Well, I made a test....
AND, it works well..
Heres what I did, no piccies at present cos I stripped it out to make a marine ply version.
10mm Plywood floor section extending forward 1.3 metres from the transom with a stiffner down to the keel underneath to stop the flexing, weighs next to nothing and the floor area is fairly flat section in this area.
No flexing to speak of, 5 knots increase in top end speed !.. now get 24 knots on the gps and the boat doesnt SUCK down into the water as the floor flexes. previous top speed was around 19 knots and the last third of gas made it worse. (Using the tohatsu 18)
I now think it could take a 25 no worries lol...
Now need to remake the test ´floor´insert in marine ply with protected anti chafe edges and padded keel spacer.
The whole sib felt completely different, far more responsive and superb even at WOT with the 18. No digging into the water as the floor flexed upwards.
Will post piccies in the next month or two as I remake the insert and am aiming for a total weight of the mod at less than 3 Kg´s. A couple of Stainless steel bracing rods from the transom should be the icing on the cake. It will also provide a solid mount for the steering system, the whole thing easy to add, easy to remove, light and simple and still retaining a reasonable degree of flex for the whole SIB.
Happy camper now. still a light weight unit.. now, If I can just find a good 30 to 40 hp light outboard Mohahahaha!!!!