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Novice question - props

Posted: 19 Sep 2014 20:44
by RAAFieChappie
I'm building a Billings kit 1/50th Bankert tug which I've resurrected after lying dormant for many years (my first project). The 40mm prop has split and beyond repair (see photo). I can't seem to identify a source for a replacement nylon prop that fits the existing shaft. Can anybody suggest a source please? Should I buy a completely new prop & shaft to be safe? Hope you can help.

Re: Novice question - props

Posted: 19 Sep 2014 22:34
by BsHvyCgn9
Work out what thread it is (ie: M3 or M4) its most likely M3 hop on to GT Siteks website and use his Contact link to ask for a 40mm 3 blade Brass prop with M3 thread. The bonus is it will look way better than a nylon prop and go better in reverse too.... (those nylon props seem to go better fwd!)

Cheers Bruce

Re: Novice question - props

Posted: 19 Sep 2014 22:50
by MichaelB
Or give Floataboat in Melbourne a call and get a bog standard 4 blade Raboesch prop for it. 4 blades seem to be more appropriate for a tug.

Re: Novice question - props

Posted: 20 Sep 2014 09:34
by RAAFieChappie
Thanks guys. Is there a easy way to discern if the thread is M3 or M4? I've got the LH & RH sussed out and fortunately the tug is a single prop. The Bankert kit came with 2 fairly thick wooden rudders. To me they seem overly thick and prone to damage (eventually). Any suggestions? Brass sounds logical.

Re: Novice question - props

Posted: 21 Sep 2014 00:24
by BsHvyCgn9
Just measure the thread on the shaft. M3 = metric 3mm so should be around 3mm across the threads. Or go to Bunnings with the Shaft and see what size nut fits.

Also how closely does(did?) the prop come to the sides of the kort nozzle? if there was a reasonable gap say 2-3mm you could get a proper 4 bladed kort prop to suit the inside diameter of the nozzle much more efficient then!

With the rudders I would taper them down a bit to an aerofoil shape if possible....

Cheers Bruce

Re: Novice question - props

Posted: 21 Sep 2014 10:09
by RAAFieChappie
Thanks Bruce. I'm off to Bunnings. One last question (I think). Is it necessary to put grease on the prop & rudder shafts to stop water being ingested into the hull? Probably elementary stuff but I'm an absolute newbie.
cheers,
Paul :hlp:

Re: Novice question - props

Posted: 21 Sep 2014 11:05
by BsHvyCgn9
Yup wack some marine grease in the shaft tube and on the rudder post. Also prevents corrosion of the bits...

Cheers Bruce

Re: Novice question - props

Posted: 22 Sep 2014 18:05
by cootafleet
Korts props have squared off blade tips to fit the nozzle.
Bruce B1