I'm hoping somebody can help...

I need to replace the direct outlet hose from this y-valve to its seacock. (looks like PO used a flexible grey vacuum cleaner hose! - strange, the other hoses are all 'proper' white hose, but I don't know where to find more)


Jabsco says it's has 40 mm ports, but W/worths don't seem to supply hose that big, and I can't seem to find any pipe with a 40mm ID.

I did find this:
but I don't know whether it's appropriate - its ID is 38mm, does that mean I'll need to manipulate it on? (using heat I'd imagine)

If this isn't the right way to go, could somebody point me in the right direction please. I only need about 1.5m.
Many thanks in advance.