Gwen's all metal scratch built 1/32 Type VIIc

[Guest]

Re: Gwen's all metal scratch built 1/32 Type VIIc

Really difficult trying to calculate displacement accurately with a hull shape like a Type VII.

A cylindrical boat would be a lot easier, even then you need a fudge factor.

One thing is for certain, you will need a fair degree of floatation below the waterline to make up for high density of the metals you are using. That's where plastics and composite materials shine- they generally tend to be between 1-1.5 times the gravity of water, whereas aluminium is about three times, and brass is over eight times!

In a nutshell, a metal boat will give you small ballast tanks, but the boat will probably be heavier to cart about dry.

[steveneill]

Re: Gwen's all metal scratch built 1/32 Type VIIc

I would bet you are. I have a 1/32 boat but not metal. I love it the best of all my big boats. Something about the type 7.
Steve

[JWLaRue]

Re: Gwen's all metal scratch built 1/32 Type VIIc

Really difficult trying to calculate displacement accurately with a hull shape like a Type VII.

I agree that calculating from scratch would be very, very difficult. But to be clear...calculating based on the full-size boat is a mathematical exercise. (for a dry hull model)

-Jeff

[Guest]

Re: Gwen's all metal scratch built 1/32 Type VIIc

If the the fullsize boat is has little to no free flooding areas, and the model follows suit, you can use basic matematics to give a pretty accurate figure of what the model will displace.

With a boat like the Type VII, which was a twin hulled design, even if you make the inner cylinder the same shape and volume- unlikely in practice- the chances are the outer skin will be considerably thicker in scale terms than a full size boat, unless you're making the hull from cigarette papers!

It'll give the builder a rough estimate, but I wouldn't want to rely on it for calculating ballast tank volumes, etc.

[JWLaRue]

Re: Gwen's all metal scratch built 1/32 Type VIIc

...which takes us full-circle back to my note that we're talking rough estimates.

-Jeff

[gwen]

Re: Gwen's all metal scratch built 1/32 Type VIIc

I'm thinking the best way for me to calculate the displacement is to build the hull, submerge it, and measure the displacement. I plan to build it in sections so I could conceivably fit the whole thing in a bathtub and mark the waterline and measure the volume.

[bwi]

Re: Gwen's all metal scratch built 1/32 Type VIIc

We all love Archimedes......EUREKA

Great built!

Grtz,
Bart

[Guest]

Re: Gwen's all metal scratch built 1/32 Type VIIc

That's really the only accurate way to do it. Plus it's a heck of a lot easier than trying to calculate it.

[JWLaRue]

Re: Gwen's all metal scratch built 1/32 Type VIIc

The point in attempting to provide an estimate is to allow Gwen the opportunity to do some planning on the size of the dive module she will need. This especially so given the full framing type of construction being used. Going back into that hull after the fact to try to find more space is likely to be an act of major surgery.

-Jeff

[Ralph --- SSBN 598]

Re: Gwen's all metal scratch built 1/32 Type VIIc

The boat is being built in sections.
At one or two of the section breaks, there could be space allowed to slip in the necessary ballast tank and even allow for changes to it's length if needed.

If an over sized tank is used then a bleed vent tube can be used to change the amount of air the tank will hold.
Or plastic blocks can be added to reduce the inside volume.

As long as there is enough room to have a ballast tank that is too big, it's volume can always be restricted to get a true waterline.

[gwen]

Beginning the hull plating

I started working on the hull plating today. I started with a complex piece on the stern and with hammer and anvil shaped a piece of .025" aluminum to fit. I only have the one plate in place so far but I think this proves I can just epoxy aluminum plating to the structure.

[gwen]

Re: Gwen's all metal scratch built 1/32 Type VIIc

Does anyone happen to know the actual size and spacing of the rivets on the Type VII/c by any chance?

[ober freak]

Re: Gwen's all metal scratch built 1/32 Type VIIc

Hi Gwen

The hull framing on probably all german u-boats where 500mm (19.685") for the outer hull and 700mm (27,559") for the pressure hull.
The outer hull plating was welded and riveted to the frames with one row on each frame. The pressure hull was welded completely, no rivets at all in those areas.
But remember the rivets where barely visible compared to the weld lines.

some rows on U-505 in front of the anchor


and some on U-995 above the dive planes (restored areas on U-995 where welded only)


Marco

[gwen]

Re: Gwen's all metal scratch built 1/32 Type VIIc

Thanks Ober, that helps

[gwen]

Re: Gwen's all metal scratch built 1/32 Type VIIc

Hull plating work progressing slowly...