Tug Forum

Specialist Types Of Tug Boat => Classic Diesel Tugs => : sea monkey September 27, 2017, 20:50:48

: 1960s Refinery Tug – Parahaki
: sea monkey September 27, 2017, 20:50:48
Well, I’ve had 6 months away from the bench and I’m definitely ready to start another project.

I still have a couple of tiny things to do to completely finish my USN YTL James O’Brien. Only the anchors and the deck rain awning framework – hopefully only a few hours, maybe a day in total.

And a few days work to finish the little Hikurangai. Small fiddly stuff but after so long away from the bench I need to psych myself up before I start on any fussy detail work. I’ll ease myself back into those 2 projects over the next few weeks.

So in the meantime I’ve started on a new build – another New Zealand tug, display only.
This time it is a 1960s refinery tug – the Parahaki from Whangarei, the northernmost port in New Zealand.

The Parahaki and an identical sister ship, the Ruamanga, were built for the Northland Harbour Board in 1963 to service the Marsden Point oil refinery. These 40m (131.5ft), 375 ton, diesel electric, 1500HP tugs were designed and built in the UK by Brooke’s of Lowestoft.

They are big – even at 1/50 I’ll have trouble convincing my wife that we have room for this big bugger.

While they don’t have particularly attractive lines, they are distinctive and look powerful and business like. It may be stretching the point to call them 'classics'. They were designed for handling large tankers, rescue work, and had some impressive firefighting equipment.

In 1997, after 34 years in Whangarei, they were sold, renamed Alfred Brown and Stanley Brown, and moved to the Cook Islands up in the Pacific.
In 2001 they were sold again, renamed Ralik and Ratak, and moved to the even more remote Marshall Islands.

: Re: 1960s Refinery Tug – Parahaki
: sea monkey September 27, 2017, 20:53:12
There is very little reference of either tug and this is everything I have, just a few photos. I contacted the present owners several times but no response.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey September 27, 2017, 20:53:40
There is a 1/32 model, built in the 60s, of the Parahaki in the Auckland Maritime Museum. It’s not a makers’ model but it is pretty good and that is what I’ll be basing my version on.
: Re: 1960s Refinery Tug – Parahaki
: 2tugboats September 29, 2017, 05:25:00
Nice collection of pictures for your build Sea Monkey. I find the "classic" lines refreshing and
as you said, ". . .they are distinctive and look powerful and business like." Thank you for
sharing here. . .made my day.

: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 01, 2017, 17:23:43
Some of you may have seen some of my previous builds and this one will follow pretty much the same same process.

All of my subjects are local NZ tugs and some don't have much reference material. This is one case in particular – all I have is 8 photos found online, and a series of photos of the old model in Auckland museum shot through glass, so not very good quality.

I started by drawing up the hull profile. I based this on the ST Cruiser with some alterations to the bow, stern and deck sheer. The Parahaki has a very large, single screw, steerable kort nozzle so the "cruiser' stern needed a bit of alteration.

Using the model photos for comparison, the 'Cruiser' deck wasn't too different so that only needed a few alterations too. I also added slots for the bulwark frames, really easy at this stage.

With the deck and the keel profile sorted out it was just a matter of figuring out the hull frames/ribs to make sure that the hull curves were as smooth as possible. Sounds good in theory!

The drawing took about 3 evenings on the Mac. The superstructure took about the same amount of time and takes quite a bit more intuitive thinking/guess work. I also figured out the heights and angles of all of the bulwark struts – much stronger this way, and simpler than trying to figure it out later.

I ganged up all of the hull components onto an 800 x 500mm sheet of 3.6mm ply, and the deck and superstructure pieces all onto a similar size sheet of 1mm birch ply.

