Again, I ask why?
Trying to see any worthwhile definition on a 2" or smaller screen has got to be nutz.
I own an Apple iphone, the 5c
Trying to see that screen in bright sunlight is an effort in futility.
Even when I go in to the settings and crank it all the way up.
Modern day fishfinders have screens built to be viewed in bright sunlight.
As a matter of fact, most of them also have backlighting to see them at night.
Viewing them is not normally a problem.
And the larger screens allow you to see more detail.
Now mix in a rolling and rocking boat.
Another thing I'll mention is that you don't need to spend $1000 to get a decent fishfinder or GPS if your budget is low.
One of my units is an old Lowrance M68C (thanks Pete)
It's a combo fishfinder and GPS.
The GPS is acceptable but the fishfinder is unbelievable for a small inexpensive unit.
I can see a 3/4 oz sinker and the dropper #6 hooks with an emerald on each at the bottom in 80 FOW.
You can't buy these new anymore but I just looked on ebay and saw two for $160 and the other for $175.
And the one for $160 was the more expensive ice machine unit.
The SonarPhone T-BOX that is required for this app runs $150-200 on ebay.
smartphone apps are awesome technology.
I love them.
But this one?
So again, I ask what's the point?