2008 Honda 8 HP performance

[DAKOTA2]

I have a 14' fiberglass open bow tiller that achieves a maximum speed of 6.5-7 MPH with my 8 HP Honda at 3/4 throttle & rpm at 3250. At full throttle the rpm & speed does not change. Is this normal ? I was expecting a bit more speed than that.
I believe the manual says around 5,250 is max rpm, but I never get close to that. Is it because the weight of the boat & 2-passengers has maxed the engines capabilities & it just won't turn the prop any faster ? ?

DAKOTA2

 

[Alumarine]

How much does the boat weigh including gear and passengers?

 

[DAKOTA2]

My best estimate of the weight with two passengers, the outboard, Minn kota trolling motor, two golf cart batteries & the rest of the gear is between 900-1000 lbs.

 

[Alumarine]

I'd try taking out all the weight that was easy to to take out and see if you can get up on plane with only 1 person.
That will tell you if the motor will perform properly.
Is it the right shaft length for the boat?
What size motor is the boat rated for?

 

[DAKOTA2]

The first thing I did upon purchasing the boat was to make sure the motor height etc was set up right. Everything is good in that respect. The boat is rated for up to a 25 HP . I'm coming to the conclusion that in order to gain more speed I will need a larger motor. I may take your suggestion & remove some weight & try that also.

 

[Alumarine]

If the boat is rated for a 25hp I'm guessing you won't be happy with anything less than 15-20.
I'd go for a 25. I doubt if you'll ever get it on plane with an 8hp.

 

[DAKOTA2]

Marc,

Thanks for your help & advice on this situation.

Dakota

 

[Alumarine]

Marc,

Thanks for your help & advice on this situation.

Dakota

You're welcome. But remember, I'm just guessing!