Japanese liftable propellor shaft.

japanese liftable propeller shaft

Try it for yourself with a simple set up like this you can check vibration and loading at different angles and how much angle you can get which can be up to 30 degrees. Other more modern constant velocity units are available.
It works similar to top flight surfce drives but can be cheap and simple.

 

In those photos am I looking at a standard car prop shaft with UV joints connected to an outdrive, with a rubber bellows/ membrane to seal the hole in the transom?

That's a clever idea to save lots of cash, rather than paying through the nose for a Merc or Volvo input shaft/UV joint setup.

 

You are looking at a propellor shaft with a constant velocity joint and a self-aligning thrust bearing to allow the shaft to pivot at that point and a torque tube with water gland bearing fits over the prop shaft which has an anti cavitation plate which slides up and down at the transom..briefly this fits into a covered slot similar to a centre case on a yacht and there is a flexible water seal. I have more photos if you are interested.

 

I am having problems visualising your setup........
Could you post some more photos.

Thanks.

 

No, that is not what the photo shows. The exit point is fixed to make the two U joints work at opposite angle so they cancel out rotational accelerations as all CV joints do. That is what I knew must happen for vibration free prop rotation. Tom Kane did not make that point clear but the location of that exit pivot point is critical and directly related to the internal shaft length length and location of the two U joints. Otherwise the angles will not cancel each other.

 

japanese liftable propeller shaft

The black and white images are of the first model to evaluate and prove the principle and used for Patent Application information and was used for a long time. It was very robust and very light using the hull for part of the drive.

The color images are later fully rubber mounted drive insulated from the hull. You have no end to the options that can be incorporated into this drive.
Naturaly I can not show the latest development designs except the Smart drive on youtube.

 

Thanks Tom,
I've just separated up the photos if that's ok with you. (with your approval of course?)




Just guessing this is mk1 version: it's heavy and you need a "p' bracket at the prop end and another little 'prop tube' at the other end. Guessing that there's a stuffing box on the end of the 'prop tube'



Is this Mk 2 version? the prop shaft runs in a big 'prop tube' like a long tail setup; much lighter and easier to lift as a one piece unit.



The final version ? instead of a wooden or fibreglass ' prop box' you have fabricated a copper funnel for the prop shaft, prop tube and assembly to run in. A big rubber bellows seals the end with a stuffing box of some sort.
Very clever: I like it! A sophisticated version of the Indian 'bob' setup; or rather they sort of copied your idea!

Does the 'prop tube' exit the bellows, then enter into a stuffing box ?
What is the downward facing 90 deg pipe in the copper funnel?

 

Re. The Japanese 'Zen' solution.

Here's a 38' Irish boat with a big reputation for seaworthiness, the latest hull form has a much reduced Skeg and keel to reduce broaching in a following sea.

http://www.safehavenmarine.com/2011 PILOT 38 HOME PAGE.htm



This is the old design with the big keel.



The new mini-skeg version.

Testing the new hull in storm force winds....!!!!


Nice little work boat version of the hull.



It should be very easy to incorporate a UV or cv joint into the prop shaft where it exits the hull.....

extend the prop shaft to stick out behind the transom.....

Build a frame that lowers and raises the shafts and props that's bolted to the transom.....

Bolt a couple of rudders to the 'height adjustable frame'.......

Simple simple simple!

Question: what sort of cv or UV joint would be happy submerged in salt water 24/7?

 

Just thinking of some of the bonus' of a lifting prop setup on a twin screw boat:

In shallow rivers and canals the shore-side prop can be lifted to avoid grounding.

Another bonus of lifting props is easy access to the props in 'the raised position' to untangle and cut off rope caught around the prop.

When cruising a displ speeds one prop can be raised to reduce drag and save fuel with single engine use.

The boat can be run up on the beach for cheap maintenance like anti-fouling.

On the mooring the props can be left in the lifted position out of the water to avoid fouling.

In conclusion: you can get all the advantages of a single screw boat in a twin screw!

 

japanese liftable propeller shaft

HI rusty barg. But there are a lot more advantages you have not thought of.
You are getting close to how it is built but you have not got the water seals right there is only one. . The mk1 model is not heavy about 25 lbs as the wooden parts would be part of the hull. With motor power to weight ratio like an 25 HP outboard.
Yes the mk2 is similar to a longtail set up but much more convient.
The waterline level is below where the water seal is and does not leak water like a log down on the keelson. The only water seal is near the thrust bearing and I used dairy industry stainless steel bellows from Mono concentration pump plus a flexible silicon sealer, plus neoprene cover seal. No other seals are needed.Other models were fitted in a stainless steel slot cover.
There is much innovation you can add.Why would you install a shaft drive any other way. The whole drive is rubber mounted from the hull.? PS>> the down facing pipe is just a cheap support.

 

I really like your idea. The bellows being located above the waterline makes a fantastic safety feature; this was going to be my main objection: the bellows bursting and sinking the boat.

Using an agriculture pump bellows has to be better than the rubbish marine grade stuff: how they can sell that stuff specially designed for boats I don't know!

Ah ha, I thought the 90 deg pipe was a water intake, not a cheap support; but it did look very large for that job.

The only hitch I see is the hull would have to designed for this system; it would be possible to incorporate it on a finished hull, but it would be very difficult and time consuming to cut and fibreglass the shaft box into place.

 

japanese liftable propeller shaft

Modifying a hull would be childs play for a capable person and you would finish up with a stronger boat because you would be building a stronger transom and support knee or whatever. I have not spent millions on this project just pocket money.

 

When you consider both pod drives and saildrives require the modification of the hull, there should be a commercial application for your setup ; but of course they are designed into the hull by the NA.

...and when you consider all the boats that have sunk when the Merc 'gear change cable bellows' jubilee clips rust and fall off, and yet there is no alternative offered to I/O installations.

I for one think you should be able to licence this design.

 

Image added to previous post. Yes we can all dream but you would first need to create a sales market and have deep pockets and make the idea known to the customer base and get them to understand the merits...I have been through the patenting process which cost me practically nothing as I did most of the work myself.There sure are possibilities for someone.

 

Looks neat!