what is a good prop for a 115 optimax?

[vroom ZOOM]

Hello

Recently bought a 2010 lund 1725 explorer ss with a 2010 115 optimax. have not ran it yet because I don't have a usable prop. It does have a prop but I am not sure if it is the one that the boat actually had on it or if someone had one lying around and just threw it in, and sold the original good one that was on there. The prop is a 13.5 x 15 evinrude aluminum prop, doesn't even have the hub on it, I thought for a second that the lower unit was blown but after taking off the prop I realised that it is missing the rubber hub. The prop is damaged, so should I go get this one fixed or should I look for another one? I looked at the mercury prop finder thingy and it told me to use a prop from 13 x 19 through 13.25 x 21, so this one seems way too small! Or they also told me to use a smaller 4 blade. I boat around where there are tons of underwater rocks, prop strikes sometimes happen, so I probably want to go with an aluminum prop, it will have a smaller chance of damaging the lower unit, and be cheaper to repair. I usually go camping with my boat, so often it is pretty well loaded. However when I unload on some island i'd like to have some decent speed. What would be the best prop, and should I maybe get two props and what size?

Thanks

 

[jimmbo]

Someone sold a Boat with a Mercury Engine that had a Hub less OMC Prop slapped on it? I wonder what other surprises are lurking in the Shadows?
As for what Prop, have you tried the Prop Selector Tool on Mercury’s Website?

 

[vroom ZOOM]

It was an auction boat. Not an OMC prop, but one of the newer evinrude ones. Yes the boat has a dent in it, I took the entire boat apart yesterday to get to the dent and the other side of leaking rivets - I don't want to pop rivet this thing, so I had to take the consoles and floor and livewells out lol. I looked on the prop selector thing and yes it told me to go between a 13 x 19 all the way to a 13.25 x 21. Also will I maybe want a 4 blade? I started looking around and saw a guy selling a ss prop, a 13 x 19 but he said he had it on his merc 90 fourstroke. I have a 115 optimax two stroke so I guess I will need more pitch right? The 13.5 on the boat almost maxes out the diameter. Oh yeah and as for the mystery hubless prop, it does not have the rubber thing but it did come with a mercury inner brass spline hub thingy or whatever that is called.:noidea:

 

[jimmbo]

Maybe they exist but, I have never seen a Hub Kit for BRP Prop that would permit usage on a Merc.

That SS 19 might be Perfect for your combo. The 90 it came off and your 115, if the same displacement, will have a different RPM point where the highest power occurs, so your 115 would have greater ability to spin the Prop at a Higher RPM. If the engines were of Different Displacement, they would likely have Different Gear Ratios, the 115 geared to spin a Prop at a higher rate than a 90.
Engine manufacturers will select gear ratios over several models of engines so that the majority of times the Props needed are condensed. That way the Dealer doesn't need to stock Pitches from 10" to 30", when the majority of times 17 - 21 will do

Don't fret about Diameter, for some reason, the past year that seems to be the new Rage on this Forum, Diameter. Let the Prop engineers be concerned about that. A lot of Prop Lines, have the Diameter decreasing as Pitch increases.

 

[vroom ZOOM]

:facepalm: Doh! totally forgot about the fact that the ratios in the lower are different in different engines! ok the guy is asking $150CDN for the stainless prop, looks to be in good shape, he also has one two sizes up in aluminum nib, ill try get those! At least it will be a good starting point.