Thank you all for your replies, very useful. I have scrapped that idea now. 2 x120ah batteries is just too much weight, I thought an elec motor with battery would have been a quiet and easy (Lighter) option than lugging the Evin 6hp about and petrol tank for going up and down the canal (my wifes pleasure). Although the elec will be quieter the thought of carrying those batteries gives me back pain, and that is my trade!!
Thanks once again guys, I might just invest in a smaller 2 stoke
Blessings to you all.