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Author Topic: 1970s Diesel Harbour Tug RANGI  (Read 10100 times)

Steve Mahoney

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1970s Diesel Harbour Tug RANGI
« on: April 08, 2016, 08:59:22 AM »

At this time of year we are officially 7 weeks into Autumn but this year weíve had a record breaking summer and the extended spell of great weather has distracted me from my latest project. It has started to cool down a little over the past week so Iíve spent a bit of time back at the bench.
I had decided to build a 1/50 model of the Karetai, a 1970s diesel harbour tug from Otago, here in New Zealand. It is 28.6m LOA and is quite nice looking boat. There are several very nice models of this tug around the country so I thought that Iíd give it a go too. Not a motored version this time, just something to gather dust on the shelf. Any viewers from Otago feel free to offer any advice.
In 1974 the Otago Harbour Board ordered 2 identical tugs, designed by Eken & Doherty in Sydney and built by Sims in Dunedin, Otago. They are hydroconic hulls with twin ASD drives and have very clean lines and uncluttered deck/superstructure areas. My last build was a hard working ocean going tug that was cram packed full of equipment and this build has no winch and very little deck gear Ė yahoo!
The Rangi was built first and then the Karetai was delivered in 1976. They served Otago until being sold off to Australia a couple of years ago.
Although they were supposed to be identical, some design flaws were ironed out in the second build and there were some minor cosmetic differences. Apparently one engineer was a stickler for cleanliness and his boat was kept in showroom condition while the other had a slightly rougher life. Rangi had the design flaws and Iím betting that it also had the scruffy appearance. When I was young describing something as Ďa bit rangií was a very derogatory term for poorly made or maintained, shonky or shoddy. The first stages of my build were Ďa bit rangií too.
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Steve Mahoney

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #1 on: April 08, 2016, 09:03:29 AM »

The developers of the hydroconic hulls were very protective of their designs and didnít let any hull drawings out of their control. Now days these type of hulls are all over the place but back then it was all new technology so not many hull plans are floating about.
I managed to find some reasonable drawings of the Karetai, drew up the hull and had the parts laser cut out of 3.6mm ply. Those were my first 2 mistakes.
The ply I used I had picked up on special a few years ago (canít resist a bargain) and it is hopeless: too flexible, very coarse grained, splinters and split easily, and warps in the slightest sunlight.
The original drawings I had found were not accurate, probably on purpose so that no competitor could use them. It didnít become apparent until I started sheathing the hull Ė some of the curves were very clunky and the hull just didnít look right with bulges and bad angles. After a few days it also developed quite a warp/twist and it took some serious clamps and about 500ml of resin to straighten it out again.
Then the crappy ply really came into its own and the hull needed about 7-8 rounds of filler/sanding/undercoat/repeat to even start to get smooth enough. Quite satisfying going at it with 60 grit, things smooth out pretty quick then.
So much for saving a dollar on the ply! Unfortunately I still have 1/2 a full sheet of ply left so Iíll probably go through this all again sometime.
Thatís when I realised that I must be making the Rangi instead of the Karetai so the subject was changed 2 weeks into the build.
I was too embarrassed to photograph the hull construction (it was sloppy workmanship) so in the next post Iíll jump ahead a couple of weeks to a slightly smoother, straighter, cleaner hull.
The first 2 images are Day 1 just before it all hit the fan.
Bottom image is stage 1 of the hull straightening, with half of the fibreglass bracing that went into it.
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Steve Mahoney

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #2 on: April 17, 2016, 12:06:08 PM »


After much filling and sanding I finally got the basic hull to a stage that I was happy with
Still plenty of imperfections on the hull finish but nothing a little more filler and some 800 grit won't sort out.Fitted the bulwarks and made a basic error at the stern. Had to re-fit the stern bulwark, there's plenty of filler in there but luckily the fender housing hides most of the mistake.
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Brian60

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #3 on: April 17, 2016, 02:00:47 PM »

Someone else with a laser cutter :-)) I'm liking the lines of this build from the start, also the minimising of waste material by cutting out the bulwark supports from the part of the deck to be cut away. I look forward to your next update.

