15 hp outboard question-gctid364602

[RAVEN_SONG Seasoned Member Find all posts View Profile Close RAVEN_SONG]

Hello all,

We have an Avon RIB 3.10 10' 3" that we currently use with a 9.9 2 stroke Merc with a dolephin bolted to the cavitation plate to aid with planning. As our kids our getting older (12 and 15) we've lost our ability to get up on plane and so I am wondering if we upgrade to a 15 hp (2 stroke) if we could get the boat on plane with 4 "adults"? The boat does not have a steering wheel or any other extras other than a standard 6 gallon plastic tank that I usually hold 3-4 gallons in. It is rare that we are going very far with the 4 of us but I am considering if it is worth up grading

Thanks for the comments!

Trev

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I doubt it. I have almost the same (10.5' Zodiac RIB w/ 15 HP Nissan) and won't plane with 4 adults, but it will with three. By myself, it's crazy fast!

[Sunnydude Seasoned Member Find all posts View Profile Close Sunnydude]

I had a 15hp evinrude on my 11' Apex with helm seat. With 2 adults and two kids it will get up on plane...takes a bit but it does. Just swapped out for a 20hp Merc 4 stroke.

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Isn't it a very simple mod to the carb to make the 9.9 a 15 hp? I thought otherwise they were identical. That should make it easy to find out what 5 more hp will do.

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Don Buxton wrote:
I doubt it. I have almost the same (10.5' Zodiac RIB w/ 15 HP Nissan) and won't plane with 4 adults, but it will with three. By myself, it's crazy fast!

That is my experience too. My Zodiac Yachtline 310 w/ a two-stroke Mercury 15hp flies w/ just me (it is faster than my boat) and plods along w/ four.

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My Aquapro 11.5' aluminium RIB with a Yamaha 15HP 4-stroke would not plane with 4 adults. That was with a Doelfin. With proper Smart Tabs, it would plane. The Doelfin was of questionable value.

I sold the 15HP and put on a Yamaha 25HP 2-stroke. It really flies now.

[RAVEN_SONG Seasoned Member Find all posts View Profile Close RAVEN_SONG]

Thank you all, this is about what I expected....tough to rationalize getting into a different motor for minimal results, but the again if I were rational I wouldn't own a boat:arr

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I'm surprised by what I'm reading here. We have an 11' Flexboat, rigid bottom with a 15hp 2 stroke Merc that gets up on a plane pretty easily with 4 people. I don't particularly like the engine, but it sure seems to have enough power for our purposes.

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http://www.maximarine.com/products/lifters/index.html

http://youtu.be/Zjhc4T7kExw

I was disappointed with my dinghy performance. Avon 10' RIB...

With 4.5 HP 2-stroke:

• No lifters, no planing (regardless of weight of person)
• With lifters, will easily plane w/ me (close to 185-90 lbs) :worth
• With lifters, will *almost* plane with 2 persons (370-380 lbs combined)

With 8 HP 2-stroke:

• With lifters, SCREAMS with just 1 person onboard nthego:
• With lifters, will easily plane with 2 adults (same 2 as above, haven't tried 3)

I read the testimonials, they all just rave about these things. I found them hard to believe, but for $120 bucks, thought it was worth a shot. The testimonials are NOT exaggerating! It's insane the improvement these things make. Another upside - less wake off plane and better control when I am cruising in the docks/no-wake zones...

IMO for $120 bucks, it's worth trying them out... Cheaper than re-power.

[Stompor Fresh Face Find all posts View Profile Close Stompor]

RAVEN SONG wrote:
Hello all,

We have an Avon RIB 3.10 10' 3" that we currently use with a 9.9 2 stroke Merc with a dolephin bolted to the cavitation plate to aid with planning. As our kids our getting older (12 and 15) we've lost our ability to get up on plane and so I am wondering if we upgrade to a 15 hp (2 stroke) if we could get the boat on plane with 4 "adults"? The boat does not have a steering wheel or any other extras other than a standard 6 gallon plastic tank that I usually hold 3-4 gallons in. It is rare that we are going very far with the 4 of us but I am considering if it is worth up grading

Thanks for the comments!

Trev

I have a similar sized dink that I use to run a merc 25 on. It ran like a cat on fire.

I have since added a helm so I could give you a good price on my old merc.

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I just purchased a West Marine RIB 310 by Zodiac, rated for a 15hp motor.

I got a crazy good deal on a brand new 20hp Mercury, which is 31 pounds heaver than the 9.9hp motor. I was a bit worried at first until I got out on it and wow what a perfect combo!

Most manufacturers under estimate max recommendations, probably because of liability issues not performance qualities?

The boat with two adults in it really runs like a dream. I can't wait to really put it to the "test".

I have now ordered the the lifts that were recommended on this thread and can't wait to install and test those.

One word somes it up - FUN!

[RAVEN_SONG Seasoned Member Find all posts View Profile Close RAVEN_SONG]

HarleyDawg wrote:
http://www.maximarine.com/products/lifters/index.html

http://youtu.be/Zjhc4T7kExw

I was disappointed with my dinghy performance. Avon 10' RIB...

With 4.5 HP 2-stroke:

• No lifters, no planing (regardless of weight of person)
• With lifters, will easily plane w/ me (close to 185-90 lbs) :worth
• With lifters, will *almost* plane with 2 persons (370-380 lbs combined)

With 8 HP 2-stroke:

• With lifters, SCREAMS with just 1 person onboard nthego:
• With lifters, will easily plane with 2 adults (same 2 as above, haven't tried 3)

I read the testimonials, they all just rave about these things. I found them hard to believe, but for $120 bucks, thought it was worth a shot. The testimonials are NOT exaggerating! It's insane the improvement these things make. Another upside - less wake off plane and better control when I am cruising in the docks/no-wake zones...

IMO for $120 bucks, it's worth trying them out... Cheaper than re-power.

Great info, that is why I love this forum so much! By any chance are you aware of the performance with a 9.9 on an Avon 3.1 with 4 adults??

Thanks again!!

T

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RAVEN SONG wrote:
Great info, that is why I love this forum so much! By any chance are you aware of the performance with a 9.9 on an Avon 3.1 with 4 adults??

Thanks again!!

T

I don't - but weather permitting, I'll see if I can round up a couple of extra people on the dock this weekend, and give my 8 HP a go with 4 people on board.

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Sunnydude wrote:
I had a 15hp evinrude on my 11' Apex with helm seat. With 2 adults and two kids it will get up on plane...takes a bit but it does. Just swapped out for a 20hp Merc 4 stroke.

What did you do with the 15hp evinrude? was it a two stroke?

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HarleyDawg wrote:
I don't - but weather permitting, I'll see if I can round up a couple of extra people on the dock this weekend, and give my 8 HP a go with 4 people on board.

I do not think the 8 hp is going to handle 4. I have an 8 hp Nissan four stroke and with me and my daughter it will plane, I am not a small guy so adding my wife to the mix makes the same as four and we can not get on plane.

We can get close but not quite there.