Wildman_grafix

My buddy has a stepped 36 with 250 Verado's he said 60mph.

phil_p999

I had a 36' with twin 275's - 23pitch 4 blade Merc's -- ran 63mph consistently.

danrad

I had a stepped 30 with twin 300 Verados, top speed was 74 with 25 Mirages.

davlan88

Hello all! I have a 97 Concept 28/30, Im running 97 t200 Evinrudes with 4 blade 19p PowerTechs. Fully trimmed, Im only getting 51.x mph at 5600 rpms. There has to be more in my setup. I dont thi,k these are the right props for my boat. Any suggestions on props to get my top speed up?

jadento

A quick google search shows the peak RPM for your motors to be 5600/5700. So it seems your at the right RPM. Do you know your gear ratio? I did another quick google search and found 1.86. If that is true and your RPM and Speed stated are correct your at 5% slip. Seems like a really low slip number. My first thought is one of the numbers I used is wrong. I do think you should be going a couple MPH faster. So long story short check your efficiency with a prop slip calculator and accurate numbers...then go from there. Another question is...Are you easily on the limiter with throttle left or is it just making it there?

phil_p999

The gear ratio is 1:75 and max RPM range is 5800-6400

if you calculate this on a prop calc.

Pitch: 23 - Gear: 1:75 - Eng. RPM: 6200 - Actual speed: 63mph - Slip: 18%

http://www.mercuryracing.com/prop-slip-calculator/

https://www.mercurymarine.com/en/us/...specifications

jadento

phil_p999, I am a little confused. I quoted and was replying to davlan88's question about his 1997 30' CC with twin 97 Evinrude 200's. I am not sure why you quoted my response to davlan88 in your response.

I have no doubt that your previous 36 with 275's ran 63 and your numbers add up as one would expect.

John

phil_p999

sorry John, I only read your reply to his quote. Regardless you are right, 5% slip is too low as you can see in my comparison.

davlan88

Its a lot of tweaking to get it to 5600 and throttles are buried. Even though rpms go up, mph does not. I can get to 51mph fairly easily, no trimming, at 5000-5200 rpms. If I tweak and play, ill get my 5600, but mph stays at 51.x and thats all I get. Also, I never hit the limiter. Just doesnt seem right to gain rpm, but not mph. This is gps mph also.

jadento

Gaining RPM and no MPH is not what you want. So at 5000-5200rpm you are at 51 and trimming to get 5600rpm yields no MPH gain? There seems to be a x-dimension/CG problem or prop problem or both. The only way you gain RPM and no MPH is to increase prop slip, which is no benefit to anyone...except the gas station. Does the boat feel tight/stuck or bouncy/loose trimmed out? I am not familiar with the brand prop your running I would suggest that since you are only 50hp down from me, that you try and find/borrow a set of 20 or maybe 21 pitch Mercury Bravo 1's. Bravo 1's seem to generally be the best prop for our boats.

John