Results 1 to 17 of 17

Thread: How did they do it.

  1. #1
    Join Date
    Jan 2013
    Location
    UK
    Posts
    1,488

    Default How did they do it.

    In the 60's I was taught how to mark the building berth to accept the single plates of the ship's keel.

    This involved a simple straight line inclined at a declivity of say 5/8" in a ft (For launching) and dead straight for plumbing the rest of the ship construction in its length. (Which ran into hundreds of ft)

    Simple to achieve with a stretched chalk line but the length of ships excluded that option.

    As this procedure had been developed over the years the Yard Owners wouldn't have released money for lasers or even theodolites, which were available then, How did they do it.
    Last edited by Chippie; 09-21-2022 at 12:24 PM.

  2. #2
    Join Date
    Oct 2008
    Location
    Walney, near Cumbria UK
    Posts
    59,318

    Default Re: How did they do it.

    Are you talking about the declivity or CL?
    Chalk lines were shewn to not be great. Over a long distance, even a light line will sag, so a dumpy level or light boxes were better.
    If for the CL a chalk line will wiggle as it is lifted and snaps down.
    It really is quite difficult to build an ugly wooden boat.

    The power of the web: Anyone can post anything on the web
    The weakness of the web: Anyone can post anything on the web.

  3. #3
    Join Date
    Mar 2001
    Location
    Grosse Pointe, Michigan, USA
    Posts
    15,855

    Default Re: How did they do it.

    A a former surveyor, this sounds like a job for a surveying level.

  4. #4
    Join Date
    Oct 2008
    Location
    Walney, near Cumbria UK
    Posts
    59,318

    Default Re: How did they do it.

    Quote Originally Posted by Dan McCosh View Post
    A a former surveyor, this sounds like a job for a surveying level.
    My yard did use dumpy levels AKA theodolites. But light boxes had their place as well, as well as taught piano wires and plum bobs.
    It really is quite difficult to build an ugly wooden boat.

    The power of the web: Anyone can post anything on the web
    The weakness of the web: Anyone can post anything on the web.

  5. #5
    Join Date
    Oct 2002
    Location
    N. Thetford, VT
    Posts
    431

    Default Re: How did they do it.

    My hunch is that they would've done it with water levels. A length of hose with some clear sighting risers at ends and you can lay out dead level for as far as your hose is long.
    https://en.wikipedia.org/wiki/Water_level_(device)

    -Leif

  6. #6
    Join Date
    Jan 2013
    Location
    UK
    Posts
    1,488

    Default Re: How did they do it.

    [QUOTE=Peerie Maa;6729141]Are you talking about the declivity or CL?
    Chalk lines were shewn to not be great. Over a long distance, even a light line will sag, so a dumpy level or light boxes were better.
    If for the CL a chalk line will wiggle as it is lifted and snaps down.[/QUOTE

    Let's start again.

    A vessel is to be built that is 500ft long on a surface that stretches DOWN to the river.

    The surface falls downward at 1/2" to the foot.

    The Naval Architect requires a fall of 5/8" to the foot.

    How does the Liner Off tackle that to provide a datum for the vessel to be built by the Shipwrights?
    Last edited by Chippie; 09-22-2022 at 12:46 AM.

  7. #7
    Join Date
    Jan 2013
    Location
    UK
    Posts
    1,488

    Default Re: How did they do it.

    Quote Originally Posted by Dan McCosh View Post
    A a former surveyor, this sounds like a job for a surveying level.
    Can you describe how that would provide the required datum something tangible to work to as we weren't aware of that method?

  8. #8
    Join Date
    Jan 2013
    Location
    UK
    Posts
    1,488

    Default Re: How did they do it.

    Quote Originally Posted by Torna View Post
    My hunch is that they would've done it with water levels. A length of hose with some clear sighting risers at ends and you can lay out dead level for as far as your hose is long.
    https://en.wikipedia.org/wiki/Water_level_(device)

    -Leif
    The sloped surface she is to be built on limits the length of producing a line long enough for our purpose.
    Last edited by Chippie; 09-22-2022 at 02:17 AM.

