Props on Ebay, and what pitch to choose?

[kaboominator]

Hi there i am lookin at replacing my rough lookin prop. I have found a few good deals on ebay but am unsure about a couple of things. I know the part numbers, and i know that in the merc book it shows two pitches available for my 15 hp merc (88). I can get either a 9x9 or a 9x10.5. I am not sure if i know what to get. If i go to the 10.5 pitch will this increase speed on top end or decrease it? I havent quite grasped the pitch theory yet. Any ideas would be greatly appreciated. I would love to get a little more speed so any ideas are greatly received.

 

[kaboominator]

Re: Props on Ebay, and what pitch to choose?

After looking deep into past threads i can see i should have a little more detail. I have a 14 foot v-hull that i generally run with 2 people and a fair bit of gear (hunting and fishing) I know i don't have a large engine like most of you on here but im assuming pitch is still an issue with smaller motors? or am i wrong? I would like to get some more speed. Will a 10.5 inch pitch give me more top end as compared to a 9 inch pitch that i have now? any suggestions would be great...

 

[tiller7104]

Re: Props on Ebay, and what pitch to choose?

Hey if you use the search feature here on Iboats forum there is tons of really good info, but if you have a specific question by all means wip it out

 

[Silvertip]

Re: Props on Ebay, and what pitch to choose?

Without knowing what the wide open throttle rpm is with average load, selecting a prop is a crap-shoot at best. Since you don't know how fast you go now and what maximum rpm is, we can't help you. You need a tach to measure engine rpm and a gps or speedometer to tell you how fast you are going. If the engine is not operating in its recommended rpm band (probably 5500 rpm or so) you need to decrease pitch (like shifting to a lower gear). that won't speed you up but will keep from lugging the engine and eventually killing it. On the other hand, if the engine is over reving, you need more pitch (shifting to a higher gear) to bring the rpm down. You would likely pick up a little speed as well. Right now, you are totally in the dark with no numbers.

 

[kaboominator]

Re: Props on Ebay, and what pitch to choose?

Ok, this upcoming weeknd i will take out the GPS and get a top speed with average load and will try to get an RPM reading at WOT so i can get better advice. Thank you and i will keep you posted...

 

[walleyehed]

Re: Props on Ebay, and what pitch to choose?

Hang in there...this testing is the fun part! even with a 15hp...That RPM figure is really what we need..the GPS just tells what the result of said prop is...doesn't mean it's right.
Post back!

 

[kaboominator]

Re: Props on Ebay, and what pitch to choose?

Well your right i can get the GPS reading anytime its the RPM that im having trouble hookin onto. Dont really want to pay 100 bucks just to test this puppy. Buddy of dime is supposed to have one that im looking at taking for an afternoon. I'll keep ya posted on my sucess..But your right id be some curious to know. I love this ****. Its my first boat and motor, only had for about a month and have gotten so excited to rebuild everything this winter. Use to do it all the time with my old dirt bikes but never boat so im looking to learn and experiment. very addictive...the motors not even that bad but it just is all gummed up so of course im gonna rip it all apart to get rid of old grease and replace all new stuff...yeehaa