I'm pretty sure the manual says to fillet the inside corners, and leave space above your fillet for the quarter knees.  The quarter knees add a huge amount of strength to this joint.  There is no reason you couldn't tape the inside corners as well.  

Thanks but the phrase, "NO TAPE ON INSIDE CORNERS OF TRANSOM" is pretty darn specific. They do say to "tack weld" the inside corners, so it can't hurt to add a fillet for appearances, at least. They may be just making sure you do nothing that interferes with the quarter knees or the seat.  

   Having already built this boat, I don't see any reason you couldn't tape the corners. There are things in the manual that don't make sense, this seems to be one of them

In this picture from CLC's own Jimmy Skiff II gallery, there's a very nice view of the inside corners of the transom. I must say that I have to totally agree with Briancb that there's no obvious reason not to tape the corners.

I have a Brand X dinghy of a similar size and transom construction and I put tape in the corners with no adverse effects, Considering that corners are typically the first at the scene of an accident when travelling in reverse and that the transom has to be able to handle the twisting forces of an outboard if one is installed, I find it puzzling not to reinforce the corners.

Maybe a phone call to CLC is in order to see if this is a typo (missing section or something) in the manual?

Laszlo

I just took a closer look at the image above with higher magnification and there is in fact tape over the corner fillets. Starting to sound very much like a typo.

Laszlo 

   To be honest I didn't read the instructions much.  I just did it. I put tape and fillets where they seemed right.  AND as I recall I had to cut some out to get some things installed. Like the seats at the transom.