# Merc 15 on a Rigid



## Bob_Ruoff (Sep 23, 2009)

I need advice. I'm trying to get a 10' Rigid (looks like an inftatable but is all fiberglass) to plane easier. The motor is a 2004 15hp 4 stroke Merc with trim and tilt. The boat is a side console with remote steering. The hull weighs 330# and my friend and his weigh 300#. 

I attached a tachometer and discovered that the upper RPM is around 4500 rpm. The motor is rated at 5500. The boat really struggles to plane with even me, by myself, at 250#

The current prop is a 9"X11" stainless by Pro Tech. What aluminum prop do you guys recommend? I know the boat could use more horses, but really think the 15 should at least plane with two small people aboard.

I don't know hwether to go down to a 10" or 9" pitch.
Any and all advice will be appreciated.


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## noeettica (Sep 23, 2007)

post photo of powerhead 


A prop shop can drop it 1 pitch

If tohatsu 9 pitch 

here is 'hatsu













if yamaha 10 pitch


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## Frank_Sebastian (Oct 15, 2007)

On a flat bottom boat like a Carolina Skiff it takes about 1 horsepower for each 50 lbs. There is also the amount of flat surface for the boat to plane on. A 14' Carolina with a 15 HP engine will plane off with 2 adults. Put the same engine and crew on the 12' version and you will be lucky if it will get on plane. The difference is about 8 more ft² of area on the bottom. I think that is your situation although I have never seen the boat you speak of.

Frank_S


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## Bob_Ruoff (Sep 23, 2009)

The boat may be viewed at www.rigidboats.com


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## Robert Roossien (May 14, 2019)

Frank_Sebastian said:


> On a flat bottom boat like a Carolina Skiff it takes about 1 horsepower for each 50 lbs. There is also the amount of flat surface for the boat to plane on. A 14' Carolina with a 15 HP engine will plane off with 2 adults. Put the same engine and crew on the 12' version and you will be lucky if it will get on plane. The difference is about 8 more ft² of area on the bottom. I think that is your situation although I have never seen the boat you speak of.
> 
> Frank_S


I have a J12 with a 15hp and it had issues planing. I tried going down in pitch and went to a four blade. Also installed smart tabs. Better but not fixed. Found I could get to 20hp with a different carb. Did that and now on plane easy. This combo had issues with rev limiting so I went back to old prop. That issue gone and boat flies. Can get 25mph with myself and dog. I agree the orig poster needs more horse power.


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