I have had a hydraulic 12v solar Hewitt lift going on 5 years. The solar system is pretty solid and as long as you have a fresh deep cycle battery you will be good there. Depending on how fresh battery is you can discharge the battery if you lift it more than 3 or 4 times a day, but can always jump it with boat battery in a pinch.
Here are some of the times when I ran into trouble. A couple of times our lake 'flooded' and the the motor box went under water and bushings went on the motor 2x, so you got to keep that motor out of water. I now have motor box stored on cinder blocks to keep it above high water when everyones dock goes under water. I have had the hydraulic lines fail 3x. Two of the times I had a line blow out, a beaver chewed through them. Anyone need a beaver pelt???? The lines are not hard to replace as long as it is not too cold out and you can get replacements at tractor shops or the local NAPA dealer here can custom make them.
You are spot on with the lack of redundancy or back up. If motor goes, or lines blow, or seals on hydraulic pistons fail, your boat is stuck unless you could winch it or pump the fluid with an alternative mean. I have used a drill motor with a blade bit that fit in pump flang to get it off the lift, but it is slow going and more than a trivial hassle.
Last edited by bmartin; 03-09-2010 at 7:33 PM.