Shaft length for spare engine and use with dinghy

[ihaveissues]

All, I'm hoping to buy a spare engine for my Bayliner Classic but I also want to use it in a dinghy if I can.
I know that it's normal to use a short shaft engine in a dinghy and something with low HP, 3.5 approx, but will this
be any good for a backup engine for the Bayliner? Also happy to go with a long shaft and just loose some power in the dingy.
I have a spare engine bracket mount for the bayliner.

Thinking of getting this; https://marineparts.ie/3d-tender-world- ... ht-21-kg./

Is there any way I can merge the two, if so, how do I know what length backup I need for the Bayliner?

[MartinC]

What length is the bayliner?? You would want one hp per meter of boat anyway for an aux engine,, id imagine it would be too small,,, might be fine for a dinghy though,,

[ihaveissues]

Hi, boat is just under 6meters. So I'm going to need a dinghy that can handle a 6HP engine?

I was hoping to get an inflatable dinghy that could fit on the boat and I could blow up and go on shore with for visiting islands.
Sounds like getting a dinghy with an engine that'll do what I want for both might be tough.