Model Boat Mayhem
Technical, Techniques, Hints, and Tips => Other Technical Questions... => Topic started by: hazmat on May 06, 2010, 03:45:01 am
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Being VERY old school (well past the sale by date) , I've always used Vaseline to pack my prop and rudder shafts but I'm trying to bring myself up to date and have been told that the 'modern' trend is to use oil {:-{ ?!?
Could you please advise me :-
1/ What grease or oil does everyone use for packing prop shafts and rudder tubes? and
2/ if you use oil, do you need to fit rubber seals to prevent the oil leeching into the water?
Thanks, Paul
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Waxoyl (usually used for rustproofing underneath of car bodies).
FLJ
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Prop shaft grease.
http://www.cornwallmodelboats.co.uk/acatalog/prop_shaft_accessories.html
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Prop shaft grease.
http://www.cornwallmodelboats.co.uk/acatalog/prop_shaft_accessories.html
Seven and a half quid fior that little tube? Don't you ever try playing the poverty card again, Richard! <:(
FLJ
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Just out of curiosity, what is wrong with using Vaseline anyway?
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Just out of curiosity, what is wrong with using Vaseline anyway?
I suppose it depends on what you are suffering from. They say KY jelly is a good substitute....
As far as boats are concerned Vaseline is too stiff and saps power. Everyone seems to have their own preference in this line, no two of us seem to agree. I use motor oil on the basis that it is designed for fast moving metal to metal contact and creates no drag but as our friend FLJ says - suit yourself.
Colin
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Just out of curiosity, what is wrong with using Vaseline anyway?
A bit too thick, my man - certainly for this particular purpose %)
FLJ
(That man Bishop is just plain rude!!)
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Vaseline is water based and breaks down over time i think aswell PMK. :-))
nothing wrong with using motor grease as long as its not too thick to cause drag on the shafts.
Jay
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Ah, right. So it's too thick, creates drag and it's water based.
Thanks for the heads-up.
Where can I buy Waxoyl?
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What about that black grease they use for CV joints on cars. Seems to be quite thin stuff.
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Where can I buy Waxoyl?
Scrape it orft a sheep, basically lanolin disolved in parraffin.
Strange that one FLJ, cos once the parraffin starts to dry off the "Grease thickens up"?
CV joint grease contains Molybdedendum disushics -- Black Moly - runs quiet with that in the tube. Mix yer own similar by using Castrolese (or whatever they call it now) H/T wheel bearing grease and add Graphite.
Regards Ian.
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Cheapest grease you can find in your local car spares shop....
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Seven and a half quid fior that little tube? Don't you ever try playing the poverty card again, Richard! <:(
FLJ
If I played the poverty card Dave I would not shop with you {-)
That little tube has lasted 16 boats over the last 4 years. Not bad I think.
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If I played the poverty card Dave I would not shop with you {-)
:P
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Strange that one FLJ, cos once the parraffin starts to dry off the "Grease thickens up"?
Never mind the theory - it just works (for me and several others).
FLJ
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Just out of curiosity, what is wrong with using Vaseline anyway?
Its water soluble Dude
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Halfords LithMoly CV grease is the best we have found. A single 500g £5.99 tub will outlast you oldies...
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Halfords LithMoly CV grease is the best we have found. A single 500g £5.99 tub will outlast you oldies...
Watch it sonny !!!
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I suspect that the fact that everyone has their own favourite simply demonstrates that anything oily will work within reason. Just that if you stuff the tube with thick grease you will greatly reduce your battery life or worse.
Colin
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Its water soluble Dude
Peace and love, brother.
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Cheapest grease you can find in your local car spares shop....
Try COPPER EASE. Works from -40°C to +150°C. Water resistant and sticks like the proverbial ****.
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Has anyone tried the stuff the big boys use? Or would that not be pc?
http://www.marinescene.co.uk/category/520/grease-amp;-lubricants
Is the stern tube what I've been calling the prop shaft?
At the risk of being too nerdy, doesn't the viscosity you need depend on the rpm of the shaft and the tolerance/condition/material of your bushes?
Vaseline does sound pretty eco-friendly, if it doesn't disolve too quickly
I think that's about two-penneth worth.
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The stern tube is what the prop shaft runs in.
Barry M
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Thanks for that Barry.
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Try COPPER EASE. Works from -40°C to +150°C. Water resistant and sticks like the proverbial ****.
Do you mean this stuff? %)
http://www.screwfix.com/prods/22070/Sealants-Adhesives/Adhesives/Grab-Adhesives/High-Performance/Sticks-Like-Sh-t-290ml
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Maybe we ought to get back to basics a bit here.
There are essentially two reasons for oiling/greasing the prop tube.
The first is to reduce friction between the bushes at the ends of the tube and the revolving shaft. In most models this really only means the inboard end as the water itself will act as a pretty effective lubricant with most bushes at the outboard end.
The second is to help prevent water finding its way up the tube and entering the boat. Now, with most of the sorts of boats we run it isn't the grease or oil which stops the water although it does help. On the end of your shaft you will have a propeller(!). Inboard of that you should have a lock nut to stop it unscrewing and falling off. Inboard of that you should have a washer of at least the external diameter of the prop tube. This could be brass or nylon etc. When the boat is going ahead the propeller will push the washer up against the prop tube and and effectively seal it which will very effectively stop water getting in. Unless you have some sophisticated engineering setup with internal thrust blocks etc. it is the pressure of the propeller on the washer and thence to the prop tube which actually takes the load and drives the model forward. As it is submerged the water acts as a lubricant.
