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[lesfac]

I tried out my 1/12 Severn yesterday and I was pleased with the performance but there is one big problem. The boat was leaking quite badly and i had to bail it out regularly.
I am thinking the only suspect areas are the bow thruster, the cooling water scoops I fitted and the propshafts. I would think the most likely reason is water coming up the propshafts.
It has been suggested that I could pack the propshafts with grease. Does any one know if this is a good way to seal the propshafts?
Is there another way to seal the propshafts?
It was good to get it running after 2 and a bit years building. The build has slowed a lot in the second year. I think being able to use it will rekindle my enthusiasm.
Les

[Liverbudgie2]

Grease is Ok(ish) but it will "cake" in time i.e. go hard and is difficult to remove. I 've always used a heavy (ish) oil such as steam oil, perhaps gearbox oil will work as well, but I've yet to try it. Before fitting the prop tube, it is a good idea to drill a small hole in the tube near the top and solder a small brass tube into it,; this acts as a filler to top up the oil in the prop tube from time to time. However, I would suspect that it to late to do this in your case.

LB

[Colin Bishop]

The best way to seal the propshafts is to ensure that you have a washer hard up against the end of the tube so that the propeller presses on it when going ahead. You might get a bit of water in when going astern but again you can have a washer on the tuble at the inboard end.

The thrust from the prop should be taken against the prop tube and not by the motor bearings which is a common error. Grease will inevitably introduce drag and increase current consumption to a surprising degree.

Colin

[Neil]

I was talking to Adrian Gosling last Wednesday when he came up to see me, and we were chatting about this problem and what he uses in his jet drives on the Shannon and mentioned that there is someone on eBay that sells light grease which he is using on the jets for about 2 quid a syringe. I told him that I have been using since I designed the Ann Letitia Russell with short 6" tubes in 1995 Vaseline mixed with graphite/carbon powder to give the shafts both watertight and very smooth operation............never had a tube leak yet, and only need to repack them once a year.

[Klunk]

i use lithium grease in a syringe. bit messy packing it but it works. ron dean has a mixture he uses i believe. i also have an old tube of graupner prop shaft grease

[jaymac]

If you don't want to solder
https://www.google.co.uk/search?q=retro+fit+oiling+tubes+for+propshafts&oq=retro+fit+oiling+tubes+for+propshafts&aqs=chrome..69i57.32354j0j8&sourceid=chrome&ie=UTF-8

[Klunk]

found the mix
 Mix 1 part WD40, 1 part Vaseline, 1 part 3 in one or similar oil in a small container.  Mix it up until it is a little stiff.

posted by RoyV!!!

[gra2]

Try Chain saw oil thick and lumpy.

[cos918]

I tried out my 1/12 Severn yesterday and I was pleased with the performance but there is one big problem. The boat was leaking quite badly and i had to bail it out regularly.
I am thinking the only suspect areas are the bow thruster, the cooling water scoops I fitted and the propshafts. I would think the most likely reason is water coming up the propshafts.
It has been suggested that I could pack the propshafts with grease. Does any one know if this is a good way to seal the propshafts?
Is there another way to seal the propshafts?
It was good to get it running after 2 and a bit years building. The build has slowed a lot in the second year. I think being able to use it will rekindle my enthusiasm.
Les

Hi les
first you need to find the leak . So I would make sure she is bone dry. If the boat will fit in the bath try it there . Ie remove the top/opening . put the boat in the water and watch to see were the water is coming in . If after 5 min no water then holding the boat run the boat thruster and see. Do the same for the prop shaft. but run in reverse . The try forward and watch the top of the rudder post to make sure water is not being forced up the rudder tubes . once you have found the leak you can start to address the problem .
For prop shaft lube i use a mix of grease and oil .


john

[david48]

