Cantilevered suspension dock

My friend bought a lakefront cottage last fall. It has a 6 foot wide, 30 foot long wood dock sticking out over the water. The far end is supported by guy cables up over tall posts ending at 2 anchor eyebolts in his yard. He's not sure what's underground but the anchors are bent and appear inadequate to the task of supporting so much weight.

Would it be preferred to dig deep holes for concrete piers to anchor the eyebolts, or use long ground anchor rods driven in the earth (perhaps with underground concrete?) at the same angle as the guys--like what's found on utility poles?

(there is no "Bridge Construction" topic so I'm hoping to find good suggestions here)

 

I'm not a pro on this topic, but I would imagine that a helical pier (guy anchor) screwed into the ground inline with the angle of the cable would be best.

 

I would first determine when or why the anchor attachments bent. You didn't mention any movement or failure of the anchorage in the ground so it might just be a problem with that bit of hardware.

 

Only time I've heard of "helical piers" was for foundation repair & used special heavy equipment to drive them in. Is there a DIY version?

What is the proper name for the galvanized cable anchors that hold up utility poles? The Google results I'm getting are for short eye bolts.