Floating dock which way ? Mast derrick ?

[2Tizwoz]

Derrick is no doubt the simplest arrangement to use

The guy lines must be well anchored.

There is some description of a homemade timber one here

I can remember seeing a timber pole with hand winches used for steel erection 50 years ago. They lifted steel trusses using timber the size of a telegraph pole.

 

[Refueler]

[ QUOTE ]
Yes, you're probably correct. I just looked at the way you had drawn the examples and made my judgement based on those proportions.

Sorry, if I assumed that you had posted something that was accurate /forums/images/graemlins/grin.gif

[/ QUOTE ]

No prob ... originally we were thinking at about drum size for width ... but then realised later it's a bit narrow. So increased the width a bit. My apologies that I failed to let people know ... you can appreciate what with running companys' and doing the house / pontoon stuff - my head can be spinning sometimes. Believe it or not I am also ill ! No joke ... I am ! But I'm one of those daft people that don't stop.

 

[whisper]

Get well soon.

We'll allow you to take a break over the next 4 days.

 

[Refueler]

[ QUOTE ]
Derrick is no doubt the simplest arrangement to use

The guy lines must be well anchored.

There is some description of a homemade timber one here

I can remember seeing a timber pole with hand winches used for steel erection 50 years ago. They lifted steel trusses using timber the size of a telegraph pole.

[/ QUOTE ]

Excellent link.

The diagram you show - I would not put the guy lines at the points indicated (named as 'swing-lines' in the sketch) ... I would fix them to the head of boom as we do on ships - it reduces the effort needed to swing a boom under load and also reduces the stress on its fittings. But the idea is good.

I was on for sheelegs - but was losing the ability to swing the boom to place dinghy to side after lift ! With this arrangement I regain the arc of swing without the need for substantial pile driving of king post - I'd completely forgotten about Scotch Derricks with base frames.
The basis of the design is to have scantlings of timber that are easily handled / erected but stayed and supported like a mast against bending etc. The timber providing compression support.

Back to drawing board and thge Pros & Cons sheet !

/forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

 

[Refueler]

[ QUOTE ]
Get well soon.

We'll allow you to take a break over the next 4 days.

[/ QUOTE ]

I wish I could ... Easter may be a holiday - but ships do not stop and oil traders want their blends etc.
Tomorrow once I get my guy back from his night duty in town ... think he found a lass !! we carry on ... most likely - him with a hangover but beeming smile on his face ... me feeling like a tank has run over me !