same question(prop) different new guy :)

[capt_j_low]

Hello fellas, first off sorry for the long post and thank y'all in advance for taking time to read my post and give any thoughts.

my current setup:

boat :flats and bay 18x8(pad hull similar to a bass boat or well a flats boat)
motor :2000 Yamaha f115
prop: rapture(Michigan wheel) 13 1/4x15
factory manual jack plate with I would say about 6" offset
running cav/av plate about even with bottom of hull maybe a bit higher( at work can't be exact right now)
dry weight is listed as a light 900lbs
dead rise unknown


ok. so when I run it WOT I get to 6100 which I believe to be the rev limit on my motor and top speed is 40mph

when I run the numbers in a prop calculator I get less than 1% slip which is hard for me to believe but that's the numbers and the speed was confirmed by gps.

My question is what size prop do yall think I can step up to to get a higher top end. My ultimate goal is to get top end as high as possible so I can then cruise at around 40 without running WOT. I do sometimes run roundtrip 60+ miles in a day of fishing. >30 miles roundtrip without trying so I just wanna be able to cruise a bit faster. Right now I can cruise at 35mph at about 5600 I think.

The thing is I have been told by a prop guy that I will not be able to get much more or better than the 15"pitch(me and him disagree on what the rev limit on my motor is and I think that is why he is thinking I cant do better) I don't agree with that just yet. I believe that since I believe I am hitting the REV limiter that I got some HP left. I have looked at a few Yamaha performance bulletins and based on those I can't see how in the great blue world I can't get at least 45-47 with a 19"pitch prop. I will include a link to three different Yamaha performance bulletins below.


Any help or thoughts would be appreciated even if you think I am crazy and have the same frame of mind as the guy that told me I can't get but maybe 1 or 2 more mph



this one has weight similar to mine but has a narrower beam and maybe less tested weight
http://yamahaoutboards.com/sites/def...sa6466.tmp.pdf


this second one might be closer but it still has a higher dry weight of 500#... and still running a 19p
http://yamahaoutboards.com/sites/def...-06-20_FLT.pdf

and a bass boat just because.
http://yamahaoutboards.com/sites/def...sa6e51.tmp.pdf



Anyways, Thanks again for taking the time to check out my post and help.

[pt-73]

Most of us try several props to find what we like best. Look for a used one and try it, you can always resell it.

[RIVERRUMMER 70]

Did you test the boat with all the normal weight and gear as well as a full tank of fuel?
Do you fish alone or...did you take a guy with to test for normal load?
If your on the limiter loaded and under normal conditions try a 17" see what happens....not rocket science.
400 rpm per pitch. 15 - 17 -19 ....you would have to be really hard on the limiter to pull another 800 rpm.

[RIVERRUMMER 70]

Any results yet?