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[Ben123]

Hello folks, new member here looking to fix a commercial bait boat because of extortionate money being asked by the manufacturer to fix it. It's a dual prop model and basically one of the prop shafts is bent allowing water to get inside.

I have opened the boat up which basically entailed removing the top half (sealed together with silicone) and I am now a bit stuck. I have gathered that the motor spindle is attached to the prop shaft via a coupler but have a few questions about what to do next:

How are props attached to the prop shaft? Screwed on and then glued?

Where the prop leaves the hull, there appears to be a rubber seal of some kind, yet googling parts sites find no seals, so are the seals built into the prop shafts?

Am I going to have to remove the motor to do this fix? I see no way of undoing the coupler as they seem to be white plastic things with no hex/allen key fitting to release the prop shaft.

I have attached a photo that hopefully help illustrate my questions better. This is a view looking down on the motor from above with the prop shafts exiting to the left below where the silicone is massed. I can post any other pics required if it would help.



Any advice gratefully received.

Ben

[modelboatbits]

Hi,

your first move ist to remove all silicone mass so you can better see what is the best course of action.

If there are twin prop's I guess you would be better of replacing both with easy maintainable shaft's.

Either way you firts have to gain clear access of existing shaft. Then post more photo's

Steve

[Ben123]

Thanks mate. The silicone mass isn't a huge amount actually - there's a layer of it which covers the recess for the prop and weed guard. It looks like it's there to waterproof where the 4 screws that hold the weed guard in place are fixed. I'll take more pics so that it is clearer how it's set up and post them up later.

Thanks for your input

[Ben123]

More pics, better quality. EDIT - forum doesn't like me posting pics direct so please click links.

http://img192.imageshack.us/i/dscf0026o.jpg/

http://img227.imageshack.us/i/dscf0025c.jpg/

http://img411.imageshack.us/i/image073b.jpg/

I'm gradually coming to the conclusion that I'm going to have to remove the motor to fit a new shaft - correct?

If so, it looks like I'll have to remove the propeller - if so how are they fixed? Screwed on and then glued?

What do you mean by easily maintainable shafts?

[malcolmfrary]

What do you mean by easily maintainable shafts?

Basically, the kind you get from a model shop.  These normally are threaded at the outer end to accept the kind of prop also available in the shop, which would usually have a locknut to prevent unwinding when being chucked in reverse.  Threadlock is good for peace of mind.  The other end of the shaft is usually plain, and takes one end of the universal joint assembly (yet another model shop item), which is often grub screwed.

[Ben123]

Thanks for that. When he said 'maintainable' I wondered how you would go about maintaining a shaft once it's fitted into the boat, but it seems I mis-understood the meaning.

So, the propeller may unscrew, but if not then it's probably been threadlocked, in which case I'm going to have to saw it off to pull it back through the hull to remove it, since the seal would stop it being pulled out of the boat by the propellor end, correct?

I'm also a little confused about what stops water getting in as I see no mention of seals when talking about prop shafts - do I need a prop shaft which has a seal built into it, or is it just accepted as normal for water to get in?

Sorry for all the newbie questions.

[malcolmfrary]

Ideally, the threadlock should be susceptible to being weakened by a bit of heat, or just a healthy application of spanner and pliers, so its not like welding the prop on.  What keeps the water out is usually a combination of close clearances and water repellent grease or oil.  I find that a couple of brass washers with a neoprene "O" ring trapped between them between prop and shaft end makes for a good thrust washer/seal arrangement.
Before attacking the original prop, I would measure it, just in case it doesn't survive removal.  The infallible way to totally waterproof a shaft is to ensure that the inside end is above the waterline, but this is not always possible.

[Ben123]

Excellent, that is very helpful.
The manufacturer mentioned the word 'seals' to me when discussing it, but I have found nothing when googling the term. I can just about make out some kind of black 'o' up against the inside of the 'hole' (excuse my lack of technical term here!) that the prop shaft exits the hull from, so perhaps that's what they have used.
Thanks for the info re: removing the prop. The props are plastic so I'm not sure how much force I can apply, but I will try.
So, just to clarify, am I going to have to remove the motor to do this repair? I would imagine so, but obviously I would prefer not to.

[ZZ56]

Thanks for that. When he said 'maintainable' I wondered how you would go about maintaining a shaft once it's fitted into the boat, but it seems I mis-understood the meaning.

So, the propeller may unscrew, but if not then it's probably been threadlocked, in which case I'm going to have to saw it off to pull it back through the hull to remove it, since the seal would stop it being pulled out of the boat by the propellor end, correct?

I'm also a little confused about what stops water getting in as I see no mention of seals when talking about prop shafts - do I need a prop shaft which has a seal built into it, or is it just accepted as normal for water to get in?

Sorry for all the newbie questions.

No, you would be able to remove the coupling and thrust washer and pull the propeller and shaft out to refresh the grease and oil in the tube.  



This is what a simple stuffing tube looks like.  They have a bushing at each end to hold the propshaft and the space between is filled with thin grease and oil.  Some have vertical tubes soldered on to add more oil and grease without having to take the shaft out.  the tubes are permanently fixed in the hull with glue. 

