[PSUBS-MAILIST] Ribs outside hull

[Raphael SOULIAC via Personal_Submersibles]

I see, the easiest solution is the good old internal ribs. Thanks.

Raphael

Le ven. 1 sept. 2023 à 20:21, Sean T. Stevenson via Personal_Submersibles <
personal_submersibles at psubs.org> a écrit :

> The ABS Rules provide a separate set of equations to use for determining
> all of your critical pressures when using external framing. You need to
> calculate accordingly. In general, external framing provides more stiffness
> than internal for the same amount of material, but there are drawbacks.
>
> Welds between your hull shell and any external stiffeners must be CJP, as
> opposed to simply continuous.
>
> Also, be aware that free filling spaces between the pressure hull and any
> external hydrodynamic fairings represent a large volume of water which must
> be moved along with the hull, and that inertia will consume a substantial
> fraction of propulsion power. If you have no fairings, you will still be
> moving a boundary layer defined by the drag of the exposed stiffeners, so
> you must plan your power budget accordingly.
>
> You also need to figure out how to mount all of your internal equipment,
> since external framing implies the loss of what would otherwise be a bunch
> of convenient structure for clamping to.
>
> Sean
>
> -------- Original Message --------
> On Sep. 1, 2023, 11:44, Raphael SOULIAC via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>
> Hey guys, i've got a quick question. The design i'm working on has a very
> narrow hull (ØID 650mm) so i wanted to put the renforcing ribs on the
> outside of the hull.
>
> The ABS spreasheet give me 1113ft of max depth but it's for the ribs on
> the inside.
>
> What would be the difference between this and the real max depth ?
>
> Raphael
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