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Old 15 January 2009, 02:17   #1
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5.4SR engine offset

how far should I offset my motor, my center consul and seat are offset all the way to the right (starboard) side. My fuel tank (12 gallon) will be under seat and battery under consul. I have read on here that it should be offset about 1.5" to the right to componsate for tourqe. Thanks stan
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Old 15 January 2009, 04:38   #2
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Hi

With a 35hp it wont make much difference, if the holes are drilled it would be a mistake do re drill close by. They will go from o to 0

Jono
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Old 15 January 2009, 04:39   #3
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Depends on the size of the engine, bigger engine = more offset.
1.5" is fine for most engines commonly fitted. 75-90HP range,
smaller engines theoretically need less offset but its not critical, if the transom is already drilled i would use the existing holes.
What size is the engine? not the 35hp you have on your details i hope? that wont be very exciting you will need a fine pitch prop on that to get anywhere at anything other than displacement speeds with any weight on board, it may take a while to get out of the hole if you have the flooding hull
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Old 15 January 2009, 05:54   #4
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upgrading to a 90hp yami so it should perform a lil better. Although the lil 35hp merc would go right at 25mph with two on board without dive gear. Start adding gear and it would start dragging it down pretty quick.
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Old 15 January 2009, 06:55   #5
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upgrading to a 90hp yami so it should perform a lil better. Although the lil 35hp merc would go right at 25mph with two on board without dive gear. Start adding gear and it would start dragging it down pretty quick.
You should get 36-38 knots with a good 90 yam on a 19"prop.
my 80 yam has a 17" prop and i get 34kts with 15 stone and 100l of fuel aboard.
Nos has a 19" and a yam 90 and gets 38kts with 100L of fuel and him aboard. i guess 40 knots would be achievable with less fuel and a racing snake at the helm
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Old 15 January 2009, 07:48   #6
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Nos has a 19" and a yam 90 and gets 38kts with 100L of fuel and him aboard. i guess 40 knots would be achievable with less fuel and a racing snake at the helm
I do wonder if that's actually true. I noticed that with 2 aboard my WOT revs don't change-slip increases a bit and I lose a bit of top speed.
That might be down to my specific prop though. ( I suppose it might slip less at WOT with even less weight...)
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Old 15 January 2009, 09:49   #7
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The old motor mounting holes are filled up. So with 2-4 divers and gear on board plus 70l of fuel and other gear, what prop would you go with, a 15",17" or 19" prop. Stock Yamaha aluminum. Thanks again.
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Old 15 January 2009, 10:19   #8
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The old motor mounting holes are filled up. So with 2-4 divers and gear on board plus 70l of fuel and other gear, what prop would you go with, a 15",17" or 19" prop. Stock Yamaha aluminum. Thanks again.
Assuming it's a 90 2 stroke, start at a 17"-but watch the revs if you're solo.
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Old 15 January 2009, 11:22   #9
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Assuming it's a 90 2 stroke, start at a 17"-but watch the revs if you're solo.
I will second that, 17"or19" a 15 will be too fine i would think especially if you use the boat solo. I would think a 19" may be just about OK depending on how heavy all the gear is and how often you use it with that load. assuming its a K series yam prop.
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Old 15 January 2009, 12:08   #10
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how far should I offset my motor, my center consul and seat are offset all the way to the right (starboard) side. My fuel tank (12 gallon) will be under seat and battery under consul. I have read on here that it should be offset about 1.5" to the right to componsate for tourqe. Thanks stan
I was told once the searider is an exception to the slight offset of an outboard as the reason for the console being offset is to counter act the engine torque and not as many poeple beleive to carry a stretcher(it came from the military but i cannot prove if its right or not maybe someone can ask avon
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