  9. #9
    Join Date
    May 2017
    Location
    Cumbria, UK
    Posts
    359

    Default Re: How did they do it.

    Re surveyor's level it is a telescope with a fine horizontal line on the lens. You can set it up level on a tripod using its built-in sensitive spirit level.
    You look through it at a staff (a tall rectangular pole) which has a scale on one face. the reading you get tells you how far below the level the ground is.
    You look at the starting point, known, as a bench mark, then swivel round to where you want to set the next keel block, measure the distance in feet, multiply that by 5/8 inch and add the result to the original reading.
    The person holding the staff slides it up and down until the surveyor sees the reading he wants.
    Carry on down the dock as far and as often as you like.

    BTW they used that method for the survey of India and it was amazingly accurate.

    Re the hose, as above you can do it in steps. You do not need to do it in one go.
    Last edited by oldcodger; 09-22-2022 at 03:58 AM.

  10. #10
    Join Date
    Oct 2002
    Location
    N. Thetford, VT
    Posts
    431

    Default Re: How did they do it.

    Quote Originally Posted by oldcodger View Post
    Re the hose, as above you can do it in steps. You do not need to do it in one go.
    I've never actually done a long sloped reference with a water level, but this is how I would do it if tasked:
    Grab an 8' long stake and make a "grade mark" every 5" along it's length. Go to the lower end of your site and pound it into the ground nice & vertical. Set more short "grade stakes" 8' apart going up the slope. Every 96' set an 8' grade stake.
    Again starting at the bottom grade stake use the water level to transfer the 2nd lowest grade mark to the 2nd grade stake, 3rd mark to 3rd grade stake, &c.
    The 8th grade stake (which is an 8 footer) gets the 8th grade mark. Then on that one, make another set of grade marks every 5" above. Lather, rinse, and repeat.
    A couple blokes, a pile of grade stakes, and a 100' water level could lay out a sloped reference every 8' over a 500 foot run in a couple hours.
    Done in five 96 foot "shots" it'd probably accurate to 1/4" over all. Most of the error would creep in because the reference stake changed 4 times - and that was only dictated by using reasonable height stakes and the specified slope of 5/8" per foot. On a more level site and with a 500' water level, you could establish a set of level reference marks accurate to 1/16" anywhere and overall.

    -Leif

  11. #11
    Join Date
    Mar 2001
    Location
    Grosse Pointe, Michigan, USA
    Posts
    15,855

    Default Re: How did they do it.

    Quote Originally Posted by oldcodger View Post
    Re surveyor's level it is a telescope with a fine horizontal line on the lens. You can set it up level on a tripod using its built-in sensitive spirit level.
    You look through it at a staff (a tall rectangular pole) which has a scale on one face. the reading you get tells you how far below the level the ground is.
    You look at the starting point, known, as a bench mark, then swivel round to where you want to set the next keel block, measure the distance in feet, multiply that by 5/8 inch and add the result to the original reading.
    The person holding the staff slides it up and down until the surveyor sees the reading he wants.
    Carry on down the dock as far and as often as you like.

    BTW they used that method for the survey of India and it was amazingly accurate.

    Re the hose, as above you can do it in steps. You do not need to do it in one go.

    Beat me to it--the level is used to determine the height above the ground, and can be used for some distance. I was on a survey crew, and the usual tolerance was a tenth of an inch. We were measuring the volume of an excavation, but it would work for a straight line.

  12. #12
    Join Date
    Oct 2008
    Location
    Walney, near Cumbria UK
    Posts
    59,318

    Default Re: How did they do it.

