By chance are the cables that are not winding properly, newer than the
others? I'm guessing that may be the case, since newer=stiffer (usually).
Let me ask this: if it works fine with the boat on the lift, why would you
run it up without the boat on the lift? Just checking operation, I
understand, but the lift was designed to, you know, lift a boat. It would
seem like a drag to have to lower the lift first, then drive the boat on it,
to lift it out...if you know what I mean.

--Mike

"Chuck" wrote in message
news:7QaDg.86278$FQ1.35449@attbi_s71...
I recently purchased a home on the water that included what I call a
cradle-type boat lift. Simply put, it's 4 pilings with an aluminum cradle
mounted between them, and the boat is lifted from the water on this cradle
via two electric motors. There are blue plastic pulleys (sheaves) at the
end of each beam and a few other places. The cradle has 2 long, carpeted
bunk boards that run the length of the cradle. It has 5/16" cables and is
rated for 10,000 pounds.

I haven't moved my pontoon boat to the lift yet, and when I run the empty
lift up and down I noticed the following problem when the lift comes up
(not down). The two bunks appear even and level but the problem is that
when there is no pontoon boat weight on the lift and I raise it up, the
sheaves on one side nearest the dock where the controls are lose cable
tension and the cables then windup unevenly on the spool. If I push down
slightly on the nearest plastic PVC upright used as a guide bumper the
cables get tight and all is well. Said in another way, if there is even a
slight amount of weight on the lift like from my foot pressure on the
inboard (dockside) bunk board there is no problem. This is not a buoyancy
problem from floating bunks because the bunks are already out of the
water. This is not a bound or frozen sheave problem because I used a
come-along to take the weight off of each of the pulleys and they spin
freely. Going down is no problem at all.

I suppose I could just add some solid cinder blocks to the center of the
cradle I-beams, but I really want to know is the physics of why it's
acting like this? Someone please help me diagnose this.

Chuck