Monday, 11 March 2013

Progress update

To date I have been describing the context and background to our current activity. This is the first post of 'news'.
We are concentrating very hard at the moment on the 'Installation Phase', by which I mean the installation of the new support cradle, and we are under pressure of time for a variety of unavoidable reasons. As soon as we were able to agree the basic design, at the end of January, we instructed the fabricators to proceed. In the past two weeks we have been addressing in greater detail the method by which we will remove the boat from the cellar.
The design, a small glimpse of which I include here...

... is effectively for two cradles, one for display and the other for lifting. The lifting cradle has a superstructure of girders and braces to rigidify and reinforce it, whilst the display cradle is more refined. The display cradle will be galvanised, too, and eventually willl be painted. The central steel beam upon which the boat sits is common to both. The arms and ribs of the display cradle can be removed and replaced with those of the lifting cradle one at a time, meaning the boat will remain well-supported throughout.
We had imagined that the boat would be pulled out of the cellar on its lifting cradle, but in the event we have had to abandon this idea. This is because we checked and re-checked the tolerances and realised that the cellar opening would have to be widened by 15 cm. We did a little exploratory work on site and established that the door jambs are substantial and original. It wouldn't be possible to alter them. We have instead opted to modify the design of the display cradle a little to provide anchors for tensioning ropes; these will brace the arms, one to another. And Geoff Mitchell, Head of Technical Services at MNH, has devised some Teflon skids for the cradle that'll help it slip easily down the rails.
Geoff and I also took some careful measurements of the vertical distances in the cellar. We are confident that we have enough room to lift the boat sufficiently to allow us to insert the longitudinal girder. We have worked out how to get the girder into position using manhandling alone (it'll weight 400 kg). And we've also devised a means of laying the the rails before we lift the boat. And that reminds me, I've got to arrange for their delivery to site - can't stop! Until next week.....

No comments:

Post a comment