[Tombsy]

Does the brass coupler next to the motor have a set screw or two in the side? If it does you should be able to pull the shaft out with the prop attached.
It should attach the motor shaft to the drive shaft and they usually come apart some how.

[Ben123]

Does the brass coupler next to the motor have a set screw or two in the side? If it does you should be able to pull the shaft out with the prop attached.
It should attach the motor shaft to the drive shaft and they usually come apart some how.

The coupler doesn't seem to be like many I have seen while searching the internet the last few days - as you can see from the picture, it's a white plastic thing with a nut type fitting at the prop end. I'm a bit confused as to how it would be released to be honest as most I've seen on parts sites seem to have some kind of allen key or grub screw that locks the shaft in. There is a little bit of it that's hidden from view under some silicone that has been splurged in, so maybe that's where it can be released. I will have a go at removing some silicone to see if I can see any more.

[Tombsy]

The nut on the prop end probably unscrews sounds like maybe a plastic version of a collet type coupler like a nitro motor.
But that is where you want to take things apart then the shaft will pull out through the seals and you can see what your dealing with.
The shafts should be regularly lubed you wouldn't think they would make it so difficult.
What make is it?

[Ben123]

OK, thanks for that. It's basically two halves joined together with some spots of araldite and sealed up with silicone, so not very easy to maintain to say the least.

It's called a Blue Sky Angling Lakestar: http://www.blueskyangling.co.uk/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=75&category_id=28&option=com_virtuemart&Itemid=53

There are a couple of videos on the site there if you're interested.

[Ben123]

OK, have removed shaft by gripping with pliers and turning coupler nut with a spanner. Have attached pic below.




I'm now not sure what to do next. Will be getting shaft checked by my old man, to see whether it's bent by using his lathe and some kit or other he has, but it doesn't appear bent going by rolling it on a worktop.

The seal arrangement is still in the boat. I don't know exactly what it is but looking from the outside there's a few mm of black plastic/rubber and then what looks like brass or some other metal, which appears to have a thread on it. Certainly if you look at the pic you will see some grooves in the shaft just below the thread which fits into the coupler.

I hope the above may give some clues as to how it is arranged so you can suggest what to do next and/or why it may be leaking. I can put up any pics you need so just ask.

Cheers

Ben

[Tombsy]

Can you get a pic of the seal from the back? Could it be maybe two sets of bronze bushings that caused the grooves in the shaft?
I have a Traxxas Villain that has shafts that are sealed by bushings at each end but there is a nipple fitting to keep them lubricated.

[Ben123]

Sorry about the quality of this - it's hard to get the angle right and the flash is reflecting off the ABS hull.

As I said, when I look at it with a torch, I can see maybe 5mm of plastic/rubber and then metal which looks threaded. I was assuming it was a stuffing tube as illustrated above, but the threading is a bit confusing. I was wondering if the marks on the shaft were maybe due to misalignment on the shaft with the stuffing tube and/or motor, which would explain the leak.

I've also run the motors since the one on the problem side has some rust on the outer case, and it sounds rough compared to the other which is smooth and also looks newer so it has likely been replaced before at some point. This then leads me to the question of finding and fitting a replacement - how would I identify what I need, and how would I align the motor, coupling and shaft correctly?

It's all held in place using big splodges of silicone sealant, so how to remove that is another issue. It looks as if the stuffing tube/seal is held in position with lashings of silicone also. I was thinking some silicone remover might be needed, although the manufacturer was talking about a heat gun/glue gun which worries me with the hull being plastic. I have also considered a soldering iron to melt the silicone.

[Tombsy]

Hard to tell from the pic but it looks like a bronze bushing that's worn into an oval shape. That would definately cause the grooves in the shaft.
The easiest fix might be to replace the bushings they probably press in, I think they are called oilite bushings and they are pretty common on RC Cars.
If that's what it is you still need a way to lube the those bushings, maybe add a grease nipple?
The motors should have been mounted so they can be removed they are not siliconed in as well are they? The motor mounts should already be lined up with the shafts.
You can give the motors a tune up, flush out with motor spray and oil the bushings/bearings, they look like they shouldn't be too hard to find maybe take one down to your local hobby shop.
For the price they want on the website it's hard to believe it's all put together with silicone, unless someone added it later to try and plug leaks.
Try to cut and pick away at it to see what you've got I'd be leery of heat though.

[Ben123]

Thanks mate. Yes, I thought the same of the build quality myself when I opened it up. They are considered the market leaders too! One of the other main manufacturers has battery compartments sealed with velcro  A friend has one and if there are any waves on the water the battery compartment fills with water 

I think it's actually a plastic weld that holds the motors in place, but it's definitely silicone that seals the two halves together. It did occur to me that anyone with knowledge in the field could make a good living making boats because carp fishing is very poular in the UK and europe. I know in canada they are considered pests in rivers etc, but here and in europe they are much sought after - a friend has just paid £1500 for one year's fishing!

