Help identifying this?

[mhinnc]

From a box of extras left on the boat when I bought it. A Google image search didn't provide an exact answer. Wondering if I can toss it? Thanks for any info.

[Stingo]

Yep, you can toss it, but you will regret doing so.

I think it's the plug for when you pull your speed log out to clean it.

[mhinnc]

Lol. I'll keep it. Thanks Stingo!

[Stingo]

My pleasure.

If my guess is correct, and because you didn't know what purpose it served, before using it, make sure it is spotlessly clean and grit free. Then just before inserting it, liberaly apply some silicone grease to those two o-rings so that it goes in quickly and seals properly.

Most people have it tied close to the speed log so that it is always close to hand eg if you need to take the speed log out in an emergency or simply to clean it

[AKA-None]

And be aware that a lot of water will appear to be sinking your boat but it won’t unless you are really slow