But when you go astern (which will normally only be a small proportion of the time spent going ahead) the propeller is pulling on the shaft so the load is taken on the nut and washer that you should have installed at the inboard end. if you haven't then the load will be taken on the motor bearings which is maybe not a good idea except at very low power. Now, if there is a lot of 'play' on the shaft; i.e. you can move it up and down appreciably, then going astern will move the outboard washer on the shaft away from the outboard end of the prop tube which may allow water to enter which is when your grease/oil comes in handy. So the best practice is to tighten up both ends of the shaft until it is locked in place and then ease off just sufficiently to allow the shaft to move freely. This will minimise the likelihood of water entering when going astern.
Some water will get in, it is inevitable, even on full size craft so the oil/grease in the tube will help prevent corrosion while the model is laid up at home.
Colin
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Lovely! All the answers in all of the colors and technical descriptions to boot.
All the comments greatly appreciated. (even the 'witty' ones).
Thanks for all your help
Paul
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Just to be different %) I use outboard motor grease. It's waterproof and quite cheap, as a half kilo tub will last for years because, after all, not much is used in a prop tube.
Peter.
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i use castrol grease from car spares shop.
no water gets up my shaft.
jabba.
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Excellent info Colin! am on my first model and now at the stage where, as a newby, I've found your thread really helpful - so thanks for that :-))
Anyone ever tried silicone grease as used by plumbers for lubricating 'o' rings and pipe seals? cheap, tremendous temperature range, waterproof and safe even for potable water.
Regards, Tony.
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I've got a tube of Dow Corning 7 Silicon grease and it works blilliantly. Silicon grease tends to be a bit more expensive than lithmoly grease though.
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Like nd3500, I tend to go for the cv joint grease (Lithium) and I use it on the subs. It is low on viscosity and despite being totally submerged in unsealed shaft assemblies it remains as a coating on the rotating and bearing surfaces. It is not water soluble either and as with all propshafts, it is not a good idea to fill em up to the brim with any grease as it will create drag and sap amps, especially on high speed direct drive units. Thats whyI use it on the subs, as Amps count for everything.
As my old Pappy used to say.. "enough is as good as a feast"
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Traditional lubricants advice is to use a Lithium-based grease in the presence of water. Thus grease for bike-chains etc is lithium based. Such a grease is often called 'water-pump grease'.
However, these greases are usually high-viscosity, which is a bit two-edged if you're looking to pack a prop-tube with it. If I have to put a prop-tube below the waterline, I usually use one of those submarine seals....
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Hi Dodgy,the only product I have laballed 'water pump grease' is a Shell product and is a thick yellow waxy type grease which we used in the 'Lady May', our old 18ft motor launch. This was used on the full size propshafts and of course, in the water pump. The lithium grease I use on the subs is is a much lower viscosity and even a little of it leaves a fine film on the bearing surfaces which doesn't go away even though continued submergence and constant running. It also gets used in the dive unit packing glands and does not affect the rubber seals either so all in all it seems a very suitable product. I might add, it does not leach out into the water as the sub shafts are delibeartely designed as unsealed sealed units as they are not designed to keep water out.
There are so many lubricants to choose from, it's a bit of a minefield but I guess if you find one which works in your application you tend to stick with it... (no pun intended here).
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product I have laballed 'water pump grease' is a Shell product This was used on the full size propshafts and of course, in the water pump.
Search Shell Marine Grease for stern tubes and you get Shell Strombus MP
Uses : Speciality marine product.
Product Code : 901LU760.
It is a 17 page Adobe.pdf file for "light" reading
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Hi Dodgy,the only product I have laballed 'water pump grease' is a Shell product and is a thick yellow waxy type grease which we used in the 'Lady May', our old 18ft motor launch. This was used on the full size propshafts and of course, in the water pump...
I remember it well...My father was a lubricants troubleshooter for Shell, so one of the perks of my childhood was access to all kinds of slippery stuff...that, and trips to foreign climes...
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Just read through my last post to you blokes, can't believe the spelling mistakes and typo's I found. :police:
Yoo muss awl fink Iym a nidi yot! :embarrassed:
I'd like to blame the computer as it's very old now but you know what they say "rubbish in... rubbish out"!
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My turn.
I'm playing the 3-in-one card.
http://www.wd40.co.uk/index.cfm?articleid=1933
White lithium grease sounds pretty exotic.
(http://s3.postimage.org/DKpLJ.jpg) (http://www.postimage.org/)
Dunno if it's any good though.
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My turn.
I'm playing the 3-in-one card.
http://www.wd40.co.uk/index.cfm?articleid=1933
White lithium grease sounds pretty exotic.
(http://s3.postimage.org/DKpLJ.jpg) (http://www.postimage.org/)
Dunno if it's any good though.
Used it successfully for years. Preferred the old tube though. aerosol a bit violent <:(
Doug
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ive always used oil , normally 3in 1 type although im now useing semi synthetic motor oil ! the problem with grease is when cold its very thick which in turn makes anelectric motor labour ( meaning it will draw more amps ) ! greaseis ok when you have an ic motor .