SS Stephen Hopkins by schooner - FINISHED - BlueJacket Shipcrafters - Liberty Ship

[schooner]

Hull shaping

 

When I first read through the directions I was surprised to see that the bulwarks were attached before the hull was sanded - I thought they would be fragile and would complicate the hull shaping but I pressed the “believe” button and went with the kit’s building sequence - I’m glad I did. Trying to add them after shaping the hull would have led to inevitable “knuckles” at the joint, requiring even more sanding and they probably would still have not looked right. By adding them first they are treated as an integral part of the hull and after sanding they are fair with the hull. The design and depth of the rabbet also makes for a very secure joint so I have no more worries about them.

 

The sanding to shape of the hull is going relatively quick and easily, mainly because of the simple shape of the hull (bluff bows with no flair, slab sides amidships).  Here's an example of how the templates are used to check the shape of the hull:

 

At this point the forward 75% of the hull has been shaped and rough sanded, the stern area is next and will probably take as much time as the rest of the hull combined because of its shape and the need to thin it.

This basswood sands very easily yet keeps an edge, nice stuff to work with.

 

Edited July 16, 2016 by schooner

[dgbot]

Your bulwark looks to be opening up from the hull or is that an effect from the camera?

David B

[schooner]

David,

It's neither. The bulwarks fit tight, inboard and outboard and are flush to the hull. I think what you are referring to is that the bulwarks are made out of 5-layer (very thin layer) plywood and as I sanded the outboard sides some areas had to give up more wood than others so what you see is the 2nd, and in some areas, the 3rd layer (they alternate between light and dark wood for some reason.)  When I prime them the bulwarks will appear as part of the hull without seams. Any variations in the bulwark thickness will be hidden by cap rails which i intend to install, both for accuracy and to provide more drilling/glueing surface for the 100+ pad eyes and eyes that will sit on them along most of its length.

Edited July 16, 2016 by schooner

[schooner]

The hull bottom

 

This is the 4th solid hull kit I’ve worked on and the first where I have had to give any thought to the bottom of the hull. With “traditional” hulls you shape the sides, which extend to the keel. Any discrepancies between the main deck to keel height on the plans and what comes out of the box is usually taken care of by taking some wood off the main deck (i.e. lowering it), although I have never had to do that.

 

In the  hull design of the Liberty ships the bottom of the hull is really a separate, distinct area. For most of the length the hull is a box shape with vertical sides and a flat bottom. After shaping the sides I was not happy with the  curve of the hull between the bottom and sides - it should be a very small radius curve, basically a 90-degree angle that is rounded. The rough hull in the kit has a much larger radius curve, leaving a gap at the corner of the templates.

 

There are only 2 options to address that; take more off of the sides or off the bottom. The sides cannot be reduced anymore without affecting the dimensions of the main deck or inaccurately slanting the sides toward the keel - they would no longer be perpendicular. So the answer was to take wood off the bottom. To find out how much I had to play with I compared the keel to bulwark measurements with the plans (something I should have done earlier) and found that the my hull was 3/16 to 1/4 inch too tall. Obviously the hull was machined to allow for this - I just didn't think to check it.  Taking off that amount of wood would solve 3 issues: it would reduce the radius of the turn of the bilge, it would make the hull match the plans and it would fix a problem with the bottom - it should be dead flat from the foot of the stem to the tip of the rudder rest but as you can see below mine had a rise towards the stern:

After several boring hours running a hand-held sander back and forth across the bottom everything fell into place. The curve at the turn of the bilge is good, the hull height matches the plans and the keel is flat.

 

Next will be shaping the stern area, priming the hull and then resanding to remove rough spots and low areas (like the ones you can see in the photo above).

Edited July 21, 2016 by schooner

[schooner]

Hull shaping done

 

I’ve finished the initial shaping the hull using the templates (adjustments may be needed based on what the primer shows). Some minor file and hobby knife work remains to be done around the rudder post and shaft housing to make sure the prop and rudder fit OK. 

