Model Boat Mayhem - Forum

Please login or register.

Login with username, password and session length.
Pages: 1 [2]   Go Down

Author Topic: Floating Crane information  (Read 3557 times)

pompey

  • Shipmate
  • *
  • Offline Offline
  • Posts: 4
  • Model Boat Mayhem is Great!
  • Location: Portsmouth
Re: Floating Crane information
« Reply #25 on: July 13, 2019, 11:09:18 PM »

I have emailed you back from a different email address as my tablet seems to have died!
Logged

raflaunches

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 2,687
  • The Penguins are coming!!!
  • Location: Back in the UK, Kettering, Northants
Re: Floating Crane information
« Reply #26 on: September 25, 2019, 05:32:25 PM »

Hi everyone


We started the crane build over the weekend, well the easy part of it anyway!
We decided to build to 1/96 scale for 1) practical size
                                                      2) matches the majority of my fleet


It is small in some dimensions but when complete the height will be close to 3ft!
The hull is essentially a barge measuring 24.9 inches long by 10 inches whilst the overall depth is only 2 inches! We have had loads of fun sticking the rubbing strips on, makes it look quite decorative.
At the moment the sides and bottom are 1/16Ē marine ply supported by 8mm square wood strips.
It will have lead ballast in the bottom and will be permanent with some to trim the model when we are finished.



Logged
Nick B

Help! The penguins have stolen my sanity, and my hot water bottle!

Illegitimi non carborundum!

tigertiger

  • Global Moderator
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 7,034
  • Location: Kunming, city of eternal springtime, SW China.
Re: Floating Crane information
« Reply #27 on: September 26, 2019, 02:20:00 AM »

I know nothing about models of flat bottomed vessels, so feel free to ignore me. With the effects of wind and water being 'not to scale', is there a risk that the flat bottom and high crane sides will cause the barge to drift a lot if there is wind? If that is the case, would it help to add a long keel to the construction, even if not part of the original vessel?
Logged
The only stupid question is the one I didn't ask

derekwarner

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,085
  • Location: Wollongong Australia
Re: Floating Crane information
« Reply #28 on: September 26, 2019, 03:41:43 AM »

Following on from the interesting and concise examples of flotation & rolling moments by Glynn Guest....we could consider the flat bottom crane barge of Nick B ......[and understanding 1 cubic " of water  = 0.036 lb]


25" length x 10" beam x 1" draft  = 250 cubic " or ~~ 9lb [water] weight displacement on a 250 square " footprint


If we maintain the length, halve the beam & double the draft.....


25" length x 5" beam x 2" draft = 250 cubic " or ~~ 9lb [water] weight displacement but on a 125 square " footprint

So any breeze [considered as constant] has to move the same 9lb of water friction against/over the surface of the underwater hull, however the righting forces are to the order of the same change in beam ratio & resultant surface footprint area of the hull in the water

Most un-powered barges have push/pull assistance movement by tug or tender vessel, or if stationary use of anchors or mooring wires for positional stability

1. I am pretty sure GG would concur with this premise
2. Nick.......how do these displacement estimates match your build considerations?

Derek
Logged
Derek Warner

Honorary Secretary [Retired]
Illawarra Live Steamers Co-op
Australia
www.ils.org.au

ballastanksian

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,594
  • Model Boat Mayhem inspires me!
  • Location: Crewkerne
Re: Floating Crane information
« Reply #29 on: September 30, 2019, 08:54:11 PM »


Nick, Great start! What a whopper she will be when complete.


We need a topic or room just for all these useful formulae to drop into.
Logged
Pond weed is your enemy

raflaunches

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 2,687
  • The Penguins are coming!!!
  • Location: Back in the UK, Kettering, Northants
Re: Floating Crane information
« Reply #30 on: October 02, 2019, 09:01:28 PM »

Hi everyone


A bit late in my replies-sorry about that!


The crane is completely unpowered (other than to move the crane itself) and will be towed around the lake by a couple of 1/96 scale tugs I also have under construction. When not being towed it will be moored up thus negating any need for a keel or any form of anti drift tech.
Iím not sure about the rolling moments at the moment as I canít find the actual tonnage of this particular crane lighter, the original vessel I was asking about (CLIV) had a tonnage of about 3500 tons but it was a larger vessel. We know the waterline so we will see how much lead is required to get to it! Just got to get it fully waterproof. :-))
Logged
Nick B

Help! The penguins have stolen my sanity, and my hot water bottle!

