About landing crafts

Discussion in 'Boat Design' started by karayelhb, Sep 15, 2011.

  1. yipster
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    yipster designer

    i asume you want CG centered but you cant find the waterline first without having ALL weights
    as waterline is 1 liter discplacement for every kilo total weight, better start drawing plans first
     
  2. Wavewacker
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    Wavewacker Senior Member

    Rfleet, good luck figuring that out, I'd be going for a low slung bridge deck between those tanker-toons, I see there are deck flanges on top. There is a pod catamaran in the forums I have seen that might be inspiration for you. I see you have your project in another thread as well so I will follow it there.

    Great CO, thanks! I will look up your suggestions. It looks to me to be simple enough for me to do. That cut away section tells me alot and I like the idea of the sole being flat. I wonder if closed cell foam between the bottom and sole is a good idea? Thinking of a little security but also insulation for humidity since I want a cabin.

    Look forward to more pics if you can without much trouble...much appreciated!

    I think you said the sides were about 30", do you see any problem going up to 40" on the outside (as the sole appears to be about 6" at the center from the keel providing 3' to the gunnel inside)? The bottom may come out a bit keeping porporations similar. This would push the beam out above and taking the ribs up for the cabin allowing more room for the cabin walls going up about 24" and then come in with the roof say 12" with a rise of say 6" and crowning the center to provide about a 6'2" headroom at the center....if you can picture that.

    Forward of the cabin, perhaps the sides could sweep upward slightly to the bow as you described. If sides could be contoured with the cabin providing a little more height a sliding or lift up hatch over the forward area would be fantastic to enclose the cargo.

    Ah, yes, displacement speed is fine, If I can run 10/12 knots I'll be running as fast or faster than most cruisers, low power and good fuel consumption is more what I'm looking for for a long haul.

    I realize weight will be an issue adding so much, but if you (or anyone) thinks this is doable at 26 to 28', (maybe longer) I'll clean out the garage!

    Initial stability seems to a concern with these, has anyone ever added proas or sponsons to reduce the roll?
     
  3. Wavewacker
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    Wavewacker Senior Member

    Question?????

    How are the forward sides of a landing craft supported or tied in without a bow tied in? The stern behind a cabin is not an issue as it is all tied in, but when the bow ramp is down seems like the sides would just flap around.

    I can see the sole providing support above the bottom, but if sides are say 4' high....then what???

    Thanks!
     
  4. cor
    Joined: May 2008
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    cor Senior Member

    Wavewacker, the open front is deffinately a structural issue. On my boat I adressed the issue a couple ways.

    There is a frame right at the door opening. The joint on this frame where the side meets the sole has a gusset on it that does take up a little bit of the opening space. The larger the gusset the stronger the frame, but the more space it takes up.

    The second thing that I did is make very heavy wales on both the inside and outside of the side panels. These curved laminations make a beam in plan view that resists the in and out flex of the sides.

    The last thing that I did to strengthen the front is make the ramp a structural part when it is closed. There are two latches that pull the ramp closed and two that pull the sides in tight to the edge of the ramp. The sides of the ramp has a step that locks into the sides of the hull when it is closed. These stiffens up the front of the boat when under way.

    The photo show the front of my boat. The latches that hold it closed are mounted on top (stainless DeStaco over center clamps). The sideways latches are not installed in this photo, but the yellow ratchet strap is there to pull the sides together when closed. If you look close you can see the trianglular gussets in the corners.

    The purple ropes hold the ramp up (keep it from opening too far). Normally the ramp is closed when underway, but occasionally when traveling in twisty rivers or when fishing I will leave it down. It is a great platform to stand on when casting.

    One other thing to note in the photo is the two anchor lines that come off from the sides of the boat. On this boat the ramp hinge line is rather low and a regular bow eye would not work well for an anchor line. I run a Y bridal from those eyes on the sides to a single anchor in front. I also have another anchor that I tie off to the stern and run at an angle back to the beach. This keeps the boat perpendicular to the beach if there is a wind or current.

    Remember, I am not an expert. Any advice you get from me is worth what you are paying for it.

