Well I have never see that before.....   Maybe time for me to clean my winches as well.

I just received my boat, it's been on the hard for around two years. I've been dutifully fixing the broken bits, ya know, a thousand here, a thousand there. Here I was thinking I was close to ready, and you go and show me something I would have never thought of! 

Ross is correct. BTW, the thermostat deletion should only be temporary. Could be as simple as air in the system. Here's what I would be doing/checking. First, install a new thermostat and burp. Here’s my procedure: Remove radiator cap Fill to 1” below cap Leave cap off and start engine. Check for water being expelled from transom. This should be part of every engine start! Test the coolant temperature with finger. Should be getting warm within a few minutes. Monitor temp gauge. After a few minutes, rapidly rev up/down the engine a few times to expel air Coolant level may change. Carefully add some if it goes too much below the 1” below cap level When coolant becomes hot or overflowing, install cap, fill reservoir. Should not take very long, perhaps 15 minutes Shut down engine, let it cool. Level in reservoir might go down. This is normal. Add some to keep at a known line Start engine, allow to get to normal temperature and can maintain Leave dock and test those winches!