Motion compensating ship personnel transfer gangway - GIF

**Toolmaker51** · Sep 16, 2018, 10:28 AM

Originally Posted by ranald

When there is no wind you are invited to plot the course in the engine bay, breathing in the diesel fumes. I just KNEW they wanted me along for some reason other than my magnetic personality! LOL

Wouldn't having you plotting courses be counterproductive? What with the magnetic personality and all?
Sure, we're heading north, if I stand over there...

**ranald** · Sep 16, 2018, 11:19 PM

Hi Frank, mother nature can be so unpredictable. I remember a father & son trawling the west coast of Tasmania :trawlers less than 30 miles apart & the father got a call regarding a freak storm, which he could not see on the horizon. All the gadgetry on the sons vessel was totally destroyed from swamping etc, but did not sink. Lucky he did the mayday call to dad and all crew were saved & lucky to be alive. I believe the Great Lakes are wonderful places to lose a ship or plane (bit like bermuda triangle). We seem to know less about what is under the sea than in outer space.
Like Carolina, I've only been to Galveston in my mind.

**Ralphxyz** · Sep 18, 2018, 11:02 AM

Hope you don't have a seat on the couch along the sides, you'd lose your legs!!

Ralph

**Jon** · Sep 20, 2018, 10:02 AM

Circular Stewart platform. I like how a clock is in the background of this GIF.

**Frank S** · Sep 20, 2018, 12:43 PM

Yep the clock is running a little fast due to the accelerated gif speed LOL

**Loose Ctrl** · Sep 20, 2018, 02:01 PM

That too seems like a lot of stuff to fail in a boat. The last thing anyone wants is a system in a boat that fails and throws of the center of gravity and weight distribution. It could lead to a capsize or knockdown if weather and sea conditions aren't good.

**Frank S** · Sep 20, 2018, 08:54 PM

Loose crtl, you are absolutely correct even the simplest form of ballast weight transfer can go wrong at the most inopportune time. the transfer of fuel or water from side to side as ballast is about the simplest there is in larger vessels. Smaller pleasure or racing yachts the crew becomes the ballast. Try forcing yourself to hang over the rails in 20 ft seas on a 40 ft yacht while the captain desperately ties to maintain head way He can't even drop the mainsail because the the throat halyard and gaff are fouled If he could somehow manage to drop it to half mast then the lower portion could be lashed and the remaining would be about the size of a storm sail about the only thing you can hope for is that the peak halyard holds because once it goes the gaff will drop on 1 end and you loose all control.
All of the human ballast is fighting to hang on to scared to be sick. About this time the top sail shears away then suddenly the halyards are free and you manage to lower the main sail to quarter mast get everything lashed now it is just a matter of being able to hold steerage into the waves everything is peachy.
As human ballast you swear never to crew on one of these death traps again.

**owen moore** · Sep 20, 2018, 11:52 PM

Years ago, one of the model airplane magazines had a project similar to this that had servos that would tilt a glass plate in a similar fashion. The glass plate had a bullseye with concentric rings painted on it. The object was to place a marble on the bullseye and try to keep it there while operating a hand held transmitter. This was a training device for the early days of model helicopter flying. It looked very difficult.

**PJs** · Sep 21, 2018, 12:05 PM

That covered quite a number of degrees of movement in the first 40 seconds or so and appears that they changed cameras for the additional 5+ minutes and another rash of degrees movement. 6 degrees of freedom (6DOF) is quite a complex system.

Here is a doctoral thesis by two Swedish students...a bit long and necessarily math heavy, but the conclusion and their parameters and proofs are sound...I imagine they got their PhD's. Note: first part is in Swedish but the body of it is English.

Pretty cool Jon!