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Old 31 May 2015, 18:24   #1
zip
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7M performance. I/O is better than OB?

I took a look at a brokered boat for sale today and the broker made the claim that the performance of your standard diesel I/O is far superior to an OB setup. He stated that this was because of where all the weight was located in your IO, and when you take a tight turn with an OB your stern tends to slide out from underneath you, or something like that.

I didn't want to debate this with him, since I have no clue, but I know that there are a fair number of people on this site that have the OB setup.
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Old 31 May 2015, 19:00   #2
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Old 31 May 2015, 19:02   #3
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1100 lbs of steel in center of the bilge makes for a smoother ride in the rough stuff. Also, having the engine under the console helps you plane quicker - weight forward. I go 0 to 20 knots faster than a friend with an H733 OTH with a 300 hp Yanmar back against the transom.

When think of "performance", I think speed. A Cummins turning 2600 rpm will never outpace a comparable outboard on the same hull.
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Old 31 May 2015, 19:23   #4
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^ What he said.

There's not many (if any) inboard ribs the same size or smaller than my Ballistic with the 225 Opti that'd be faster on a flat calm day. However, there's a lot more to it than just out and out speed.
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Old 31 May 2015, 19:26   #5
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Dubrus, LOL!

Tom, That's interesting. I didn't know that. I told the broker that I am looking at two other 7M ribs right now, and one that I have been thinking about is an OB. I believe this broker may be primarily a sailboat guy, so maybe he just doesn't know?

On taking a tight turn at high speed, much difference?
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Old 31 May 2015, 20:53   #6
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turns will be almost the same, keep in mind when you make a turn in a IO you are generally going slower than an OB.

Willard 730 2x150 OB 38kn & I/O with Cummins 180 26kn. you can run a more steady pace in heavy heavy seas with all the weight of the I/O.

M2C
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Old 01 June 2015, 06:33   #7
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The debate between inboard or outboard could go on forever I think a lot is down to personal preference the two are different but which is best Is subjective
Best advice is go & sea trial both then decide
Also take into account maintenance is greater on an inboard
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Old 01 June 2015, 10:37   #8
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And how do you plan to drive the boat? We are talking performance at the extreme end here. I haven't pushed my OB to the edge of turn capability and already I'd be worried about everyone (family) being able to hold on even if they know it's coming. It's a sports car/ rocket ship. If people were shooting at me I might think more about it.

The issue of IO vs OB in a heavy sea might be a valid though with the winds in CA but as a recreational user you probably aren't going out in that. As a commercial operator you could operate in that more. The OB will still get you home through anything.

My OB is very light and it will do low 20 mph comfortably through a central California small craft advisory. My wrecked back being the limiting factor and though it never really slams, it eases down into the next swell

Jason
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Old 01 June 2015, 11:16   #9
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No one has mentioned the elephant in the room. The inboard elephant that takes up all the space
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Old 01 June 2015, 11:55   #10
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That's a whole different question....
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