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Author Topic: Model Slipway Al Khubar - a couple of questions  (Read 619 times)

clockworks

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Model Slipway Al Khubar - a couple of questions
« on: August 29, 2020, 10:59:52 am »

I've just bought a secondhand Al Khubar, getting it ready to try on the lake tomorrow, but it failed the bathtub test while sorting out the ballast.
There's about half a cupful of water in the hull after sitting in the bath for a couple of hours.


The water appears to be getting up the propshaft tubes. I thought I would just take the shafts out and re-grease them, but I can't.


The boat is fitted with two Torpedo 500 motors with 2.5:1 gearboxes. The motor mounts are screwed to wooden blocks, and I can't access 3 of the screws because the deck gets in the way.


It has fixed Kort nozzles, with the rudders about 5mm behind the boss at the centre of the prop, so very little clearance. The props aren't fitted with locknuts, and I can't get the shaft out of the prop - I guess they are glued on. I can't remove the rudders to slide the shaft out along with the prop, because the bottom of the rudder shaft fits into a fixed skeg. It looks like everything is stuck together with epoxy and car body filler.


So, I can't remove the motor or coupling, or the prop, or the rudder without some drastic surgery.


To top it all, there's quite a bit of axial play in both propshaft bearings. The bearings are black plastic rather than bronze/brass, and the threaded part of the shaft goes inside the bearings - looks like the shaft is a bit too short, or the tube a bit too long. I'm guessing that this has worn the bearings out, and no amount of greasing will stop the water getting in. The bearings should run on the unthreaded part of the shaft, but they don't.  No thrust washers fitted either - the prop is touching the bearing at one end, the coupling locknut is touching at the other end.


I think I'm going to have to remove everything, fit new shafts, etc - unless anyone has a better idea?


Does anyone have the build instructions for the Model Slipway Al Khubar, so I can see how the Korts, skegs and rudders go together? It'll make life easier dismantling everything if I can see where the various parts are glued together, it's a bit of a mess with glue, paint and filler covering everything.


Also, is it possible to remove the gearbox from a Torpedo 500, so that I can unscrew the motor from the mounting bracket? As I said, I just can't get a screwdriver onto the woodscrews that fix the bracket onto the wooden blocks that are fixed to the hull.


Looks like whoever built this boat didn't give any thought to taking the running gear out for maintenance.....
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derekwarner

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Re: Model Slipway Al Khubar - a couple of questions
« Reply #1 on: August 29, 2020, 11:15:34 am »

Well clockworks, your safety plan of the bathroom test proved great value  :-))


You have clearly stated quite a number of issues, and it would suggest as you note ...that  "drastic surgery" ...we term this as "Refit Modifications", may be required

There are a number of Al Khubar builds here, however every one is a little different so photographs of the areas in question with your model would help experienced builders to offer assistance


Derek
« Last Edit: August 29, 2020, 11:26:00 am by derekwarner »
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Derek Warner

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justboatonic

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clockworks

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Re: Model Slipway Al Khubar - a couple of questions
« Reply #3 on: August 29, 2020, 12:15:49 pm »

For some reason, I can't "upload images".  I get a pop-up window asking me to sign in (despite already being signed in), and it rejects my username and my email. If I try and reset my password, it tells me that my username and email don't exist!


I've got that exact flexible screwdriver. Unfortunately it's not flexible enough to work where these screws are positioned. I've tried an angled/cranked screwdriver too, but there's not enough clearance to actually turn it. They are phillips head woodscrews.
I think whoever built it must have fitted the running gear before gluing the decks on.

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Colin Bishop

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Re: Model Slipway Al Khubar - a couple of questions
« Reply #4 on: August 29, 2020, 12:22:56 pm »

Those offset screwdrivers look useful. I have ordered a set.

This site shows the model clearly. The writer removed the lower skeg mounting, presumably to allow the rudders to be removed and the shafts extracted. If you could do that then it might be possible to fit new bearings in the tube to avoid major surgery.

http://www.alansboats.co.uk/flatbild.html

Edit: My post clashed with Dav'e below. Thinking along the same lines...

Colin
« Last Edit: August 29, 2020, 12:30:35 pm by Colin Bishop »
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DaveM

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Re: Model Slipway Al Khubar - a couple of questions
« Reply #5 on: August 29, 2020, 12:24:21 pm »

It's a while since I built my Al Khubar and the instructions were hand-drawn rather than with CAD, so I've no copies which I can refer to. However your best option - or least worst -  might be to grab the rudder shafts with someting like a mole-grip and see if you can twist off the rudders. They were probably epoxied onto the plain shafts and may be removable with a bit of grunt. You can then slide out the props and shafts to get at the bearings etc. When reassembling the rudders to the shafts you might consider the modification which I incorporated when building it - the attached sketch shows this. The shafts and tubes used would have been from SHG.
BTW it is possible to take the gearboxes off the motors but you need to slide the red pastic shrouds off to access the screws.
Dave M
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clockworks

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Re: Model Slipway Al Khubar - a couple of questions
« Reply #6 on: August 29, 2020, 12:39:22 pm »

I've built a couple of boats myself that were designed to have fixed skegs. In both cases, I made the skegs removable. I've also made sure to fit motors and servos where they are easily removable at a later date, or fitted an extra hatch in the deck if necessary.


All that extra work and thinking time to spot potential future problems is probably why my builds seem to take so long, lol.


I like the idea of cutting collets into the rudders. Just need to get it all apart first.




Regarding image uploads, I found a post that says you have to create an image upload account first. i've tried doing that, but I don't get the activation email. Checked my spam folder using BT's webmail, as well as my normal Apple Mail.
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justboatonic

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Re: Model Slipway Al Khubar - a couple of questions
« Reply #7 on: August 29, 2020, 01:23:19 pm »


Regarding image uploads, I found a post that says you have to create an image upload account first. i've tried doing that, but I don't get the activation email. Checked my spam folder using BT's webmail, as well as my normal Apple Mail.
Try logging out of mayhem, clear your cache and reboot your device. Then log into Mayhem again and try reloading pics. Im not sure about this image account but if you still cannot access it, you'll have to ask the site admin to investigate and maybe rest your credentials.
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tonyH

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Re: Model Slipway Al Khubar - a couple of questions
« Reply #8 on: August 29, 2020, 01:45:19 pm »

What's the diameter of the prop tube? If it's a standard one you may be able to put a slimline tube/shaft through it after, of course, you've shifted the rudder? :-))
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clockworks

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Re: Model Slipway Al Khubar - a couple of questions
« Reply #9 on: August 29, 2020, 03:31:42 pm »

I'll measure the tube, and see if I can get a new one that'll fit inside - good idea.


Still no luck with the "image upload". How do I contact admin on this site?

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clockworks

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Re: Model Slipway Al Khubar - a couple of questions
« Reply #10 on: September 05, 2020, 04:17:02 pm »

Still can't get image upload to work, and still haven't figured out how to contact site admin...... HELP
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