stern tube engine alignment

[Hannah and Jay]

ok be warned for improper use of technical terms...

 

We've taken old engine out of the boat and have bought the reconned Perkins to put in. Now, looking at the angle that the prop shaft goes through the boat, its not vertical as it looks on other boats but on a slight incline towards the hull. My engine guy says that he plans to cut this prop out, build the engine mounts, get the engine in and then reweld the prop shaft perfectly flat, no angle.

 

Fine I thought.

 

Then my oh so wise father intervened (a sea dog, NOT a canal wanderer..) and pointed out that the engine mounts on the Perkins are at slightly different levels front and back any way, meaning that if the engine were mounted on mounts of exactly the same height, the engine would be tilting at a funny angle towards bow direction. He thinks the engine is actually meant to sit so that it tilts towards the stern a little and that this would also suit the current angle of the prop shaft. And reckons that the angled prop would give for better power in the steering.

 

As this is my first rebuild adventure I don't know who to believe! any thoughts welcome and apologies for poor explanation

 

Hannah

Edited March 27, 2011 by Hannah and Jay

[Nobag]

Recently my boat went in to have the drive coupling replaced, when they removed the old coupling, they found that the new one would not align. and they have done as you say, cut out and made sure it fitted correctly, Maybe they know best

[casper ghost]

I expect your "engine guy" will build the mounts to ensure the engine is horizontal then it should be fairly simple.

Gary

[nb Innisfree]

Fit a Python Drive or Aquadrive, probs sorted.

[Chris Pink]

 

 

As this is my first rebuild adventure I don't know who to believe! any thoughts welcome and apologies for poor explanation

 

Hannah

 

 

Most sea going boats have the engine tilted slightly downwards towards the stern and most narrow boats have the engine flat, personally, if it will line up as is, why go to the extra expense of replacing the stern tube (not cheap)?

 

Perkins are common sea boat engines which would explain the engine mounts.

 

It should be possible to find an original engine installation manual which will have instructions and specifications.

[Hannah and Jay]

Thanks... I like the look of the Python Drive, don't like websites that don't list prices though! I'll have to measure up to see if there's enough room between engine and coupling to fit one in, although I'm likely to defer to my egine experts desire to cut out the prop.. which all seems a little harsh but there we go

[hughc]

Measure the angle of the propeller shaft relative to the bottom of the boat. If you are going to have to alter the engine beds mount the engine as far forwards on the new beds as possible. If the total angle i.e. the angle of the shaft to the bottom plate + the angle between the shaft and the engine will not exceed around 7degrees then fill the gap with a cardan shaft which can be any shaft that carries a universal or constant velocity joint at each end. The longer the length you can allow for this shaft the better. Cardan shafts will only accept mis-alignment in one plane. A good solution for the new shaft is to have CentaFlex make up one with two rubber joints and the correct couplings for the engine and original prop. shaft. Tghis will also reduce noise and vibration. It aint cheap but it is much cheaper than welding in new stern gear and still having to play around with shafting. Regards, HughC.