MV/HMNLS Macoma 1935/1942 by FreekS - 1:144 - 3D-print - RADIO

[FreekS]

Inspired by the beautiful liner/troopship made by @shipmodel I am embarking on a  similar project.

 

pre-Ww2 Royal Dutch Shell had built a series of oil tankers colloquially known as “Triple twelve” - they could carry 12000 tons of crude, cruise at 12 knots and use 12 tons of fuel a day. Some of these were operated by a subsidiary of Shell Netherlands, and some by a subsidiary of shell UK (shell was Dutch/English at the time).

 

 

These tankers transported oil to Uk during the war, and to provide air cover to convoys some of them were converted to MAC ships - aircraft carriers carrying three/four Swordfish biplanes on their deck. They seem not to have sunk any U-boats, but no convoy with a MAC ship attached appears to have lost any merchant ships either.

 

 

MV Macoma was built in 1935 (in a now long defunct shipyard in Amsterdam) and converted to MAC ships in 1944 in UK. Basically the deckhouses were cut off and a flight deck installed. The ships thus had no aircraft lifts or hangars, but retained their role as oil tankers while functioning as carrier. Macoma also retained her Dutch civilian crew and the air complement was made up by Dutch pilots from the Dutch Fleet Air Arm. Although the two Dutch converted ships (to my knowledge) were never referred to by “Hr. Ms.” (Her Majesties), they were in effect the first Dutch aircraft carriers. After the war they were converted back to tankers (to make it easy for modellers not exactly to the same configuration) and went back into Shell service.

 

Aim is to build Macoma at 1:144 scale (making her 1 meter long) and making her radio controlled.  Initially my plan was to build one hull with two decks, one for the tanker and one for the MAC-ship, but then the hull colour would not fit with both periods. So now I’m leaning towards having the port side MAC ship and the starboard side tanker (interesting stability issues foreseen).
 

The ship will be designed in Fusion360 and printed with PLA, which will need epoxy waterproofing. I’m not an expert in Fusion (of 3D printing) so it will be a nice learning. I have collected photos from the internet but have no plan of the ship. I’m thus going to have to construct the ship from photos, and some silhouettes. I have some plans from American “t2-tankers” from the same period which I’ll use for the hull lines. Also still a shortage of detail photos.

[KeithAug]

Sounds interesting and i'll be particularly interested in how you master 3D printing. I look forward to seeing progress.

[Jim Lad]

Tankers of that period have a beauty all their own.

 

If you build her "half and half", how will you handle the masts for the tanker half?

 

John

[FreekS]

Yes John, those masts worry me too - they will obstruct the view of the half flight deck. Also as they are on the centreline I’d have to halve the masts - tricky. Not solved that one yet!

 

Ive reviewed a bunch of Fusion 360 tutorials and build logs on making a hull - and it’s clearly very tricky. I’ll report on my efforts here but it won’t be an expert view! 
 

[Jim Lad]

Of course, you could just build two models! 😀

 

John

[realworkingsailor]

What about something like this:

 

 

Make one bottom hull that contains all the machinery and RC equipment. At the waterline, jog the outer “shell” inwards to allow an interchangeable upper hull to nest over top. Carrying the overlapped up to the deck line should mean that any water issues would be no different than any other RC ship. Then make two different tops, one aircraft carrier, one tanker.

 

Andy

[FreekS]

Andy, that’s sort of my plan too; one hull with all electrics. I can make several “decks”; tanker, carrier and half/half. 
given the size of the build and the size of my printer the hull and the decks will each be made from 5-6 parts. So I’ll need glue surfaces between them as well as some grams to maintain the hulls rigidity. For the  moment I’m planning to screw the hull and decks together, your solution could also work but with a 1 meter deck sliding over a 1 meter hull looks daunting.

 

I’m going to aim for the half half carrier tanker as that allows me to have the tanker hull have both peacetime colours as well as war time grey. Unfortunately these ships appear not to have had dazzle camouflage patterns!

[FreekS]

I started designing the hull. First, I imported three images I found; a side view  sketch of the tanker, a top view of the deckhouse arrangement and a rib-plan (from a US tanker). These can be scaled to 1:144 and placed on the three perpendicular planes as “canvases”. This allows me in Fusion360 to trace the main lines in the three dimensions.

the ribs were traced and placed in their location along the keel, the deck was made including the front to back and starboard to port curves using a “sweep” command. The hull itself is made by “lofting” from the keel surface to the deck along the ribs and the bow and stern lines.For that to work it is required that the ribs, bow and stern lines exactly touch the keel and deck edges. That is achieved by intersecting the rib plans on these two surfaces. 
All this took me days to find out - and I tended to forget exactly how I did it minutes after it worked. Luckily you can look back in the history of your project….

 

As the first level of the deckhouses in the bow, stern and midships follow the hull shape, I used for a deck the top of this level. Then I constructed the actual deck level and used that plane to cut out the hull including the first level of all three deckhouses.

Above a side view at this stage, superimposed on the scaled side view of the tanker. As the rib plans were traced from a poorish image, at this stage I spent some time changing the rib drawings until the hull appeared best. This is very powerful as you see the hull shape change instantly. Without actual Macoma plans this was the best I could do.

And here is the same hull body superimposed on the carrier side view. It fits both quite well.

 

The hull was now a solid body, and Fusion has a function to hollow it out from the top deck surface. This worked but made the program very slow for subsequent operations and its finicky and dependent on the hull shape and desired wall thickness. Much easier proved to delete the top deck from the solid body, converting it to a keel surface and two side surfaces. These can easily be “thickened” and joint again with much better results. 
Another few days of internet searches and discovery (and frustration) spent….

 

There are lots of helpful videos and forum posts on the topic of designing a hull including CAD. It’s quite time consuming and frustrating to a beginner, until one realises a non-engineer can now do in a few days what dozens of droughts-men used to do (better of course). It gave me the feeling that this kind of 3D design fits in our hobby - it’s detailed, fun, full of problem solving - and as you will see later does not reduce the amount of sanding and detail modelling needed for a nice result!

[thibaultron]

I save my work several times during a session upping the "Revision" number each time (i.e. File_011.f3d, File_002....). This allows me to both not loose the last X (mins, hours) time of work, if the computer or program hiccups, (or a cat jumps on my keyboard), or I think of a better way to do an operation. And Yes, I have some of my projects that have run into hundreds of revision files. I can always delete or Zip them when I finish.

 

Do not be afraid to go back and redo something, if you find new information/details during the design, or something you did does not print and fit like you thought.

[FreekS]

After the hull I designed the basic superstructure for both the tanker and the MAC ship. This is relatively straight forward, using basic Fusion functions.

 

Then I split the ships in two halves lengthwise and combined the tanker and carrier into one design. Here is where I think the concept will work for this ship - the half width deck still looks typical for a carrier and the tanker deckhouses are well recognisable. Have to decide how to paint the “cut” surfaces that would not be seen in the individual models and the masts of the tanker will still affect the overall view.

 

also at this stage I cut the three sets of model parts (hull, tanker superstructure carrier superstructure and carrier deck) into 5-6 parts each to fit the side of the printer, making sure there are big enough glue surfaces between them. Several bolt closures are included also. 
 

next is printing. At least to see if it all works.