Cracks around under the outdrive and transom boot on 86 Renken - Safe or not?

We have a 86 Renken that has a OMC Stringer with the rubber transom boot.
It looks like someone previous to this purchase has banged into something and there is a ding on the edge of the bottom of the transom that has been half repaired. But what is concerning is there is staring with long cracks that run across almost the entire bottom of the transom. It so happens the transom boot has a hole cracked in it as well so we pulled the boot and don't see any cracks apparent that go all the way through. It appears that the cracks are pressure/stress cracks perhaps from the impact that dinged in the spot and may be only the gel coat. We thought about drilling a hole about 1/4 to 3/8 inch diameter into one of the cracks to see if we can see if the crack goes deep or not also. It's just that the drilling may smear the glass and gel making it impossible to see anything of value. Has anyone else had experience like this or does anyone have a suggestion what a good course of action to check this may be? We don't want to put money into the boot and other repairs needed if the transom is bad.
Thanks
Sparks

You'll likely hear a lot of advice on how to proceed. However, if I were in your shoes, I would pay a qualified INDEPENDENT marine surveyor to evaluate the entire transom. Call your insurance company and find one near you, or go up on BOATUS and find one. DO NOT use a boatyard surveyor, they have a vested interest in finding something wrong.

you should go ahead and drill a hole or two into the transom, this will let you know if (1) the transom is holding water, (2) if the wood behind it is dry and solid or wet and punky. From what you are describing, the long cracks across the entire transom, sounds like you might have some real problems.

To be honest, Renken boats from that time frame really are NOT worth putting a lot of time or money into, especially in today's market...