Steve Mahoney

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #4 on: April 19, 2016, 10:41:21 PM »

Thanks Brian. No I don't have a laser cutter. I could never swing that past the wife. The house would constantly smell of burnt ply.
There are several firms that provide a cutting service in my town and to get all of the hull and superstructure components cut out only costs about $50 (20 quid). Saves tons of time, super accurate and I get plenty of spares.
Managed to get a few solid afternoons at the bench over the last few days and have got the hull to 95% finished.
Cut out the scuppers, added the cap rail, fender housing, bracing on the bulwarks (not sure what they are called) and hawser holes (not sure what they are called either).
And yes, the forward bulwark braces are supposed to be further apart than the aft ones.
The ply template is the base for the superstructure.
Only a few blemished left to correct and then onto the wet & dry!
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Brian60

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #5 on: April 20, 2016, 07:39:17 AM »

Sometimes I think its a good thing not to own your own laser, I've found I spend more time at the computer designing stuff on Coreldraw than actually modelling!

Your build is coming on great and the finish you have got on that hull makes it look superb, look forward to the start of the superstructure.

Steve Mahoney

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #6 on: April 24, 2016, 11:41:09 AM »

Managed to get the hull finished, undercoated, wet & dry polished as smooth as a baby's bum, and prepped for painting.Added some anodising plates although I guessed at their placement as the only photos i have seen of the boat out of the water are when it was being repainted and the plates had been removed.
Also added some details to the hull.
I had brass etched some fender tie loops. They are 2 separate pieces Ė the hull plate and an eye that slots into it and through the hull ply.
Worked out OK. I attached the bases for the bow and stern fender straps.
Don't worry about the rough finish inside the fender housing, it will be hidden by the rubber fender.
And scribed out the outline of the ASD hull section. The ASD plate has rounded corners in a square cut hole in the hull.
You'll never get to see these lines but at least I'll know that they are there.
Now ready for the paint job.
Over the years the 2 tugs have had several colour schemes. The hulls have always been mid blue and the superstructure white but the decks have been pale grey, pale blue, light blue and the same blue as the hull. The bulwarks have been white, hull blue, pale blue and light blue.
The funnels have been white, hull blue, dark blue and yellow.
Plenty of options to choose from. I'm tending towards pale blue decks and bulwarks (yes, that happened) and yellow stack.
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Steve Mahoney

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #7 on: May 03, 2016, 12:34:02 AM »

This next part Ė the ASD drives, was quite easy. I thought that I might have a try at 3D printing so I drew up the drives and tried to convert them into a 3D modelling program. That's harder than it sounds unless you're a tech savvy teenager. The initial 2D drawing was easy, knocked it out in Indesign in about 20 minutes. After much trial and tribulation battling with a 3D program (another battle lost in my continual struggle Ė man versus machine) I eventually sent it to a 3D specialist and he cranked it out in about 20 minutes.
Then off to Shapeways. For a test run I chose strong, white and flexible, hit 'print' and waited. Nothing turned up for 3 months, apparently it was lost in transit somewhere in Brussels. The help team at shape ways where very helpful and re-printed the file, however for some reason the file kept hitting a print error and failing and the final stages of printing. After a minor file adjustment and a change to polished, strong, white and flexible, the finished products arrived. 2 weeks from ordering to delivery in New Zealand Ė not bad. The finish is a bit rougher than I had anticipated and the material doesn't handle sanding too well. I've read that you can smooth out the material by washing it in acetone. Acetone will melt ABS pretty quickly so I'm not really game to try it on something expensive.
Getting the props printed at the same time was quite cost effective. Getting 2 brass props sent from Europe would have cost 4 times as much as the total cost of printing both drives and props.
Still, not bad for a first attempt, and nothing that can't be fixed with a few extra layers of paint.
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Steve Mahoney

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #8 on: May 03, 2016, 12:36:26 AM »

I hadn't been able to find any pictures of the ASD drives on the actual boats before I made them, and as is always the way, the day after the drives arrived from Shapeways someone sent me a great photo of the Karetai in dry dock, with the drives in full view. Damn! I had made my main shafts cylindrical while the real ones are much more elliptical and only have 2 fixing points. They are almost like small rudders or vanes in front of the drives.
But if I hadn't just told you no-one would ever know. I'm sticking with my cylindrical versions as I can't really afford or be bothered reprinting them. Better luck next time.
After a few coats of undercoat and some extra layers of top coat they look OK. The props even spin freely. I'm satisfied with the result and know how to improve next time.
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Antipodes

