Italcraft 35 fast, get on plain problem

I recall the case of a lunatic who tried to take a fairly small power boat from southern Australia, to New Zealand, he took a 200 litre steel drum of fuel along, and whether that would have got him there is severely doubtful, but he did not restrain that drum, and the boat was eventually found afloat, upright, the interior badly smashed around, and the drum still full, and rolling around inside the boat. He wasn't there. Quite the mystery.

 

So despite everything going against him, if he'd only properly restrained the drum, he'd have at least managed to die of thirst in his boat rather than drowning after the bull in the china shop chased him overboard.

Considering the distance, he'd have needed to do 5 nm per liter. That would be good for a van on the highway. Inconceivable for a powerboat! He should have gone up against the Sicilian.

 

As Ad Hoc suggested a good step is to make flaps at the good size. The pics sent by Tonipu show far smaller and worst far less rigid flaps, not having the flanges. The simplest remedy is to reproduce the big and strong flaps shown by the pics posted by Ad Hoc. I would remake the hinges for some beefy ones, those hinges work hard and must be functional in any circumstance.
It's not a very complicated job. Maybe Gurtney flaps added to the extremity of the big flaps will give further improvement. To try them is pretty easy as it would be simple alu angles (I guess around 2 to 4 cm deep) bolted at the stern extremity of the flaps easy to install and to take off if not needed. Gurtney flaps seem very counter intuitive at first sight but excellent results at very low cost have been obtained in similar situations.

 

So how is that advice different to what I suggested, Ilan Voyager ? The simplest remedy is not to replace the flaps, but modify them.

 

thank you for all good advice

- firsts i replace now old version iveco 8061srm27 270hp 2700rpm with new nef250 250hp 2800rpm ( 100kg lighter engine) without changing prop and gear for now
- will enlarge the flaps
- make few holes on the and of the flaps so i can experiment with wedge, and Gurtney flaps

any sugestion how i can inprove steering without eding to much drag, maybe enlarge semi-cylindrical ducts in one part litle bit?