I have no idea what you do for a living... But I know it's not a marine technician... LOL good stuff thanks for posting showing how actual end-users do things...
I've had this same thing happen when I changed props but used a different brand. The pitch is just one factor. Cup and blade size are also important, and aren't the same brand to brand. Have to use Oem to compare.
What length is this boat? The factory prop is perfectly fine. Don't worry about rpms. Just experiment with the trim adjustments on the motor and try to test with nice water conditions and the least amount of weight. I have a 14-foot v hull aluminum with a mercury 6 hp, and I get it up to 15 easily. Of course with another person on board plus gear, I will average about 12 mph
You have to test two props with the same conditions. The weather, waves, boat load and etc. Take to props to the lake and test them at the same time. Low pitch - less top speed but more torque more power. In your case you have to use 6" because your boat is heavy for 6HP motor.
How can you draw a comparison between 2 props if you also changed the trim between tests? Just change one thing at a time. Changing the trim affects engine load thus affecting rpm.
You are right about the trim.I tried it at both trim levels when I took it out . returned the prop and got a solas prop same size .motor now runs in correct rpm range and picked up a few mph.
Decreasing prop pitch WILL increase rpm fact, raising engine will also increase rpm effectively as it releases load on engine. 2 possibilities number 1 like you said the prop isn’t trust worthy second the tach isn’t accurate Another thought is water conditions make sure they are the same for every test Next step would be put the original prop back on and retest, and keep trimming engine up one at a time until the prop cavitates ( it may not) you should find each time you tilt the engine further you will gain rpm If you tilt it all the way to the top and still haven’t found the rpm needed drop a pitch in prop and repeat You may also find that the weight of boat and all things in boat are too much, regardless of that though you will need to get correct prop to avoid engine damage
i’ve got a 5 ho 2 stroke , i was thinking to change prop and get a hydrofoil (Why are hydrofoils useful, what is the advantage of getting on the plane quicker and reduced cavitation) also there’s five I think slots on my engine angle and I just have it in the middle which one should I use
@@TheHoop614 thanks for sharing, cuz i ordered prop thats lower by 1 pitch, and lower in diameter from 7.8 to 7.7 thats the only thing thats available :/
Did you ever had any issues when youd hit some rocks lightly and later on prop would spin at higher rpms? I guess some rubber piece inside got messed up, now need to replace new prop
@@TapiaOutdoors thank you, so i have same factory prop as u do 7.8x8 and replacement thats available is 7.7x7 ...do you think it will lower the speed by a lot? Im familiar with pitch but not sure when diameter also lower than original...how would that affect my speed i wonder....?
@@amigo439 more torque, but less top speed. Its like riding bicycle on first gear (lower pitch) vs riding bicycle on higher gears (higher pitch) which gives you less torque to start off With, but higher speed overall