What would cause the bushing to oval would you think? Poor initial alignment of the shaft/bushes/coupling/motor? Or just general wear? The boat is 4 years old or more to be fair but I have only acquired it fairly recently. Presumably the former owner was experiencing leakage problems before offloading it, but by the time I had realised the full extent of the problem, he was long gone from ebay, which was nice 

The motors have mounts but the mounts are fixed in position with plastic weld to the bottom of the hull, and each side of the motor is fixed to the side of the hull with a big blob - my initial pic or one of the links may show this. I've just had a poke with a stanley knife and it looks like it's possible to get it between the motor and the blob, so I will get my old man on the case with a chisel type tool he thinks would be better suited.

My old man has worked with electric motors for years to an expert level, so I will get him to have a look at it once it's out, but he doesn't think it is something that can be fixed going by his assumptions of what kind of motor is used and the bearing seals involved etc. It does look like the other motor has been replaced at some point because it looks newer and it is also fixed a little further from the rear of the boat and a longer coupler has been used.

[ZZ56]

The motors look like standard 400 or 500 sized can motors and the good news is that replacing both of them is very cheap, and there are tons of stores that would have them.  You can try to fix them but sometimes it's not worth the time. 

The bushings might be worn because the short shaft wasn't properly supported and it 'whipped' side to side a bit as it turned.   I've never seen an assembly like this and i fear it was someone's cost-cutting idea.  I think the best thing to do now is to remove all the globs of sillicone in the hull and see what might come out.  If you can't take the bushing out by itself you might as well replace the shafts/stuffing tubes in one go.  If you can replace the bushing, you can reconnect the motors with lengths of sillicone fuel tubing which should make up for misalignment. 

Carp fishing is becoming more popular here in Canada, but the damage they do to reedbeds means we won't see any sort of stocking measures.  As it is now, i think you can take as many as you want from public waterways.

[Tombsy]

I think it was just a lot of wear to score the shaft and oval the bushings. Bearings or bushings would work if you find the size to fit. See if you can pop out one of the old ones and measure it.
If the motors still work and you get it sealed up you might get some more life out of it with out spending a ton.
Is it 6 volt or 12? I think the motors are probably easy to get, the scale boat guys would know more.
And if those are regular bronze bushings they are cheap cheap.
Here's 10 for under $3.00 for example.
http://www.rcboca.com/oilite-bushings-nitrov-10.html
I've seen some US versions of bait boats as well there are a few available now.
When I lived in Jasper Park we used to bank fish for some big rainbows up to 20 lbs, we would row our lines out 200 yards with night crawlers and mini marshmallows. One of these boats would have been great for dropping our lines.

[Ben123]

Thanks gents. It's a 12 volt single battery setup.

I'm going to try to remove the motor today and then try to work out how to get the seal setup out, which looks like it will be tricky. It's looks like it's been plastic welded into place so how to get that out I haven't a clue at the moment.

As for the motors, they look like the top one in the following listing - does that look about right?

http://www.cornwallmodelboats.co.uk/acatalog/standard_motors.html

[malcolmfrary]

As for the motors, they look like the top one in the following listing - does that look about right?

Unfortunately the link does not provide dimensions, but if you measure the case length, a 540 is 54mm long, a 380 is 38mm long. 400 series motors are renumbered 380s to avoid confusion(!!).
Mounting the motors by embedding them in something rubbery might not be just a cheap bodge (as in my case) but could be an attempt at keeping things quiet (my excuse).

[Ben123]

Thanks for that. As for the mounting method, well it may be done for a reason, but it's a hell of a job getting them out I can tell you. I can't prise the mount away from the hull due to lashings of plastic weld, and I can't get at the mounting screws because of the sides of the hull prventing getting a screwdriver on them.
Any suggestions for solving the above issue would be much appreciated.

[Ben123]

OK, so we've managed to get the motor out - here it is with the coupler and shaft reassembled - coupler pushes onto the motor spindle:

 

The seal arrangement doesn't seem to be like anything I've seen on forums/parts sites - I've tried to show it below - that's a screwdriver being poked through from outside :



It's basically about 15mm long and seems to be a kind of rubber sleeve that's pushes into the hole in the hull - the best way to describe what it appears to be is like one of these, with the base of the tee in this case up against the inside of the hull:



As was just about visible in an earlier picture from outside the hull, the rubber has a thread running through it - presumably this is wear which caused the leak but what caused it I don't know.

Any suggestions as to what kind of seal has been used, whether I should replace it like for like or do it another way etc etc would be much appreciated. Also how to ID the motor from the numbers on it, or do I just measure it as suggested above? EDIT - have measured it and it is 68mm long which doen't seem to correspond to any sizes I have found thus far. It's 12v.

BTW- the bronze looking part that can be seen in the other picture re: the seal arrangement, was just the thread in the coupler.

[malcolmfrary]

Some sizes and weights of Graupner motors here -
http://homepage.ntlworld.com/edward.matthews/ddmbc_files/motors/graupner.htm

The "thread" may have been caused by some foreign matter working its way in, but there appears to be some marking on the shaft, which might need a really good clean-up with wet&dry or similar.  After that its probably a case of building a new outer from brass or copper tube, after finding some thats a sliding fit.  Repacking the original with water repellent grease might do the job.