The Ship Model Forum

Thanks for this description of how the rams worked. It explains why the two elements can be at different heights.

Guess what? A really good image of these had been hiding in plain sight from me all the time:

page 28, photo 22 of David Griffith's "Ship Models from Kits" shows a builder's model of a KGVII-class battleship directly opposite to the main mast, derrick and rams (plus their upper pulleys). I wonder which model this is and if there are any more pictures online?

Cheers,

GrahamB

Hi
a rough decsription of their operation. There's a twin sheave (2 pulley wheels) on either end of a piston/cylinder (the ram). One end of the ram is fixed, the other can move, as it is basically a pulley system that pushes the pulleys apart or constricts.

As the piston has steam, oil, etc, applied under presure, the sheaves get further apart and more line is taken in which would 'lift' something. If the distance between the sheaves decreases, the line is let out.

In the upright version, I'd guess the base is the fixed part allowing the top half to move?

It was an interesting question.
Cheers

Hi TCC,

this sounds about right to me and the photo of Agamemnon's versions show them pretty well, also the asymmetry. The KGVII rams tend to be more equal in height though.
Understanding the purpose of a structure goes a long way to helping get the modelling right!

Many thanks! :thumbs_up_1:


GrahamB

[quote="GrahamB"]Hi,

something I can't fathom yet. I'm building a 1/700 Combrig HMS Britannia as HMS Commonwealth but am stuck on some prominent structures either side of the mainmast that feature in photos of the whole KGVII class, but are not included in the kit. These are column/pillar like but seem to be slightly different port and starboard. I thought they might be boat-derrick stumps (this could be attached to the starboard ''thing" mostly?). Can anyone enlighten me please or point to a clear photo of (builder's model for example?)? Any help gratefully received.

Cheers,

GrahamB

P.S I've got the Burt volume and the Warship 2001-2002 article.[/quote]

I think they're to do with the main mast derrick, yes, pretty certain now. They are the 'hydralic rams' of the main derrick hoist... one controls the purchase, the other the topping lift. In some ships they are horizontal and below decks (thus protected) and can't be seen... in some ships they are horizontal and above deck and in some, the two are sited upright close to the mainmast, one either side. [I have them chronologically in the wrong order. first are upright, then Horizontal, then horizontally below decks]

If you look at photos of the Lord Nelson and Agamenon, is this them? the higher being between the searchlight?

[img]http://i60.tinypic.com/2u71xt3.jpg[/img]

The only other thing they could be is for the 'helm indicator' line.... but I'm not convinced. They're not for the helm indicators as on the Lord Nelson class they are both to port of the mainmast, not either side as in later ships.

Hi,

something I can't fathom yet. I'm building a 1/700 Combrig HMS Britannia as HMS Commonwealth but am stuck on some prominent structures either side of the mainmast that feature in photos of the whole KGVII class, but are not included in the kit. These are column/pillar like but seem to be slightly different port and starboard. I thought they might be boat-derrick stumps (this could be attached to the starboard ''thing" mostly?). Can anyone enlighten me please or point to a clear photo of (builder's model for example?)? Any help gratefully received.

Cheers,

GrahamB

P.S I've got the Burt volume and the Warship 2001-2002 article.