After 24 years the white plastic drain screw-in insert fittings at the top of the drains cracked, on the port side broke clean away (see Photo #1).

NOTE: The 'basket' in the left drain is new, not original (was just dropped into the hole), while the drain is original with its flaked-off chrome.

After shopping for a tight right angle fitting at Home Depot, Lowe's and Canadian Tire I came up empty and the quote to order parts from the marine store started at $80 per drain, however a bath tub drain at HD was the right fit and a light grey coloured rubber step-down hose-clamp adapter at the Canadian Tire hardware store looked about right (see Photo #2).

All that was required was a right angle drain fitting without any flange on the top, for which the original white fittings could be re-purposed (see Photos #3 & 4).

While plumber's putty is recommended for around the new drain fittings against the opening of the stainless steel sink, experience has taught me that it dries out to a chalk over ten years AND there is quite some flexing over the years under a galley sink, so I used a more flexible glue -- Automotive GOOP (see Photo #5).

On top (with a 1/4 turn of the new fitting to ensure coverage), and as there is a considerable gap in around the stainless steel, also around the neck/collar of the new fitting (see Photo #6).

Once the lower nut is tightened up to the flange with a medium-sized monkey wrench the drain is 100% solid for years to come (low expectations...) (see Photo #1]7).

Then twice around with self-adhereing electrical/plumbing black flex tape to ensure a tight hose clamp compression fit around the thread of the drain fitting (see Photo #8).

Slip the flexible rubber adapter on the two fittings and tighten all three hose clamps and repeat on the starboard side drain and we're good to go for many years (see Photo #9 attached) at a significant savings over the marine suppliers' prices -- I hope!