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Small sailboats with hull speeds near 5 knots regularly and safely circumnavigate the globe, and can weather storms, and navigate the southern capes. Without en

by _yb2s 4y ago

Small sailboats with hull speeds near 5 knots regularly and safely circumnavigate the globe, and can weather storms, and navigate the southern capes. Without engineering details on why it’s limited to 5 knots there’s no reason to think that’s a red flag. 5 knots is a speed against current, and ocean currents are much much less than that. Perhaps (likely) it would be able to still do 5 knots upwind in a storm.

consumer451 4y ago
>Small sailboats Yes, SAIL boats which can configure their sails to move in directions other than downwind.
- jabl 4y ago
  Also, ships, particularly sailing ships/boats, have hull forms with significantly less drag in the direction they're trying to go, vs sideways. This things, shaped like a giant tortoise with those massive (presumably rigid ) flippers, not so much.
- _yb2s 4y ago
  I don't understand your concern here. Sailboats can only sail ~45 degrees to the wind. This is a powerboat, so it can motor any direction, including directly upwind. Assuming the 5 knots is a hydrodynamic limitation of the (admittedly very silly) hull design rather than an engine power limitation (most likely, because you could always spec a more powerful motor), the boat could still go 5 knots any direction, including directly upwind into a storm. Just because a boat is slow doesn't mean it can't handle a storm, even more-so with powerboats than sailboats. Case in point, look at old fashioned displacement trollers, e.g. an old wooden salmon troller. These usually have an ~8 knot top speed yet can run directly upwind into a storm for days on end with no problem, at almost exactly the same speed as they would go downwind... because the speed limitation is entirely from the hull speed and not affected by wind. Boats like that have been weathering the worst ocean storms for over a hundred years safely and reliably.
  - jabl 4y ago
    Yes, but that displacement troller has a hull shaped like, well, a proper boat (or ship). I doubt the troller would be making significant forward speed against storm wind and seas if it was wider than it was long, like this abomination. It's like an upscaled version https://en.wikipedia.org/wiki/Russian_monitor_Novgorod https://en.wikipedia.org/wiki/Russian_monitor_Novgorod except made for parting schmucks from their money instead of serving some military purpose. (Well, in it's defence it seems at least the submerged part of it has some resemblance to, well, a hull form. Or several hulls bolted together.)
    - _yb2s 4y ago
      You're absolutely right, the skeuomorphic sea turtle shape is ridiculous, and this boat is a terrible idea. My disagreement here is only that a 5 knot top speed is not, by itself, a reason to dismiss a boat design without any other information.
      - consumer451 4y ago
        This design is basically a square aspect ratio. One of the reasons one turns into the the wind is to reduce windage. Because this design is square, you get no real benefit from doing that. But that's just in a storm event, which would probably be fine way out to sea. If you only have 5kts of speed to throw at the problem of navigation, you will almost always be getting pushed down wind. Again, this could be resolved with a bunch of very powerful tugs, which I suppose could escort the "ship" through troublesome areas. As in, anywhere near land or shallows. Say there is a 30 knot wind blowing. You negate 5 knots of that. Now you are moving at a maximum of 25 knots in the wrong direction. Of course, this is limited by the hull speed, but I don't think it's the hull speed that limits this design to 5kts. So say it can get pushed through the water at 10 knots by the insane amount of energy absorbed via windage... that's 240 nautical miles per day. Possibly in the wrong direction! That's 444km or 276 miles. Assuming the wind could blow for 5 days in a direction towards land, that's a lot of distance from shore until the captain is happy. Even if the hull speed is 5 knots, that's still a big problem once you multiply by time.

by _yb2s 4y ago

consumer451 4y ago

>Small sailboats Yes, SAIL boats which can configure their sails to move in directions other than downwind.

jabl 4y ago
Also, ships, particularly sailing ships/boats, have hull forms with significantly less drag in the direction they're trying to go, vs sideways. This things, shaped like a giant tortoise with those massive (presumably rigid ) flippers, not so much.
_yb2s 4y ago
I don't understand your concern here. Sailboats can only sail ~45 degrees to the wind. This is a powerboat, so it can motor any direction, including directly upwind. Assuming the 5 knots is a hydrodynamic limitation of the (admittedly very silly) hull design rather than an engine power limitation (most likely, because you could always spec a more powerful motor), the boat could still go 5 knots any direction, including directly upwind into a storm. Just because a boat is slow doesn't mean it can't handle a storm, even more-so with powerboats than sailboats. Case in point, look at old fashioned displacement trollers, e.g. an old wooden salmon troller. These usually have an ~8 knot top speed yet can run directly upwind into a storm for days on end with no problem, at almost exactly the same speed as they would go downwind... because the speed limitation is entirely from the hull speed and not affected by wind. Boats like that have been weathering the worst ocean storms for over a hundred years safely and reliably.
- jabl 4y ago
  Yes, but that displacement troller has a hull shaped like, well, a proper boat (or ship). I doubt the troller would be making significant forward speed against storm wind and seas if it was wider than it was long, like this abomination. It's like an upscaled version https://en.wikipedia.org/wiki/Russian_monitor_Novgorod https://en.wikipedia.org/wiki/Russian_monitor_Novgorod except made for parting schmucks from their money instead of serving some military purpose. (Well, in it's defence it seems at least the submerged part of it has some resemblance to, well, a hull form. Or several hulls bolted together.)
  - _yb2s 4y ago
    You're absolutely right, the skeuomorphic sea turtle shape is ridiculous, and this boat is a terrible idea. My disagreement here is only that a 5 knot top speed is not, by itself, a reason to dismiss a boat design without any other information.
    - consumer451 4y ago
      This design is basically a square aspect ratio. One of the reasons one turns into the the wind is to reduce windage. Because this design is square, you get no real benefit from doing that. But that's just in a storm event, which would probably be fine way out to sea. If you only have 5kts of speed to throw at the problem of navigation, you will almost always be getting pushed down wind. Again, this could be resolved with a bunch of very powerful tugs, which I suppose could escort the "ship" through troublesome areas. As in, anywhere near land or shallows. Say there is a 30 knot wind blowing. You negate 5 knots of that. Now you are moving at a maximum of 25 knots in the wrong direction. Of course, this is limited by the hull speed, but I don't think it's the hull speed that limits this design to 5kts. So say it can get pushed through the water at 10 knots by the insane amount of energy absorbed via windage... that's 240 nautical miles per day. Possibly in the wrong direction! That's 444km or 276 miles. Assuming the wind could blow for 5 days in a direction towards land, that's a lot of distance from shore until the captain is happy. Even if the hull speed is 5 knots, that's still a big problem once you multiply by time.