Variable Pitch Prop

[Liam]

I'm looking to get a replacement Sabb engine for the boat... the ones I have seen advertised on-line mostly state that they are "Variable Pitch".

 

I think I have an idea of what this is but could somebody tell me whether I could mate the "new" engine with my current gearbox which has the single lever control set-up?

 

Thanks.

[John Orentas]

I'm looking to get a replacement Sabb engine for the boat... the ones I have seen advertised on-line mostly state that they are "Variable Pitch".

 

I think I have an idea of what this is but could somebody tell me whether I could mate the "new" engine with my current gearbox which has the single lever control set-up?

 

Thanks.

 

 

Part of the idea of a variable pitch prop is that you do not need a gearbox, perhaps just a neutral 'dog clutch'.

[Liam]

Hi John,

 

Could you please explain further?

 

Thanks.

[saltysplash]

I think most ships these days have variable pitch props. They generally have the engine reving at a set speed and then vary the pitch of the prop to whatever speed they require. I imagine smaller vessels have a similar set up but its only a guess. As John says, a gearbox is superfluous as its the pitch control that sets the speed either forward or reverse.

[Liam]

Thanks for explaining..

 

Would it be possible to remove the variable pitch prop setup from an engine to replace with a standard 2:1 gearbox?

[NB Willawaw]

Could they be variable pitch for sailing boats, so that a neutral pitch could be selected for feathering, to reduce drag when sailing ?

[Timleech]

Thanks for explaining..

 

Would it be possible to remove the variable pitch prop setup from an engine to replace with a standard 2:1 gearbox?

 

 

If you get one complete with its variable pitch prop & shaft, can you give me first shout on that part of it? Please.

I've got a Sabb semi-diesel which is looking for a suitable variable pitch propellor.

 

 

Tim

[Liam]

Hi Tim,

 

I currently have a Sabb 10hp in my boat, but would like to replace it with another, reconditioned one. I have been searching online for suitable replacements but the only ones I have seen advertised so far have this variable pitch setup.

 

What I would like to know is, can I buy an engine with this, and then remove it to be able to match it up with my existing gearbox. If this is possible then I will let you know how I get on.

[Proper Job]

Hi Tim,

 

I currently have a Sabb 10hp in my boat, but would like to replace it with another, reconditioned one. I have been searching online for suitable replacements but the only ones I have seen advertised so far have this variable pitch setup.

 

What I would like to know is, can I buy an engine with this, and then remove it to be able to match it up with my existing gearbox. If this is possible then I will let you know how I get on.

Liam

 

Sabb seem to pitch its lower power engines (the 'G' series) at the yacht market these days and sell them as standard with a variable pitch prop set-up. This, as Willaway mentioned allows for full feathering when sailing to reduce drag.

 

You would need to get hold of Sabb to see if the engine you are thinking about could be mated to your existing set-up.

 

Could you not send your existing engine away for reconditioning?

 

One thing you will also have to check on is if the two engines have a like for like power/rpm/torque characteristics. A more modern engine may operate at a higher rpm for the same power output as your old one. This could potentially lead to gearbox ratio/prop pitch diameter problems.

[larkshall]

Note variable pitch does not always mean reverse pitch.

 

The prop can be feathered, thru to full ahead. but has a neutral and reverse on the drive... Often used in combination to a variable pitch folding prop. Only available for low powered auxilary type engines (I have see a setup like this on one of the smaller Jeannaeu (spelling) boats

[Derek R.]

An example of using a REVERSE pitch prop can be viewed here: http://tinyurl.com/3cflqa

Harbour manoeuvring with a Norwqegian ex-fishing boat powered by a Wichman, 40hp semi-diesel single.

 

Skipper uses the railway styled handbrake to vary the prop pitch, a small lever for throttle, a third lever for clutch (not used until under way at the end). The helm (a wheel) is hardly touched. There's another vid of him priming and starting the Wichman if you hunt around for vids by the same author.

[magnetman]

There's a sabb G (variable pitch prop version) cutaway drawing here showing the mechanism:

 

http://images.google.com/imgres?imgurl=htt...%3Doff%26sa%3DG

 

I reckon it'd be possible to fit a small hurth gearbox onto one of those engines, or the sabb cone clutch gearbox supplied with the fixed prop version. The cone clutch gearboxes are a bit troublesome.

 

 

Sleeman and Hawken are the people to talk to about it they do sabb parts and probably know a bit about it.