flexible propeller shafts

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flexible propeller shafts

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31 December 2020 at 15:50 #92945
jeffrey mundell 1
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@jeffreymundell1
i am just starting on a model boat with twin Korts nozzles,which i purchused from MMJ and very nice mouldings indeed,as the korts have to be mounted in horizonal position and motors are quite high up in hull i think it would be best for a pair of flexable shafts,but where can i obtain some?

the model is a American pusher tug of 750mm size

Has anyone any thoughts on this matter

regards Jeff
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31 December 2020 at 15:50 #4706
jeffrey mundell 1
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@jeffreymundell1
31 December 2020 at 15:53 #92946
jeffrey mundell 1
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@jeffreymundell1
Just a tought the Korts were purchused from MMJ, not the tug which i am scratch building

Jeff
31 December 2020 at 19:15 #92948
ashley needham
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@ashleyneedham69188
Jeffrey. Flexishafts are really meant for racing boats which have motors forward, to keep the prop line flat.

They require a lot of maintenance, as the wire wound drive is not rustproof and ideally needs stripping, drying and re-greasing after every run. Usually this means loosening the solid coupling grub screw or collet, and withdrawing the shaft rearward.

Cant say that I have heard of flexis being used in a tug, but I may be horribly WRONG!

I would think that a small downwards angle should not be that detrimental to the Kort? Also, why are the motors so high? Normally something you would install low down.

Ashley.
31 December 2020 at 20:40 #92952
Charles Oates
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@charlesoates31738
Hi Jeffrey, yes the korts need to be horizontal, but there is no practical reason why the props and shafts cant be angled, it's what I and hundreds of others do. Normally we just adjust the motor and shaft layout in the hull to give as flat an angle as is practical, remembering to position the motor and coupling where they can be easily accessed for maintenance.

Like Ashley, I've never heard of flexies being used in a sedate model, all that messing about in a delicate scale model wouldn't be for me.

Charles
1 January 2021 at 09:40 #92956
Malcolm Frary
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@malcolmfrary95515
Tugs do need reverse, flex shafts tend to unwind themselves in reverse, so they don't get used on tugs.
1 January 2021 at 09:59 #92957
Chris E
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@chrise
Posted by Malcolm Frary on 01/01/2021 09:40:13:

Tugs do need reverse, flex shafts tend to unwind themselves in reverse, so they don't get used on tugs.

Agreed. Never use flexible shafts if you need reverse which you most certainly do with a tug.

I am not familiar with MMJ, and thus clearly not your model, but with a tug hull it is normally possible to mount the motors quite low. Yours must be the exception.

Edited By Chris E on 01/01/2021 10:03:42
1 January 2021 at 10:20 #92958
Charles Oates
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@charlesoates31738
Hi again, as you can see, people on here would all like to help. I suggest you post some pictures, this might make a big difference to the advice you get. If you haven't posted pictures before, go to all topics, and look at the item on posting pictures.

Charles.
2 January 2021 at 15:08 #92986
jeffrey mundell 1
Participant
@jeffreymundell1
many thanks for your replies,i did not relise that with the kort mounted horizonal the prop inside could be at an angle very slightly,as this was pointed out in the post by Charles Oates ,so this has solved the problem.

all have a happy and good New Year

Jeff

live in New Malden
2 January 2021 at 15:28 #92987
Charles Oates
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@charlesoates31738
Perhaps this will help.
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