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Old 13-02-2015, 10:30   #1
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horsepower to plane a 10' RIB

We just bought our first RIB: a used 10' 6" Avon with a hard fiberglass bottom.
It came with a 4 stroke 6 HP suzuki that just plows the water, doesn't come close to planing with two people.
We need suggestions on what size outboard will reliably push the RIB on a plane with two not too large people.
Thanks
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Old 13-02-2015, 10:33   #2
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Re: horsepower to plane a 10' RIB

I have a 9.9 Honda on a 310 Rib and can plane with 3 adults at a good clip.
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Old 13-02-2015, 10:34   #3
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Re: horsepower to plane a 10' RIB

I have a 10hp 2stroke on ours and it rockets along. I would imagine 6hp isn't far off


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Old 13-02-2015, 10:37   #4
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Re: horsepower to plane a 10' RIB

Depends on load and on bottom cleanliness.

10HP is marginal in my experience. Much better and more reliable for planing with 2 adults and a load of groceries is 15HP.

Oft times a clean bottom makes all the difference between planing and not.

Bill
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Old 13-02-2015, 10:45   #5
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Re: horsepower to plane a 10' RIB

Manufacturer horsepower ratings are more marketing than engineering. The 6hp Suzuki has the same displacement (8.4 in.) as the 4hp. They just run it 1000 rpm faster.

I once had an 8hp that did OK with an optional prop meant for heavy loads and a fin on the outboard that helped lift the stern up while getting on plane. 10 or 15 would be safer - but recognize that these are much heavier engines if you plan to lift it on on off the dinghy.
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Old 13-02-2015, 11:08   #6
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Re: horsepower to plane a 10' RIB

We had to turn downwind to get up on a plane with the 2 of us with a Honda 5 then we could slowly come back into the wind. But only people (we are both smallish), no gear.
New dingy has a 15 hp...
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Old 13-02-2015, 12:01   #7
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Re: horsepower to plane a 10' RIB

Quote:
Originally Posted by btrayfors View Post
Depends on load and on bottom cleanliness.

10HP is marginal in my experience. Much better and more reliable for planing with 2 adults and a load of groceries is 15HP.

Oft times a clean bottom makes all the difference between planing and not.

Bill

I've got the 20 HP Suzuki on mine, and it's slightly underpropped as it'll bang the rev limiter easily, with four "Americans" on board (also know as fat people in the rest of the world) it takes every bit of the 20 HP to crawl onto plane, but one person it leaps on plane is less than it's own length, so it's of course very load dependent. Spotless bottom
My opinion is I'd rather run a bigger motor at half throttle than a smaller one wide open all the time. Bigger is more money and weight though

If your small people re-propping your motor might get you on plane, assuming your overpropped now.
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Old 13-02-2015, 12:11   #8
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Re: horsepower to plane a 10' RIB

Not mentioned is that it really matters what kind of dink you have. What kind of bottom - soft or rigid. Also how heavy is the dink itself. How much weight in the dink - as noted. Where the passengers sit - all as forward as possible, including the operator. You need to get the weight away from the stern as much as possible.

Also the adjustment of how the motor tilt is important, as is the prop.

Water conditions matter - smooth is easiest to plane on. Wind on you nose, etc.

We had a 9.9hp 4-stroke that would plane fine with two of us and not a ton of cargo. Three and it wouldn't plane worth a damn. 15hp is a better choice if that matters. But in WA state, you don't need to register (and pay annual tax on) a dink if it has 10hp or less as a motor. So most use those.

Some people don't care if they ever plane. But you can get from A to B faster on plane and use less fuel, comparatively. But you also have a much heavier motor to haul up and down. A heavier motor on the rear also is counter-plane that is overcome by more horsepower.
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Old 13-02-2015, 12:42   #9
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Re: horsepower to plane a 10' RIB

I had that same dinghy for years and it did great with a Mercury 2-stroke 15hp. Here in the tropics 2-strokes are still easy to get so I have no idea about which 4-stroke would work...
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Old 13-02-2015, 14:29   #10
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Re: horsepower to plane a 10' RIB

Quote:
Originally Posted by a64pilot View Post
I've got the 20 HP Suzuki on mine, and it's slightly underpropped as it'll bang the rev limiter easily, with four "Americans" on board (also know as fat people in the rest of the world) it takes every bit of the 20 HP to crawl onto plane, but one person it leaps on plane is less than it's own length, so it's of course very load dependent. Spotless bottom
My opinion is I'd rather run a bigger motor at half throttle than a smaller one wide open all the time. Bigger is more money and weight though

If your small people re-propping your motor might get you on plane, assuming your overpropped now.
Are you sure you are under-propped? If it takes a lot of time and hp to get onto plane with 4 people, it sounds like you may be over-propped, not under.

We have the same outboard with probably the same standard prop. Our 12' 350lb dinghy will take all 20hp to slowly bring 4 "American" people on plane. I recently borrowed another prop that was 1 inch less in pitch - and with this prop the dinghy popped right up on plane with 4 people instantly and stayed on plane at 1/2 throttle.

Mark
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Old 13-02-2015, 14:38   #11
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Re: horsepower to plane a 10' RIB

40 h.p. merc or evenrude otta do the trick.
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Old 13-02-2015, 14:38   #12
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Re: horsepower to plane a 10' RIB

I have a 25hp 2stroke on the back of my 10ft rib..............but I would not recommend it without some one in the bow to stop it flipping............just a tad overpowered.....
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Old 13-02-2015, 14:55   #13
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Re: horsepower to plane a 10' RIB

Some ribs are heavier than others (double floor or single?) I had a 15hp on mine and it would plane with 3 adults or 4 if you tried real hard.... The 15HP was the same weight as the 10 hP so it was a no brainer....
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Old 13-02-2015, 15:00   #14
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Re: horsepower to plane a 10' RIB

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Originally Posted by atoll View Post
I have a 25hp 2stroke on the back of my 10ft rib..............but I would not recommend it without some one in the bow to stop it flipping............just a tad overpowered.....
I have a 25 hp 2 stroke that did the same on my 12' rib. I added those plastic automatic trim tabs, the kind with the gas strut. Made a huge difference. It planes off really quick and flat, and also minimized chine walk, which gets real scary. Definitely worth the $120. I got them from defender.com. They are the Nauticus Smart Tabs SX. Their website helps you pick the right set.

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Old 13-02-2015, 15:32   #15
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Re: horsepower to plane a 10' RIB

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Originally Posted by CaptNemoO2 View Post
I have a 25 hp 2 stroke that did the same on my 12' rib. I added those plastic automatic trim tabs, the kind with the gas strut. Made a huge difference. It planes off really quick and flat, and also minimized chine walk, which gets real scary. Definitely worth the $120. I got them from defender.com. They are the Nauticus Smart Tabs SX. Their website helps you pick the right set.

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the rib is only rated for a 9.9 hp max............

hydrofoils might work better!
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