Additional Planking on Coal Bunkers in Tenders

Good Morning All,

I'm just sitting here working on my Blackstone engines, putting in some real coal loads. I have noted this on many other engines, but I am wondering if there is a specific reason that the additional wood planks were added to the top of the coal bunkers on the tenders.

I know that it would give them more coal capability, but why was this not done in the original design of the tenders?

Just curious. Might not be a specific reason behind it or not, but I find it intriguing that some tenders had the extensions and others did not.

Thanks for the info.

Craig
Somewhere up in NoCo