Noob: Motor Tune VS Prop question 2.0 merc

[grendle]

I hope this is in the right forum,

I feel kinda dumb asking this , but i'm a few beers in:

I swapped props from a stock merc 23p to a laser II 21p . the new prop has the tuning vent system , the old prop did not , so I basically tuned the motor originally (low speed advance) to run the best holeshot with the old prop . Now I can adjust the prop to the motor.

the top end is great and i can spin this one to 5800 , I could only spin the 23 to 5200. But the hole shot is much slower (cavitation) with the 21p/ no plugs in , much worse holeshot than the 23p.

should I tune the prop with the plugs to the motor as is , or tune the advance to the best the new prop will handle when I get the plugs sorted out? or both?

I am assuming what i eventually am trying to achieve is the motor reving as quickly as possible with as little slip (cavitation) of the prop as possible for the fastest hole shot . Is this correct ? or am i lost?

[jallen355]

Not sure where your hull weighs in, but the Laser series props are not made for the "above average" weight hulls, imho.

[grendle]

not sure on the weight , but she's not a pig like a ranger,lol. the 21 or the 23 laser are the recomended prop from merc. They only go back to the XRI or 6 though for 150's. at least thats the best I could find for the combo.

[sl!ck]

That motor should have no problem with the 23 prop. I had an 84 mariner in factory spec that would spin a 24" with no problem to 5500-5800 RPM on an 18 1/2' skeeter.

It might be time for a compression test .

[grendle]

Thank you everyone for all of the help and comments. Spent some time getting the prop sorted out today and definatly very happy with the results. I was able to get the hole shot tuned in to about 2-3 sec on plane. very different than before as well, the nose comes up a bit and the boat just goes, nice and smooth, the motor sounds a lot less stressed and gets into the rpm band quickly. the best i was able to get today (20-30 mph wind 1-1 1/2' waves) was 52 on GPS. i think this is about the best I can get with my current setup and the boat handles well also you guys rock !