Hey incxalx,
I assume that was you with the Pirate Flag that my dog and I passed as we were headed in. Sorry I was not able to help with the fish finder as I have never owned one and know nothing about them. It's one of those things on my list to think about getting one day.
As Iceman mentioned, the conditions were not the best for catching fish in the HH. I fish here quite a bit. I knew that for the time period I was fishing, the tide was not optimal. We were out for a short 2-1/2 hours without a bite. However, this is what I expected to find and may have fullfilled my own prophecy. We went out more for the sake of paddling around to get some sun, fun and exercise.
Here is a good site to use for checking tides:
http://tbone.biol.sc.edu/tide/sites_uswest.html. You can also get nice apps for your phone, I use one called 'US Tides' on the android. Both show a graphical representation of the tides.
You will get different advice on how best to use the tide charts to increase your catch. This advice from experienced anglers will help shorten up your learning curve as Patrick mentions. Be aware of the tidal movement and note when you have the best luck and you will start to develop your own theory. If you log your fishing success, you will start to see the patterns with time of year, weather/temperature, tide, species targeted, etc. Personally, I have found the best luck when the water starts really moving on both sides of a high tide. During the peak, my luck usually tapers off.
The water looked like a cup of black coffee when I launched. For these conditions, I have usually had better luck with a black spinner (as a reminder, I caught no fish on this day!). One theory is that the vibrations and flash from the spinner have a chance at attracting a fish even though the visibility is limited. I have always heard to use dark colors in murky water. This has worked well for me and also in the evenings or early morning. Perhaps it is because I have had luck doing this and have confidence in what I am using through experience. Until I can actually see and sense as a fish, the explanations are all theory. This is why the guys recommend changing colors often. After much more time casting, you will start to find what works best for you in certain conditions.
The same goes for the retrieve, vary it and you will start to see what works best for you. I have fished my entire life and am happy to still have those moments that surprise me when I change up the retrieve due to a different reason. For instance, on more than one occasion, after an accidental overrun of the spool and resultant delay in the retrieve, I have unexpectedly hooked up a halibut. I then started incorporating the long delayed retrieve as one variation. Another time, I was using the same slow typical, bounce the bottom technique with no success, then due to an approaching power boat operator with no regard to my presence, I reeled in as fast as I possibly could and got a violent hit by a sand bass. That made me more conscious to incorporate the ultra fast retrieve variation.
The forum is a great place to pick up ideas on different things to try. For instance, I only started using spinner blades after tips from Iceman and Landwhale. This has worked so well that now I usually set one rod up with a spinner blade and one with a plastic.
I'd be happy to show you the areas I have had best luck in HH, but again, I did catch a skunk yesterday.
Good luck!