Long story short – speed versus efficiency.

Submerged drives come out of the hole like a ******* because of the prop/water interface but the faster you go – the more drag. Therefore, are considered more efficient overall.

Surface drives don’t (for the most part) come out of the hole worth crap because of the mount height and the blade design, but, the faster you go the harder the water/prop interface becomes and therefore the faster you go the more efficient they get. Typically, a surface prop runs with approximately 1/3 of the prop diameter in the water. You’ll notice the blade design is fatter towards the outer edge for this purpose. Therefore, are considered less efficient overall for general use.

NOTE
The surface prop can be made more efficient if the vertical height of the drive can be changed on the fly along with the trim angle. This allows the prop to be submerged during take off and pulled back up once up to speed. Large ships that need to go fast will use jet drives to get them going and Arneson surface drives take over once speeds are up (two completely independent systems).

Hope this helps.

Having said all of this i'm going to change to surface drive next summer and experment with that!
Took all summer to convince my self to get that boat up to a great speed! without to many tweaks.

I would definatly stay with a flex cable, this allows the "set up" for easy changes!

have fun!

C.