: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 01, 2017, 17:25:05
Then I took the drawing files off to a laser cutting service and had both sheets cut out the following day. It may be cheating to use a laser but it's much more accurate than by hand and saves about 2 weeks work. Besides, I don't have a power saw capable of doing it.
: Re: 1960s Refinery Tug – Parahaki
: VANYA October 02, 2017, 01:30:41
Hi Steve,
Welcome back to NZ. 6 months away, bet you had a great time.

Another masterpiece in the making I see. They are both particularly inpressive and in the tradition of some of those classic British tugs from the 50/60's. Great stuff.

A long time ago I read in a report from the Northland Harbour Board that someone had built a 1/24th scale working model of the Parahiki. It was big as you can image at that scale.

I am coming up to Wellington on Friday. Might give you a call, have the wife though this time.

Hope to catch up.

: Re: 1960s Refinery Tug – Parahaki
: Kiwinz October 02, 2017, 02:05:30
Looking at the hull of your new build the old AUCKLANDER came to mind..of course both built in the UK.


: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 02, 2017, 12:23:26
Hayden – At 1/24 it would be over 1.6m – what a beast. I'll be here on Friday so give me a call if you have any spare time. Still trying to get used to this cold weather after 6 months of summer. So cold the other day that the resin wouldn't cure!

Simon – It does look a bit alike. I'd like to make an 'Aucklander' but reference is just as hard to get as it was for the Parahaki.
The real thing is still moored in Wellington as a floating restaurant but it has been altered so much it is barely recognisable these days.
A sad end to a great old boat. I think that Russell Ward may have some plans in amongst all of his stuff. I'll have to see if he can dig anything up.
: Re: 1960s Refinery Tug – Parahaki
: Kiwinz October 02, 2017, 19:56:23
Yes not the best end to a tugboat being eaten up as a floating restaurant! Still some of her lovely old lines showing. Imagine if she got back to Auckland..a new venture for Russell W maybe..


You better school Hayden up on CAD and laser cutters as I feel this is on the shopping list..maybe a 3D printer is not too far off either! It's been talked about here.

What was the situation with the OHAU cut outs? Still keen to work on that project too.

: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 03, 2017, 13:44:38
Got the Ohau files sitting here all done. At 1m length it works out to an 85mm prop.
I'll get them cut out of 9mm ply and give them to Hayden this weekend as he said he was coming up.
I can get the deck done as well if I can get hold of some 2mm ply.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 05, 2017, 12:37:18
OK, so it begins...

The laser cut pieces all appear OK. A quick scrub to remove any burn dust and they are all ready to go.
The keel section is in two pieces (so it could fit on an 800mm sheet) so they needed to be glued, and braced. I used some serious clamping and a good straight edge to keep everything in line.
Once that was set it was transferred to the trusty old construction jig. This holds the keel nice and straight while the rib frames are attached.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 05, 2017, 12:48:49
I've used this building method a few times and it certainly makes things quick and easy.
After an afternoon I had the rib/frames all in place and and securely braced. I had a hull warp at this stage a few years ago and it was a pain in the proverbial to fix so I'm paranoid about keeping everything straight and true.
Hence the oversized bracing blocks – they add strength and square things up.
This is a display only model so I can use as much interior bracing as I like.
The deck is crucial to the lining up of the frames. At this stage I use a square and a level at every step. An uneven deck is also a nightmare to fix – done that too – Doh!
: Re: 1960s Refinery Tug – Parahaki
: des October 05, 2017, 15:51:05
Hi Steve

I'm new at this hull-building stuff.  So can you explain what the Lego blocks are doing in the photos - I wouldn't have thought they'd have enough weight to be useful as alignment blocks.

: Re: 1960s Refinery Tug – Parahaki
: Kiwinz October 06, 2017, 02:12:58
More nice work Steve. Great boat building weather forecast this weekend..expect it finished by Monday! The return of LEGO blocks.

