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setting dock post underwater

dug | Posted in General Discussion on July 30, 2006 09:42am

   I want to build a small dock on my  pond.The dock will probably be about 5′ wide and about 8′ to 10′ long.The water is down this year due to drought but is still about 2′ deep where I want to put the post.

    The plan is to use 6” x 6” pt. I was thinking of renting a large air compressor to basically evacuate the ground under the post but I was reading in another thread about using a trash pump in reverse to sink post in sand and it got me to thinking.

  I’ve never done this before so does anyone know which method would work best underwater or if ya got any better ideas throw em out at me.   thanks

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  1. MikeSmith | Jul 30, 2006 09:50pm | #1

    that's how all the dock builders do it.. they jet them in with water pump..

    if you google on jetting piles  you'll get lot's of info..

     basically you can tie your pipe to the post and use the post to guide the jet

    leave the post in place and pull up the jet

    Mike Smith Rhode Island : Design / Build / Repair / Restore
    1. dug | Jul 30, 2006 10:20pm | #3

           So let me get this right. I get a trash pump and connect a 2'' pvc pipe to the exhaust end of it and strap it off to the side of the post and try to hold the post as plumb as possible and fire up the pump and sink it in until it hits hard bottom an I`m  guessing it will backfill itself. Sounds simple, is this right?

      1. MikeSmith | Jul 30, 2006 10:26pm | #5

        yeah, you got it.. course .. it might be like rasslin a 'gator

        usually these guys have a small barge with an A-frame and a  hoist

        you could also rig a gin-pole and hang the operation from thatMike Smith Rhode Island : Design / Build / Repair / Restore

        1. dug | Aug 01, 2006 12:13am | #14

          yeah, you got it.. course .. it might be like rasslin a 'gator

          usually these guys have a small barge with an A-frame and a  hoist

          you could also rig a gin-pole and hang the operation from that

           

              I saw a funny commercial on tv today, the one where the guy had a gin pole set up on his roof with his kid hooked to it. He was gonna run him down in the chimney with a brush to clean it out. His parting words were scrub good now; or something like that.

            Anyway, I thought of this thread.  I can see it now, me on the tractor,with a site cut pine tree bale wired to the hay spear on the front, my 10 yr old boy bale wired to the end of said tree, hanging out about 10 ft over the water holding the post plumb......... OK, son hold er straight I'm about to turn this hose on!  :)   I have a plan!!! 

                And I thought this was gonna be complicated.   :)

  2. MikeSmith | Jul 30, 2006 09:51pm | #2

    BTW.. for dock work you special order your posts treated to .60 retention instead of the .4 or the .25

    .60 is also spec'd  for pole -building construction

    http://www.adobelumber.com/treated_lumber.shtml

    Mike Smith Rhode Island : Design / Build / Repair / Restore



    Edited 7/30/2006 2:54 pm ET by MikeSmith

    1. dug | Jul 30, 2006 10:23pm | #4

          .60.... do it once and do it right, Thanks

  3. frenchy | Jul 30, 2006 10:28pm | #6

    dug,

        Please don't use pressure treated.     The pond doesn't need the polution.    Go to a nearby sawmill and buy some white oak timbers that size they will cost about the same price and resist rot just as well.

     

  4. bldrbill | Jul 30, 2006 11:51pm | #7

    dug--I used 4X4 posts for mine, shaped like a tee with a 5'X10' leg and 6'X12' on top.  I drove the posts into the bottom mud with a steel post driver/slide hammer made to fit down over the posts with handles on each side.  They drove down about 30" to 36"until they wouldn't go any further.  I built up the 2X8 framework for the dock on the bank, floated it out into the water and used that to locate the spots where to drive posts. The framework is heavy, you will need a helper or two.My dock is solid as a rock-I don't think you need 6x6.   Bill

    1. johnharkins | Jul 31, 2006 02:18am | #8

      if you're talkin still water
      a way I've done it is drive say three pieces of 3/4" rebar in pond bottom 4" apart then put a sonotube over them and fill w/ concretegood crossbracing a must as they need each other to maintain erection

      1. User avater
        McDesign | Jul 31, 2006 03:53am | #9

        Heh-heh!

        He said "erection"

        Heh-heh!