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #9 on: May 03, 2016, 02:49:40 AM »

Nice job!!  :-)) :-))
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Re: 1970s Diesel Harbour Tug RANGI
« Reply #10 on: May 03, 2016, 04:51:47 AM »

Great work Steve, it looks great.
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Brian60

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #11 on: May 03, 2016, 08:16:37 AM »

They look fantastic with paint on. A bit rough looking in the raw plastic. I'd never thought of having them 3D printed, I might have to draw one up and give it a try myself, my next project has an azimuthing (360 degree turn) kort nozzle and prop. The fly in the ointment for me though is that it also has to retract into the hull.

She is coming on famously man, but I've just realised with those props/housings does this mean she is a static model?

Steve Mahoney

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #12 on: May 03, 2016, 09:53:53 PM »

Thanks boys. Yes, Brian, this one is just for gathering dust. What have you got in mind for your ASD drives?
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Brian60

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #13 on: May 04, 2016, 06:12:30 PM »

Well it has two main drives in Korts at the stern. Two tunnel thrusters at the stern, two tunnel thrusters at the bow and then the retractable azimuth thruster used for station keeping. I'm hoping to get them all working along with a daughter boat launched from a 'garage' in the stern and a working ROV - I did say HOPING :}

I won't give the name away just yet as it was only launched last year and has only been on active service for 9 months. :-))

Steve Mahoney

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #14 on: May 05, 2016, 01:24:39 AM »

In the end I decided to go for the mid blue decks and bulwarks. The OHB didn't use this scheme for long and it tends to camouflage the vents and deck equipment but that's how it is in several of the photos I have. So now the basic hull is completed and I can move on to the superstructure. The bow bull's eye isn't attached yet, just there for the photo. I'll leave the deck equipment and fendering till later and I always leave applying the hull markings and name until the very last thing Ė sort of signing it all off.  Plenty to do before then.
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Steve Mahoney

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #15 on: May 05, 2016, 01:25:59 AM »

... a couple more.The flash has made the deck colour appear yellower than it is. The colour in the previous post is correct.The deck will have another few coats of clear satin once the deck equipment is installed.
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Steve Mahoney

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #16 on: May 05, 2016, 01:28:33 AM »

And finally, a question for any Otago boys out there. What are these?Is it a valve of some sort behind the door? The only photos I have all have the door open and obscuring whatever it is. And what is the safety valve/cut off towards the stern and what would the text around it say?
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derekwarner

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #17 on: May 05, 2016, 03:46:48 AM »

Steve....the AFT lever system will be a fire damper...on the stern vertical face of the engine house casing will be a pair of louvers which allow external air to be drawn into the engine room for both combustion and ventilation

In the event of an engine room fire, the dampers are closed so to inhibit fresh air [oxygen] from fuelling the fire....you may find that the handle lever is cross pivoted athwart ship on one shaft so to be operated on either the port or stdb side

Words such as Air Damper - Open - Closed would be a good bet  O0

Not really sure what the handle/lever behind the door is...would be specific to the vessel, however is certainly of questionable design  >>:-( with respect to access when the door is open %% ............. Derek
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Brian60

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #18 on: May 05, 2016, 08:18:46 AM »

The quality going into this build is superb you are doing a grand job Steve.

Antipodean

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #19 on: May 05, 2016, 02:05:54 PM »

The one behind the door looks like it has a hose or cable leading down away from it. Unfortunately I couldn't clean the picture up enough when I enlarged it to see what it actually is. If you look closely there is a similar hose or cable at the front of the superstructure next to the hatches.
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Antipodes

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #20 on: May 05, 2016, 10:06:34 PM »

Go to the source.....