: Re: 1960s Refinery Tug – Parahaki
: model tugman October 06, 2017, 02:57:51
Very tidy work Steve , nice job matey.👍👍👍
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 06, 2017, 11:36:27
Thanks George – sorry I never made it to Bluewater. Family commitments every weekend while we were in the UK. I know where I would rather have been. Back next year hopefully, so I'll make sure I get some free Sundays.
Are you familiar with Brooke's of Lowestoft? Did all their boats look like this one?

Des – The Lego is glued onto the board and holds the keel in place and dead straight. I can easily lift the keel out and back in if I need to. I use them because: they are dead square, and we have a ton of them in cupboards around the house. When I'm planking the hull I clamp it deck side down to board again (on spacers). Seems to work for me. Did I mention I'm paranoid about getting a twist in the hull?

Simon – Yeah, a weekend of rain, and sanding in a confined space – bliss!
: Re: 1960s Refinery Tug – Parahaki
: model tugman October 06, 2017, 12:41:58
Hi Steve Brooke’s built some nice tugs over the years,,but I think that this design was spot on, now thinking along the lines of a 1/24th one.
I like your new design how about a set of drawings for me?
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 07, 2017, 17:55:24
Sure thing George, I'll see how the hull turns out and then adjust the drawings as needed, and send them over.

Russell Ward (Aucklander on this forum) is the 'go to' guy for any information about tugs in NZ. He has a lot of stuff on his website www.tugboats.co.nz and much more that isn't on the site yet. He's currently rebuilding the site and hopefully it will get bigger and bigger.

This is what he remembers of the Parahaki:

Ralph Trimmer was chairman of the Northland Harbour Board in the ‘60s. The NHB fleet was called Trimmer's Navy.
He was quite far sighted and things moved fast under him although there was a feeling that he was not quite straight. In those times there were great moves up there. The oil refinery, potential for the new glass works –lots of coastal stuff.
He got the two big Brooke tugs and several smaller line handling tugs as well as a fabulous, though a bit fugly, pilot boat Manaia built out of wood and nothing but the very best by Percy Vos in Auckland. Sad that her designer Alex Collings didn’t have any sort of eye and she sort of missed out on what she could have been. Look her up. She is usually on Trade Me for sale quite cheap –a lot of boat for the money. I watched her being build and was invited to her launch in c1964. With all the teak and fine timber, the shop smelled like my uncles cigar boxes. Just a fabulous ship
Word went round that she was built as a maritime board room for the lads and questions were raised.
The maritime salvage that they all envisaged, never happened on the coast and the tugs never paid their way.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 07, 2017, 18:02:30
Made a bit of progress over the past few evenings. Attached the uppermost section of the hull. This is the only flat section on the hull. This is 2mm ply. It's Hoop Pine which is very flexible but also very poor quality (very coarse grain) but I'm on a budget with this build so I'm using any scraps and off-cuts at hand. Unfortunately I've still got about 1/4 of a sheet of the stuff left over.

Also made some good progress packing out the hull with balsa blocks to give the planking some backing and more surface area for the glue. These were sanded down to the approximate curves that the planking will follow. The complex curves in these areas are always the most difficult to plank.

: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 07, 2017, 18:07:10
Hi to the 11 guests reading this at the moment.
Why not register and join in? New members are always welcome – and the first drink is on the house.

Back to the build – It all looks a bit rough at the moment but it will eventually all be hidden by the planking – and a lot of filler and primer.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 07, 2017, 18:09:41
This all went together without any drama but managed to use about $30 worth of CA glue up to this stage. Planking will probably use as much again.

After a light sanding of the frames it was ready to lay the first plank. I'm using 2mm balsa strips. Started in this spot for no particular reason. I can glue, pin and clamp one plank on each side of the hull at the same time. It takes about 20 minutes curing time before it's safe to remove the clamps so the whole planking process will take about a week of evenings.

