YTL-710 in 1:10

PATMAT · Post by **PATMAT** » Thu Dec 25, 2008 9:48 am

If you have the 1:1 displacement of a ship, you can quickly calculate your model's displacement (weight)-- 1:1 disp / scale^3 . But I don't have a reliable figure for this tug... so using my 2D CAD model, I quickly tallied up the submerged area of each frame, averaged neighboring pairs, multiplied by the station spacing, and tallied up all the volumes to get 1630 cubic inches displacement. Multiply by .036 lb/in^3 water density, and wow, about 59 lbs! Not atypical for a large model like this, but more than I expected.

If I load it light and show about 1/2" of red bottom, it goes down to about 50 lbs.

With about 20 lbs of battery and drive gear, that leaves 29 lbs for structure and ballast. I don't have the hull and cabin weights yet, but I guess I should protect for 10-15 lbs of lead. I'll design in removable containers (like capped PVC pipe) to hold the lead shot; knowing the density and packing factor of lead shot, that lets me design the right volume into the pipes.

rmay · Post by **rmay** » Thu Dec 25, 2008 2:26 pm

Yea that was the problem with the 45" model YTL I built. I had to add so much weight to get it down to the WL that is wasn't easy to move around. I like your idea about PVC pipe. That would be much easier then the weights I added at lake side. Looking great so far!

PATMAT · Post by **PATMAT** » Fri Dec 26, 2008 6:13 pm

Planking continues.
Had to re-set up my plank factory-- underestimated the requirement by about a dozen.

ARH · Post by **ARH** » Fri Dec 26, 2008 6:51 pm

Pat, Thats one of the best planked hulls I have seen for a long while.

les · Post by **les** » Fri Dec 26, 2008 7:21 pm

Arrrgh, the last one you saw was the one you had to walk, you scurvy dog!!

PATMAT · Post by **PATMAT** » Fri Dec 26, 2008 8:18 pm

Thanks Ron, but you can only say that because I don't show close ups!
And sorry about the pirate thing, did I leave the door unlocked??

desron48 · Post by **desron48** » Fri Dec 26, 2008 8:24 pm

exelent piece of craftsmenship there pat....sorry you gotta cover it up with glass and paint

.....joe

ARH · Post by **ARH** » Sat Dec 27, 2008 4:33 am

PATMAT wrote:Thanks Ron, but you can only say that because I don't show close ups!
And sorry about the pirate thing, did I leave the door unlocked??

I dont need close up,s to tell a nice piece of work,

as for leaving the door open, them pirates will get in to anything, thats why the RN are always on stand by, and building new ships.

les · Post by **les** » Sat Dec 27, 2008 9:13 am

ARH said:

them pirates will get in to anything, thats why the RN are always on stand by, and building new ships.

Because we sunk all the old ones!

PATMAT · Post by **PATMAT** » Sat Dec 27, 2008 4:09 pm

Popped in the last plank, and popped the hull off the board.

MUCH more to do! Build the skeg, sand/fill/glass/sand/fill/sand/paint... and maybe some interior finishing too... and that's all before adding the deck and bulwarks... wait, no, I need to mount bulwarks before glass, and finish interior before deck, and the deck goes on before the bulwarks... um, no, wait- I think I'll have a beer...

desron48 · Post by **desron48** » Sat Dec 27, 2008 10:38 pm

a ship that size with all the detail and still tote under your arm.....what more can you ask for??...joe

rmay · Post by **rmay** » Sun Dec 28, 2008 10:11 am

This is the dust jacket of a book my wife gave me for Christmas a few years ago. Nice book for those who like Tugs!

PATMAT · Post by **PATMAT** » Sun Dec 28, 2008 11:15 am

A nice little ST tug with a number of modifications visible...

PATMAT · Post by **PATMAT** » Mon Dec 29, 2008 5:46 pm

Been working most the day on this, and I don't know where all the time went!

But added some bracing here and there, things are getting more solid all the time.

ingura · Post by **ingura** » Mon Dec 29, 2008 8:39 pm

PATMAT · Post by **PATMAT** » Tue Dec 30, 2008 7:36 pm

Closed up the skeg with plywood, and arranged the prop shaft tube and its greasing fitting.

The tube is by Raboesch-- their biggest one, 6mm shaft for M5 prop, big honkin' tube with Oilite bearing below and ball bearing above. It also comes with a grease tube and zerk fitting, which you can arrange as liked.

I put the fitting in a well under the poop deck manhole... the well is turned from a 1-1/2" PVC pipe cap. The grease tube is silver soldered for strength, but the design completely supports both the prop tube and grease tube so that no load will go into them during over-zealous grease-gunning.

PATMAT · Post by **PATMAT** » Tue Dec 30, 2008 8:48 pm

More frame art...

PATMAT · Post by **PATMAT** » Tue Dec 30, 2008 9:31 pm

Here's the first look at the motor and battery loosely in place.

Motor is a nice old Pittman that turns the big prop at the right RPM. Battery is a 12v 12Ah unit that looks tiny in the hull, but its capacity should drive the low-draw motor a good 2 hours.
Coupler is the Robbe spline unit, 6mm x 1/4" with a spacer in between to provide the proper double cardan configuration. Even using lasers and my angle finder, small misalignments are inevitable, and a double cardan minimizes any resulting vibrations.

Reid · Post by **Reid** » Wed Dec 31, 2008 2:53 am

WOW!!! looks what heppens went u go away for afew days... pat is almost done with his boat!!

that looks great pat!! and u are sooo fast!!

PATMAT · Post by **PATMAT** » Thu Jan 01, 2009 12:10 pm

It's really best to do all the equipment installations before finishing the hull interior, and certainly before attaching the deck.

Here, I've put in a battery tray and a removable electronics shelf. Again, having a CAD layout let me design the shelf and its supports for a near-perfect fit... a luxury I miss when working on commercial f/g hulls.

Also, found that the bent aluminum motor mount that came with the Pittman was too flimsy and ugly for my taste, so a wood one was made from 1/4" ply.

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YTL-710 in 1:10

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Off the board

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Progress? What progress?

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Skeg & Prop tube

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Motor & Battery

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Interior decorating