I am using the grease for variable pitch props on real yachts consistency of that set honey that's sold by Rouse (as a example),the grease comes in a standard grease cartridge size and is available from a company called Darglow  ,that  quantity will last for years .The grease is still in the prop on the yacht from one year to the next when we lift out for yearly checks .I greased my prop shafts using a syringe without the needle through the tube clamp type greaser  .It might not be as cheap as you would like but it works.
David   

[Colin Bishop]

I think we can all agree that there are as many recipes for propshaft grease as there are days in the year, if not more. However this only really addresses the symptoms rather than cure the real problem which is to restrict the amount of water getting into the tube in the first place. For that you need a decent seal where the shaft leaves the tube, either a washer at the back of the propeller or some sort of collet where shafts are extended on A frames. In both cases this is where the prop thrust is transmitted to the hull on a model. Full size vessels will usually have an arrangement of internal thrust bearings and shaft seals which perform the same purpose.

It is not uncommon for there to be a small amount of leakage in either full size vessels or models, especially in the latter where the inboard end of the tube may be at or below the waterline. This need be no concern in a model as it should amount to only a very small amount during a sailing session which can easily be contained within a tray or similar arrangement mounted beneath the inboard ends of the tubes.

There is a place for oil/grease on a model driveline though. Greasing the shaft will help prevent corrosion and some lubrication is needed at the inboard end to avoid having a dry bearing. The outer end of the tube will normally be adequately lubricated by being in the water.

A similar tendency to 'treat the symptom' is when people water cool their motors to stop them overheating when the real cause of the problem is an inefficient driveline which is placing too much of a load on the motor in the first place - an overstuffed prop tube for example! 

Colin

[lesfac]

Well egg on face time.
I resorted to getting the dogs paddling pool out. (Yes dog  ).
The boat was too big for it but it served to show up a small hole in the hull right by the inner end of one prop shaft.  On looking underneath there was a blemish where the paint was cracked. I dont know how the hole got there. I might have accidentally caused it but I dont know how. It definately wasnt caused from the outside of the boat. It was on a flat area of hull not where I had installed the prop shafts.
Anyway once found it was an easy fix with glass fibre and resin.
In testing it I found nothing was coming up the prop shafts so I am hopeful for a dry boat now.
Thanks for the suggestions
Les

[Bosse]

After reading this interested subject I was thinking if i should complete my Tamar Kiwi with bow thruster. With i didn't put in in the start of building this model.
But now i´m thinking of that.
Is it worth it? Are Yamar going to be better in the water?
Which bow truster should i buy. Where to place battery for thruster?
My Tamar is Slipway 1/16 model and i am not ready with building this model. It take more time that i thought.
Best Regards Bosse Sweden

[lesfac]

Hi Bosse  I have fitted a bow truster to my 1/12 Severn. At one point I was thinking about not fitting it but I did in the end. I have to say I don't use it much when sailing. It's a bit of a party trick when I use it but on the other hand to be authentic it's supposed to be there. I think everyone has to find their level with the amount of detail that they put into a model.For me I reason that I want to use the boat and I want it to look quite good but I don't want to put so much work into it so that it becomes too precious to risk using it regularly. Also I didn't want the build time to be extended by fitting fine detail above a certain level. I wanted it to be ready to use.The boat motors are two brushless Emax BL4030 running on two 5 cell 5000mah  Lipo batteries connected in parallel and 2 Hobbyking 90 amp speed controllers. The bow truster  is a Roboesch running on a separate esc (because it's a brushed motor on the bow thruster).  I use a 7.2 volt Nimh battery pack for the bow truster. The above motors power my 1/12 Severn nicely so I guess they are bigger than you need for your 1/16 Tamar.
Les

[Bosse]

Thanks för yours answer.  I was thinking in same way as you re if they really needs for "happy driving".
So after a little mind braining i decide to drop that idea.
Yippe for that, no more drilling under waterline.
Thanks a lot for yours helping..
Med vänlig hälsning, Bosse

[Taranis]

