Gunboat observation & rudders

Discussion in 'Multihulls' started by nero, Nov 1, 2007.

  1. nero
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    nero Senior Member

    Just had a good long look at the outside of a Gunboat that spent the last few days docked here in Marseille. They are headed to the Barcelona Expo.

    Observations were that the helm is in the inside of the salon. There were solar pannels on top of the cabin so seeing the sail is difficult.

    There is also a double door that opens to a cockpit in front of the salon. The front cockpit is in front of the mast and all control lines run to it. Nice and clean looking. Not sure how they evacuate water that has come into it in heavy seas.

    The boat is about 14.5 meters long. One of the crew said it was 7.60 overall width. Interesting that it is so fast for being narrow for it's length.

    Most stricking was the rudders. The are 35 cm wide and very long. Very high aspect. They are held in cassets and pivot at the front of the blade. They can be pulled up from the top. They are the same as a square sterned boat with rudders hanging off the back. Nothing to stop them from ventilating. Nothing to protect them from impact. Clearly they work well so perhaps rudder ventilation does not occur that easily?? This is the first time I have seen this thin and high of an aspect on a bridge deck catamaran. Are there other examples of this?

    The bridge deck clearance appeared to be about 75 cm. The cabin top seemed high. Great for anybody tall. From the other side of the port and up the hill a ways, the boat looks ugly! It is the cabin that doesn't work for me. It is all flat and square. From the dock the cabin looks spacious and not that bad.

    Anyone else seen a Gunboat?
     
  2. Pericles
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    Pericles Senior Member

  3. nero
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    nero Senior Member

    anjella

    The catamaran I saw was ANJELLA out of Brehm (Germany). The paint color looks much better in real than on the website.

    They are built for tall people. (not my case) Many nice design features. Still they are not very asthetic on the outside. Very unfortunate that I did not make more of an effort to visit it. The skipper and his crew were very friendly.
     
  4. BWD
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    BWD Senior Member

    I was aboard the 48 "sailing lickety split" at Annapolis last year. It looked good at the dock.

    In general, bridgedeck cats aren't good looking to me from the perspective you describe. Like flat roofed office buildings with masts, unfortunately. Can be nice aboard and from the water though.

    The bridgedeck clearance is not huge but they do limit its extent from aft the mast to maybe 4 ft forward the stern. Hopefully adequate. Probably good or some bad rumor would have come out of the delivery trips from SA.

    The difference in displacement and motion between the 48 and other cats parked nearby at the show was stark. The fat cruisers looked aground, the gunboat rose to every ripple in the harbor. Just to consider, Gunboat lists the 48 as 17700 light, max 22500, the 62 is(was) 34483 max according to M+Ms website, and the 66 is 34000/40120.
    Food for thought.

    The tall "greenhouse" of these boats I think is needed to give safe visibility 360 degrees from the inside helm. A few degrees of heel and a lower roofline would have the helm seeing nothing to leeward but the water next to the boat. Scary at 15 or 20 knots I bet. It's not the most beautiful, but to me it looks beautifully functional. Prettier than some others, I think.

    The light weight construction was very apparent aboard. The joinery looked very nice, but so light, I wondered if it would ding. Seemed solid when rapped upon though. Only thing I remember not liking was some "floating" panels that would give a great place for grime to stick under.

    It seemed a fantastic boat on the whole. They let 8 aboard at a time, and that would have been very comfortable had we all known each other. In fact there was plenty of space for 8 strangers. PM me if you want to ask anything else I remember.
     
  5. brian eiland
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    brian eiland Senior Member

    You probably want to look at the VARA rudder system
    http://www.socasailboats.com/VARA_System/body_vara_system.html

    I tend to agree with you there, it is a rather 'boxy' design...no sheer, all flat surfaces, square plum bow, square sterns, etc.

