Model Boat Mayhem

Technical, Techniques, Hints, and Tips => Tutorials & "How To’s" ... => Topic started by: rob on May 21, 2017, 08:21:24 am

Title: Propshaft 'stuck' due to saltwater.
Post by: rob on May 21, 2017, 08:21:24 am
any advice on how to unstick seized prop shaft please ?
A very nice Robbe Koh I Noor is suffering.
It is fitted with a Robbe Navy type motor/gearbox/shaft so my idea of taking out the shaft and replacing it is a no go.
If I can't free it, the owner is going to put it into the local antique/curio/junk shop !
As its lovely,  fitted with a wing keel, Nylet sails and 2.4 Futaba this will be a great shame.
Title: Re: Propshaft 'stuck' due to saltwater.
Post by: derekwarner on May 21, 2017, 08:45:46 am
Rob.....

You could immerse the offending shaft in very warm water with a small squirt of liquid dish washing detergent in a stove top Pyrex dish

The dish washing liquid alters the chemistry/make up of the water and actually makes it thinner and slippery

The very warm soapy water will migrate up into the prop shaft tubing & hence loosen by dilution, the salt build up .....[this may take a number of hours in keeping the water very warm on the stove top]

Is this the same vessel from your 2004 Mayhem questions?...........Derek
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Reply #1 on: February 10, 2014, 10:22:37 AM »

Robbe Koh I Noor

I am about to overhaul a model that I built many years ago, and the owner would like a more scale like sail set.
Anyone done this before ? And would share what they did ?
Anyone have a recommended sail supplier ?
Many thanks in advance for your ideas/recommendations.
 
Title: Re: Propshaft 'stuck' due to saltwater.
Post by: rob on May 21, 2017, 08:51:55 am
Thankyou Derek, I think it's worth a try.
Yes, it's the same (very nice sailer now) boat.

Title: Re: Propshaft 'stuck' due to saltwater.
Post by: Netleyned on May 21, 2017, 08:56:51 am
https://www.rcgroups.com/forums/showthread.php?432983-Robbe-Navy-Kompakt-Motor-and-Drive-help%21


Does this help?


Ned
Title: Re: Propshaft 'stuck' due to saltwater.
Post by: rob on May 21, 2017, 09:02:34 am
Thanks Ned, probably not though.
When building it, it was a case of mounting the motor on its wooden framework, glueing it in and the glueing the shaft. It's pretty tight in there space wise.
Title: Re: Propshaft 'stuck' due to saltwater.
Post by: Sonar on May 21, 2017, 10:14:13 am
Really very very Very nice boat    http://www.hmbc.nl/cat/kohinoor.php (http://www.hmbc.nl/cat/kohinoor.php)

Hope he gets it sorted out it a keeper that,s for sure..

you could try two things.

Coke cola  or silit bang that, s if it is spelt that wa
Double posted due to my poor internet connection.

But still worth saying twice
Title: Re: Propshaft 'stuck' due to saltwater.
Post by: Sonar on May 21, 2017, 10:16:51 am
Really very very Very nice boat  Way to nice to send away    http://www.hmbc.nl/cat/kohinoor.php

Hope he gets it sorted out it a keeper that,s for sure..

you could try two things.

Coke cola  or silit bang that, s if it is spelt that way
Title: Re: Propshaft 'stuck' due to saltwater.
Post by: rob on May 21, 2017, 10:18:48 am
Sonar, that might be worth a try. It's arriving next week I will try anything to sort it for him. Unfortunately I fear it may end up on the 'for sale' page as he has decided this morning that he wants me to do a dragon 95 as a replacement.
Title: Re: Propshaft 'stuck' due to saltwater.
Post by: Plastic - RIP on May 21, 2017, 01:57:27 pm
As the shaft sits in a larger-bore tube, it's only seized at the bearing ends - more likely the outer end in contact with the water.

Why not remove the prop, lock a couple of nuts together on the shaft and get wiggling with a wrench while adding penetrating oil or even putting a soldering iron firmly on prop end of the inner shaft to heat it gently and wiggling to free it. The Cilit-Bang or Coke may work too.
Title: Re: Propshaft 'stuck' due to saltwater.
Post by: Netleyned on May 21, 2017, 04:36:02 pm
The replacement does not have a motor,
so if all your efforts are to no avail, just
remove the prop and sail it?
She is a much nicer yacht than the DF 95.
The motor will only be a get you home in
case of problems, I would just like to sail
her.
If she goes for sale, please put her on here first.


Ned
Title: Re: Propshaft 'stuck' due to saltwater.
Post by: rob on May 21, 2017, 06:10:58 pm
Plastic, thanks for the idea.
Ned, I couldn't agree more, especially with her Robbe wing keel and the Robbe lengthened boom and Nylet sails giving her much more.
Ok, she goes on here first, though what price with the 2.4 Futaba ?