So I'm looking at getting a few various attachments for my yak. So if I'm wanting to attach something to the side of the yak, lets say an anchor trolley for example, what kind of screw do you use? Do all the kits for things like this come with the screws needed? If I'm wanting to make some home made stuff, are there screws at home depot that I can use for this purpose?

Most kits come with hardware... that being said, I keep spare hardware on hand just in case.

The screws I use from hardware stores(Lowes,home depot) are stainless machine screws. I use either a nylon insert locknut or well nut(expansion nut is what they're called at the hardware store). Depends on location if I use a washer and locknut or wellnut. For size I find the #10-32x1" is pretty versatile and works for most applications. Sometimes I use a longer or shorter screw depending on the thickness of the accessory being mounted.
Most important thing is making sure they're stainless. Use goop if going the washer/locknut method, do not if using wellnuts.

Thank you. Could u please post a pic of your spare hardware? Im a visual prrson

ETBA nailed it. Good advice

These are the kind I use, they're just size #8-32 instead of the size I mentioned in my previous post.
The expasion(well)nuts are pictured at the bottom. They're usually located in a drawer with the specialty fasteners.
Hope that's helpful.

This video might be long but you'll be a pro at attaching any kind of accessorie and know which type of attachment is best for each situation. It's really an all in one video.

The cutaway kayak is great for seeing how each type affixes thru the hull.

https://m.youtube.com/watch?v=OO4oMI3wWm0

stainless