The first smooth sanding is done, now it’s a matter of priming and resanding, repeated as needed to get a smooth “steel” finish.

Edited July 18, 2016 by schooner

[Red]

Hi Tim,

That looks really neat.

Looking forward to seeing more.

Regards

Red

[dgbot]

I have seen some models where sheet styrene was used to simulate the plating.  Once applied and painted they came out great.

David B

[schooner]

Red- thanks for the kind words.

David B - I thought about adding plating with aluminum tape ( the thickness of sheet styrene would be over scale) but after playing with it on scrap wood I've decided not to. 90% of it looked OK but there were enough problems (wrinkles, uneven edges, etc) that I had no doubt I would have ended up stripping it all off. I've got a good, smooth finish on the hull and I'm just going to go with that.

[schooner]

Underwater stuff

 

The first item to add is the Paravane Chain Bracket to foot of the stem. The kit provides a nice piece of laser cut ply for the bracket:

 

After cutting a thin slot in the stem with a razor saw it slides into place:

 

The bilge keels are next. They are first cut to length, then the ends are shaped and finally both sides are sanded to bring the outboard edge to a knife-edge:

 

The slots are marked on the hull using the drawings. These are fairly straight with almost no rise at the ends, probably because with this hull shape and an 11 knot top speed these ships did not throw much of a bow wave. The slots were cut with a hobby knife and deepened and widened with a narrow file:

 

The starboard bilge keel in place prior to touching up with filler and primer:

 

Next up will be fabricating the rudder and prop shaft.

Edited July 21, 2016 by schooner

[dgbot]

Tim Evergreen Plastics has thin sheet that might work

http://evergreenscalemodels.com/Sheets.htm

 

Plastruct also has very thin sheets as well.

http://plastruct.com/

 

David B

[schooner]

Thanks for the links David but I've decided not to plate the hull, I might try it sometime on a smaller, and less expensive kit.
Tim

[schooner]

Running Gear

 

The Liberty Ships had a style of rudder that I have not seen before. It’s basically 2 airfoil shapes stacked on top of each other, the top one would give thrust to port and the bottom to starboard. The only reason for this that I can think of is that the relatively crude prop would have more side thrust than more complicated (and expensive) ones would so this was an attempt to reduce wear on the rudder bearings. 

 

Here’s mine. For those who may build the kit I recommend using.20 wire drilled into the rudder , covered by 1/16 tubing above it. The 3/32 stock recommended in the kit is too big after the rudder has been shaped.

Drilling a 1/8 inch hole into the thin after section was a little intimidating, I started with a 1/16 bit and worked my way up.

 

After the shaft opening was drilled it was time to finish the final shaping of the hull in that area:

Here’s the final product ( the prop and rudder are off plumb because they are not glued in place, I’ll glue them near the end of the build to save them from getting wacked.) The eye pads above the prop are scratch, you can see the real things in the first 2 pix above.

The anchors were easy to add. At this point the hull “outside the lifelines” is done except for painting.

[captainbob]

The prop rudder area looks great. What is the white filler you used to shape those curves?

 

Bob

[schooner]

Bob, for small areas I use Elmers Carpenters Color Change Wood Filler. It dries quick and sands easier than Bondo. For larger areas, or where I need more than minimal thickness, or where adhesion to the wood is an issue (like on a thin or pointed areas) I'll use Bondo.

Tim

Edited July 23, 2016 by schooner

[Roger Pellett]

Bob,

 

The kinked rudder is an example of what naval architects call a contraguide propeller, more specifically a contraguide rudder. The swirling wash coming from a rotating propeller contains kinetic energy. With the propeller operating in open water such as with a twin screw ship this kinetic energy is lost as eventually the water slows down to match that of its surroundings. This energy is then lost.

 

When this propeller wash is interrupted by an appendage such as the rudder of a single screw ship the flow is affected and some of this kinetic energy is transferred to the ship. In the case is of a single screw ship the rudder captures some of this energy by straightening this flow.

 

It therefore stands to reason that if the rudder is twisted in a direction opposite to the rotation of the propeller it will be even more effective at straightening this flow and will recapture even more of this lost energy. This "twisted" rudder is therefore an energy saving device.

