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Old 06-10-2017, 12:04 AM   #1
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Country: england
Location: southampton
Occupation: electronic engineer
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Boat make: scorpion 8.1
Engines: 250HO
Cruising area: solent

Join Date: Mar 2004
Location: southampton
Posts: 1,324
Removing jack plate.

I have a long shaft etec on a 24.5” transom.

I was concerned about it being too high so instead of cutting transom down, I chucked the motor on a 5.5 cmc manual plate. The gearbox bullet runs level with transom and it runs pretty good on rev4 prop.

It annoys the hell out of me that the steering impacts the transom top when I tilt and I can’t go up more than 1/3. So now I’m trying to choose between cutting transom down. Adding moooore offset, or chucking it straight on transom, where I would have a good 2” of down movement available to me.

Question is will I lose speed removing my 5.5” setback? Currently 60mph and some discrepancies on rpm between crew but somewhere around 1000rpm to low.

Has anyone got direct comparison with or without setback?
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Old 14-01-2018, 10:46 PM   #2
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Country: UK
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Boat name: Jeepster
Boat make: Marina 16 G.T.
Engines: Suzuki DF50
Cruising area: Thames and the Solent

Join Date: Jan 2018
Location: London
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Hi Glen...The gearbox "bullet" should be below your transom...The general rule of thumb is that it is the anti-cavitation plate that should be level with the bottom of the transom for best performance. (although if you are already getting 60mph, I would leave it where it is!).
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