and the owner sailed it back from Puerto Rica where he bought it 25 odd years ago (with a 2 blade prop)!

Before you do anything ascertain the exact size of the prop you have. Diameter is easy but you will need to clean the crud off the hub where you will find the size stamped on. You have more than enough power to achieve hull speed and if sized correctly you won't find much difference between a 2 and 3 blade. Also worth doing some real world tests by doing runs at 200rpm intervals from about 1800rpm, plotting speed through the water against revs. If the prop is right you should be able to achieve over 3000rpm at full throttle and about 7.4 knots. Cruising speed of 5.5 knots at around 2400rpm.

 

[vic008]

Tranona- why couldn't a one inch (25.4mm) shaft not be turnable down to 25mm? I agree, don't make any assumptions when dealing with these shafts. Ordered a new one inch shift (in NZ) and blooming thing sure wasn't one inch

 

[Tranona]

Tranona- why couldn't a one inch (25.4mm) shaft not be turnable down to 25mm? I agree, don't make any assumptions when dealing with these shafts. Ordered a new one inch shift (in NZ) and blooming thing sure wasn't one inch

The question was about machining the taper in the hub of the prop, not the shaft. while the different tapers are convention there is nothing to stop a 1:10 taper being put on an imperial shaft or the other way round provided the prop is machined to match. so always check both size and taper.

 

[[185615]]

Usually vp2003 are LH anticlockwise rotation but you never now it might have a non standard gbox for some reason.

1inch and 25mm are very close together and a pretty common shaft size but never say never.

Either way it's not so hard to alter the taper if needed though it will mean drawing the shaft and taking it to a machine shop, but it's not that onourous.

Sent you a pm give me a call if you like

The question was about machining the taper in the hub of the prop, not the shaft. while the different tapers are convention there is nothing to stop a 1:10 taper being put on an imperial shaft or the other way round provided the prop is machined to match. so always check both size and taper.

Taper reamers of both sizes are available, use the one required. Doing so will mean the prop will sit further up on the shaft than originally intended

 

[scottie]

Usually vp2003 are LH anticlockwise rotation but you never now it might have a non standard gbox for some reason.
M
1inch and 25mm are very close together and a pretty common shaft size but never say never.

Either way it's not so hard to alter the taper if needed though it will mean drawing the shaft and taking it to a machine shop, but it's not that onourous.

Sent you a pm give me a call if you like

T aper shaft not applicable to sail drive requires different s lined hub

 

[jwfrary]

T aper shaft not applicable to sail drive requires different s lined hub

The boats a long keel with an apature

Shaft will need to be modified if it doesn't fit as kiwi props can't be reamed out in the same way as conventional prop.

 

[scottie]

Taper reamers of both sizes are available, use the one required. Doing so will mean the prop will sit further up on the shaft than originally intended

What use is a tape reamer to cut a spline?

 

[jwfrary]

What use is a tape reamer to cut a spline?

None, but the OP has a shaft!

Vp2003 came with both shaft and sail drive options and also a v drive (kudos if you have ever seen one in the flesh though!)

 

[Laminar Flow]

I thought the point of a two blade prop on a sailboat was so it could be put vertical (no idea how) so it was shielded by the keel for less drag when sailing. Not a sailor so no personal experience!

The point is actually that the prop has less blade area and hence, if locked, less resistance. The locked vertically means locked behind the "deadwood" and presupposes a deadwood and in all probability a long keel.
Letting the prop mill reduces resistance by about half, but requires a gear box that can be left to turn out of gear.

Our prop shaft is 1 1/2" thick, heavy and the bearings are good; we can barely hear it turning under sail.

 

[Laminar Flow]

It usually stops wherever the engine decides, I know of no known mechanism to stop the prop at a particular point

There are shaft locking devices. Some gearboxes do not tolerate being left to rotate and some hydraulic types cannot be stopped and can be damaged by shifting into reverse when not under power.

 

[Laminar Flow]

OK So the prop should be 2 blade 16*11, 3 blade 15*11 - much as I suspected. This assumes a 2.2:1 reduction. A 2.4:1 would mean the shaft runs slower so would swing a larger diameter prop, so 1" larger diameter but same pitch. Shows the importance of getting all the details, particularly gearbox ratio exactly right.

We have 2 Freedoms in our club. One has a Yanmar 29 and the prop is a 15" 3 blade Featherstream. The other, I don't know what engine but has a 2 blade prop. I have seen many Freedoms out of the water over the years and mostly had 2 blade props, probably because as mentioned elsewhere you could stop the shaft rotating with a shaft brake when the blades are vertical and hidden behind the keel. This significantly reduces drag which is good for long distance sailing that these boats were designed for. Bit old fashioned now because you can achieve similar results with a feathering prop as in the Freedom that is in the next berth to me. This one is US built and the owner sailed it back from Puerto Rica where he bought it 25 odd years ago (with a 2 blade prop)!

Before you do anything ascertain the exact size of the prop you have. Diameter is easy but you will need to clean the crud off the hub where you will find the size stamped on. You have more than enough power to achieve hull speed and if sized correctly you won't find much difference between a 2 and 3 blade. Also worth doing some real world tests by doing runs at 200rpm intervals from about 1800rpm, plotting speed through the water against revs. If the prop is right you should be able to achieve over 3000rpm at full throttle and about 7.4 knots. Cruising speed of 5.5 knots at around 2400rpm.

All spot on.
The reason to choose a 3 or more bladed prop has to do with blade loading and available space to give the necessary clearances such as when a prop is run in in a well in a deadwood, or rudder, or to make sure the prop has enough clearance under the hull. A multi bladed prop will have a smaller diametre and can also help to reduce tip velocity to reduce cavitation without having to throttle back the RPM or change the gearbox.

Before switching props I would make sure you have at least 10% prop diametre clearance from tip to hull, 3% to the bottom of a well or skeg, 8%, but at least 200mm to the rudder, and 15% to a deadwood or strut.

 

[[185615]]

The boats a long keel with an apature

Shaft will need to be modified if it doesn't fit as kiwi props can't be reamed out in the same way as conventional prop.

I am not aware of that, I am under the impression the prop has a straight forward taper of either mm or inches.

 

[[185615]]

All spot on.
The reason to choose a 3 or more bladed prop has to do with blade loading and available space to give the necessary clearances such as when a prop is run in in a well in a deadwood, or rudder, or to make sure the prop has enough clearance under the hull. A multi bladed prop will have a smaller diametre and can also help to reduce tip velocity to reduce cavitation without having to throttle back the RPM or change the gearbox.

Before switching props I would make sure you have at least 10% prop diametre clearance from tip to hull, 3% to the bottom of a well or skeg, 8%, but at least 200mm to the rudder, and 15% to a deadwood or strut.

Much more to it than I thought, thank you for your obvious insight will certainly do the checks on dimensions.

 

[[185615]]

There are shaft locking devices. Some gearboxes do not tolerate being left to rotate and some hydraulic types cannot be stopped and can be damaged by shifting into reverse when not under power.

My previous had a shaft locking device, not sure if this has.

 

[[185615]]

What use is a tape reamer to cut a spline