While handsawing the last bit of the limbs (thickness) of a maple board bow, I spaced out for a few seconds and my saw tracked in toward the belly.  The gash is now about 5/16ths from the back.  If I put on a 3/16ths backing strip of hickory, would that suffice to be able to still make 40+ lb @ 27"?  Or should I give up and just make yet one more for the kids?

I had drawn it as a 68" NTN bow, 2" at fades.  But haven't cut the pyramid shape out yet so it can be shortened or redrawn however I want up to 2.5" wide.

That's why I like to start with a 3/4" thickness and reduce that with a rasp and scraper. power tools can screw up a bow real quick.
At 5/16" with a 3/16" backing only gives you 1/2" overall. You might be fine at 1/2" but it will probably be close.  You can also reduce the length to 66" if necessary to gain a few extra pounds. Try the backing first before you do anything else.

QuoteOriginally posted by Pat B:
That's why I like to start with a 3/4" thickness and reduce that with a rasp and scraper. power tools can screw up a bow real quick.

Live and learn  :(

My question is would the hickory over power the maple?

It shouldn't. He could also do a maple backing.

Maple isn't great in compression - I would use a maple backing.
Also there is no need to go more than 1 3/4 wide at the fades.

QuoteOriginally posted by mikkekeswick:
Maple isn't great in compression - I would use a maple backing.
Also there is no need to go more than 1 3/4 wide at the fades.

Forgive the newbie question - is a maple backing the same effect as having an unbacked bow (as if I hadn't screwed up the board in the first place)?  Or does a backing of the same material as the main bow have any additional benefits?

It has additional benefits in that you can add reflex at glue up and the glue joint itself helps add draw weight too.

QuoteOriginally posted by Pat B:
It has additional benefits in that you can add reflex at glue up and the glue joint itself helps add draw weight too.

Interesting.  I would have thought that a glue joint would be weaker.

I haven't yet backed a bow with wood (just paper & burlap so far).  Would it be better to clamp the backing with several c-clamps or with an innertube wrap?

I've had better luck and better glue joints with inner tube wrap.
Another trick is to drill two 1/8" holes at the handle, through the backing and into the belly. Use bamboo skewers or 1/8" wood dowels as alignment pins during the glue-up and wrap to keep it all together. Believe me, this makes it a lot easier to get everything aligned and keep it aligned while wrapping. Your handle wrap will cover these pins when all done.

Innertubes are the way to go, i suggest you put a narrower strip of wood on the back to help to keep it from cupping, also i wrap it with stretch wrap before the tubes they last longer that way and they help hold it all together

Thanks for your help, everybody!  I am grateful for the wealth of knowledge on this forum & your willingness to help a rookie out.