A Prop Question

[Radar13]

Hi Guys
here is my Specs 1996 Skeeter DV1850 with a 175 EFi, my prop is a Trophey 48-825934A45 21P
13.75 Diameter. My Thought is maybe my Prop Diameter is a little small as there is a Gap as seen in these photos, do I want to step up to a 14inch or maybe 14.625 inch


My other Question is What prop size do you guys think I should have for best overall performance,
Currently reaching 48 mph @6200 RPM WOT my recommended rpm's for this motor are around 5600 RPM's
I was reading some other post from Google that others recommended the Fury or the Tempest in 24 or 25 pitch, with more opted for the Fury as a better performer, these posts are old. also do I want to stay with a 4 blade or switch to something different?Thanks for any input.

 

[REY_off]

I'd say your on the right track with your thinking. I'd definitely wouldnt be running my motor over the recommended RPM.

Visit - https://www.mercurymarine.com/en/us/propellers/selector/#/step-one

The tempest plus 3 blade seems to be a good setup for alot of boats. Just need to figure out your pitch.

 

[Mr.Mike]

Looks like you have a small hub prop on there. You need the large hub on a 175.

 

[Radar13]

I was on that site. Thanks. But how do I figure what pitch, without buying 2 different props at $500 apiece. I don't think they will let me return one If i use it?

 

[Wild and Free]

Ask around at the dealers, most have props you can borrow or rent for trials. or try one of the prop shops like Bismarck prop works ect.
I find that on the boat and or engine manufacturers web sites a lot have performance charts with different engines on specific boats and what prop performed the best with each setup.
A 6200 you are not too far off so don't get too wild, how does it handle load and how does it plane out fully loaded? is it doggy or does it cavitate or blow out when you mash the throttle from down low?

If it performs good all around but just has too high of rpm then keep the pitch and blades the same and go up 1/2 inch diameter.
Not all props are the same either, I have identical factory yamaha props 15X15 one in black stainless and one in aluminum and both perform a lot different as the aluminum props have flex in them under heavy load where as the stainless doesn't.

 

[Radar13]

I'll do some checking tomorrow,Thanks Wild

 

[Sub_Elect]

First of all there are 3 types of ways props exhaust. First is a thru-hub, second is an over/thru-hub and third is an over hub exhaust. That prop fits correctly, but it is an over/thru exhausted hub. They are designed more for bass boats then walleye boats. If you like how it performs then go up in pitch to make your combo work within the WOT recommended rpm.

If you don't like how it runs then a rule of thumb is this;
-If you go up 1" in pitch you will loose 200 rpm, ie: 21P spins 5500 rpm, 22P spins 5300 rpm
-If you go from a 3 blade prop to a 4 blade you will generally see a 100 rpm decrease in rpm.

These are generalities but are usually pretty spot on.

 

[Radar13]

Thanks for that Info Sub that makes sense, this prop seems to preform good just top end is a little low for the RPM.
Does anyone have experience with Power tech Props? pros and cons.
I stopped by Prop Works today and that's what brand Prop they were recommending, and asked me if my Tack was right? I thing so but how does a guy know for sure
River city demo's props so I might try that if they have what i'm looking for. that will probably be my next step.
Thanks for all the info guys it is very appreciated.

 

[Sub_Elect]

I would suggest a 21 or 23 pitch tempest on that hull and motor. That rig should run close to 55.

 

[Radar13]

21 is what I have now, I'm thinking 23, should run 5800 rpm by the calculations. but then a different style hub would change rpm's also.

 

[Captain Ahab]

21 is what I have now, I'm thinking 23, but if that calculates right I would still be at 600 rpm so maybe a 24 pitch

The larger prop will be like going up in pitch as well. I would be surprised if you could turn a 24 with that rig.

 

[Radar13]

Thanks Captain, that must be true, that is the 2nd time I heard that today. surprised if you could turn a 24 with that rig. I know nothing about props just what I learned the last three days and that is scary and dangerous,

 

[Sub_Elect]

The larger prop will be like going up in pitch as well. I would be surprised if you could turn a 24 with that rig.

I agree 100% I would strongly consider finding a demo 21P Tempest at River City. I think you will be pleasantly surprised at a better hole shot and more top speed.

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My other Question is What prop size do you guys think I should have for best overall performance,
Currently reaching 48 mph @6200 RPM WOT my recommended rpm's for this motor are around 5600 RPM's
I was reading some other post from Google that others recommended the Fury or the Tempest in 24 or 25 pitch, with more opted for the Fury as a better performer, these posts are old. also do I want to stay with a 4 blade or switch to something different?Thanks for any input.

You have trim tabs on that boat!?

 

[eyexer]

as mentioned pitch isn't the only thing that determines rpm. diameter also does. but what many forget is that actual blade size (square inches of surface area) also plays a role. If it was me I would demo a 21P tempest and go from there. Sub elect hit the hub issue dead on the nuts.

 

[Wild and Free]

All of us fools running old school outdated outboards with submerged props will always be looking at the tail of the leaders, Those running the newest lastest greatest thing to be making waves lol.

All need to check out the surface drive prop systems. They have been around for a long time but only recent years are they realizing the efficiency and performance they are capable of versus fully submerged out drives.
They make conversion kits to convert Personal water crafts to surface drive props now too and they water fowling boats have these setups as well also known as shallow water mud boats.

 

[Radar13]

yes I have trim tabs. with the kicker motor and live well on the port side it leans a little. it wasn't bad but i knew it was leaning and it bugged me.

 

[Sub_Elect]

Sweet, I have me on my new boat and love em.

 

[Radar13]

Tabs were a great investment.

 

[TFX 186]

Is that a Lund??:;:stirthepot

 

[eyexer]

Is that a Lund??:;:stirthepot

nope. I don't see a trail of rivets

- - - Updated - - -

but it appears that could be one of the Vallely's hanging out the back.