Platforms

[Don Case]

I've been making the forward and aft platforms for the Discovery1789. There doesn't seem to be any clamps or anything for the platform to sit on. The shape of the hull will support them but when you get to the midship platform the hull sides are almost vertical. What supports the midship platform?

[allanyed]

 Hello Don

David Antscherl's TFFM, Volume 1, pages 187 and 213 to 215 explains this in detail.  Too much to copy here without violating copyrights.   Suffice it to say there are no clamps, at least for the forward and aft platforms.  Also, there would be a solid construction of lodging knees, not just the beams that rest on the ceiling.   

Allan

[Roger Pellett]

Naval architects consider platforms to be minor deck like structures that do not contribute to the longitudinal strength of the ship.  (Modern definition)

 

Decks, on the other hand do contribute.  In steel hulled vessels the deck plating, welded or riveted and not broken up by hatches is a major strength member. This is less true in wooden ships as the planks are not joined end to end.  Here the deck clamp is the structural member that contributes to longitudinal strength, the beams to transverse strength, and the stanchions transfer loads from the beams to the keel.   It is therefore possible for a ship to have what a Naval Architect would consider to be a deck that is unplanked.

[Don Case]

I'm too quick to post. Dug a little deeper and Steel calls for hanging knees on every other beam. It doesn't work out nicely with four beams but it'll do. I'm tempted to put hanging knees on all four beams.

[allanyed]

Hi Don,

I believe Steel calls for hanging standards on the midship platform rather than hanging knees.   This is not the case for the fore and aft platforms where lodging knees are used on each side of each beam or sometimes a combination of a lodging knee and a hanging standard.   

Cheers

Allan

 

 

Edited June 22, 2021 by allanyed

[Don Case]

Thanks Allan, I missed that. Found hanging standard in my Oxford glossary. They should be easier to install.

[allanyed]

Glad to help Don, but for me hanging standards are more difficult. Hope that is not the case for you.   The only problem for me with doing a thorough piece of research to get all the information  is that I wind up seeing 10 other things along the way that I wind up reading.  In the end though I suppose that is a good thing as I learn 10 things I did know about before the search on the original subject began.  

 

 

Good luck.