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Old Dec 13, 2008, 01:30 PM
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RingTheBellsThatStillCanR ing
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Build Log

Y T L - 7 1 0


A new project! We're going to get a new 45' Navy YTL (= 45' Army ST) tug! (I figure if the Navy owned it, it's a warship...).

YTL-710 is the tug that Tom Hershey modeled and described in the November 1987 Scale Ship Modeler-- "The Navy's Cutest Tug". I've only found specific evidence on the Web of three 45' YTL's in the Navy...709/710/711. I'd like to find more, but there seems to be enough photographs available of 710 to document her condition at least in the mid-80's. So that's good enough for me!

And we've seen another one of these before-- see RMAY's thread:
https://www.rcgroups.com/forums/showthread.php?t=666749
Last edited by patmat2350; May 11, 2009 at 07:27 PM.
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Old Dec 13, 2008, 01:42 PM
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cute
Old Dec 13, 2008, 02:04 PM
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Where to start? Well, if you'd like to build off a nice fiberglass hull, there are several available from Microglass up to 1:16 scale.

I think we're going to need a bigger bathtub...
But this one will be a tad larger... more on that later! But a scratchbuilt hull will be needed. And where better to start than a set of original builder's drawings from Paddlewheels & Props? ("Diesel Harbor Tug").

Note that such drawings do not show how to build a model! But there is nothing like original drawings to work from to get your details right.

My first step is to ignore the drawn hull lines and sections... yes, many just photocopy/enlarge/reduce these to use directly as templates to make frames... but I want to get the geometry in CAD where I can do a lot more with the lines. And for that, I go directly to the Table of Offsets... a rather confusing table that once decoded, lets you draw all the body plan sections. But watch out! The data is recorded in feet-inches-eighths... and in this table, redrawn in 1951 from the original early 40's drawings, several lines are off by a foot. Who knew? And I wonder if there are real tugs out there with the deck a foot higher than planned- which is what this error produces!

Note that the sections do not necessarily represent actual frames on the ship. The naval architect follows standards and divides the hull shape into usually 20 stations (only 10 here) for calculations on volume/displacement/stability etc. Others will create drawings as needed for each of the 33 actual frames used on this tug... but we modelers can usually be happy to use the body plan's stations for a model's frames.

Also, these lines represent the "molded" shape- the volume INSIDE the hull's plating or planks. No big deal on a ship with thin plating, more of an issue on a wood planked ship, where the hull planking is quite thick.
>>> Oops, wrong- of course it's important! The lines reflect NEARLY the outside of the hull for a steel ship... but the modeler needs to offset this line by the substantial thickness of his planking on the model when creating the frames.

The lines also reveal things like the deck's crown at center, and knuckle or bearding lines. Many ships have near-vertical plating from the gunwales and down for a bit-- easier to weld rub rails onto-- and the line where this transitions to the curved hull shape is the "knuckle".

My next steps are to take the drawn lines (drawn at 1:1 scale, BTW!), scale them as needed in CAD, and then develop the actual keel and ribs' shapes. I'll also lay in a datum plane which represents the building board, as the hull will be built upside down with the ribs attached to the board.
Last edited by patmat2350; May 11, 2009 at 07:31 PM. Reason: Correcting dumb statement!
Old Dec 13, 2008, 02:26 PM
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i'll be reading this thread with a passion...
that is a beautiful tug.
Old Dec 13, 2008, 03:20 PM
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I guess this is going to be another of the Patmat specials that will teach us all how to build a scale tug... properly..

*sigh*...

Looking forwards to seeing this build Pat....
Old Dec 13, 2008, 03:40 PM
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This is going to be interesting...
Old Dec 13, 2008, 04:34 PM
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I might have to dust off the old plans and build one in a size that will better fit in my Jeep . Looking foward to watching this build!
Last edited by Rmay; Dec 13, 2008 at 06:40 PM.
Old Dec 13, 2008, 06:27 PM
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Pat we're waiting for the first pics...
Old Dec 13, 2008, 06:38 PM
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Patience, Grasshopper...
Old Dec 13, 2008, 07:45 PM
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he-he.
i'm impressed by the little i've read/review about these tugs, apparently they were long lasting workhorses, i'm sure that wherever you show this one once finished, more than one modeler will remember the real ones.
they look great on the water.
Old Dec 14, 2008, 07:53 AM
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Just a few more shots of my dusty YTL.
Old Dec 14, 2008, 11:40 AM
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how cool...
Old Dec 14, 2008, 11:57 AM
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Good plan to make it a bit bigger- I used Microglass' smaller hull and it was a nice build but a bigger one would be better to run.
There are a bunch of them still working on the Great Lakes.
I did the one from Bay Ship Building.
Patric
Old Dec 14, 2008, 01:00 PM
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and here it is!
http://michiganmodelboats.com/gallery_pat_l.htm
(4th down)
Old Dec 14, 2008, 01:05 PM
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Machinery


Before cutting the first scrap of wood, I need to determine what equipment is going in and how it will fit. Here, the prop, shaft, Pittman motor, and 12v 12Ah battery are laid in (approximately). I can check them against the body plan to be sure they'll fit between their frames at the height I choose.

With this established, I can strike lines for floor boards etc., and lay out exactly where those will connect with the frames.
Last edited by patmat2350; May 11, 2009 at 07:32 PM.


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