I have a 7 hp Merc on my Ariel it just fits. Maybe a 2 stoke...? oil has to be mixed with the gas. I can lift it out without to much trouble and store it in the compartment when not in use. Runs well, power seem enough, backing up is not the best, but saved me when I gunned it from going into the back of another boat, when I misjudged a solo docking effort against the tide. I have to work on the backing up part. Drifts/pulls to one side more.

I picked up a big paddle as a back for emergency, do not know if it will help , and hope not to find out :-)