Author Topic: Naval tugs  (Read 18508 times)

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sea monkey

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Re: Naval tugs
« Reply #45 on: July 05, 2019, 23:39:08 »
Thatís looking great Jeno
For some reason our members have become quite quiet lately - plenty of viewers but not many comments.
Keep the photos coming, we are always interested in projects like yours.
Steve

des

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Re: Naval tugs
« Reply #46 on: July 06, 2019, 02:52:35 »
I'm interested to know how members make their hulls - especially for RC, where internal space is necessary for motors and battery, etc;  and where weight is a necessary consideration so that the model actually floats.

I've just started out making a hull using the frame and plating method;  I've only partially framed the aft end only, and already I'm getting worried about weight.

I've checked out Jeno's photos, which show a typical deck support frame, but the hull seems bereft of any internal structure to give it shape.  So I'm guessing it is fibreglass.

I really don't want to make a mould for fibreglass hull.  Nor do I want to use the bread and butter method.  I have zero experience with fibreglass moulding; and bread and butter is too heavy due to the thickness of the hull sides and bottom.

Des.

JEno

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Re: Naval tugs
« Reply #47 on: July 06, 2019, 04:27:18 »
Des,
 You are correct that my ARS is a fiberglass hull. I have also done a planked hull and scale makes a huge difference with weight considerations when doing so. That said, what scale are you working in, and what kind of a ship are you building...warship( destreyer battleship ect) merchant or working ship ( tug ect). The smaller the scale, the more careful you have to be to calculate your weights. One way to estimate your needs is to estimate the required finished weight to get your model to ride at the waterline. You should be able to do this by scaling your displacement. Next estimate the weight of your components, motor(s), radio gear, batteries and sundries. The difference between the two weights is approximately the allowed weight of the COMPLETED hull. The are numerous threads about doing this over on the RC Groups forum (sorry Moderator).
I hope this helps.

des

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Re: Naval tugs
« Reply #48 on: July 06, 2019, 15:09:12 »
Hi Jeno

Yep - done all that.  I'm making a hull for a 1970's era twin screw tug, in 1:50 scale.  Calculated total displacement is around 4.5 kg, based on cross-sectional area of each frame below waterline, and spacing between frames.

So far I've got the aft end (around 40% of the total length) mostly framed up - this is currently weighing in at 200 g - so far so good, it seems.  I'm thinking that the full frame will be a bit less than 500 g;  then the hull sheeting and deck will probably bring it up to around 800 - 1000 g.

Then there's the upperworks, detailing, paint, motors & drives, battery, etc.  Plus ballast to bring it down level onto its lines.

I think I'm okay so far, but I may need to grind out some frames once the hull sheathing is done and it becomes more self-supporting.

Des.

JEno

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Re: Naval tugs
« Reply #49 on: July 07, 2019, 03:48:00 »
Des,
You definitely want your frames to be open rather than solid. 1) for the weight savings, 2) for access to as much on the inner hull as possible. You super structure should be a s light as possible, I have been using a lot of Sintra, expanded PVC board ( sign board ,100") and styrene. It sound like you should have a good weight reserve to play with.