AC 36 Foiling Monohulls

Discussion in 'Sailboats' started by OzFred, Sep 13, 2017.

  1. Doug Lord
    Joined: May 2009
    Posts: 16,580
    Likes: 298, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

  2. Doug Lord
    Joined: May 2009
    Posts: 16,580
    Likes: 298, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    FromETNZ:
     
  3. wet feet
    Joined: Nov 2004
    Posts: 455
    Likes: 35, Points: 28, Legacy Rep: 124
    Location: East Anglia,England

    wet feet Senior Member

  4. sharpii2
    Joined: May 2004
    Posts: 1,875
    Likes: 87, Points: 48, Legacy Rep: 611
    Location: Michigan, USA

    sharpii2 Senior Member

    I guess still no word on how fast these puppies go. My guess is 30 to 40 kts. Anyone know?
     
  5. wet feet
    Joined: Nov 2004
    Posts: 455
    Likes: 35, Points: 28, Legacy Rep: 124
    Location: East Anglia,England

    wet feet Senior Member

    Given the nature of the competition they are intended for,they just need to be faster than the other boat.With the concept being so new,we are at a very early stage of the development of the type and they are certain to be faster in a few months than they are now.Ask yourself whether you would be telling the world how fast the boat went if you were a team manager-would you be understating the real figure or exaggerating it to demoralise the opposition?It may well be that some of the teams will have boats observing the development sessions around the world and they may be intently studying radar plots of the actual speeds reached.
     
  6. Doug Lord
    Joined: May 2009
    Posts: 16,580
    Likes: 298, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    The ugliest AC boat ever but she flies:
    4
     
  7. sharpii2
    Joined: May 2004
    Posts: 1,875
    Likes: 87, Points: 48, Legacy Rep: 611
    Location: Michigan, USA

    sharpii2 Senior Member

    This kinda reminds me of an espionage movie. All the spies on each side know their counterparts. Only the bewildered civilians are left on the sidelines without a clue. I bet all the teams know how fast the already operating boats are going. Maybe not to the nearest knot but probably to the nearest five knots, which is all I'm asking. With their deca-million budgets, they have probably, no, almost certainly, hired one or two cheap spies. All such a spie would need is a boat, a camera, and a background with two known reference points. The distance between the reference points can be measured after the recording.
     
  8. Earl Boebert
    Joined: Dec 2005
    Posts: 375
    Likes: 46, Points: 28, Legacy Rep: 302
    Location: Albuquerque NM USA

    Earl Boebert Senior Member

    No need to risk a physical presence in the vicinity. Plenty of satellite companies capable of tracking an object of that size.

    Cheers,

    Earl
     
  9. OzFred
    Joined: Nov 2015
    Posts: 477
    Likes: 47, Points: 28, Legacy Rep: 16
    Location: Earth

    OzFred Senior Member

    Any ides of the cost of maintaining coverage over an area when you don't know when or exactly where the boat will be sailing, and a satellite in the required orbit can provide maybe 5 minutes of surveillance of a site in a 90 minute orbit? I expect if your personal wealth doesn't run to at least 9 figures before the decimal point you can't afford it. A couple of local stooges might be a little more affordable. :)

    The target is +50 kn, but don't expect to see it until the AC final. I don't think anyone is trying to find their top end yet, it's more about learning to sail the boat. Nathan Outteridge said of the F50s something like that up to about 48 kn they're pretty good, but over that they're right on the edge, mostly because of cavitation affecting lift and hence stability.

    An AC75 has more freedom to optimise the foil (compared to an AC72 or 50) as it's really only doing one job: lifting. It's not trying to also resist leeway and automatically maintain ride height in the one linear component without flaps. So an AC75's foil can be more optimised for speed and potentially produce a higher top end. But much over 50 kn will be very difficult due to the physical limitations of submerged hydrofoils.
     
  10. Doug Lord
    Joined: May 2009
    Posts: 16,580
    Likes: 298, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    ==============
    So what foil resists leeway on an AC 75?
     
    Doug Halsey likes this.

  11. OzFred
    Joined: Nov 2015
    Posts: 477
    Likes: 47, Points: 28, Legacy Rep: 16
    Location: Earth

    OzFred Senior Member

    As you know, the foil is angled/canted to resist leeway. From the foil's perspective, it's just lifting at a different angle. The curved AC72 and 50 foils were trying to do two separate jobs: one part lifting, another part resisting leeway which resulted in much more complex foil shapes (which is not to say the AC75 foils are simple).

    On a different note, this video reveals some interesting detail of the ETNZ boom and just how complex it is:
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.