Merc 15 on a Rigid

Discussion in 'Prop Shop' started by Bob_Ruoff, Feb 5, 2011.

  1. Bob_Ruoff

    Bob_Ruoff I Love!

    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.
  2. noeettica

    noeettica Well-Known Member

    post photo of powerhead

    A prop shop can drop it 1 pitch

    If tohatsu 9 pitch

    here is 'hatsu


    if yamaha 10 pitch

  3. Frank_Sebastian

    Frank_Sebastian Well-Known Member

    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.

  4. Bob_Ruoff

    Bob_Ruoff I Love!