I'll start with some questions and grand speculations since I'm no Yanny expert.
Q: Raw water or Fresh water cooled (anti-freeze) ? I'd guess FWC from the pic.
Q: How old or new is the engine? Original? What boat installed in?
Q: Does the white smoke dissipate pretty quickly or is it persistent?
- The silver upside down 'U' shaped thingy seems to be where your raw water enters your exhaust. Call it the exhaust mixing elbow or something like that. Clearly it should not be venting steam in your engine compartment so that is problem #1.
- How did problem #1 arise? It could be that water was left in that fitting and froze. We've had a few months of real winter in NY and probably the same where you are.
-- If it was cold enough to freeze then I'd question how well your engine was winterized in the first place. If the raw water pump was not drained or at least allowed to suck through a gallon or 2 of anti-freeze then your raw water pump impeller may also need looking at or replacing.
-- If it was cold enough to freeze then I'd also look into the thermostat which, if malfunctioning could cause cold(er) water to come out of the exhaust. There is a thing called a 'bypass loop' on some engines that is controlled by the thermostat which might keep cooling water from entering the engine block by sending it out the bypass loop.
Here is a temporary
fix for the symptom, but maybe not the cause: JB Weld.
"It stays pliable for about 30 minutes after mixing, sets in 4-6 hours, and cures fully in 15-24 hours. It's water-proof; petroleum-, chemical-, and acid-resistent; resists shock, vibration, and extreme temperature fluctuations, and withstands temperatures up to 500° F. J-B WELD is super strong, non-toxic, and safe to use. Before it sets, you can clean up with soap and water."
J-B Weld Company - J-B WELD Product Information
I'm not sure you have the time to even try this as this high temp. epoxy cures in 15 - 24 hours or so.
Be glad you also have sails. Good luck.