Illegitimi non carborundum!

Capt Podge

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 3,289
  • Location: Blyth, Northumberland
Re: Floating Crane information
« Reply #31 on: October 02, 2019, 09:24:03 PM »

When not being towed it will be moored up thus negating any need for a keel or any form of anti drift tech.



Just to clarify please Nick... do you intend mooring the barge away from the quayside or mooring up against it?
... just curious  %)


Regards,
Ray.
Logged
Pop top campervan needed

raflaunches

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 2,687
  • The Penguins are coming!!!
  • Location: Back in the UK, Kettering, Northants
Re: Floating Crane information
« Reply #32 on: October 02, 2019, 10:14:53 PM »

Mmmmm, youíve got me thinking now! At Wicksteed we have a wooden strip to protect your boat from colliding with the concrete edge- it usually sits just beneath the waters surface. I have a feeling that the model will sit away from the edge of the lakeside when moored. I donít intend to moor up too far from the edge due to me probably having to get my feet wet! :D
Logged
Nick B

Help! The penguins have stolen my sanity, and my hot water bottle!

Illegitimi non carborundum!

Capt Podge

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 3,289
  • Location: Blyth, Northumberland
Re: Floating Crane information
« Reply #33 on: October 02, 2019, 10:30:09 PM »

I see what you mean.
You could try attaching two chains to a weight - one chain goes to the vessel, the other (longer one) attaches to the shoreside.
Put the barge in the water, toss the weight whatever distance suits, remembering to hold onto the shoreside chain for securing in place.


I think that should work  %)

Then it's just a case of hauling in when you want the barge alongside.
Regards,
Ray.
Logged
Pop top campervan needed

raflaunches

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 2,687
  • The Penguins are coming!!!
  • Location: Back in the UK, Kettering, Northants
Re: Floating Crane information
« Reply #34 on: October 02, 2019, 10:40:58 PM »

Hi Ray,


Iíll give that a go when the hull is fully waterproof- many thanks for the idea :-))
Logged
Nick B

Help! The penguins have stolen my sanity, and my hot water bottle!

Illegitimi non carborundum!

derekwarner

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,085
  • Location: Wollongong Australia
Re: Floating Crane information
« Reply #35 on: October 02, 2019, 11:40:11 PM »

Nick....


If Ray is suggesting chain as a weight, remember when the presumed weight of anchor and chain is deployed to the bottom, the combined weight negative to the flotation of the vessel......chain out = displacement reduced = free board increased


 :o  .....if the vessel were tethered to a wharf [in a perfect world] the weight of chain is shared equally between the vessel & the wharf


1. Sharing equally means the vessels 1/2 alters it's displacement
2. The other 1/2 is neutral to the mass of the earth as the total mass was always there in the first place  :embarrassed:

I understand tethering usually refers to horses.,.....but am sure you get my drift  {-) 

Derek
Logged
Derek Warner

Honorary Secretary [Retired]
Illawarra Live Steamers Co-op
Australia
www.ils.org.au

Capt Podge

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 3,289
  • Location: Blyth, Northumberland
Re: Floating Crane information
« Reply #36 on: October 02, 2019, 11:49:48 PM »

Some good info there Derek. Of course, the medium doesn't have to be chain - twine or something similar could be utilised, like the type used in fishing line / nets, just as long as it's waterproof  :-))


Regards,
Ray.
Logged
Pop top campervan needed

dodes

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 654
  • Location: Hampshire
Re: Floating Crane information
« Reply #37 on: October 18, 2019, 02:58:21 PM »

Hi Nick, looking forward to seeing your crane completed. Someone was mentioning wind effect, well that was always the problem with the real ones, one pilot moving CL5 at Devonport manage to get the crane driver to move the crane jib round , the pilot said it was then like sailing her. Usual power was a dog alongside with the stern overhanging a bit and a single unit tractor tug of the Felicity class in the bow.
Logged
Pages: 1 [2]   Go Up