On another boat I had similar problem.
You need to find a welder, preferably someone who makes tops, who is willing to do it while its on the boat. Going to be really tough to get them to do it in the water...
They will weld the crack and then add reinforcing plates.
Pic below show plates in the corners
I doubt you have any wires in those so you should be ok.
Don't wait...it won't get any better on its own.
Think about adding some rod holders at this time because at $100 a pop they make doing the job more enticing to the welder...
I just helped a buddy with snaking back in the pipe wires after he had the the same problem repaired on his 87 Trophy Pro last week.
It's a common issue, the cracks develop over time and especially if you carry heavy rods up in the hardtop holders while slamming through rough seas.
He used L+E Welding, a local guy here in South Jersey who did an excellent job repairing the damage for only $500 bucks. He cut the pipes where they were cracked and inserted a smaller diameter short piece of pipe inside, then joined the two broken halves and welded everything solidly together.
By the way, he drilled holes at the lowest point in each branch of the pipes like the one that is evident in the pic of KY's pipe above.
He explained the holes are needed for boats stored up in the Winter cold since condensation forms in the pipes and without those drain/evaporation holes, ice could potentially form inside the pipes and cause additional damage and cracks.
I also had really bad cracks in the pipes on my 88 Trophy Pro that developed after having my boat hauled on a trailer back and forth to Florida in the Fall and back to NJ in the Spring (5 times) a few years ago.
(1200 miles X 5 = 6000 miles on a trailer with hard suspension over the highway at 60+ MPH with hundreds of bumps and potholes along the way cracked the pipes, and even the gelcoat in some spots, and loosened screws throughout the boat!
Had mine re-welded by a local guy in Miami who also did a great job, he fabricated triangle shaped angle-aluminum trusses and welded them under each pipe branch which give them additional support. (like the pic of Skunkboats reinforcing plates)
I don't expect the cracks will re-occur since I no longer transport it and keep my boat up on my lift in Florida year-round and fish on my buddies boats up here in NJ during the Summers and enjoy my own boat in Florida during the Winters.