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How does Skydiver's "seaskim" mode works?


I always wondered how Skydiver was able to go on “seaskim” mode. In Chris Bentley’s UFO book, he states the sub uses hydroplanes to achieve this. After doing some research, this is what I came up with: hydroplanes that swing out of Diver 1. These are not “hydrofoils” per se – while the hydroplanes lift the sub in the water, but not where the hull clears it. I always envisioned Diver 1 having air and hydro jet engines. When Sky 1 is attached to Diver 1, its wings will help attain the needed lift-sort of “carrying one’s own weight” while in that mode.

The second illustration is to disprove the small vents ahead of Skydiver’s blast vents as being missile launchers. I do not have the UFO Technical Manual, so not sure if this is covered. I know of cutaways that show these vents as missile launchers. It wouldn’t be practical: 1.) they are too small, 2.) the wrong shape, 3.) too close to the heat and exhaust of Sky 1’s rocket engines. If a missile is needed, it could be launched from the sub’s torpedo tubes. Kind of similar in principle to the SUBROC UUM-44 missile.


  • UFO Skydiver Seaskim.jpg
    UFO Skydiver Seaskim.jpg
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  • UFO Skydiver blast chamber.jpg
    UFO Skydiver blast chamber.jpg
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Interesting. I never thought of hydrofoils. I always took it to be a hovercraft-type mechanism but hydrofoils sound feasible.



I rewatched the episode Sub-Smash, and when Skydiver goes on "seaskim" mode, there are flashes of light and smoke coming from the bottom of the sub. It is like watching a jet engine start up.

I trust Chris found the info of the hydroplanes while doing research for his UFO book. Yes, I agree. Hydroplanes/hydrofoils is a more realistic explanation for "seaskim" mode. While they were not seen on the filming miniatures, I presumed the hydroplanes retracted when not in use. My suspicions were confirmed when Fanderson's UFO Annual came out, and the feature article on Skydiver mentions this.

The reason I didn't use one of two traditional hydrofoil designs (U-shaped and T-shaped foils) is that Skydiver's hull does not clear the water (as a hydrofoil craft is supposed to do). A portion of the hull is still in the water. The fins help lift the sub up in the water, but I see its main purpose is for stability. Also, while doing such research, the term 'hydroplane' seem to be reserved for submarines, while 'hydrofoil' is used for surface ships.
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The jetfoil is a variation of the T-shaped foil. Of all the hydrofoil configurations that are known, it would probably be the closest to what could be used on Skydiver. However, I was looking at stability and the ship's center of gravity when Sky 1 is attached. If it was only Diver 1, the jetfoil would work. But when you attach something as big as Sky 1 to it, I have my doubts. That is why I thought of the hydroplanes only attached to the sub and not the connecting support. By allowing the hull to be still in contact with the water, it might slow it down, but it helps ground it because of its unusual design.

But then again, you could be right and it is a jetfoil, and 'seaskim' comes in different modes-with or without Sky 1. Which leads to the question of...

Diver 1 is not a very big submarine, and when you think of all the hardware it should carry, it wouldn't fit! Science fiction can allow us to think up of ways on how things could work. That is one of the reasons why I have been doing this. Its been a hobby and exercise. Glad to see I am not the only one trying to figure all this out. As another forum member mentioned on another thread, if UFO lasted another series, we could have had the answers.
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