I've only just read this thread and regarding Speedline jet drives some of us radically altered them to install prop tubes with lubrication stand pipe. There was an issue with seal failure originally and our mod did away with seals completely. Initially I used oil but since found the grease is far better. I get zero water ingress even at 20,000 rpm. I sometimes get some water in under the deck but I fitted a bildge pump that runs continuously as self priming

[Bosse]

Which brand and itemnumber is it you are using?
Thanks Bosse

[Taranis]

I bought from here. They do bigger quantities at better prices
https://www.ebay.co.uk/itm/TWIN-PACK-FULLY-SYNTHETIC-WATERPROOF-MODEL-BOAT-PROPELLER-SHAFT-GREASE-/391351329285?hash=item5b1e5b6205


10 pack
https://www.ebay.co.uk/itm/10-PACK-FULLY-SYNTHETIC-WATERPROOF-MODEL-BOAT-PROPELLER-SHAFT-GREASE-/171784303066?hash=item27ff2471da

[Bosse]

My luck is this sort.

Postage:
Doesn't post to Sweden
[/color]
[/color]
[/color]So what to do?
[/color]
[/color]Do you know what brand of grease inside the tube?
[/color]
[/color]
[/color]
[/color]Hope I do.Best Bosse

[Taranis]

This grease is a blend of fine synthetic oils in an aluminium complex binder.
To this is added white lubricating solids and P.T.F.E sometimes referred to as Teflon.
Capable of working in extremes temperature from -50 c to 150 c
Has a 4 ball weld rating of 400 Kg
EMCOR corrosion rating of 0:0
Water wash out rating @ 38 deg C less than 1%
Copper corrosion test of " NEGATIVE "
dn factor of 400000
NLGI Class 1
Suitable for lubrication of plain and anti friction bearings
It has been awhile since we stopped production of prop shafts, however some of our old customers have been asking what we used to lube them.
Well here it is. whether you use a steel shaft or stainless steel shaft. whether you have brass, bronze, nylon, needle bearings, ball bearings or lead teflon. this is it.
The synthetic oils and binder prevent water washout and help to maintain optimum lubrication to parts.
One of the first main problems we encountered when it came to lubricating shafts was the lack of free space within the outer shaft, we were the first to make 4mm shafts with 6mm outers, so with only 0.5 mm free space around the inner shaft there is not a lot of space for movement of the grease.
Due to this lack of space and using grease you actually create drag on the inner shaft,this in turn causes the motor to draw a higher current as it has to work harder to turn the shaft. simple physics ! so the first thing to remember is not to over pack the shaft.
To overcome this the base oils used in the grease are of a very low viscosity added to this the overall thickness of the grease is a low NGLI class . this allows better movement in the confined space helping to reduce drag.
To help even further the added white solids and P.T.F.E aid to lower the drag even further.
And you thought grease was just grease.
We put as much thought and time into lubrication of our shafts as we did the shafts themselves. Not everyone prefers grease for there shafts, we will be releasing a fully synthetic oil as well soon..
You will have to remove your inner shaft to apply the grease within the shaft outer or through a stuffing tube if fitted, sorry for saying this but it is just in case!

[Bosse]

PROPSHAFT GREASE
MBB-PSG

WATER RESISTANT PROPSHAFT GREASE LOW DRAG MOLY-FORTIFIED LITHIUM GREASE 20ml SYRINGE
[/size][/color]
[/size][/color]
[/size][/color]
[/size]Dynamite Marine Grease 5 oz - S-DYNE4201  in eBay.[/color]
[/size][/color]
[/size]Which one do you think fits me [/color][/size]purpose??[/color]

[/size]Bosse[/color]
[/size][/color]

[Andyn]

Best stuff  I've  used so far is TF2 Ultimate, is lithium  grease available  from bike shops or Ebay


I use this on open flexi shafts at far higher rpms than this, stays in place and does the job well


https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F264147013367

[clockworks]

What's the best type of washer to use as a thrust/sealing washer on prop tubes?  Brass, stainless, nylon, teflon, etc.?