"Good morning

The object behind the closed door is the shore power cable connection to the inlet supply on the cross alleyway at the top of the access way to the Engine room on the port side of the tug Karetai

On the Rangi and Karetai this was only on the port side of the vessel.  The electrical meter was positioned on the port side of the E/R cross alleyway

The other small lever at the aft end indicated in red is the lever for remote shut off of the fuel supply valves from the daily service tank to the main engine and generators.  This was a lever system connected to wire rope and through a pulley system to the trip block on the fuel supply valve.  -  There was a lever on each side of the vessel in this position.  Ie Ė Port side shut off the Port Main Engine and on the starboard side similarly shut off the starboard Main Engine and Generator.

The writing is Ė Fuel shut off valves or Fuel Trips Ė Open and closed are indicated.

Hope this clears this up.

Regards

Hugh M

Hugh Marshall
Chief Pilot
Port Otago Limited, 15 Beach St, PO Box 8, Port Chalmers, New Zealand"
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Steve Mahoney

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #21 on: May 05, 2016, 10:43:59 PM »

You beauty, Hugh!
Thanks, Steve


Go the mighty Hurricanes!
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Steve Mahoney

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #22 on: May 14, 2016, 10:23:39 PM »


I'm sure I'll be asking Antipodes a lot more questions as I only have limited reference of the boats.
In the meantime I've been making slow progress. The hull is pretty much completed and I'm happy with the paint job, only a couple of minor touch-ups required.
Now onto the superstructure.
I had the basic form laser cut and in theory it should have slotted together smoothly and quickly. In fact it took ages and quite a bit of interior bracing. I used ply 50% thicker than probably needed and had had it cut with the grain running the wrong way Ė it's 3 ply so bends better one way than the other. Getting it to comply to the curves required lots of cross bracing to bend around. I think I ended up with as much glue on me as on the wood and some serious clamping action. Once constructed I was able to cut out some of the excess bracing.
Here are the basic carcasses.
I can never resist putting the pieces together to see what it will eventually look like.
Still plenty to do and it looks pretty rough at the moment but you get the idea.
... and yes, I will have to cut out a section of the wheelhouse ceiling to glaze the windows. I didn't think of that one beforehand Ė Doh!
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Steve Mahoney

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #23 on: May 16, 2016, 10:06:38 PM »


Had some time over the weekend and managed to give the build a good crack and added the lip to the top deck, some of the etched brass stairs, hand rails and deck plates/covers to the superstructure. Also cleaned up the surfaces and got a couple of layers of undercoat and filler applied.
At this stage I realised that the plans I had were not 'as built' and that the portholes were not in the same position port and starboard. A bit more filler and drilling new holes but I really should pay more attention to the reference photos.
Skinned the funnel carcass with styrene and added the exhaust vents. I couldn't get the 0.5mm styrene to bend smoothly to form the curved front section of the funnel so it is made up of 3 layers of 0.2mm styrene. Worked out OK and is very solid.
I had expected the guttering on the wheelhouse roof to be quite difficult but it went on really easily. Glad I decided to add it, could easily have left it off. The wonders of CA glue! Couldn't do without it.
Still a way to go but it's starting to look the part now and there seem to be fewer blemishes after each session.
One more round of filler/sanding/undercoat and it'll be about ready for a topcoat. Fingers crossed.
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Steve Mahoney

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Re: 1970s Diesel Harbour Tug RANGI
« Reply #24 on: May 30, 2016, 01:32:28 AM »

Slow progress on the build at the moment. Making lots of fiddly little bits that seem to take ages. Spoke too soon about the easy installation of the guttering. Took most of a weekend to install the window frames. Made a real hash of it and had to start again several times. Took the best part of another day to make the 2 engine room vents. Got a box full of completed hatches, vents and doors.
[/size]I've assembled the funnel/mast and added the very small life raft rack and radar/running light brackets. Just about ready for last undercoat and topcoats.[/size]The roof is not installed yet as that needs to be painted the same blue as the deck. Too hard to mask up when attached to the funnel and wheelhouse.Also, the downpipes from the guttering won't go on until later.Trying to dodge making a decision about fitting out the interior.
Still need to make the lights, searchlights, radar and safety equipment.Only major bits left to make are the anchor windlass and railings. No idea what the anchor windlass looks like as every photo I have shows it covered with a tarpaulin so I'll have to decide whether to make a best guess or get some more research. The real boat now works out of Australia and the owners where quite helpful at the drawing up stage but I don't really want to hassle them anymore so might be a 'close enough' scenario.
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