Model Boat Mayhem

The Shipyard ( Dry Dock ): Builds & Questions => Seaport Tugs => Topic started by: StuartL on November 14, 2013, 11:37:16 am

Title: My turn...
Post by: StuartL on November 14, 2013, 11:37:16 am
Phase 1 complete...
Title: Re: My turn...
Post by: john44 on November 14, 2013, 01:53:19 pm
Hi StuartL, my mate has just bought a Seaport in view of converting it
so your build should prove very interesting.

john
Title: Re: My turn...
Post by: HawkEye on November 14, 2013, 08:00:18 pm

Go for it ! , they're a lot of fun   :-))
Title: Re: My turn...
Post by: DocPL on November 14, 2013, 08:37:43 pm
Go go go - you will have fun with it.
How did you disconnect the cardan ? Was it easy ?
Title: Re: My turn...
Post by: StuartL on November 14, 2013, 08:50:50 pm
How did you disconnect the cardan ? Was it easy ?

I've never heard it called a cardan before.  I removed the motor first (four screws and cut the wires) and the plastic dog bone separated with minimal persuasion.

I had more of a problem with the prop shaft itself.  There's minimal clearance around the prop and the Kort for removal and I can't convince my prop shaft to separate from the hex drive to the prop itself.  I unscrewed the prop retention screw and the rudder mechanism to allow the Kort to move more freely and wiggled the prop free from the shaft.  The forward end of the prop shaft is a knurled push fit into the drive cup and a screwdriver levered the drive cup off the prop shaft pretty easily.  Once the drive cup was removed the prop shaft came clear pretty easily.  The rest of the mechanics mostly came off with a screwdriver but the ballast tank required a Dremel.  I used a cutting disc to remove the bulk of it, a sanding wheel to bring it back to the hull and a polishing wheel to smooth the surface.  Impatience meant I overheated the polishing wheel, hence the discolouration around the ballast tank, but I'm not worried about it at all.  It's smooth enough to bond to and all the discolouration is internal.

I've done a lot more today and will post an update tomorrow with photos.
Title: Re: My turn...
Post by: DocPL on November 15, 2013, 10:44:17 am
Thanks for quick answer. I used "cardan" thinking about coupling between engine and prop shaft (it looks cardan like). As far as I remember engine shaft is 2.3mm - correct ? How about prop shaft diameter ?
Title: Re: My turn...
Post by: StuartL on November 15, 2013, 11:23:03 am
Thanks for quick answer. I used "cardan" thinking about coupling between engine and prop shaft (it looks cardan like). As far as I remember engine shaft is 2.3mm - correct ? How about prop shaft diameter ?

Motor shaft is 2.26mm and shaft is 3.74mm.  Note that a 4mm prop shaft is tight and my replacement shaft (details in an update later) needed quite a lot of shaving to be loose enough to not overheat.
Title: Re: My turn...
Post by: Martin [Admin] on November 15, 2013, 12:45:44 pm
 
Doesn't "cardan" usually refer to 'double couplings?

(https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcR8-BiCQa8TcTKBOOiClwoHFJxPNuNnX8nruECgMIKdgA82O_z0)
Title: Re: My turn...
Post by: Circlip on November 15, 2013, 01:14:19 pm
  cardan joint/ˈkɑr(http://static.sfdict.com/dictstatic/dictionary/graphics/luna/thinsp.png)dæn/  [kahr-dan]    noun  Machinery . a universal joint consisting of a crosslike piece, opposite ends of which rotate within the forked end of each of the two shafts connected.
 
 
      Regards  Ian
Title: Re: My turn...
Post by: Martin [Admin] on November 15, 2013, 01:24:20 pm
 
Ahhhhh!
Title: Re: My turn...
Post by: StuartL on November 21, 2013, 05:32:24 pm
There's been a dearth of updates although there's been a lot of progress.  I've kept some of it quiet for now since there's still work to do.

For now a teaser, please forgive the colour of the photo.  It was taken on a phone camera in a badly lit living room.  Bonus points for identifying the part in the centre of the deck.

Title: Re: My turn...
Post by: Netleyned on November 21, 2013, 05:38:10 pm
If you mean the centre of the aft deck it's the
drain hole. Otherwise I can't see owt {-)

Ned
Title: Re: My turn...
Post by: StuartL on November 21, 2013, 05:42:06 pm
How about the massive hole in the aft deck, just astern of the superstructure? :)
Title: Re: My turn...
Post by: Netleyned on November 21, 2013, 05:57:09 pm
Crew's swimming pool?

Ned
Title: Re: My turn...
Post by: StuartL on November 21, 2013, 05:58:50 pm
Nah, it's for something else.  What I was getting as is where the plastic had come from.  Looking at the pic it's probably not obvious so I'll save that for later...

Title: Re: My turn...
Post by: StuartL on November 24, 2013, 10:06:05 am
All the mechanics are together, 1.2kg of rocks from the garden in as ballast, and it's time for the first 'sea' trial at Eastrop Park.
Title: Re: My turn...
Post by: tugboat pete on December 07, 2013, 07:31:11 pm
 :-)) Nice job you have done on that seaport tug mate hope all goes well with the water test my jenny is running very well will be putting some deck fittings on and a new 3 amp battery for the spring so best regards TUGBOAT PETE YAAAARG
Title: Re: My turn...
Post by: StuartL on December 09, 2013, 10:33:00 am
Well, it's been a few weeks without updates here.  Unfortunately little has happened due to family issues but I can post the updates from the result of the sea trial...

Bath tub needed about 1200g of weight to get the water-line right but that was WAY too much for the boating lake.  About 650g worked out ok but I had a big stability issue with waves.  Some of the fellow boaters said about moving the weight up to the waterline, rather than at the bottom of the keel.  I'm not sure about the physics of this, it seems counter-intuitive, but it's easy enough to try later.

The winch worked well but the modified servo was too sensitive.  The slightest radio interference or nudge on the stick caused the winch to slowly pay out rope, requiring repeated stick movements to keep it in check.  I'll probably throw together a simple digital on-off speed controller or see if I can find a cheap speed controller online which has a wider dead-band.  I can wire this speed controller directly to the servo motor, bypassing the servo electronics.

The boat as pictured above is bare wooden boarding and this is how I ran it in the sea trial.  The boards expanded in the humid air and a couple of them popped off.  I always intended to varnish the deck so I dried the boat on a radiator and applied the varnish.  Unfortunately the absorption of the varnish has the same effect and I'm now in a quandry as to how to deal with it.  I may rip the deck off and start again, I may not.

I've also been working on the superstructure but because it's rebuilt from the original structure and some plant pots I've been unhappy with the finish.  I've been round many sand/fill cycles and still am not happy.

More updates to come later, for now it's on the window-sill in the conservatory awaiting some time :)