Steam tug Edna G of 1896 1:32

[smonsma]

This will be a build log for a scratch build of a live-steam driven R/C model of the steel tugboat Edna G, commisioned by the Duluth & Iron Range railroad for service at their ore docks in Two Harbors, MN.
Starting from lines and drawings from the builder, Cleveland Shipbuilding, from 1895-1896 but aided by measurements and historic/current photos- she still floats in Two Harbors as a museum ship!

 

[smonsma]

I think it will need several sections, so I’m putting this as an index of sorts:

• Plans
• Hull construction
• Power plant
  • Graham TVR1ABB twin cylinder
  • MACC horizontal boiler
  • boiler feed pump and motor
  • Throttle/reverser
  • Steam throttle
  • Whistle
• Electronics and accessories
  • Reciever
  • Battery
  • Servos
  • Relays
• Decking
• Deck houses and pilot house
• The eagle

Here are a couple more pictures from the era I want: With eagle, one whistle, rubbing strakes, square windows, small lifeboat & slender davits, fire monitor in front of pilot house, original smaller stack…

 

[smonsma]

Plans
I was assisted in getting reproductions of the 1896 plans by Tom Koehler of the Friends of the Edna G, and the Historical Collection of the Great Lakes at Bowling Green State University (https://greatlakes.bgsu.edu/item/436894) - reproduced from the records of the Cleveland Shipbuilding Co. for Hull 25. With not too much finagling, the lines drawings were combined into one big graphic, and then cut up into the different planes to use as background images in Fusion and in Affinity Designer.
There was some discrepancy in the forward station lines - total width versus the aft station lines so I upscaled by a few percent horizontally since the front and back of the centerline should be equal width. In the 2d tracings in AD, I then inset what will be laser cut lines for the bulkheads by 1/16" to account for the hull thickness- debating if this should be made as a mold master, from which to pull an exterior mold with plate lines/rivet detail added so as to make an all fiberglass hull, or pull the planked hull off the forms and seal/fiberglass that. Versus going full Fusion and trying to 3d model the hull, then print in PLA and seal that... not sure how well that would work out in the long run, versus the wood approach.

 

[smonsma]

My so called 1/8" MDF arrived today thanks to the Amazon stork, so of course I had to try laser cutting the first test... and it was not happy. Two passes at the suggested power/speed didn't even cut through it (possibly a dirty/smoky lens, have to clean that- I have an Emblaser 2 with upgraded laser diode). But worse, I neglected to account for the laser kerf, and didn't measure the MDF. Turns out, it's only 0.116" thick and I'm losing 0.010" to the kerf, so the slots are way too big. Back to the drawing board to adjust all the slots down, and try a test cut again before going too far down that track!

 

[Namabiiru]

Got my chair and drink.

 

[smonsma]

I tightened up the notches on the bulkheads, and decided to keep the center frame notches slightly looser, so I have a little play for the bulkheads fore/aft. Heres the center section about ready for gluing and lapping the joints with some scrap. Cutting the third of 5 bulkhead sheets now

 

[smonsma]

The notches along the base of the center section are for 1/4” guides to be glued on the board for making sure the bulheads are perpendicular to the keel. In theory at least! Looks like some filing will be needed here, too. I’ll use some shorter bits between the bulkheads for the fore/aft center section - gotta do a home center run now!

 

[smonsma]

All the cutting is done, now for cleanup and build board prep.

 

[smonsma]

Had a false start using that plastic veneered fake wood shelf as a building board- it was more warped than I expected, and the woodglue popped right off! Thank goodness for the isopropanol trick for softening wood glue, I had to adjust a misplaced frame about 6 hours after gluing! Got a proper oak multipiece (composite? made from smaller sections of oak glued up) board that I’d used prevously for another hull, nice and thick with minimal distortion. Got the main frame pieces glued together, and in the process of adding 90 degree guides for the bulkheads.

 

[smonsma]

Time for a decision and input is welcome! Along the lines of @JerryTodd’s Constellation (https://shipsofscale.com/sosforums/...ar-c-1856-in-1-36-scale-for-r-c-sailing.1679/), I am unsure whether to plank a fairly standard hull that can be glassed and lifted off the frame, or attempt (for the first time) to make it as a plug, then make fiberglass master that can pull off and used as a mold for a fiberglass-only hull.
Gluing the bulkheads is done, it probably needs some fairing and possibly edge bevelling before going further.
Thoughts?

 

[MThomas]

Well, to turn that into a plug will require tons of work. You will need to turn what you currently have into something solid and smooth as glass, 'after' you first spend umpteen hours filling in the spaces between formers... faring, hardening and effectively sealing everything to perfection. If there is any 'tumblehome' involved in the shape of the hull, even the teeniest bit via by design, or by mistake you will have to split the plug/hull into two separate plugs otherwise the glass shell will not release from the plug without destroying the plug and all the work that went into it! In all honesty, if it were me, I'd simply plank it, glass it, sand it then paint it! Plugs take a lot of work and are only truly useful if you want to manufacture a lot of hulls. Too much work involved to make a plug for a simple 'one-off' model.
Just 'my' personal opinion...

 

[smonsma]

Thanks MThomas for opening my eyes! I can see a problem already looming- there is a bulge to accomodate the prop shaft just forward of the rudder- which will prevent lifting the hull off the form if built in at this stage…
Looks like I might need to cut those off the bulkheads before planking.

 

[Roger Pellett]

That last picture where Edna G is getting her stern worked on was taken in the Duluth Harbor and the work is being done by Duluth’s Marine Iron and Shipbuilding Company.

Marine Iron as it was locally known was owned by Duluth’s Meierhoff family. It existed into the late 1980’s. I worked for another company owned by a member of this same family. Although long since retired he and I regularly meet for lunch.

Roger

 

[smonsma]

I realized I havent posted in a while, so here is an update on the planking with 1/16” x 1/4” basswood. The stern gave me trouble with trying to form 1/32 sheet wood and plywood, so I resorted to brass sheet with balsa fill. Not sure how well it’ll work in the end, I’m avoiding taking photos of it

 

[smonsma]

Filling and sanding, filling and sanding… The CA holding the garboard plank to the aluminum keel has popped off repeatedly. I want to apply a penetrating epoxy sealer before lifting it off the forms but then I think I’ll need to rough up the aluminum more and use an inside epoxy filler/fillet to really make it stick.