Landing craft un-beaching

Discussion in 'Boat Design' started by Steve P, Mar 18, 2015.

  1. Village_Idiot
    Joined: Oct 2007
    Posts: 382
    Likes: 15, Points: 18, Legacy Rep: 138
    Location: USA

    Village_Idiot Senior Member

    We use a landing craft on a smaller scale (with around 3-4000lb load). When unloading the LC, we anchor it in place (spud anchor at the bow gate, plus anchors from the stern going each direction to land). The bow anchor prevents fore/aft movement, and the stern anchors keep the stern from shifting to either port or starboard. We then unload and keep the LC in place.

    Upon re-loading the LC, we are far enough from shore that we can usually back off with little problem. This LC has an outboard (150 Merc), and since it is flat-bottom, I designed it to have square front, rather than a mod-V bow. Therefore, we are able to wiggle the stern to port/starboard and that process will "walk" the bow off of the shoreline. This cannot be done with a pointed bow (although it could be done if you drop two push bars off the bow, on either side).

    Btw, if you do use a winch, keep in mind that you can double (or more) the pulling power with a block-and-tackle, when needed.

    Another option is to have a second boat on hand to help pull the LC from shore - use two tow ropes, or a double-ended V- or Y-bridle.
     
    Last edited: Mar 19, 2015
  2. daiquiri
    Joined: May 2004
    Posts: 5,373
    Likes: 255, Points: 93, Legacy Rep: 3380
    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    When I was a kid I remember witnessing several times a technique of disengaging beached military landing craft.

    The helmsman would engage the engines in full reverse, and would then apply left and right helm in alternating way (left, right, left, right, etc. - very slowly). In that way, there was a constant pull in reverse, and an alternating rotation of the hull to the left, to the right, to the left again etc.
    If necessary, in order to facilitate the rotation of the boat, the crew would be shifted aft towards the gunwale on the side to which the boat needed to rotate.

    Example: to help a badly stuck vessel rotate to the left while in reverse, all the crew would move to the aft left gunwale. In that way, a pivot was created at the forward left corner of the hull, while the forward right corner was unloaded and free to slide over the beach bottom. When the left move was completed, the helmsman would give the right helm and would order the crew to move to the right, thus un-beaching the fwd left hull bottom.
    It usually took no more than 3-4 repetitions of this procedure to un-beach the craft from nearly any situation.

    It is the same principle which we use every day to pull out various objects from a stuck position (think of a cork in a bottle, for example). We tend to make alternating sideways movements while applying the pulling force. :)

    Cheers
     
  3. daiquiri
    Joined: May 2004
    Posts: 5,373
    Likes: 255, Points: 93, Legacy Rep: 3380
    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    Looks like Village Idiot has described the same procedure in the post before mine. Had I saw it in time, I would have spared me a lots of writing... :rolleyes::eek:
     
  4. jowfx
    Joined: Mar 2015
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Long Island NY

    jowfx Junior Member

  5. daiquiri
    Joined: May 2004
    Posts: 5,373
    Likes: 255, Points: 93, Legacy Rep: 3380
    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    Anchor and winch method is generally used on LCU's, not on LCVP's and LCM's. Small LC's generally don't have stern anchor winches, as far as I know. We have some ex-Navy folks here in the forum, so they can correct me if I'm wrong.

    Anyways, if there is a possibility to install a winch anchor, it might be a good option IMO. A positive side-aspect of using the winch is that the pull of the anchor cable reduces the possibility of broaching if the vessel is beached in a surf zone. A possible problem is that the tow line must not become slack during LC retracting from the beach, or it can foul the prop.
     
  6. philSweet
    Joined: May 2008
    Posts: 2,493
    Likes: 288, Points: 83, Legacy Rep: 1082
    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    I hope you mean something off a telecom truck and not a J C Whitney special.

    https://www.aceindustries.com/p-10664-8000lbs-thern-power-winch-4hwf-series.aspx

    You will need to be careful that you can spool enough line, and that it is not figured on 3/16 line size. Duty cycle also figures in.
     
  7. FAST FRED
    Joined: Oct 2002
    Posts: 4,519
    Likes: 110, Points: 63, Legacy Rep: 1009
    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    Line might work much better as only a couple if ft of movement is required to get off the beach , and you may have to retrieve 100+ ft of anchor line.

    Far faster to hand over hand the line as you back up.
     
  8. Village_Idiot
    Joined: Oct 2007
    Posts: 382
    Likes: 15, Points: 18, Legacy Rep: 138
    Location: USA

    Village_Idiot Senior Member

    Also keep in mind that most winches are rated at full pull when they are nearly empty. A full spool will have considerably less pulling power due to decreased leverage. A secondary short cable (or anything, really, like a piece of driftwood) should be draped over the winch cable to absorb energy in case the cable snaps.

    As a distantly-related tangent, you can set up a good winching point on nearly any non-rocky soil, say for helping a truck get up a slippery boat ramp, or pulling through a deep mud hole. Simply carry a length of chain with you, maybe 12' (anchor chain will work, also) and three or four re-bar, about three feet long, preferably with a T welded on one end. Lay the chain on the ground where you want your winch point (in-line with the vehicle to be pulled), pound the re-bar into the ground, through about every twelvth link in the chain. This will make a very secure winching point. When done, you can pull the re-bar (which is why I suggested T-handles) and take with you for next time.
     
  9. Mr Efficiency
    Joined: Oct 2010
    Posts: 10,401
    Likes: 1,029, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Use of a long loading ramp seems like good insurance against getting stuck, you can edge away gradually as loading proceeds, but still have contact with the shore.
     
  10. TANSL
    Joined: Sep 2011
    Posts: 6,881
    Likes: 518, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    I think to know what equipment is best suited for this boat it would be very important to know the type of beach / coast which will operate, the type of load carried, the type of propulsion, and some other things.
     
  11. Tiny Turnip
    Joined: Mar 2008
    Posts: 792
    Likes: 222, Points: 43, Legacy Rep: 743
    Location: Huddersfield, UK

    Tiny Turnip Senior Member

    I like the brutal efficiency the little CALMAC RO-ROs use when landing - when the door/ramp hits the slip, the rams keep on pushing, effectively slightly lifting the front of the ferry and exerting enough force on the ramp/slip point of contact that the ferry is anchored by it. They unload and load vehicles, then retract the rams, which sits the ferry back down in the water and unanchors it at the same time. Of course, this is on a concrete slip, but the principle might work for a landing craft if the beach was steep and firm enough. Oh, and they do use the thrusters to hold the boat against cross currents...

    [​IMG]

    [​IMG]
     
  12. whosail
    Joined: Nov 2014
    Posts: 10
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Henderson,NV

    whosail Junior Member

    Daiquiri has the solution.

    Dave, the old guy
     

  13. keysdisease
    Joined: Mar 2006
    Posts: 794
    Likes: 43, Points: 28, Legacy Rep: 324
    Location: South Florida USA

    keysdisease Senior Member

    The cruise ships that call on the private islands in the Bahamas use tenders with ramps to load and unload on the beach. The bigger ones take 200-300 pax. What they do is just back off a little as they load up so as not to get stuck.

    If the have to use a lot of reverse it knocks fat drunk sunburned tourists on their buts a hundred feet in both directions from the landing, very entertaining
     

    Attached Files:

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.