What are the signs of a bad (soft) transom? Pics would be great to see if you have them.

Push down on your motor while it is trimmed up. Any flex in the transom is an indication of a problem

Lots of people hit it with a hammer. It has a different sound if it is solid or if it is waterlogged. Sorta like thumping a watermelon.

Tap with rubber mallet or your hand, solid sound good, hollow sound bad.

I think it's a lot easier to tell the difference in sound if you use the butt end of a screw driver to tap on the back of the transom.

Core samples is the absolute best minimally evasive way to check it. Use a small hole saw or a large drill bit and cut in about 1/2" - 3/4" from the bilge side of the boat. Take samples in various places. If it all comes out clean wood, then you're good. If you get any mush/black wood/water, then you've got a failed/failing transom. If you do this and all is well, you can buy a very cheap fiberglass repair kit, some 3M Marine filler, and fill/repair the small holes made without any problem at all.

Another option is to knock out your thru hull fittings and feel/look/dig out some of the wood. Same thing as above in terms of what you're looking for.

Bouncing on the skeg or listening for differences in tone can give a false positive; such as it did in my case; both of those tests cleared with flying colors, but after taking core samples, I found that the transom was toast. These tests work best on transoms that are long gone, but for ones that are only partially rotted, they don't tend to work so well (and a partially rotted transom will continue to rot. You might get 1 year out of it, or you might get another 10 before it's all gone).

What if at one time you had some water penetration due to the lack of sealing or improper sealing. If you fixed it and it is confined to a small area will the rotten area grow and overall the transom get weaker?

Yes once water gets in it will continue to degrade the wood. In winter each time it freezes it will further seperate the plywood and in the warmer months it will mildew between the layers further rotting the wood. The fiberglass encapsulates the water keeping it inside the transom bulkheads with minimal evaporation. Also since wood can never be perfectly dry it will always contain a bit of water and due to condensation of encapsulated wood, degredation will happen eventually with out any added water due to leaks.

In my case there was no doubt-the fiberglass was cracked and the bolts were sloppy. Once I pulled the bolts it was easy to see the wood had turned to mush. Kingfishers and early Skeeters were notorious from what i have heard.

Ok, I was on the water today and it was quite rough out. I looked back while cutting across the main body and saw what I think is quite a bit of flex. I am guessing this is not normal.... Think I will make a run over to Denton this week.