    [QUOTE=Chippie;6729276]
    Quote Originally Posted by Peerie Maa View Post
    Are you talking about the declivity or CL?
    Chalk lines were shewn to not be great. Over a long distance, even a light line will sag, so a dumpy level or light boxes were better.
    If for the CL a chalk line will wiggle as it is lifted and snaps down.[/QUOTE

    Let's start again.

    A vessel is to be built that is 500ft long on a surface that stretches DOWN to the river.

    The surface falls downward at 1/2" to the foot.

    The Naval Architect requires a fall of 5/8" to the foot.

    How does the Liner Off tackle that to provide a datum for the vessel to be built by the Shipwrights?
    If the 1/2 to the foot declivity is accurate and constant, the liners off/shipwright only have to know how far down the ways they are to be able to set the height of the blocks above the ground. If it was an old-fashioned earth berth with a timber mat that could not be relied on to be true, then a dumpy level set to the correct declivity on the top of the first blocks to be erected will give you what you need.
    It really is quite difficult to build an ugly wooden boat.

    The power of the web: Anyone can post anything on the web
    The weakness of the web: Anyone can post anything on the web.

  13. #13
    Join Date
    Jan 2013
    Location
    UK
    Posts
    1,488

    Default Re: How did they do it.

    A dumpy level can only do horizontal.

    Old fashioned ground it certainly was Nick.

  14. #14
    Join Date
    Oct 2008
    Location
    Walney, near Cumbria UK
    Posts
    59,318

    Default Re: How did they do it.

    Quote Originally Posted by Chippie View Post
    A dumpy level can only do horizontal.

    Old fashioned ground it certainly was Nick.
    Sorry, I meant Theodolite, I did not realize that dumpys were dumbed-down theodolites.
    A theodolite (/θiˈɒdəˌlaɪt/)[1] is a precision optical instrument for measuring angles between designated visible points in the horizontal and vertical planes.
    It really is quite difficult to build an ugly wooden boat.

    The power of the web: Anyone can post anything on the web
    The weakness of the web: Anyone can post anything on the web.

  15. #15
    Join Date
    Jan 2013
    Location
    UK
    Posts
    1,488

    Default Re: How did they do it.

    Quote Originally Posted by Peerie Maa View Post
    Sorry, I meant Theodolite, I did not realize that dumpys were dumbed-down theodolites.
    I think I have mentioned here that the Yards were in private hands in the 50's and they were reluctant to release money on ANYTHING.

    Hence the workforce became innovative and boy didn't the Owners exploit that fact.

  16. #16
    Join Date
    Oct 2008
    Location
    Walney, near Cumbria UK
    Posts
    59,318

    Default Re: How did they do it.

    Quote Originally Posted by Chippie View Post
    I think I have mentioned here that the Yards were in private hands in the 50's and they were reluctant to release money on ANYTHING.

    Hence the workforce became innovative and boy didn't the Owners exploit that fact.
    In which case you were probably stuck with piano wire and a turnbuckle to crank up the tension.
    The really fun job would be setting up the standing ways, under the hull, in amongst all the shores, with the camber required for a successful launch.
    It really is quite difficult to build an ugly wooden boat.

    The power of the web: Anyone can post anything on the web
    The weakness of the web: Anyone can post anything on the web.

  17. #17
    Join Date
    Jan 2013
    Location
    UK
    Posts
    1,488

    Default Re: How did they do it.

    No the most problematic job I encountered I think occurred strangely was when I was in charge in one of the level building docks which I mentioned "removed most of the problems" earlier.

    The Ship being built was too long to be completed owing to flair of the Stem.

    The lower section of the fore end was fitted and the draft marks were erected and she was floated out with the two top units placed in the hold.

    These were duly fitted and when welded the draftmarks were to be applied on the complex shape of the foreword plates not only homing it to the stem but also around the bulbous bow and then the outward flare on the journey upward.

    All done with the ship in motion with vessels and currents we could have well done without.

    How was it done?

    Perhaps another Thread.
    Last edited by Chippie; 09-22-2022 at 06:33 PM.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •