Model Boat Mayhem

The Shipyard ( Dry Dock ): Builds & Questions => Working vessels R&D: => Topic started by: wombat on July 23, 2006, 04:20:55 pm

Title: Submersible Recovery Barge
Post by: wombat on July 23, 2006, 04:20:55 pm
Hi All,

As most of you know I am building a tug.....

Anyway, SWMBO has said that she rather fancies a submersible barge to go with it. I think this is inspired by seeing the Mighty Servant 1 on Discovery.

So does anyone have an plans for a barge which can be submerged to go under a recovery item then re-floated. Failing that can anyone point me at any examples or offer any hints on how to implement one. 

I am looking at something with a length of about 1.5m

Tim (the Wombat)
Title: Re: Submersible Recovery Barge
Post by: towboatjoe on July 23, 2006, 04:46:55 pm
It can be built, but it's another question if it will work. Building a barge to submerge and come back up is no problem with the componets for submarines now-a-days. Here's the main factors....

1. You'll need towers on all four corners of the barge as locators so you can center it under the vessel you're trying to lift.
2. You'll need a connection to the boat that will allow the barge to go up and down without pulling the boat under with it.
3. If the vessell has very much weight to it, will the barge have enough mass ballast to be able to lit the weight.
4. If the lifted object is not centered perfectly as it's being lifted, it and the barge will roll over.
5. With those problems solved, it'll be virtually impossible to lift a vessel with a round hull unless you have hull supports in the deck.

The easiest way I see of doing something like this and making it work is to make a pontoon barge with a net that can be lowered, steer the barge into the vessel, then lift the net.
Title: Re: Submersible Recovery Barge
Post by: KitS on July 23, 2006, 04:52:54 pm
Tim,

There's an article about one of them in Chris Jackson's 'Tug Boat Book'. Funnily enough I read it this morning!

It looks like one of the main problems is to get the various volumes correct, but the author has some very good ideas, such as the barge's bridge structure slides up it's columns as the barge sinks. Then when they reach an end stop the increased bouyancy of the bridge stops it sinking any further.
Title: Re: Submersible Recovery Barge
Post by: wombat on July 23, 2006, 07:34:28 pm
Hi TowboatJoe,

Thanks for the comments.

Towers at the corners - well maybe some sort of indication of the corners, at the leading edge corners, something flexible. The MS1 has fixed towers which are used to indicate trim.

For the coupling, maybe tow lines and the facility to switch to "pusher" mode for positioning under the recovery item.

Displacement shouldn't be too much of a problem - back of a fag-packet calculations suggest that for a lenth of 1.5m and a beam of 0.5mm you get a capacity of 7.5Kg for each 1cm of displacement - if you design for a 10cm variation in displacement, this gives a capacity of approx 75Kg which should be more than adequate for such a toy.

Misalignment of the load will increase the risk of roll, but with a wide beam and alow centre of gravity, this effect could be minimised. Alignment "grabs could also be designed in to centre the barge on the load (I'm thinking that this barge would not be scale so pretty much anyfink will go)

Agreed - round bottoms would be a problem - but I see this as a toy/proof-of-concept sort of idea.

KitS,

THe volumes would be a problem - but they can be trimmed for. The biggest problem I see is maintaining trim as the barge sinks and rises. I guess you would need a set of sealed bouyancy tanks which keep the hull neutrally bouyant so it cannot be sunk by careless flooding of the sinking tanks, and have them at bow and stern.

Maybe it would be worth doing a feasibility study, just as a fun project

Tim the Wombat
Title: Re: Submersible Recovery Barge
Post by: kninghtsy on July 24, 2006, 08:03:51 am
Hi Tim
I found these pics on the web.  May be a guide to what you need.

Regards Trevor

Title: Re: Submersible Recovery Barge
Post by: wombat on July 24, 2006, 10:13:18 am
Hi Trevor,

Thats the sort of thing, thanks  ;D

I see the new owner is converting that one to be self propelled, rather than being just a straight barge.

