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Old 22 June 2015, 21:01   #1
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Country: USA
Town: Bloomfield
Boat name: Broken
Make: Futura
Length: 4m +
Engine: 20 hp honda
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Futura help!

Hey,
I just picked up a 95 zodiac futura 12'-6" put my 20hp short shaft on and took it for a spin. The water seems to be "swaling" up the motor and back I've the transom. I adjusted the tilt both directions and seems to not change the issue. I currently have a plywood floor/kit installed rather than the inflateable floor and not really sure where to go from here... Any ideas on what's causing this? Thanks for your input, joe
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Old 22 June 2015, 22:17   #2
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Country: UK - England
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Boat name: Local Hero
Make: Avon
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Engine: Mercury 50hp 3cyl
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Posts: 253
Does the engine need raising / lowering?
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Old 22 June 2015, 22:33   #3
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Country: UK - England
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Current futuras need a long shaft engine apart from the smallest IIC model. No idea about the 95 ones, although I assume a prop sitting 5 inches too high would be pretty obvious.
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Old 22 June 2015, 23:33   #4
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Futura help

From everything I read this model calls for a short shaft. It appears that the transom was built up 2 1/2" so I removed the mod thinking that was my issue but it turns out it was doing the exact same thing. Appears that the anti-cavitation plate sits like 5" below the surface of the water so that tells me the long shaft would be way too deep. I assumed that the transom was built up the two plus inches to try and better accommodate a long shaft thinking that's what the previous owner had.. I made a few calls to dealers and one seemed to think it might be a floor issue and suggested putting a swim noodle under the wood floor at the back to tighten things up. That floor is in pretty tight and I don't know if that's even possible... Does this help any? Thanks for the help fellas...
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Old 23 June 2015, 12:10   #5
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Country: USA
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It sounds like the outboard leg is too low.

The cavitation plate should be approximately 1" / 25mm below the lowest point of the transom.
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Old 23 June 2015, 13:32   #6
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Futuras can be a puzzle as they used both short and long shaft transoms over the years and with different models.

Back then all the air floor models should be short shaft but some of the larger hard floor models were built as long shaft.

You can spot the different transoms as some in the centre are made cut down from the tube height.... others have a rise to the centre from the tubes.

But if you are using a short shaft and that is already 5" below the hull sounds like yours has been cut down even more than the short shaft type.

Pics might help??
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Old 23 June 2015, 15:54   #7
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If you're getting splashing off the leg back into the boat, your motor is likely too deep. At speed, the larger (anti-ventilation) plate on the LU should be just at the waters surface (or possibly slightly above - depends on how the motor reacts in turns.) Be aware that weight distribution will have an effect on where the AV plate rides, too.

General starting point is to have the AV plate even with the lowest point of the hull bottom, and move it up incrementally from there until you start blowing out in turns. You may find that +/- a couple of (or a few) inches will be right for your boat.

jky
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Old 23 June 2015, 16:08   #8
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Helpful stuff here:

http://www.rib.net/forum/f50/abc-sib...nes-58373.html
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