Dagger depth marks

This might be a stupid question: What's the best way to mark lines on the dagger for various depth settings? I've found the sharpie to be useless...

http://www.catsailor.com/store/pc/DOWNHAUL-SCALE-485p11833.htm

Sharpie works ok if you clean the boards with acetone, but does fade away in time. You can use a paint pen which come in different colors or just put some sticker dots or shapes on the boards. If you use stickers try and find a place in the board that does not rub on the trunk and they will stay on longer.

Someone here (might have been Jake) in another thread suggested cutting into the gelcoat, filling it with a contrasting tinted gelcoat then sanding and polishing. I've never done it but it sounds like a great idea.

Thanks guys. Interesting ideas. Not sure I'm ready to grind away on my boards just yet - although if done right, it sounds like the best permanent solution.

I often sail with inexperienced crew, so saying "to the 2nd mark" is more repeatable than than saying "~about 18 inches". I guess I shouldn't be surprised at the amount of variation in what some people think 18 inches is

Whats wrong with permanent marker?

Even if you don't have experienced crew having depth marks is important. I might give the auto paint a go since I have some lying around. My boat doesn't even have marks for where the boards are completely up...rather frustrating.

So I used the auto paint. Seems to be working quite well so far but still doesn't tell you how deep the bottom is.