This model doesn't need to be water tight so my planking is a bit amateurish. Purists look away.
Hopefully the end will justify the means.
: Re: 1960s Refinery Tug – Parahaki
: VANYA October 08, 2017, 13:43:37
Hi Steve. Can you give me a call on 021 346 306 today.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 12, 2017, 23:15:26
Well that wasn't too painful. Only took about 4 afternoons and evenings.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 12, 2017, 23:17:45
As soon as the planking had gotten to halfway up the sides I gave the inside a good coating of resin, with a little matting, to strengthen the lower section of the hull.
When all of the planking was done I gave the exterior another coat to fill any gaps and to soak into the balsa and stiffen everything up.
It looks a bit rough at the moment but lets wait and see how it looks after a few sessions of fill/sand/seal.
: Re: 1960s Refinery Tug – Parahaki
: model tugman October 13, 2017, 08:18:37
That is a very nice shaped hull Steve ,nice job so far.
: Re: 1960s Refinery Tug – Parahaki
: 2tugboats October 13, 2017, 08:29:30
An inspiration Steve. . .beautiful for sure.

: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 15, 2017, 11:21:14
Thanks George and Michael,

The hull shape hasn't turned out as well as I imagined. I had based it on the 'Cruiser' hull lines and it is much fuller/blunter in the bow area than the museum model. The museum boat also has a very nice 'pot belly'. I hadn't realised how much of a flatter curve my hull had until I got some white paint on it. Unfortunately that's all I can see at the moment and I'm too far down the track to start again. Hopefully in a couple of months I will have forgotten all about it but at the moment I'm losing interest in it. I had a similar problem a few years ago when I built a couple of ATBs and the first hull had gotten to final paint stage before being binned.

I can adjust the drawings to compensate but I'm not sure if I can psyche myself up to start from scratch again.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 15, 2017, 11:23:03
This is after the third set of fill, sand and seal.

Each new coat of undercoat only shows up more flaws that need too be fixed and it I don't seem to be be making much progress. I know what you're thinking: don't put any more coats on.

I'm down to the 240 grit sand paper now so I guess that is a good sign. Hopefully the in next few days I get to the wet & dry.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 15, 2017, 11:24:31
A couple more of the godforsaken thing.
: Re: 1960s Refinery Tug – Parahaki
: model tugman October 15, 2017, 11:56:54
That stern looks alovely shape to me, I think you have the bow a bit fine down on the forefoot that’s all.
Once you get some bulwarks on her the shape will look different again Steve, don’t give up matey.  Geo
: Re: 1960s Refinery Tug – Parahaki
: model tugman October 15, 2017, 12:03:28
You think you have problems , this is my latest one all 53” x 15” beam of her double diagonal planking 5” kort.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 15, 2017, 12:47:32
Thanks George.
That's a bit modern for you isn't it? What is it?
: Re: 1960s Refinery Tug – Parahaki
: Kiwinz October 15, 2017, 15:23:41
How about piling on some bog/filler and doing a sculpting..nose job on her? Might not be the usual way you build but worth bringing it out to the shape you really want and saving what is yet another great little project. Like George says her aft end is very pleasing to the eye!

Hey if all turns to pot how about making lots of dust and running it over a belt sanding down to the water line..would make a great waterline diorama model too Steve!

With your excellent technology skills could you not redesign a new bow end section and cut it in to what you already have down aft?

: Re: 1960s Refinery Tug – Parahaki
: model tugman October 15, 2017, 22:28:44
Hi Steve it’s just about in my time era 1972 built at Hong Kong Whampoa shipyard as Kau Lung, The Local firm J P Knight bought her home to the UK and named her Kendal.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 20, 2017, 17:29:59
George, I've taken your advice and started on the bulwarks. Hopefully when they are in place I won't be so fixated on the hull.
I'll make some adjustments to the bow and see how it looks.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 20, 2017, 17:32:33
The supports are slotted into pre-cut holes in the deck. This method is very fast and surprisingly strong.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 20, 2017, 17:33:59
The holes in the deck where the superstructure goes should make sense now.
: Re: 1960s Refinery Tug – Parahaki
: model tugman October 20, 2017, 23:17:15
I like the look of that hull Steve you are doing well.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 25, 2017, 12:36:42
There comes a time in all of my builds when I manage to break off the rudder footing – and this is the time.

