today's work

[He Who Shall Not Be Named]

With respect to ballast tank size, keep in mind, that the ventilation masts and some mechanical gimmicks will also increase the above-surface volume.

I underestimated those contributions substantially with my big U1 and a not optimum waterline was the result.

Good tip, Andreas. I've already upped the ballast tank volume by about 10% of my initial finding. Since I have yet to cut the cylinders (one for you, one for me) to length, I'll add another half-inch to the length of the ballast tank section. That should cover masts, bridge do-dads, the ventilators, and deck fittings.

Better too much ballast tank than too little!

Man! I'm starting to appreciate how, from the start, your navy got the submarine structure and systems right with the first combatant. You German's! We all advanced our own fleets on the back of yours. I hope acknowledgment of that fact is never lost to history.

[DrSchmidt]

With respect to ballast tank size, keep in mind, that the ventilation masts and some mechanical gimmicks will also increase the above-surface volume.

I underestimated those contributions substantially with my big U1 and a not optimum waterline was the result.

[redboat219]

Drive motor(s) inside or outside?

[He Who Shall Not Be Named]

Yup, nothing beats actual measurements.

But did I get my computation close to needed tank length for the U1 if you use a 2" SD?

A 2.5" SD would only require a 3" length of BT.

Yeah. You pretty much hit it on the nose going the math route, Romel.

And yes, for ease of populating it with the devices and what-nots, it would have been easier to go with the 2.5" cylinder, but at that diameter there would have been precious little annular space in which to cram the foam needed to negate the weight of the fixed ballast weight down in the keel. (that little Type-21, even with the 2" WTC had little room between cylinder and hull for such foam, and as a consequence static roll stability is ... to be kind... 'marginal').

[redboat219]

Yup, nothing beats actual measurements.

But did I get my computation close to needed tank length for the U1 if you use a 2" SD?

A 2.5" SD would only require a 3" length of BT.

[He Who Shall Not Be Named]

So you're using a direct method to measure how long your ballast tank will be given the volume from weighing the above water parts (1gm of water= 1cc).

you could calculate it using this

Height of cylinder (or length) = V
Value of Pi × r²

V= volume
Pi= 3.14159
r = radius of cylinder

example:
If you have a 2" dia cylinder that requires a ballast tank volume of say 250ml (15.25 in³ )


15.25 = 4.85 in
3.14159 x 1


Your BT needs to be 5 inches long

or here's a calculator you can use
https://www.omnicalculator.com/math/height-of-cylinder

Yes. I could also put a broom handle up my ass so I could sweep the joint down as I attended to other tasks throughout the house.

But I won't.

Math is not my strong suit.

David

[redboat219]

So you're using a direct method to measure how long your ballast tank will be given the volume from weighing the above water parts (1gm of water= 1cc).

you could calculate it using this

Height of cylinder (or length) = V
Value of Pi × r²

V= volume
Pi= 3.14159
r = radius of cylinder squared


If you are holding a 2" dia cylinder that requires a ballast tank volume 8 oz. (14.4 in³ )


14.4
3.14159 x 1

=4.5 in

Your BT needs to be 5 inches long

or here's a calculator you can use

https://www.omnicalculator.com/math/height-of-cylinder

[He Who Shall Not Be Named]

[He Who Shall Not Be Named]

ALFA Build: So how do you keep the thinned Evercoat polyester filler from adhering to the upper hull half when re-contouring the hull to cover the mis-matched upper and lower hull?
Newbi

Apply masking to the upper hull on and near the edge. Coat the tape with mold release wax or Vaseline. Proceed. Still working up your replacement WTC, Joe.

[Joe oliver]

ALFA Build: So how do you keep the thinned Evercoat polyester filler from adhering to the upper hull half when re-contouring the hull to cover the mis-matched upper and lower hull?
Newbi

[He Who Shall Not Be Named]

Fancy use of a hospital overbed table.

I got two in the sheds, two in the shop, and one in our room. Most useful.

[redboat219]

Fancy use of a hospital overbed table.

[He Who Shall Not Be Named]

Best seat in the house when testing your boats. LOL!

Yikes! Just. ****ing. Yikes.

[redboat219]

Best seat in the house when testing your boats. LOL!

[He Who Shall Not Be Named]

Get'n ready for the 2025 Cabin Fever Expo next week