 

Given the fact that Liberty ships were supposed to be simple easily built and expendable, it is surprising that they built with this feature. I wonder if the contraguide rudder on the Jeramiah O'brian was added later in her life. Since you are meticulously building a model of a very early Liberty, you might want to see hi she was built with one of these rudders. Your book with all of the design memos might tell you this.

 

Roger Pellett

Edited July 23, 2016 by Roger Pellett

[schooner]

Thanks Roger! That is some great info.

Although I spent most of my working life at sea I've never seen anything like that rudder. I suspected that the liberty ships had to make do with relatively simple, and cheap propellers since the shops capable of making more complex ones would have been monopolized by the Navy. The Liberty props don't look all that advanced over what John Ericsson would have used.

Thanks again for an informative post

Tim

[jud]

The horizontal column of water coming from the props of old freighters is not spinning, it does have a boiling appearance, the props turn through stationary water and compress it aft, hence the boil. Also the liberty ship was not a new design, the hull  was a design that was at sea when the war started and had been there for some years. Accommodation were shifted for the crew to occupy the passenger spaces amidships. The crew members and Officers lived and ate in the amidships structure and the Navy Gun Crews were accommodated under the aft 5" gun. Ships were needed and this type would serve the need if there were enough and there were already plans, specifications and the teething problems had been worked through except for the rivet to a welded method of construction which did need some refining. If in fact the top and bottom of the rudder was offset as shown in the photo, 'I believe the photo is of a failed slip joint in the rudder post ', in practice would have more to do with the loaded ships draft as opposed to an empty one. Ever watch a lightly loaded freighter go by with half the prop in the air? Offsetting the rudder would cause drag when speed was a life saving part of life at sea in those times, running with brakes on, slows you down and places extra and useless stress on the rudder gear, Not buying into the idea that offset rudder halves was the norm.

jud.

Edited July 24, 2016 by jud

[Roger Pellett]

Nope, the offset rudder is an intentional design feature called a contravene rudder. It is a form of contravene propeller, a term described in the SNAME glossary of maritime terms. Any water behind the propeller moving faster than the undisturbed water surrounding the ship contains kinetic energy and in addition to steering the ship this rudder's job is to maximize recovery of this kinetic energy by straightening the flow.

 

A photo of the American Victory in dry dock shows this same rudder feature. This photo was published in the NRJ several years ago.

 

In PN Thomas's British Tramps, Volume I general arrangement drawings of Liberty ships do not indicate this feature. In fact the Liberty's British predessor appears to have a single plate rudder. Thomas also says that a number of Liberty ship rudders failed and the rudder was redesigned late in the war. So the American Liberty's rudders were redesigned. The question is whether this feature was incorporated when the Americans revised the British design or was it added when the rudders were revised late in the war.

 

Roger Pellett

[schooner]

As to when this rudder design was adopted, this pix shows the Liberty F.A.C. Muhlenberg with a contravene rudder prior to her June 1942 launching which was just two months after the Hopkins' launching so I think it's probable the Hopkins had one too. 

I always like to learn something new.

Tim

 

Edited July 24, 2016 by schooner

[schooner]

Start of the Deckhouse

 

I’m going to depart from the kit’s build sequence a bit. The next step in the instructions is to install about 100 triangular bulwark braces around the outside of the main deck. I’m going to hold off on that until I’ve fabricated the deckhouses and crane houses because of the need to place sandpaper on the deck and then rub the house bottoms on it to get a good fit with the deck. Given the limited clearance between the bulwarks I’m sure I would end up breaking off a lot of the braces.

 

The Main Deckhouse is made of up 3 levels. Each level in turn is a stack of 3 laser cut wooden pieces and a thin plastic top deck. The bottom wood piece is a framework so that the amount of surface area that has to be sanded to match the deck underneath it is minimized. The top wood piece is a 1/16 inch sheet that is sanded to form a camber, its center staying 1/16 thick and the outer edges sanded to nothing. Here’s what 1 set looks like:

 

Here’s all 12 pieces dry fitted in a stack:

Edited July 24, 2016 by schooner

[Roger Pellett]

Learning something new whether a new technique or more about the vessel that you are modeling is what makes this hobby so fascinating.

