I moor my boat every Summer for 4-5 months and deal with the same yellow haze that you've described...I started detailing cars when I was 15, so I like to test out different products and have 2 options for you.
1. Starbrite Hull Cleaner
- my first choice! Spray it on, wipe it off...and literally within 5 minutes, your hull will be sparkling white. It's actually sorta magical because when you wipe it off, you'll still see some of the yellow haze in the hull, but then it disappears! You can check out my review I put on Amazon
...18 reviews and every one is 5 stars, tough to beat that! No damage to your gel coat either
2. I used SlimyGrimy earlier this Summer and it works well, but you have to scrub the hull with a brush, unlike the Starbrite. I only used it because they do not carry Starbrite at my local hardware store and I wanted to try out this stuff for comparison. I did like the fact that you could spray the SlimyGrimy bottle upside down, to get all the way under the boat.
Definitely apply a good wax once you're done! I would never use a household cleaner on the boat, it may
work but it's going to strip away/eat your fiberglass and gel coat over time.