16ft searay sevvile 100hp outboad prop

[jbanderson]

The stock prop is a 13x19 i think. and AT WOT the Rpms are at 5000 and around 32-35mph I have been told these engine dont like to rev and am wondering if a higher pitch would benifet me any. I am the only person that skis/wakeboads behind the boat and im only 140lbs and a crack of the throttle will pull me up so im not much worried about losing bottom end.

I am just wondering if I would gain any top speed or if I am just gonna not be able to turn 5000 anymore

thanks

 

[steelespike]

Re: 16ft searay sevvile 100hp outboad prop

Need to be sure of prop demensions.
What motor are you running?Is your speed on a GPS?Approximate weight of boat?or style deep V? bowrider?cuddy?Have you tried a careful application of trim to find the ideal setting.Full out is not necessarily the fastest position.Are there any ventilation problems now?

 

[DJ]

Re: 16ft searay sevvile 100hp outboad prop

What kind of engine?

 

[jbanderson]

Re: 16ft searay sevvile 100hp outboad prop

I normally raise the trim to right before it starts to vent.
The boat is around 1300 lbs with engine and fuel and me
Its a V hull Bow rider 16'

Engine is a 100hp Searay/mercury OB

The speed is by GPS Even if I add my wife and gear (about 300 more lbs) the boat will still turn the same RPms and speed.

 

[jbanderson]

Re: 16ft searay sevvile 100hp outboad prop

also i will have to double check the prop size when i get home.

 

[steelespike]

Re: 16ft searay sevvile 100hp outboad prop

At this point it doesn't appear you should go up in pitch.You need to stay close to the max rpm.
Your rpm seems close.If its a 4 cylinder 100 I think the max is 5,250.
Most 2 strokes like to rev.Speed seems low.Should easily do 40+.Is the prop in good shape.Is it aluminum or stainless?You might want to check the compression and be sure the carbs are opening all the way.A better prop might let you raise the setup and allow you to trim out more.
Someone should be along with info on the approximate speed you should make with that prop and rpm.

 

[jbanderson]

Re: 16ft searay sevvile 100hp outboad prop

prop is aluminum

 

[Silvertip]

Re: 16ft searay sevvile 100hp outboad prop

Either the tach is wrong or your idea of speed is wrong or both. At 5000 rpm using a 19P prop speed should be 40 - 45 MPH depending on lower unit gear ratio.

 

[jbanderson]

Re: 16ft searay sevvile 100hp outboad prop

I will deffinatly have to check the prop pitch then

 

[Lakester]

Re: 16ft searay sevvile 100hp outboad prop

hello,

the Lakester Special is a 15.5 tri-hull, 85HP evinrude in good running condition. it rpms up as expected. as i the prop is a 13 1/4" x 17p alum. it will run ez 30-32 at 2/3rds throttle and upwards of 40 depending on water condtions. 2 adullts onboard. wgt about 1100 or so.

info provided for baseline addl info.

regards

lakester

 

[jbanderson]

Re: 16ft searay sevvile 100hp outboad prop

I used another GPS and it is saying 41mph, not sure what is wrong with mine.

 

[walleyehed]

Re: 16ft searay sevvile 100hp outboad prop

We need a constant "known" variable...sounds impossible right??
We need an accurate tach, and a Known pitch prop-model and make would be best so I can tell the type and extent of cup. The speed can put us in a window of what the possible pitch may be, but then again, I have 17P props that out-run 19P's on the same boat.
Prop make-model, P/N if possible and an accurate tach.

Lakester, what is your WOT RPM, normal load?..6000?

 

[jbanderson]

Re: 16ft searay sevvile 100hp outboad prop

We need a constant "known" variable...sounds impossible right??
We need an accurate tach, and a Known pitch prop-model and make would be best so I can tell the type and extent of cup. The speed can put us in a window of what the possible pitch may be, but then again, I have 17P props that out-run 19P's on the same boat.
Prop make-model, P/N if possible and an accurate tach.

Lakester, what is your WOT RPM, normal load?..6000?

Is there an aftermarket tach I buy to hook up?

 

[walleyehed]

Re: 16ft searay sevvile 100hp outboad prop

There's always the Tinytach if you don't want to buy a dash-mount.
Personally, with the tach being the only instrument to tell you the work being done, I'd go with a quicksilver dash-mount.