 

Roger

[Elijah]

Nice start on the deck house! I look forward to seeing more!

[RGL]

Great build, it must weight a ton with all that wood!

[schooner]

Thanks for the kind words Elijah and Greg,

 

It certainly weighs more than any plastic, resin, or even a POF or POB model, enough that I don't feel comfortable mounting it on pedestals since the leverage with that weight might loosen them up pretty quickly so I'll mount it on keel blocks (not sure how many yet).

Tim

[RGL]

Lots I reckon!

[schooner]

More of the Deckhouse

 

After glueing up the lifts it was time to add the thin laser cut facing pieces. 

 

While test fitting them it quickly became apparent that the superstructure was taller than the facing pieces, as confirmed by the plans. The facing pieces are the correct height but the lifts are too tall, about 6mm total when all are stacked. After removing 1.5 - 2 mm from each level everything fit together.

 

 

One of the odd features of the liberty ships was what looked to be concrete slabs around the pilot house and gun tubs like you can see here:

 

 

 

While visiting the SS John Brown I learned that it is not concrete but a British invention called Plastic Armour which is really just road paving material like asphalt. You can read about it here if you are interested:

 

https://en.wikipedia.org/wiki/Plastic_armour

 

As you can see in this pix it varied in its appearance even on the same ship; the nearest slab is smooth, the ones next to it rougher and the slabs protecting the gun tub in the background look like a sloppy job of adding foam insulation:

 

 

I decided to add it to my model. I cut thin wood to shape, drilled out the porthole lights larger than the portholes for the distinctive “stepped” look. I then sprayed them with primer and while it was still wet pressed them into some fine sawdust. A few more coats of spray primer reduced the fine granularity.

 

 

 

I then used the non-working end of a drill bit to press down to create the discs that worked like upholstery buttons to hold the armor in place:

 

 

Here’s the finished product (Additional airbrush coats of the final color will reduce the granularity even more):

 

 

Next up will be adding the gun tubs and some more detailing that is easier done before the deckhouse is mounted on the hull. 

Edited August 1, 2016 by schooner

[CDW]

So glad to have found your build thread and will be following from now on. Beautiful model indeed.

[captainbob]

I never would have thought of paint and sawdust, but it looks great.

 

Bob

[schooner]

Welcome aboard daddy rabbit, your Scharnhorst looks to be a great build although seeing that PE bender brought back some disturbing memories from my last build (it was an Orange Hobby kit - a ton of unbelievably small and complicated PE)

 

 

Bob, thanks for the compliment. I tried textured spray paint that has worked well for me before but it just didn't work this time and since I've no shortage of sawdust with this build I thought I'd give it a try.

[CDW]

Tim

 

Liberty ships are very interesting to me.

My uncle served with the US Navy as a gunner aboard a liberty ship during WW2. He is dead and gone now, but he once told me a lot about his tour of duty at my mother's request. Even after so many years had passed, he had a very difficult time talking about the combat. It was harrowing. He was with a convoy of scores of ships going through the North Atlantic headed to Murmansk. It was supposed to be safe as the allies had gained air superiority and many U-boats had been destroyed. Despite all that, they were ambushed by German Ju-88 torpedo bombers. Most of the convoy was lost/sunk. Their captain was experienced enough to take advantage of fog and disappear into it until the attack was over. I wish I had written down and/or recorded what he had to say. As they say, hindsight is 20-20.

Yes, the 1/350 photo etch is a little too difficult for me to see as well as I would like. 

 

PS: I built but did not completely finish a 1:350 Trumpeter Liberty Ship. Your photos in this thread will encourage me to finish mine. Your photos show detail I did not have access to when I was building mine and I gave up trying to figure out all the little details including all the rigging.

Edited August 1, 2016 by daddyrabbit1954