props vs speed

[lil mikey]

new to boating and the forum,,,,I have a 1993 17ft Sea Nyph,it has a 50hp Evinrude,,,I'm trying to get more speed,I have a 12" 17 pitch prop,my max speed is 25mph,,,at 5500rpm,,,I would like another 10 mph,,,Am I able to accomplish this with a different prop pitch or am I maxed out now?? Any help would be great,,thanks !!!

 

[WaterDR]

Re: props vs speed

You won't get another 10 mph w/o a bigger motor. You might get a mph or two by tweaking the prop selection, but thats about it. Your speed seems pretty good actually.

 

[steelespike]

Re: props vs speed

5500 @ 25 mph results in a 31% slip. normal would be about 10 to 12% I have a feeling your tach is wrong on the high side.
Is your speed by gps Some cells have a gps app.What model Sea Nymph?what kind of load?
Assuming a 12% slip at 25 mph rpm would be about 4300.
If you do a lightly loaded run remind us of the prop size and get us the wot rpm and gps speed.

 

[Bondo]

Re: props vs speed

new to boating and the forum,,,,I have a 1993 17ft Sea Nyph,it has a 50hp Evinrude,,,I'm trying to get more speed,I have a 12" 17 pitch prop,my max speed is 25mph,,,at 5500rpm,,,I would like another 10 mph,,,Am I able to accomplish this with a different prop pitch or am I maxed out now?? Any help would be great,,thanks !!!

Ayuh,.... Welcome Aboard,... So would We All,...

But, like WaterDR says, yer Outa horsepower,....

 

[Sea Rider]

Re: props vs speed

Do you have the min-max wot working parameters for that engine, if higher than 5500 could select 1-2 less prop pitch to pull revs up and gain slight more top end speed. What's the max HP the boat is rated for ? Probably you're underpowered...

Happy Boating

 

[lil mikey]

Re: props vs speed

Do you have the min-max wot working parameters for that engine, if higher than 5500 could select 1-2 less prop pitch to pull revs up and gain slight more top end speed. What's the max HP the boat is rated for ? Probably you're underpowered...

Happy Boating

if im not mistaken the min max is 5500 to 6000,,,,,the fishfinder has a speedometer ,,,the motor does sound like its turning what the tach says,i do have a 11 3/4 x 15 that came with the boat,,,there is a 12 x 17 on it now,,, TO ALL that replied,,,,THANK YOU very much !!!

 

[Sea Rider]

Re: props vs speed

If you're achieving 5500 revs with 17 pitch at wot, with 15, theoretically should achieve 5650-5700, will have more top end speed than with 17.

Happy Boating.

 

[lil mikey]

Re: props vs speed

If you're achieving 5500 revs with 17 pitch at wot, with 15, theoretically should achieve 5650-5700, will have slight more top end speed than with 17.

Happy Boating.

Again THANK YOU !!!And thanks iboat for the forum,,,very,very helpfull!

 

[jimmbo]

Re: props vs speed

You want a 10 mph increase? add 50 hp.

 

[steelespike]

Re: props vs speed

There are 12 different 17 foot Sea Nymphs ranging from 330 lbs to 1000 lbs. What model is yours?
If its 330 lbs a 10 mph increase is possible. If its 600 lbs More speed may be possible.
1000 lbs well you may be there.

 

[Sea Rider]

Re: props vs speed

Sorry, previous posted data is for -1 pitch, but it's -2 pitch.

1 pitch (17 to 16) + 150-200 revs added to 5500 = 5650-5700
2 pitch (17 to 15) + 300-400 revs added to 5500 = 5800-5900

Happy Boating