You have the right idea overall, but the specifics are bad. First off, how many watts do you want to drive the speaker with? Is it running off batteries?
If it's only a watt or so, and you want it to run on 4 AA batteries, then perhaps an LM386N amp and a small 4Ω speaker instead of that 741. If the drive power needs to be higher, there are other options...
Here's an attractive one -
**broken link removed**
18W into 2 channels, volume control, switch, terminals, runs on 12V, costs $10 - you can't even buy the parts for that.
It will make a "click" every time the opto flag cuts the light to the sensor - it will conveniently sound very much like the click from the reel.
If you would rather buy the sensor instead of taking a mouse apart, it's called a "photointerrupter", and there are many to chose from. Here's one with leads that might make mounting more convenient -
Digi-Key - OR562-ND (Omron Electronics Inc-ECB Div - EE-SX1088-W1)
Here's a link to the spec sheet for a different unit, there's a small schematic at the bottom that shows the output -
https://www.electro-tech-online.com/custompdfs/2009/02/en-ee_sh3_series.pdf
We can set those resistor values once we know what the power supply is.
Adding the LED is easy, there will be a 2N2222 transistor connected to that same output to blink the light, a cap and diodes on the base so it doesn't stay "on" when the shutter isn't moving.
First we need to figure out what it's going to be powered with. Got +12V on your boat you would want to run to it, or is this going to be batteries?