    C.O.
    http://whatsintheshop.blogspot.com/
     

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  5. hoytedow
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    hoytedow Carbon Based Life Form

    Since we are talking about landing crafts, this one landed several times:

    "You're a 19 year old kid. You're critically wounded and dying in the jungle somewhere in the Central Highlands of Viet Nam ..

    It's November 11, 1967. LZ (landing zone) X-ray.

    Your unit is outnumbered 8-1 and the enemy fire is so intense from 100 yards away, that your CO (commanding officer) has ordered the MedEvac helicopters to stop coming in.

    You're lying there, listening to the enemy machine guns and you know you're not getting out.

    Your family is half way around the world, 12,000 miles away, and you'll never see them again.

    As the world starts to fade in and out, you know this is the day.
    Then - over the machine gun noise - you faintly hear that sound of a helicopter.
    You look up to see a Huey coming in. But.. It doesn't seem real because no MedEvac markings are on it.

    Captain Ed Freeman is coming in for you.

    He's not MedEvac so it's not his job, but he heard the radio call and decided he's flying his Huey down into the machine gun fire anyway.

    Even after the MedEvacs were ordered not to come.He's coming anyway.


    And he drops it in and sits there in the machine gun fire, as they load 3 of you at a time on board.

    Then he flies you up and out through the gunfire to the doctors and nurses and safety.

    And, he kept coming back!! 13 more times!!
    Until all the wounded were out. No one knew until the mission was over that the Captain had been hit 4 times in the legs and left arm.
    He took 29 of you and your buddies out that day. Some would not have made it without the Captain and his Huey.

    Medal of Honor Recipient, Captain Ed Freeman, United States Army, died last Wednesday, 12-14-2011, at the age of 70, in Boise, Idaho.


    May God Bless and Rest His Soul.


    I bet you didn't hear about this hero's passing, but we've sure heard a whole bunch about Lindsay Lohan, Dr. Murray, that sicko Sandusky, and a 72- day sham marriage.


    Shame on the media !!!


    Medal of Honor Winner Captain Ed Freeman


    Now... Please pass this along. Honor this real hero.

    Please........"

    I wasn't there and never said I was. I never served due to health reasons. I still have the right to show my gratitude for those who did.
     
    Last edited: Feb 17, 2012
  6. Wavewacker
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    Wavewacker Senior Member

    Hoyt, Ed "Too Tall" Freeman was an ARMY Aviator in the 1st Cav, not the Airforce and that was in la Drang Valley in 67. Cpt. Freeman served in the enlisted ranks in WWII and Korea and was at Pork Chop Hill and was latter commissioned. I met the man but never had the honor of serving with him. I forgot how tall he was, but I believe he barely got in due to height restrictions. And, no, I had not heard that he passed away. You're right, he was a true hero and a warrior's warrior. He truly set the example for all Army Aviators who served with him and those who will forever follow him.



    And, BTH Hoyt, poetic or artistic license is not allowed with implications that you were there.
     
  7. hoytedow
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    hoytedow Carbon Based Life Form

    Thanks for the corrected information. I passed the word second-hand and did not have all the facts straight. :eek:

    Where did I say I was there? I never did.

    What does BTH stand for?
     
  8. Wavewacker
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    Wavewacker Senior Member

    QUOTE:cor;530849: Wavewacker, the open front is deffinately a structural issue. On my boat I adressed the issue a couple ways.

    "There is a frame right at the door opening. The joint on this frame where the side meets the sole has a gusset on it that does take up a little bit of the opening space. The larger the gusset the stronger the frame, but the more space it takes up."

    CO, I considered this and making them bigger as a motorcycle doesn't need much room, only a couple feet....everything else could go over the hump.

    "The second thing that I did is make very heavy wales on both the inside and outside of the side panels. These curved laminations make a beam in plan view that resists the in and out flex of the sides."

    This I had not thought of, but thought of using steel "C" channel over the gunnels, that's a great idea!

    "The last thing that I did to strengthen the front is make the ramp a structural part when it is closed. There are two latches that pull the ramp closed and two that pull the sides in tight to the edge of the ramp. The sides of the ramp has a step that locks into the sides of the hull when it is closed. These stiffens up the front of the boat when under way. "

    Yes, I thought some bolts might help as well when underway.....funny seeing some guy standing on the ramp fishing and seeing no bow on a boat!.