No matter how careful I am it usually gets knocked off at some stage. This particular model has a very long and thin footing/heel and has been asking for it from day one. I've had several close calls but finally managed to snap it off yesterday.

Luckily it's a relatively clean break. I won't fix it just yet, I'll try and finish the hull a bit more before trying to re-attach the pieces. Maybe I should stick to twin screws or tugs with skegs.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 25, 2017, 13:17:58
Thanks George, a few sessions with 60 grit paper and a bit of filler and the bow is looking much more acceptable. I can probably live with it now.

Looks like you and I are the only ones building anything at the moment. If it wasn't for your prolific output the poor old forum would be pretty quiet.

Following George's advice I added the bulwarks and the re-worked bow doesn't look so bad. Not as nice as Ted Stanforth's 1968 model but it'll do. Back in those days the harbour boards were much easier to deal with and they probably gave him a set of plans. In the 90s I was making a model of the Kupe, a local harbour tug, and the harbour board gave me their original plans – and a ride around the harbour with my 5 year old son steering the Kupe. Don't get that sort of access these days.

So – the bulwarks have been attached: 1.5mm ply – Birch for the flat sections and the dreaded Hoop Pine for the curved bow and stern sections.

As with most of my previous builds I initially make a pattern by wrapping a sheet of paper around the bulwark supports and marking the top and bottom lines with a pencil. This paper pattern gets transferred to a cardboard version and this is checked for a good fit on the model. After a bit of adjustment the cardboard pattern is used to cut the final ply bulwarks. I only worry about the fit to the deck – Always leave excess at the top and sand that down to the level of the supports. It's easier than it sounds. Must remember to get some photos of the process next time and save on some typing.

Anyway,  After a lot of sanding down they turned out OK and I added the fender strip (basswood & styrene) and the hawser holes ( styrene tubing) and anchor wells (styrene).
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 25, 2017, 13:19:39
Still plenty of work to do...
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 25, 2017, 13:20:40
Some of the remedial work on the bow.
: Re: 1960s Refinery Tug – Parahaki
: model tugman October 25, 2017, 23:14:31
Looking really nice now Steve, a little faith in yourself and a tin of filler works wonders mate 😄😄😄😇😇😇😇😇😇😇😇.
Really nice clean work we don’t seem to get much on the forum at all nowadays, another forum that I watch is supposed to be model boats but you get all sorts of crap on it from health to motor bikes , perhaps that’s what people want rather than true to the Forum name.

: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 25, 2017, 23:21:26
Thanks mate.
Although if this was a real boat I wouldn't go in it – shonky builder.
Still seem to be plenty of guests tuning in. Two looking at this at the moment. So there seems to be interest, maybe we've just struck a quiet period for building. Might kick off when the weather at your end packs up for the winter. Maybe some of the guest viewers would like to register and make some comments – I could do with a few tips.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 29, 2017, 15:53:02
Now that all of the heavy duty work on the hull has been finished, I can start adding a few details: starting with the fairleads and fender housing.

The fairlead are basically a piece of styrene tubing with some styrene rivets around the outside. when sanded down and primed they will look fine.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 29, 2017, 15:59:47
The fender housing/brackets are strip styrene with styrene rod 'bolts'.
The fenders went on quite easily and the housing took less time than I had imagined.
Also added the grates (brass rod) in the freeing ports/scuppers and a panel running above them on the inside of the bulwarks to hide any messy glueing and the ends of the grate rods.
: Re: 1960s Refinery Tug – Parahaki
: model tugman October 29, 2017, 23:26:55
Nice Steve 👍👍👍👍
: Re: 1960s Refinery Tug – Parahaki
: 2tugboats October 30, 2017, 07:26:28
Thank you Steve for your priceless sharing. Your work is a healthy portion of inspiration. I have found countless ideas for building one's tug from your pictures. For example, if I had know of your way of laying out port holes, I could have made mine that little bit more to look like a super clean job of it.