Tim the Wombat
Title: Re: Submersible Recovery Barge
Post by: kninghtsy on July 24, 2006, 10:32:19 am
A bit more.  A late friend of mine (Ray) built a working model of Mighty Servant 3 (1:100).  Went up and down just like the real thing.  It had two flooding tanks, fore and aft, each separately controlled.  When sinking and rising it tended to heel to one side because the water would fall to the side that was just that bit lower than the other.  Didn't turn turtle though.  I remember the first time Ray showed it off at a model show in a pool.  It sank; we pushed his 1:96 HMS Manchester onto it with our 1:100 tugs;  and he brought it back up.  He got a standing ovation from the crowd watching!  Very impressive.  We decided that doing it again such a model would need at least 4 tanks so that both fore and aft and side-to-side balance could be adjusted.

Trevor
Title: Re: Submersible Recovery Barge
Post by: davej on July 24, 2006, 09:21:11 pm
Not strictly an unpowered barge but here's a dutch guy's 1/50 Super Servant 4 Semi Sub Heavy lift Ship

http://www.scheepsmodelbouw.ismijnhobby.nl/








Woo, my first post!!!!!
Title: Re: Submersible Recovery Barge
Post by: J.beazley on February 01, 2007, 03:34:16 pm
did you get anywhere with your research into this wombat???
been looking at my hovercraft hull that i made 9 months ago thats 1.3metres long by 520beam.
im thinking i could make a submersible barge out it, it wouldnt be scale or anywhere near it but like you say could be an iteresting project.

Jay
Title: Re: Submersible Recovery Barge
Post by: catengineman on February 01, 2007, 11:24:44 pm
If you manage to overcome the flooding / floating points then how about an inverted V as the deck area which could center and locate the lift of rounded hulls, there could even be some frames that could be placed and locked down when you need to recover a flat bottomed vessel.

Just a thought

Richard.
Title: Re: Submersible Recovery Barge
Post by: Martin (Admin) on February 02, 2007, 11:17:20 am


Wasn't there an article about making a working model in one of last years magazines?
Can someone remind me of article....... ???
Title: Re: Submersible Recovery Barge
Post by: tigertiger on February 02, 2007, 01:56:06 pm
I don't know what I am talking about  ::) but bow thrusters at both ends might help with fine manouvering.

If you are also the owner of the vessel being recovered then maybe elctro magnets on the 'deck' of the recvoery vessel and strategically placed pieces of steel in the recovered vessel could pull every thing into line.

Just some thoughts
Title: Re: Submersible Recovery Barge
Post by: johno 52-11 on February 02, 2007, 03:04:41 pm
Just make sure it dose not do what Mighty Servent 3 did http://www.cargolaw.com/2006nightmare_mightyserve3.html (http://www.cargolaw.com/2006nightmare_mightyserve3.html)  :o :o :o
Title: Re: Submersible Recovery Barge
Post by: tobyker on February 10, 2007, 03:43:37 pm
If you had a net suspended from the "corner towers" would this not centre the hull - tho it wouldn't look very scale. Otherwise you could have some springy "fingers" (in clear plastic) on the base of the barge to centre the hull. If of course you were always lifting the same hull, you could build in all sorts of cheats. Mind you, how about a false base to the dock with a hinge on the centreline that folds into a vee when the dock submerges - either by a servo/float arrangement, or you could put some buoyancy into the outer edges of the leaves. If you use a servo, it could also be triggered by a reed switch in the barge/magnet in the ship, or by a microswitch in the end wall of the barge nudged by the bow.

It depends whether you want a scale model for demos/tug towing, with either a dedicated "target" or "any vessel" capability, or whether you want a general purpose club recovery barge. There are some photos somewhere of that destroyer that hit a rock off Australia being recovered on a barge - didn't they have to modify the barge (or the destroyer?) so that it would fit?

Endless scope of experiment!