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Old 23 March 2017, 00:09   #1
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Fastest between RIB and SIB

The title says a lot, my question is if I have a rib and a sib the same lenght with both the same motor HP, wich will be the fastest?

I had a 14' sib with a 25HP and now I have a 14' RIB with a 50 HP. I am pretty sure the RIB will be fastest... but what if both would have had an 25hp?

Thanks!
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Old 23 March 2017, 03:47   #2
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Some ultralight small RIB's shall be faster.

If weight be the same RIB shall go faster (hull is RIGID)

But I do not know any RIB size 14' weight below 100 kg

HIGHFIELD OM 420 is 200 kg and require 60 HP
CLassic 3,8 weight 80 kg and max HP is 25

RIBEYE TS400 weight 76 kg and max engine is 20 HP

So I will not compare SIB & RIB the same size but similar weight and similar max HP engine. I think you can find some DEMO Ribeye or Classic powered by 20-25 HP and test them
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Old 23 March 2017, 04:11   #3
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The rib will be faster in most cases
The soft floor of a sib causes drag and flex which slows it down.The hard hull of the rib will ride better over any kind of chop where the sib would need to slow down
So unless you comparing a very heavy rib with a very good sib then the rib will be faster
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Old 23 March 2017, 08:34   #4
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Ok thanks a lot!! Can't wait till summer!
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Old 23 March 2017, 09:40   #5
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Quote:
Originally Posted by beamishken View Post
The rib will be faster in most cases
The soft floor of a sib causes drag and flex which slows it down.The hard hull of the rib will ride better over any kind of chop where the sib would need to slow down
So unless you comparing a very heavy rib with a very good sib then the rib will be faster
Would be interested to know how an old style Zodiac Futura MK IIC (12' 7") with speed-tubes) would compare with a similar sized RIB with similar engine rating. A Futura and 40hp vs lightest RIB and 40hp in calm conditions with little wind.
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Old 23 March 2017, 10:05   #6
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You could be like my brother and try a 40hp Evinrude Tiller on a 12ft SIB. There is absolutely no drag at all underway, because the only part of the boat touching the water is the prop... That case, i think he would beat your RIB in a race.
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Old 23 March 2017, 10:52   #7
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Three boats, same Suzuki 20 motor, same 9.25" x 10" prop.
3.5 Zodiac 67kg......25mph max
3.8 Aerotec 43kg....24mph max
3.75 F-RIB 62kg......27mph max*
Hole shot about same for all.
*F-RIB felt seriously under propped so could go faster. Having said that a lightweight 62kg shallow 'v' rib gives a real 'bone shaker' ride in any chop or short swell. You can keep the power on in the Aerotec in these conditions so is probably the faster boat.
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Old 23 March 2017, 10:52   #8
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Quote:
Originally Posted by spartacus View Post
Would be interested to know how an old style Zodiac Futura MK IIC (12' 7") with speed-tubes) would compare with a similar sized RIB with similar engine rating. A Futura and 40hp vs lightest RIB and 40hp in calm conditions with little wind.
Maybe in ideal conditions there will be the odd sib will beat a rib but in general the rib will win especially if you add in a little wind and waves
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Originally Posted by Otis K. View Post
You could be like my brother and try a 40hp Evinrude Tiller on a 12ft SIB. There is absolutely no drag at all underway, because the only part of the boat touching the water is the prop... That case, i think he would beat your RIB in a race.
Again fine for the first 10mins after which driver fatigue sets in or the first few waves which slows his progress dramatically
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Old 23 March 2017, 10:59   #9
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Wow thats is very nice thanks!
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Old 25 March 2017, 14:28   #10
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depends a lot on hull design, weight distribution and a variety of other factors. If the only change is going from a solid hull to a soft hull of the same design then the rigid hull will be faster (if the weight remains constant)
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