im priming a fiberglass boat that im gonna paint , i was told to use filler primer. my question is will that fill in those tiny imperfection in the boat there arent many imperfections in it but i have noticed a few

I manage and have bodyshop experience. Yes a high build primer will cover small marks. Fiberglass is always a challenge. Due to they flex. Cracks etc. will come back in a short amount of time.

The best way to repair is resin or gelcoating.

You will be OK w/ chips but not stress cracks.