    "The photo show the front of my boat. The latches that hold it closed are mounted on top (stainless DeStaco over center clamps). The sideways latches are not installed in this photo, but the yellow ratchet strap is there to pull the sides together when closed. If you look close you can see the trianglular gussets in the corners."

    Yep, I blew up your pics to 400X and examined every inch.....thanks!

    "Remember, I am not an expert. Any advice you get from me is worth what you are paying for it."

    Duly noted, expect my check in the mail! :D
     
  9. rasorinc
    Joined: Nov 2007
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    rasorinc Senior Member

    Wavewaker.
    "Hoyt, Ed "Too Tall" Freeman was an ARMY Aviator in the 1st Cav, not the Airforce and that was in la Drang Valley in 67. Cpt. Freeman served in the enlisted ranks in WWII and Korea and was at Pork Chop Hill and was latter commissioned. I met the man but never had the honor of serving with him. I forgot how tall he was, but I believe he barely got in due to height restrictions. And, no, I had not heard that he passed away. You're right, he was a true hero and a warrior's warrior. He truly set the example for all Army Aviators who served with him and those who will forever follow him."



    "And, BTH Hoyt, poetic or artistic license is not allowed with implications that you were there."
    I have re-read Hoyts posting 3 times and find no artistic license or implications you suggest.
    Stan Rasor, USMC
     
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  10. spidennis
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    spidennis Chief Sawdust Sweeper

  11. hoytedow
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    hoytedow Carbon Based Life Form

    This is what happens when sources aren't properly checked. My fault. I will be reluctant to take the word of my source in the future.

    My apologies,
     
  12. Wavewacker
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    Wavewacker Senior Member

    Ooops, the BTH was supposed to be a BTW, by the way.

    No problem at all....

    The story as it goes was "you and 29 others" as if in the first person I think from my highschool english class, I didn't do well in english. It was as the story was told by someone there, Hoyt didn't claim to be there, it was just the style....I may have read into it as well, some of us old guys get touchy about war stories.....:D

    It's a good thread on LC's hope we can get back to them and not be sidetracked to LZ's

    I guess using channel on the gunnels is cheating some on a wood boat, but seems it would sure stiffen things up.
     
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  13. Wavewacker
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    Wavewacker Senior Member

    I have never seen a "canal boat" in my neck of the woods. They are probably unique to Europe since we have fewer canals. I really like them as they are efficient and make a nice liveaboard. Long and narrowish, crowned roofs with lower power requirements. That concept as am LC seems possible.

    A scow will work and will probably be the way to go. Small ones seem to have stability issues, so I'm thinking that small amas would give peace of mind. An aft cabin, trawler pilothouse style with a forward deck would be really nice. I think the forward deck could open up from the center to the sides like barn doors to provide a covered hold. Seems it would need to be in the 28 to 32 foot range, ply on frame.....???? Such would be something like the canal boats in Europe....
     
  14. rfleet1066
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    rfleet1066 rfleet1066

    Armed with ignorance.

    I've never designed anything that floats on water. Out of ignorance, I am proceeding in a logical progression of design and building, satisfying the basics first. I am at a point of establishing the beam, now. Only then will I be able to calculate deck weight, size and placement. To get some boyancy information, I am making a model, 1/20 scale. I had planned for a 20ft beam, but it looks a bit skinny.

    Can someone expound on the pontoon effect as it relates to landing craft?

    Ryland
     

  15. Wavewacker
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    Wavewacker Senior Member

    Ryland, just looking I would think your water line would not be any higher than half those toons and below the cone bows. Who ever made them should have known. I would try to sling my deck at least a couple feet below the TOS of those toons. I'd also try to get an arched cabin top, maybe an upper deck if desired, to support the span of 20+ feet. I would not attempt any sit on top deck like a pontoon boat at that span with the weight of those tubes....but, I'm not an NA....maybe some 3' diameter pipe could do it, similar to the legs on an off shore platform in A-31 steel I believe.

    As a LC, that thing would carry more than my bike, more like my truck with the bike in the back! Better go with a heavy deck and ramp. With that, if you had any jet ski buzzing you, you could just swat them with the ramp!

    There are tons of pics of landing crafts, some are cats, on google.
     
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