18' alumacraft w/115 johnyrude

[classic]

looking for sugestions on a new prop.have a 1966 18' alumacraft w/115
i have a 17 ss omc.boat is very light also looking for t/t for 77 115 evunrude

 

[crb478]

Re: 18' alumacraft w/115 johnyrude

How many RPM's are you turning with your current prop. Is your current engine the 77 115? If it is you should be shooting for about 5000 - 5500 rpm out of it at WOT. Personally I would keep it at 5200 for WOT, but others may suggest that you go higher. If you are not currently over reving with your 17 pitch prop you are probably about right. I would think that a 17 or a 19 pitch would be right, but you will need to define what you want first. The 17 should give you a better hole shot, but the 19 should give you a better top end. If it over rev's with a 19 you would need to go with more pitch. Each boat motor combination is different.

 

[rndn]

Re: 18' alumacraft w/115 johnyrude

Welcome to the iboats.com forum!!
It would help to kmow how your current 17" SS prop is performing for you. What are you getting for rpm's at wide open throttle(WOT) and what speed. What do you like to do with the boat, ie: fishing, tubing, high speed runs, etc.

 

[walleyehed]

Re: 18' alumacraft w/115 johnyrude

And....we want the RPM at 5800 with a normal load. 5200 is actually lugging on todays fuel.

 

[classic]

Re: 18' alumacraft w/115 johnyrude

thanks for the replies.the current set up you can go 6000 plus if you let it.
i installed a 19 omc this am heading for the river to try it out today.
we use it mostly for water sports.but i am looking more for a go fast set up.
i think the 17 works good for that.it pulls good to about 5400 before you blow out with it.hopping 19 will pull better at speed.thanks again

 

[walleyehed]

Re: 18' alumacraft w/115 johnyrude

The prop should not blow-out on a straight-line run at 5400 unless we have something out of whack.
If you can, list some P/N's of the props you are running....I can look at my data and see what's going on for sure-possibly.....