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Old 28 September 2014, 02:35   #1
Country: UK - England
Town: Margate / Ramsgate
Boat name: Ballistic
Make: Ballistic
Length: 7m +
Engine: Yam HPDI 250
Join Date: Feb 2002
Posts: 2,775
Engine setback

I'm out in Lisbon (fixing someone's big boat sky tv infact) and spotted these two police rib's.

Why the big engine set back. Some of the rib benefits must be lost with the engine prop being behind the tube comes & The "box" they are fixed to must have huge stresses on it.Click image for larger version

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Daniel is offline   Reply With Quote
Old 29 September 2014, 10:43   #2
Country: USA
Town: Oakland CA
Length: 3m +
Join Date: Feb 2005
Posts: 6,620
Same situation on my boat, though not quite the stretch the boat on the right displays.

The offset essentially lengthens the hull making the boat behave as a longer hull (which I suppose, it is.) It has the added advantage of freeing up the area just in front of the motor (usually a clutter of hoses and cables and wiring, plus an area for the motor to tilt), returning the area in front of the transom to usability (in my case, allowing the pilots bench to sit against the transom rather than forward a foot or two.) Depending on what's used for the setback, you may also gain some buoyancy in the back, which helps offset the weight of the motor.


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Old 29 September 2014, 12:37   #3
Roflhat's Avatar
Country: UK - Scotland
Town: Isle of Lewis
Make: Thundercat (TI)
Length: 4m +
Engine: Yamaha 70
Join Date: Jul 2010
Posts: 514
It's done in racing as well, you can run the motor higher if you have more setback. Usually it's for spinning big pitch props, probably not the case here
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