Changed My Pitch

[Boss Hawg]

Went from a 13 3/8x17 3 blade to a 13x19 3 blade on my 1987 16' Starcraft fiberglass bassboat pushed by a '87 70hp Johnson - I got 35mph @ 5500rpms & still had a wee bit more throttle left (room & lake activity prevented anything more at the time)
Am i in the neighborhood of what i should be
BTW i'm pleased enough with holeshot, planeing ect & i average about 400 lbs of people, gear 'n beer

 

[steelespike]

Re: Changed My Pitch

What were you getting with the old prop?I would say your in the range; 35 being the low end. Sounds like there is more throttle to be had.I see you have it jacked up pretty good.If you don't have any venting problems the new prop might allow a little more height.

 

[Boss Hawg]

Re: Changed My Pitch

What were you getting with the old prop?I would say your in the range; 35 being the low end. Sounds like there is more throttle to be had.I see you have it jacked up pretty good.If you don't have any venting problems the new prop might allow a little more height.

Do have a little more throttle - next weekend i'll find room to open it up
Dont understand the venting thing but the motor is at the highest point

 

[steelespike]

Re: Changed My Pitch

Venting is when the prop loses its bite and the motor revs and the boat slows. If you don't have any venting then the motor may be able to be raised.
The antvent plate(just above the prop)even with the bottom of the boat is considered a starting point.I'm thinking it should run closer to 40.
What brand and model prop?
I've been thinking:: Your tach may be high a 19" pitch should be around 40 + with the motor at 5,500.

 

[Gary H NC]

Re: Changed My Pitch

You will know if the prop has ventilation problems.It feels like it is slipping and the rpms getting higher.
Sounds like you may be able to go up even more on prop pitch.

 

[Boss Hawg]

Re: Changed My Pitch

Thanks to both, i do have a slow speed point where i hear (feel) a gurgleing (hope that don't sound too stupid) when it seems i slow down & kind of "wallow" (love this high tech talk ) in the water till speed picks up & then we go!
steelespike, i dont know kind of prop, i just got it off Ebay & only marking i see are size? Motor is mounted at its highest point now-

 

[steelespike]

Re: Changed My Pitch

According to NADA book the V160 is 1,000lbs. 260 for the motor,100lbs for 2 batteries,100lbs 12 gal gas,2 people 400lbs.About 1,900lbs.