my kids are exactly the same age and i had the same worries last year

but it ended up not being much of an issue because i took them out in too strong winds and frightened them so they didn't want to go out again

this year instead of taking them out in winds i wanted to sail in i took them out very light winds and they loved it

esp. swinging from the trap handles over the side and trimming the jib for me

eventually the winds died all together and while i anxiously watched for any wind i had them jump off the boat and swim under the tramp and then racing each other around the boat etc.

it was actually great practise for them as it they learned how to climb back on the boat by pulling on the side-stay and swinging a leg up

they also learned not to assist someone on board by pulling their hands but by pulling on their lifejacket

i had to paddle part of the way back but that gave them a chance to helm

keeping them in a good frame of mind is essential at this age and light winds also give me more time to be relaxed and fun to be with. it will also allow them to increase their skills and confidence at a natural rate