Hi, if you check the 'Index of Post' in my sig (bottom of this post)you will find a list of previous post's (there are many) regarding this topic.
But in short use metal brackets found at most harware shops, make sure they are square first before buying.

hi wallace is this for main keel or the launch

check out build diarys for making a jig to keep the keel level

i would ensure work bench is level with the use of a spirit level

then when placing keel between brackets check by using an engineers square

then u can use right angle brackets clamped to the ribs and keel while glue dries but check check check they are at correct angle again using eng square
i think a picture tells a thousand words so best to check build diaries for clarity

( i should learn to practise what i preach)
sure some of the other guys will post a clearer description or other methods tried & tested

yep here's an easier way (put that bit on there,check once, then screw that bit here, that's it, and glue this piece to that bit and all square.)

Here's an idea lads, and using those angle brackets, I have purchased some one inch angle brackets, and checking that they are perfectly forty five degree angle, I was considering clamping these to the keel to get the perfect rib alignment? If somebody has already come up with this idea, I apologise...