Family new to this sport. We used the kayaks in the estuary/river with calm to slight chop water conditions. We all have sit on top style kayaks. What is the suggested paddle lenght for 11 year old? Should the paddles be straight or offset.
How Big Is The Kid?
and what is he paddling. These weigh in on the size of the paddle. Generally, folks end up going to long. The kid ends up yawing back and forth (going one way and then another) because there is too much paddle there. A shorter paddle forces the kid to go with a higher angle and results in going straighter. This is from experience with my two kids.
sing
sizing paddles
Put one end on the floor and see if you can curl your fingers over the other end. If the boat is wide you may need to add some length to clear the wide beam.
paddle sizing
I use a very simple method for sizing. Sit in the boat on the water. Measure the distance from the water to the coaming or your waist with a sit on top. Double that number. Hold the paddle on top of you head with elbows bent at 90 degrees. Measure the distance between you hands and add that number to the previous number. The sum will be the length of the suitable shaft. The blade size is irelevant as is your height, arm length, shoe size, IQ or astrological sign.
Simple way to tell…
… If you can get out in a kayak with someone, here is a simple way to tell what works for you as to paddle length.
… If you are questioning the length of “your” paddle for example, close your eyes while paddling, and ask your friend to be along side and see how far the paddle goes down in the water. If the paddle blade goes “way under” as you paddle, you can do with a shorter shaft. If your whole blade does not go all into the water, you need a longer shaft.
…The wider the boat, the longer shaft you need too. For example when I had my 28" rec kayak, I used a 240 cm length. In a 22" wide kayak I like a 215 - 220 cm length.
… Another point to consider is whether you are a high angle paddler, or a low angle paddler. I used to do a lot of canoeing, so I always keep the hand “farthest from the water” up at about my shoulder height. I end up having one hand up in the air pushing straight out from my shoulder, and the other hand low to the water. I have come to realize I am a “High angle” paddler, That is why the short shaft works better for me.
… Some people are more relaxed, and keep both hands low to the deck when paddling. These people are “low angle” paddlers. The longer shaft will work better for them.
… The length of the paddle should be that the blades are just all in the water when you are doing your own personal compfortable stroke. Match the length to you, your stlye, and your kayak, not someone elses “best guess”. 
Happy Paddling!
paddle
We have him in a RTM Mambo. It’s identical to the OK Frenzy. The paddle that came with it is an OK take apart with three holes to decide how you want the angle. I’m going to take some of your suggestions. Thanks.