So have a mini crew due soon.

It's mum's happy for it be a boat baby (small yacht) in calm conditions

So reckon it can be foreman on non-toxic boat jobs and enjoy some family river boat trips

Only rule been set is 100% safe land-boat transfer process (fair enough) but otherwise no issues with it chilling inside cabin.

Current paddling a 3man canoe and keen to keep it on the cheap

How have sorted this? Floating capsule? Cheap tinny?

This is part of the Seabreeze sailor sustainability project - Help a new sailor into the game from birth

I have had my two girls on a 14ft catamaran from a bit over 2yrs old on a nice calm day and they enjoy it.

Under that its all a bit grey with saftey regs and you cant get a baby life jacket in aus unlike advertised in Europe.

Two years sounds forever but it will go quickly. Splashing on the beach and sitting in a canoe is a good start.

The big thing is if they have a bad experience it can be difficult to get the young ones interested again, so i've been told. My girls are now 5 and 3 and both still enjoy getting out on the water. We choose good conditions and everyone is happy. I just add some local club racing so i can enjoy a stiff breeze and a bit of heel.

We've just had a grandchild aboard from a few months old.

You can get baby(ish) lifejackets which certainly are designed to get an infant floating head up; but I haven't tested it and don't want to. But our transfer is from a jetty or inflatable.

The problem with these lifejackets is they leave the kid sitting like they are in a sumo wrestler suit and it's not long before they start objecting. A compromise arrangement is like a one piece swimsuit with sewn in buoyancy tubes. They won't keep the head up but at least keep the child on the surface for a rescue. Because I like to have them wearing it all the time; not just for the transfer.

If you really are thinking of taking a baby, I think you might want to think about a proper inflatable tender instead of a kayak/ canoe. Much safer all round.

What about bringing the boat alongside to get baby on board?

BTW don't forget that in most states it is a legal requirement that children wear lifejackets. Victoria at least.
We took our babies on board without issues. Smallest lifejacket we could find was 10kg.

Maybe something like this. They are trailable. Babies come with lots of accessories and a stable platform can be a benefit. Plenty of shade and the ankle biter can be kept in side.

I thought I'd do a more general search to see what else is around these days.
Here's the Google page
www.google.com.au/search?q=baby+life+jacket&source=lnms&tbm=shop&sa=X&ved=0ahUKEwj2r8qjmdXVAhVH2LwKHakrBDEQ_AUICigB&biw=1242&bih=589#spd=1812663066212808152

I note this one goes down the 3 kg
www.waveinn.com/nautical-fishing/lalizas-baby-100n/1231790/p?utm_source=google_products&utm_medium=merchant&id_producte=1283071&country=au&gclid=EAIaIQobChMI0OyNqpnV1QIV1wQqCh2obw4NEAkYBiABEgLPE_D_BwE&gclsrc=aw.ds

To me the crotch flap is critical on whatever you use.
However the real problem with them all seems to be that in order to incorporate enough frontal buoyancy for the head float to keep their head face up out of the water instead of floating face down, the chest buoyancy is so bulky that the child is basically immobilized sitting bolt upright in your lap with his/ her arms out horizontally to the side (the sumo suit effect). It was OK when she was 3 months old, but by 9 months she wouldn't tolerate it for any length of time.