        Forrest

      2. dug | Aug 01, 2006 12:19am | #15

        if you're talkin still watera way I've done it is drive say three pieces of 3/4" rebar in pond bottom 4" apart then put a sonotube over them and fill w/ concrete

        good crossbracing a must as they need each other to maintain erection

               Reckon I could just drop some of dat Viagra in them sonatubes with da crete. :)

    2. dug | Jul 31, 2006 04:11am | #10

          Yea, the 6 x 6 may not be overkill, but I could prab'ly get by with less. I'm sure they would be easier to set.

      1. MikeSmith | Jul 31, 2006 04:49am | #11

        it's not just a question of strength.. it also involves mass... the thicker one can take more abrasion... and more rot before it gives way

        piles usually go at one place.. the ice line... or the mud lineMike Smith Rhode Island : Design / Build / Repair / Restore

  5. MGMaxwell | Jul 31, 2006 03:45pm | #12

    Rent the pump. Set the suction with a filter in your pond. It is  noncollapsible. The ejection hose is collapsible and usually 2 inch diameter. They should have a reducer to take it down to 3/4 inch or 1 inch. You supply galvanized pipe either 3/4 or 1 inch about 4 feet for your needs. Flatten the business end so you get a good "jet". Fire up the pump (you may need to prime it).

    Aim the jet of water into the mud under the post you're trying to set. The post will sink into the bottom of the pond in less than a minute unless you hit old fallen tree limbs, rip rap or other junk. Wear gloves to yank this stuff out of the way if you encounter any. Hold the post in place for a few minutes and you're set. You can make plumb adjustments even the next day. They will solidify nicely.

    Use CCA water treated. It's still available for water/marine use. It's not supposed to be soluble in the water. Don't cut it and get the sawdust in your pond though.

  6. davem | Jul 31, 2006 08:27pm | #13

    down in the marsh, they sink a #4 washtub to the bottom, stand the post in it and pour concrete down a 6 inch pvc tube to fill up the washtub. but then, down here, bedrock is 10 feet from the surface of china.

  7. ponytl | Aug 01, 2006 02:03am | #16

    I've done this... and have shownothers how and most stick with my method...

    First... piles rely on side friction as much as what the end bears on... if you google it you'll find put'n posts/piles into a hole is not a great idea in most cases... a driven pyle is much more stable than a sunk one... 

    (BTW to sink one most people use a pressure washer with a long 3/8 steel pipe to "jet" the water away from bottom of the post and just let it sink down to however deep you want it... you will have a very loose pyle...)

    i mostly use 4x4 pt  but i have done this with 6x6 also...  i have a pyle driver i welded up from the base of a sign post...  8x8 or 8" round about26" long with the sign base/mounting flange still welded on (they are usually over 3/4" thick plate) i then weld loops or handles on each side and you have a post driver...  I do not cut the posts into a point... driven end stays sq or flat... driven till you can't drive anymore or where it's get'n to only drive'n down less than 1/16"  (start long with your posts)

    drive 2 or 3 or 4 posts about where you need them... no reason to be exact... then frame to  the posts you have set, i drill & bolt vs nail... but nails hold it in place first...  NOW  you can lay a few deck boards across your framing and determine where you want your other posts/pyles and you'll be able to drive them next to the faming you have in place then nail/bolt them and continue... I use alot of joist hangers and straps  and i cross brace anything i can... your framing only has to be level... it doesn't need to be real square,  I always try to place a post where a joist and rim joist  meet... thats why i frame with just a few posts/pyles set... then sink the rest of the pyles where i have 2 bolting surfaces (where rimjoist and joists meet)...

    i built a 10x20 ft dock like this with just 3 pyles set until i had the frame built then i drove the rest where they'd do the most good... some you might want to leave long for rails or boat tie ups  some will need to be cut flush before you nail off your deck...  but this way will keep you out of the water after the first few are set and basic frame'n done.....

    hope i explained this enough for you to picture it

    p

    1. johnharkins | Aug 01, 2006 03:54am | #17

      yes that wood make for a firm mixthe more I read of these water jets I'm thinking the rebar / sonotube is making a lot of sense
      not much to it - can you go three feet high w/ sonotube and never have wood framing members in water?

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