I have experienced, with building a large tug model, that being top heavy was my most huge mistake. Looking over your superior workmanship, I'm sure you will do fine in that consern.

Your contribution to the Forum here is huge and outstanding. There is a lull in the Forum participation of late and your sharing is what makes this place glow with tugboat spirit and hope for a person's build.

A pleasure to watch your building Steve, Michael
: Re: 1960s Refinery Tug – Parahaki
: VANYA October 30, 2017, 19:13:51
Hi Steve.

Have you got that webcam in yet?

I visited the patent slipway just down below your house when I was up in Wellington. It's a great spot.

Looking good!

There is a bit of scale activity at our model boat club so thinking the SeaTow 25 and barge might be needed. Will get out those frames.

I guess we can scale up the drawings to cut a bigger one too.Maybe Simon and I should hop in the Cessna and fly up for a hull drawing CAD tutorial with you.


: Re: 1960s Refinery Tug – Parahaki
: tugnut October 30, 2017, 23:13:05
Hi Steve.very interesting build great job.
regards John b.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 31, 2017, 10:33:30
Thanks George, John and Michael.

Hayden – Hasn't been a ship in the slip for about 20 years but it had plenty of use in its day.
It looked pretty impressive with a big boat in there. In the 1960s the flying boat station was in the bay opposite, a ferry came to the head of the bay, and plenty of tug activity at the fuel depot on the other side of the bay so it would have been a very interesting spot. Only the fuel depot left now and the tugs are in and out in less than an hour. Although they always race each other back to town. Those Damens can get up a fair speed when needed – gives any little yachts a nice bow wave to deal with.

The Koranui drawing will scale up easily. My previous laser guy has moved to the Wairarapa and I'm using a new outfit in the Hutt. Much cheaper and they also have a big router. Simon's Ohau in 9mm poplar ply should be no problem on their laser. A bit slower on the router – and no 90Ί inner angles. I need to drop out a sample for them to experiment on.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 31, 2017, 10:40:37
Back at the bench things have been progressing well. I've repaired the snapped off skeg and attached the shaft support struts. This all went together better than I had imagined – I love it when that happens.
The keg now has a 2mm brass rod pinning it together and is pretty solid. The struts are a sandwich of styrene/brass strip,styrene. The aren't going anywhere – touchwood!
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 31, 2017, 10:52:36
The hull has now had about 8 sessions of fill/sand/seal and that's about as far as I'll go. I'm happy with the surface.
The stern curves look OK and I've come to terms with the reshaped bow. Not much more to add to the hull exterior other than the Kort nozzle, and that's 2 weeks away (hopefully).
: Re: 1960s Refinery Tug – Parahaki
: model tugman October 31, 2017, 10:58:59
Nice !👍👍👍
: Re: 1960s Refinery Tug – Parahaki
: sea monkey October 31, 2017, 11:13:31
Final job was to attach the rolling chocks/bilge keels. These are styrene with brass pins through the hull.
I hate these things – they are asking to be snapped off. Luckily they don't sit anywhere near the cradle/stand.
The 240 grit sandpaper has now been replaced with 600 wet&dry, the hull's as smooth as a baby's bum and it's now ready for some paint. This is when things can go horribly wrong.
: Re: 1960s Refinery Tug – Parahaki
: model tugman October 31, 2017, 14:11:06
It is a lovely looking hull matey, twice the size and working would be awesome.
: Re: 1960s Refinery Tug – Parahaki
: VANYA October 31, 2017, 14:20:06

I would be keen on a scaled up SeaTow tug, something around 30-36 inches. She is big displacement but has room for big motors.