    I've written before, "And most importantly, you included the oft forgotten element, the sheer line. What a terribly important factor! Romantically stated, but oh so true, “it is simply her sheer … sheer beauty that is. She enters the harbor like a beautiful woman entering a room. Her sheer is the line we try to get right when we doodle boats.” So many of today’s boats lack this beauty, and correspondingly, some of the essence of yesteryear’s yachting

    But they are beautifully built, and they are selling boats
     
  6. Pericles
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    Pericles Senior Member

    Brian,

    All the best to you and your lovely wife. The photographs say it all and you look very proud and happy.

    And now, back to the mundane, thanks for posting the information about the VARA rudders. I was at a loss as to the description about their design in the Gunboats, although if BWD could add more detail how those are operated, l'd be grateful.

    Pericles
     
  7. BWD
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    BWD Senior Member

    From the pics on gunboat.info, it seems the 48 has this rudder type, but I am afraid I stepped right over it and up the steps into the aft cockpit. The boat was moored close, stern to the dock and I did not even notice the cutouts in the transom for the rudder. A shame, it sounds interesting!
     
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  8. nero
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    nero Senior Member

    the VARA rudder system

    I originally was planning on building in a VARA style system on my catamaran. At the time, I was imaging a barrel that would hold the rudder blade. This barrel would rotate in a cylinder that was glassed into the hull.

    With a system like this the only energy absorption when an impact occures is when something breaks. This also means that the rudderblade had to be engineered to resist navigation loads but not impact loads. (complicated)

    Looking at it now. It seems like a good idea. Carry a couple of extra blades and life quickly returns to wonderful.

    The rudder linkage system on the Gunboat most likely works well. It is not very refined however. It is more of a transom hung system tinkered thru the hull sides. It is somewhat at risk to hardsided dingy trying to board in small seas. ... Then again, who does this?
     
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  9. Pericles
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    Pericles Senior Member

    Interesting snippet from http://www.vgyd.com/appendage_refits.html

    "Gunboat 62 Catamaran (Prana) - Van Gorkom Yacht Design was approached by the owners of this fast and power catamaran designed by Morrelli & Melvin, to re-engineer the rudders and bearing system on their boat. The redesign constituted a complete revamping of the bearing materials used in the Vera rudder system where a composite of stainless steel and Nylatron was used in combination with polycarbonate ball bearings. These bearing units were fabricated by CAM Engineering in Bristol, Rhode Island. In addition, the dagger board type rudders were redesigned with a new geometry and carbon fiber laminate, which were built by Stew Wiley of Portsmouth, RI."

    Could it be that this modification was to lighten the steering effort, so that a joystick replaces the steering wheel?

    Pericles
     
  10. captainjsw
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    captainjsw Junior Member

    Good thread this does anyone have an more information on this type of VARA rudder system. I am building a forward cockpit catamaran not that disimiliar to the gunboat series. The long spade idea interests me rather than the variable capacity. I have been told some of the Grainger racing boats had them, but a few have also had problems

    Thanks John
     
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  11. charmc
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    charmc Senior Member

    Well said, Brian. My thoughts exactly, although I've never articulated them quite so well.

    Somehow though, despite the many straight lines, there's a certain sparse beauty of function in the Gunboat design.
     
  12. Pericles
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    Pericles Senior Member

    Two emails to http://www.socasailboats.com/VARA_System/body_vara_system.html for more have not been answered. Perhaps you may have better luck?

    It's a sword in a short sheath concept, surrounded with a barrel swivel, although as an alternative, the sheath could be transom mounted and the rudder blade could be raised and lowered or replaced with relative ease.

    -----------------------------------------------------------------------------------

    Typical! The Gunboat 48 pictures I had looked at previously, seemed to show the rudders mounted in notched transoms. A search just now revealed a picture of my description above. Two minds with but a single thought, honest guv!! :D :D :D :D

    http://gunboat.info/gallery_48/pages/_Y6L0008.htm

    Pericles
     
  13. david@boatsmith
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    david@boatsmith Senior Member

  14. Pericles
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    Pericles Senior Member


  15. UpOnStands
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    UpOnStands Senior Member

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