childs flat race boards

[supuk]

i have been asked to build a flat water race board for a 10year old boy 4'4 and 63lbs and the child can all ready paddle quite happily.

There seams to be two general sizes for child's race boards 9'6 and 10'6
Obviously i dont want to build something the child will grow out off but at the same time we don't want it to large to make it hard to paddle.
I am thinking 9'6 for this child would be the better size as it will be more manageable to handle in any sort of wind ect on the water.

Are there any parents/shapers out there who have any experience with child's race boards that can give out some advice as to how there child get on with there race board? 

many thanks

[DurhamSUP]

Here's one:
http://www.standupzone.com/forum/index.php?topic=16990.0

There were kids that were 90lbs riding it with no issue. 8-6,25" wide.
9-0 and 25" would stretch the water line a bit and should be a little faster.
Wide tail really helps.

It is amazing how much faster the kids are when the get on a board that fits their ergonomics.