Which prop to buy?

[miichael18]

My current prop is factory aluminium not sure what size/pitch but my question is can someone figure up what prop i need if i take mine off and get the pitch? In my manual it says wot is 5000 rpm right now my boat does 29mph @ 5600 rpm. So i need a different pitch I'm assuming? I do not have tilt/trim and its a 1974 evinrude 70hp on a 16ft dixie tri-hull. I guess since it tachs more than it should i need a bigger pitch prop?

Any info would be great.

 

[miichael18]

Re: Which prop to buy?

im not changing it to upgrade im changing it because mine is wore and pitted bad.

 

[AlanR]

Re: Which prop to buy?

Read what prop you got on it now. it should be stamped right on the prop its self. Id say maybe a 15 or 16 inch would be correct but check what you got.

 

[miichael18]

Re: Which prop to buy?

the prop reads 14 x 16

 

[miichael18]

Re: Which prop to buy?

The props ive looked at dont have 16 though. so should i get 15 or 17? i want most speed i can get. right now it runs 29mph @ 5600rpm with 14 x 16. does a bigger pitch mean geared higher? like a 17 would be faster with lower rpm? or what?

Props on here pitch are 10, 11, 12, 13, 15,17, 19, 21, 23

 

[xtraham]

Re: Which prop to buy?

13 1/4" X 17" would be my starting point...

 

[JB]

Re: Which prop to buy?

Go with a 17, Michael. That will bring your WOT rpm down to closer to 5,000 and it will probably add a bit to top speed.

 

[AlanR]

Re: Which prop to buy?

Yeh i wouldnt go any more than 19 on a 70

 

[miichael18]

Re: Which prop to buy?

will that make it faster with lower rpm? or will a 19 make it slower with lower rpm

 

[xtraham]

Re: Which prop to buy?

that 70hp does not like a 19p prop. I have a simular set up except v haul and have tested several props, @ diff. engine hights and trim my very best is with the a/v plate 1" above the haul and 13 3/4" X 17" mich. aluminum prop. jumps out of the hole and 32mph @ 5200 rpm's your haul is a little harder to push, if you want to try a 19 try to find an old oem aluminum 13"X19" they had no cup

 

[AlanR]

Re: Which prop to buy?

Yeh like xtraham You prob get the best preformance with a 17 inch aluminum prop

 

[miichael18]

Re: Which prop to buy?

so get a 14x17 and it will make it have a lower rpm and a higher mph tyhan my 14x16?

 

[mrtool2u]

Re: Which prop to buy?

Where are you located at,,I have a 17 pitch that you could try,,I am located in Western Pa.

 

[miichael18]

Re: Which prop to buy?

im in NC

 

[cougar1985]

Re: Which prop to buy?

have a buddy that owns a prop shop and for every 19p he would sell for a 70 he would sell 10 17p,s. a trihull takes more to push so id say 17 max for best all around performance.

 

[AlanR]

Re: Which prop to buy?

So, we all agree 17 is the way to go.