i have 2 small jon boats.  12 and 14 ft.  transoms are starting to go on both.  i can't figure out how to replace the rotton wood.  it looks like i would have to remove the corners off of the back.  there also looks like there are a few rivets to worry about as well.  any suggestions?  a place here in jonesboro, ar gave me an estimate of between 100 and 200 per boat!! thanks in advance

$100 to $200!?! Here's what I did... My transom was rotted horribly so I decided to replace it like you. The board was shaped wierd around the outside so getting it in was a problem. I eventually had to remove the corner plates and all the metal around the transom to get the new board in. I drilled the rivets out which was pretty simple and when it came time the put it back together, I used stainless steel bolts with finish washers on the outside... If you ever have to replace it again it will be alot easier. Sorry I lost the pic of the finsihed product but here is all the metal removed:

The boat is upside down right now (for painting) otherwise I'd just snap you another photo.

As you can see from the picture, it's pretty cut n dry. You should see what you've got to do to replace a transom in a fiberglass boat.  

thanks for all of your info.  i will try on one of the boats and see how that goes before starting on  the second. wish me luck.  

both of the boats that i have are welded to the side of the boat.  one on the oustsides and the other on both the outsided and back.  i wouldn't be able to take the corners off without cutting them, and if i did, i would not know how to get them back on.  please let me know what you would do.  thanks

To do this repair without removing the corner braces I would laminate the transom in place. After removing the rotted wood and clean up the area make a template out of poster board of the transom. Use CDX or Marine grade plywood, don't use Treated wood, the new treated lumber will eat the old style fasteners up, if it will eat a tempered screw what do you think it will do to aluminum?? If the transom is 1 1/2" I would use 1/2" plywood and using the template cut 3 pieces 1/8" longer than the template. Cut about 12" off one end of each board and dry fit them to the transom alternating the joints from one side of the boat to the other. Overlapping the joints will make it stronger, when satisfied with the fit, glue it up with waterproof glue (something like Gorilla Glue) Put some wood preservative on the cut edges and that puppy should be good to go for years.