Have a go if you like and we will get the whole lot down.

Your newbuild is looking fine.


: Re: 1960s Refinery Tug – Parahaki
: sea monkey November 05, 2017, 13:44:28
Hayden – enlarging the Seatow to double the size you have takes it up to 1080mm LOA, which works out to 40mm prop size. We could gang it up with the Ohau on a full sheet of 9mm Poplar.
I'll get a cost for the ply and the laser cutting.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey November 05, 2017, 13:58:21
While I'm waiting for the Kort nozzle to arrive I made a start on the superstructure.

The laser cut parts slotted together fairly easily although the curves at the bow end put quite a strain on the ply. I probably should have cut those pieces at 90Ί to the grain of the ply. The Birch ply is not very flexible so it needed quite a bit of glue, internal bracing and some serious clamping to keep it all square and true.

Still at the early stages but you can get the idea.

: Re: 1960s Refinery Tug – Parahaki
: sea monkey November 05, 2017, 14:02:57
At this stage I've also found another major error on my part. I had drawn up the plan for the deck and superstructure footprint from several photos I took at the Auckland Museum. That were taken from directly above the model and when drawing up the plans I hadn't taken into account the amount of distortion or fisheye that my camera gave the image. Subsequently when I measured the width of upper deck I got an incorrect measure. The whole superstructure is about 10mm too wide. It still fits but any deckhand would have to hold his breath when he tried to walk past the front of the superstructure. The gap to the bulwark is only 1m in scale. Better luck next time!
: Re: 1960s Refinery Tug – Parahaki
: model tugman November 05, 2017, 14:20:42
That looks a complicated structure Steve, very nice, but it is only 5mm too wide each side, there now that doesn’t sound so bad does it?  Geo.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey November 06, 2017, 21:16:19
Ha ha, if you put it like that, it's not much more than my usual margin of error – a mere gnat's.

: Re: 1960s Refinery Tug – Parahaki
: sea monkey November 06, 2017, 21:24:14
Shapeways came through with the the goods very quickly. Eight days from placing the order, printed in New York to delivery in New Zealand. Not bad. Let's see if PPD Etching in Scotland can match that for the brass etched components.

Image No 1 shows the initial drawing with dimensions.

Image 2 is a screen shot from the 3D stl file

Hey presto! 8 days later.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey November 06, 2017, 21:30:50
I had this part printed in strong, white and flexible as Kort nozzles are easy to knock around.

It is surprisingly strong – the nozzle wall is only 1.5mm thick but this material does show the striations from the painting process.

Printing in finer detail material would have doubled the cost.

Hopefully a few coats of paint will flatten a few of those layers – it doesn't handle sanding too well. The last time I had something similar printed (some ASD units) the looked the same and didn't look too bad after throwing on some paint.
: Re: 1960s Refinery Tug – Parahaki
: VANYA November 07, 2017, 12:56:16

Those nozzles are real tug bling! Nice they are.

I made some out of fibreglass resin then lathed them up.Also heavy gauge steel machined and silver soldered would be equally as nice for working models.

Looking good.

: Re: 1960s Refinery Tug – Parahaki
: mengam November 14, 2017, 09:43:43

Your Kort nozzle have a strange shape, it's normaly a cylinder inside, conical outside with a torus for the inlet and like a blade as trailing edge

Your conical nozzle as oulet is a typical counter intuive shape for a boat. It's possible for air propeller as compressible fluid but inapropriate for the not compressible water.

With your shape you decrease the bollard pull of your tug without any profit.

Around 2002 have seen this twice tugs at Noumιa New Caledonia, I have to search in my pictures (prior digital pics) I'm sure to have some details pics.




