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[warspite]

Although the prop shaft is new I had to cut it down to get the motor to fit in the confined space, the end of the tube was predicted to be above the waterline, now this propshaft is only being used when in trouble and for fine control when moving in and out of port, I have slick 50 grease (need to check if it is waterproof) in the tube and it all appears to run smoothly, I decided to do a static test for water ingress - I.E. leave it in the test tank overnight with 3 - 4mm of clearance under the hull to the bottom so if it did take on water it would not go too deep.
Well she is going to have to dry out, she hit bottom over a 6 hour period, water inside though not sure to what extent I am presumming it has leaked from the prop tube, so the question, I have no space in which to alter the motor, linkage and prop shaft length, the prop is just about removable as is the nut to lock it on, there is a 1 - 2mm space between the nut and the black plastic bearing in the prop tube.
Any advice on what to seal the gap with - without creating to much resistance on the rotating shaft, some mentioned o rings, not sure where to get these, I do have heat shrink tubing and wondered if this may be of use or do I just need a plastic spacer in abs or even wax melted over the end (if it is just to get out of trouble a little amount of water is not going to be a problem). will try and post a picture of the space later when I can.

[Circlip]

some mentioned o rings, not sure where to get these,

  Seal used on disposable cigarette lighters, inamongst jet or filler assemblies.
 
  Regards  Ian.

[Shipmate60]

SHG Sell propshaft inserts a plastic type material.


http://www.shgmodels.com/acatalog/


Bob

[Netleyned]

Any seal that relies on propeller thrust is not going
good much good if the motor is only used as an auxiliary
'get you home' option.
I assume this is a sailing boat, so unless you have a folding prop
to cut drag, the motion of the boat through the water
will pull the prop away from the shaft.
Good greasing will help.
Next time you test in the 'tank' spend a bit of time
looking for the source of water ingress.
Might not be the prop shaft.

Ned

[Circlip]

the motion of the boat through the water
will pull the prop away from the shaft.

   Only when it's going backards.
 
  Regards  Ian

[Netleyned]

If it is a yacht sailing merrily with the auxiliary motor
switched off then the drag of the prop will try to pull
the shaft away from the stern tube.

I am not talking about a driven prop but a trailing prop
on a sailing vessel.

Ned

[warspite]

Sailing ship - yes  , special project - yes  , details - not yet  , given too much away even now.
 
The prop is small a 3 bladed about 20mm, not really bothered about the drag, on Monday it was out in the test tank and moved at a reasonable scale speed when it moved about even when it was a slight breeze, this is not a racer, more of a lazy fair weather boat, enphasis on fair weather  , hence the 3-4mm gap under the sail board to only allow her to sink a short distance and not take on too much water, the tank is only just big enough for her to fit in diagonally and at 3/4 full, if she fell left or right would lodge up against a side. intrestingly I did not see whether the water was on the opposite side of the prop area (theres a barrier to try and limit water filling the whole vessel), so need to check this out.
 
The amount of play in the propshaft for and aft is about 0.5mm, about the play on the motor.
 
Not a smoker so unsure of what to do if I wanted that type of seal of a lighter, I suppose drilling a couple of small holes in the plastic reservior - gently !!! and allowing the fluid to drain is one option.
 
I think the problem is more down to weight inside and the extra weight is pulling her down so the end of the prop tube is below the water line (also I need to confirm that the water is getting in there as I did have to do a mod that will become evident when she is revealed), the counterbalance problem is rearing it's ugly head again, i.e. tall masts and counteracting this effect, at present a sailboard of 239g is being used, with an additional 156g added to it to maintain a vertical equilibrium, say 50mm under the keel, shortening this distance as more weight added it moves closer to the keel, if the length of the counterbalance is extended say to 100mm and I removed the equivelant weight of the additional M8 rod, would the extra length require a lesser additional weight due to the pendulum effect.
 
I am going to try a find the leak, hopefully it is the propshaft, I will need to remove a 52g weight from inside and shift this to the sail board (part of the 156g - which I hoped I could put inside rather than outside - so additionally theres 52g inside and 104g outside on top of the 239g sailboard).
 
I will also need to spend time ensuring the hull is sealed elswhere, to elimate the chance of water ingress.
 

[warspite]

Well, in the last set of tests, water was not seen entering the vessel via the propshaft, although that is not to say that water was not entering via the propshaft, the test were to reduce the weight and increase the righting moment and I am closer to the desired effect, so the chance of water entering will depend upon the use of the motor - something not done yet, or in reverse, the reduction in weight and subsequent adjustment to ballasting has lifted the rear and therefore the chance of water ingressing this way, but to secure some of the ballast resulted in a couple of points being opened to get some glue in - which need to be closed now.
 
I have to find a body of water that I can sail her in yet that is not known to contain a lot of weed or deep or choppy and has easy access if it does not sail as expected, i.e. with access all around and no obstructions. Tall order. 

[Netleyned]

If we knew your location, then one of us may be able to help with suggestions for sailing waters.


Ned

[Circlip]

Not a smoker so unsure of what to do if I wanted that type of seal of a lighter

  Neither am I (any more), but both the jet and the filler valve unscrew from the body and I'm sure someone you know will be disposing of one.
 
  Silly suggestion, wouldn't want you to harm yourself, gas is dangerous if you're not careful.
 
  Regards  Ian.

[warspite]

Thanks for the advice guys, would always do things safe in regards to lighters  , not sure about posting though - sorry stan. 
 
Project 7 is being shelved for the time being - so near yet so far, the weather is turning and although project 7 is virtually complete (99%), and I originally started this as an almost ran project - she is a fair weather boat - although I am very cautious to the nth degree, I was expecting to lose her in her maiden voyage, but now - I have got quite attached and even a tether would make me uneasy.
 
so will have to wait for good weather etc. and sorry the thread eventually went of topic and the balasting was the cause of the possible leakage.
 
thread closed. project 4 here I come.

[warspite]

 
 
guessed how 'disappointed' I am.
 
project 7 was trailed on water twice last week, the first tethered attempt was to see if see would float in reasonable water, other than a load of onlooking swans having a laugh as there was no wind, she just sat there only moving as the ripples from the geese landing moved her.
the second attempt had a little wind and more of a lack of experience with sail than the wind, she needs some mods, when she moved it was not too bad but totally none steerable, took a canadian to bring her back on course and then a rescue.
 
then after a little digging on youtube found a smaller same vessel sailing in the sea of all places, so definetly back to the drawing board for her sister in the future, need to finish project 4, sorry for being criptic but I am embarrassed about the vessel and its inability to work properly.
 
definetly closed thread