Gav
Yeah, but the notch in the Signature hull is more than just a notch, or at least that’s what they claim
Having your drive/lower unit set back, or stood off, is about trying to go quicker.
As I see it, there are two perceived advantages, although I'm sceptical about them, or at least I am where offshore use is concerned when using regular V bottoms & drives.
The first advantage is, when you're trying to go really quick, especially in a mono, with the increase in speed, the centre of lift moves further and further aft. As this happens, and gets well behind the C of G, it becomes harder and harder to attain positive trim (bow up) so the wetted area increases, ..no good! Basically, there's insufficient leverage between drive and transom to get the desired boat trim.
Setting the motor/drive off from the transom effectively increases this leverage enabling a more bow up attitude, lessening the wetted area, and letting the speed increase.
A notched transom does the same thing, basically moving the last point of contact between water and boat forward in relation to the motor/drive.
The effect is two fold, coz you change the relationship between C of G, and centre of lift, AND you also increase the leverage the motor has when trimmed out to ‘hike’ the bow up.
-----------------------------------
Second advantage
Trying to run a motor really high on the transom to reduce drag/increase speed, can cause all sorts of trouble getting on plane, as the prop will ventilate at quite low speed as the transom 'dries'.
Set the motor back 6" and the prop will get water, and ventilate less, as the water leaves the transom rising steeply at low speed, and then drops to closer to level when you get going quick, so in theory, set back is a win-win situation, although I'm not a huge fan for offshore, as I said.
All this is of course my own perception and humble opinion, and I would welcome input from any other members who have a view on the subject.
