Blackwater tank crack

[Sunfishin]

I wanted to ask y'all what the best cement or adhesive is to fix my blackwater tank crack. About 1" long on bottom center area.
Two alternatives so far. ABS cement, prolly from Home Depot. Or Plastic Tank Repair from an RV parts dept.
The ABS cement takes a few hours to cure. The plastic repair is minutes to cure.
ABS uses fiberglass screen an the Plastic kit supplies fiberglass cloth.
Presently live aboard, so time is crutial. It doesn't leak when partially full, so lucky there.
What's y'alls thoughts?

[chuckster57]

I have used the tank repair kit a few times, works with proper preparation. It is fast so get everything ready before you start mixing the packets.

[Hblick48]

I used an abs plastic repair kit (glue and screen like pvc) to try to fix grey tank. It was cracked around the outlet fitting.

Worked for a month or two and then it didn't. Ended up putting in new tank. Would NOT want to have that experience with black tank. IMHO, replace the tank. Less trouble the long term.

[Sunfishin]

Here's a followup on my tank crack. No leak now.
I used the quick set epoxy to seal the crack. It does set very quick.
Next i did the ABS Cement and fiberglass screen repair like shown on YouTube.
The epoxy patch was small, so i wanted to extend the patch size. Now after several coats of ABS Cement, it's ready for the real test. Filling it full.
Wish me luck.