That's normal with the stock installation, because of the voltage drop from the wires running all the way back to the cockpit switch and then back to the engine (it is, after all, a high current draw item).
If you haven't done so, try installing a relay to bypass this loop, as in this article form decades ago by the then-tech editor (the late Bob McCullough). Its an easy, inexpensive modification (on our boat, we screwed the relay to the wooden bulkhead, but this meant we had to detach it anytime we removed the bulkhead for access, so probably better to find somewhere on the engine to bolt it). On our former C36Mk1, it reduced the glow plug time from almost a minute to around 10 seconds: www.catalina36.org/members/technical/upgrades/glow-plug-solenoid
—
Matthew Chachère
s/v¡Que Chévere!
(Formerly 1985 C36 MKI #466 tall rig fin keel M25)
2006 Catalina Morgan 440 #30.
Homeported in eastern Long Island, NY
That's normal with the stock installation, because of the voltage drop from the wires running all the way back to the cockpit switch and then back to the engine (it is, after all, a high current draw item).
If you haven't done so, try installing a relay to bypass this loop, as in this article form decades ago by the then-tech editor (the late Bob McCullough). Its an easy, inexpensive modification (on our boat, we screwed the relay to the wooden bulkhead, but this meant we had to detach it anytime we removed the bulkhead for access, so probably better to find somewhere on the engine to bolt it). On our former C36Mk1, it reduced the glow plug time from almost a minute to around 10 seconds:
www.catalina36.org/members/technical/upgrades/glow-plug-solenoid
Matthew Chachère
s/v ¡Que Chévere!
(Formerly 1985 C36 MKI #466 tall rig fin keel M25)
2006 Catalina Morgan 440 #30.
Homeported in eastern Long Island, NY