There are many questions asked about the “best engine” for a particular boat. This page will provide some links to possible answers:

Outboard Propellor types and test on 8m Steering the outbard

Twin outboards: Many people have added twin outboards in various configurations: From attempts to make an 8m plane:

To smaller (9hp) mounted just in the hulls and retractable

I also found a note in the 2002 newsletter that said: Your readers may be interested to know that my husband & I decided to try a different prop on our 9.9HP 4-stroke Yarnaha outboard fitted to our 8m Catalac. The outboard comes with a standard 9.25“ pitch x 11”. We changed it to a prop of 11“ x 11” and found our petrol consumption virtually halved, with no loss of top speed, or thrust (we even made steady, but slow, progress against Littlehampton's mid ebb at springs!). However, Yamaha only supply this prop in plastic and it did not take long to become daII1aged. So, we found an alternative. Streamlined Props of Unit 17 Cavendish Mews, Grovenor Road, Aldershot, Hants GUll 3EH