: Re: 1960s Refinery Tug – Parahaki
: sea monkey November 14, 2017, 12:29:20
I agree, it is an unusual shape.
As I don't have any plans or images of the boat out of water I am basing below the waterline on the model at Auckland Maritime Museum. Their model is pretty accurate and was made in the tug's home port a few years after it began working there. In those days the harbour boards were quite generous about sharing plans so I'm assuming that the model is correct.
These photos of the model are a bit blurry but you can see the rear tapering of the nozzle.
They could be wrong, maybe? The nozzle doesn't look like it would have much of a turning arc either.

: Re: 1960s Refinery Tug – Parahaki
: des November 14, 2017, 19:57:47
I was looking into the shape for a Kort nozzle, and found this - check it out

http://www.propellerpages.com/?c=nozzles (http://www.propellerpages.com/?c=nozzles)

I didn't realise until a couple of days ago that there are different nozzle shapes intended for tugs (which need to develop thrust both forward and in reverse) and for others such as trawlers, AHTS / PSVs etc (which primarily need most thrust forward).

There is also a newer design, the Rice nozzle, which delivers higher thrust and better fuel consumption than either Kort shape.

: Re: 1960s Refinery Tug – Parahaki
: sea monkey November 15, 2017, 11:41:51
I'm pretty sure the shape of Parahaki's nozzle is right.
Mengam rightly points out that you can't compress water – although all Kort nozzles have a very slight taper that 'focuses' the flow into a 'directed' stream. The forward opening in always slightly wider than the rear. Often this is just in the 'wing' shape of the nozzle wall.

back at the bench – a bit of paint always helps...
I've added a skirting around the base to hide any gaps between the deck and the bulkheads. Still need to add a few more basic details such as a gutter strip around the edge of the upper decks and some trim around the top edges of the bridge. Then on to the fiddly bits.
No bridge details on this one – it would have all been guesswork and tinted glazing will make any interior details redundant.
: Re: 1960s Refinery Tug – Parahaki
: sea monkey November 15, 2017, 11:42:37
And, yes, to any eagle eyed viewers. The rear 4 port holes on the port side don't have surrounds – they will be covered by hatches.
: Re: 1960s Refinery Tug – Parahaki
: model tugman November 15, 2017, 23:54:08
Lovely work matey , looking good.
: Re: 1960s Refinery Tug – Parahaki
: VANYA November 16, 2017, 01:26:08

You really need to build the Aorangi. 

It would be most impressive and after seeing the details you build into the models it would look brilliant. Only you can do it this well and at this scale.

She is 86 feet long.

: Re: 1960s Refinery Tug – Parahaki
: mengam November 17, 2017, 05:31:41

The outside shape of this nozzle is up to the model, maybe correct maybe not, this conical section only at the end maybe for structural or industrial reason ...

Anyway for the inside shape it's hundred percent not correct.

It's a fault for a marine engineer to built a nozzle with smaller diameter at the outlet than at the propeller place

With an outside like this, the interior shoud be like that

(http://nsa39.casimages.com/img/2017/11/17/171117015339129764.jpg) (http://www.casimages.com/i/171117015339129764.jpg.html)

Then as the propeller must be at the nozzle rotation axis - you will have a problem with the leading edge of the inside rudder during rotation of the nozzle up to the regular max at 35°

As promised : the two sisters at Noumιa in 2004 

(http://nsa39.casimages.com/img/2017/11/17/171117022602298298.jpg) (http://www.casimages.com/i/171117022602298298.jpg.html)

(http://nsa39.casimages.com/img/2017/11/17/171117022602490924.jpg) (http://www.casimages.com/i/171117022602490924.jpg.html)

(http://nsa39.casimages.com/img/2017/11/17/171117022602738293.jpg) (http://www.casimages.com/i/171117022602738293.jpg.html)

It's a pity as most of the time I also take detail pictures of the aft deck (like spy in relation with my job ...)  but that time as they looked more like bohemians traveling with trailers on the deck I didn't !