I'm replacing my steaming light (not just the bulb) It looks like the original on my '84 is a Perko #PKO-0945DP0CHR. An alternative replacement is the Aqua Signal Series 25 Masthead / Foredeck Light, in the Defender catalogue as

Item #: 700239
12 Volt / 10 watt festoon and 20 watt halogen
Black housing
Manufacturer: AQUA SIGNAL
Model Number: 25404-7

My concern is that the the Aqua Signal will have to sit on top of the circular welded-to-the-mast base on which the Perko is fixed and will make fitting the Aqua Signal to the mast difficult if not impossible. It does come with adjustable side flaps for securing to masts of varying sizes but from the on-line info about the light I can't tell whether those flaps will sufficiently reach back to the mast given the height of the circular base on which the light will set.

Has anyone dealt with this or made made such a replacement? Have you found another steaming light that might be a better replacement? Thanks.

I installed this light and it works fine. Had to de-install the circular mast adapter using a grinder, but it worked out.

Be sure to tap the holes for the screws and use Tef-Gel to keep the corrosion down.

One thing I will probably do next is replace the steaming incandescent and foredeck halogen bulb with LED versions.

Thanks. Did you have to grind the circular mast adapter all the way out?

Yeah I was thinking of changing out the bulbs for LED if I can find the right ones. I found one for my Perko stern light. The bow's a bi-color lens w/1 bulb so that would require 2 separate fixtures for colored LEDS.

I have a Hella version -- steaming light and deck light -- that looks like it will fit "over" the OEM mount, but I haven't installed it yet. Too much other stuff to do this season.