More C19 prop questions

[TomTom]

Thanks guys - is there a standard conversion that I can use - don't have the luxury of trying different props so would like to be in the ball park at least!

[silentneko]

Just IMHO, no, there is no standard conversion, I learned this the hard way and ended up buying 4 different props. Problem is every different company uses a slightly different prop profile so a lot of time the general rules of 200RPM for each inch of pitch isn't accurate. That rule only applies well if you are using the same style prop from the same company.

Best thing to do is find a prop shop with a very good reputation. Tell them what is going on, what prop you are running and what RPM's, they know their products well and will be able to match up to what you need.

Or some companies will let you return a prop and swap it for a different pitch after you try it as long as it is not damaged in any way.

[Larry B]

This is the 4 blade I'm running on my OD18 with Etec 60. It made all the difference in the world in my boat.

763964 13.5 x 13 Rogue 4 blade SST Prop

[jacquesmm]

. . .
some companies will let you return a prop and swap it for a different pitch after you try it as long as it is not damaged in any way.

That is the way it is around here. Ask if you can try a 4 blade prop.

[TomTom]

Do you think a different / 4 blade prop would or could lower my RPM and trolling speed and reduce fuel consumption - which direction should I be thinking - wider diameter and lower pitch? 4 blades?

[TomTom]

Ok, so 5250 RPM with a 17 pitch (2.0 gear ratio) running 29 KTS is 21% slip.
Thats pretty high for that size boat.

If I remember correctly, you were turning 2800 RPM to go 7 KTS which is pretty awful.

OK - this is what I got from Ken Reeves at PropGods.com - seems very helpful guy....


Unless anyone thinks I am mad, I think it is worth a shot ...

Ok, so 5250 RPM with a 17 pitch (2.0 gear ratio) running 29 KTS is 21% slip.
Thats pretty high for that size boat.

If I remember correctly, you were turning 2800 RPM to go 7 KTS which is pretty awful.

A larger diameter 3 blade or a good 4 blade would definitely help you out on that trolling speed.

for a 4 blade, I'd suggest the Powertech PTR4 13 1/2 X 14 pitch.
It will have great traction, and should troll very well and improve economy.
at 2800 RPM, you would probably be on plane.

for a 3 blade, I'd probably go with the same style blade, just go to a 15 pitch.
would have good traction, and likely improve everything over your current prop, but I think the 4 blade would still win at that 7 KTS trolling speed.

PTR4 cost $375
PTR3 cost $319

Aluminum, not much to go with that I have available. Probably just go with a 15 pitch Solas 4 blade. I don't sell those though.

[TomW1]

Hi TomTom your prop dealer is close to being right. I looked up the PTR4 on my catalog and it shows it only going down to a 15 pitch not a 14 pitch. So be sure he can get a 14 pitch PTR a 15 pitch 4 blade won't be enough. Also what ever prop you end up with make sure you are in the reach the upper rev range whether it is 5500-6000 at full throttle or 5000-5500.

I agree with keeping the 4 blade configuration. If the PTR4 doesn't work out I have had good luck recommending the RED4 again from Power Tech.

I am not sure what motor you have but assuming you have one that has a max rpm between 5500 and 6000 rpms these would be your props based on your numbers with a correct prop. Rpms 5700, 2.0 gear ratio, 8.0 slip, 13 4 blade prop or 15 3 blade, 38 mph.

If you have any questions please ask.

Tom

[TomTom]

Hey Tom,

Thanks for the reply - engine is Evinrude FICHT Ram 90HP, Year: 2001, Model: E90FSLSIF, Serial: G 04900587

My main concern is that I want to bring my trolling speed revs down - at the moment I need 2800 RPM to get 6-7kts - it chows fuel and I think a slower reving prop would raise more fish too.

Ken feels the 4 blade would help the most for this trolling speed.

I am tempted to buy a 4 blade Aluminum Solas first and see if it makes a significant difference as USD 103 is a lot less than 375; but at the same time I am told there is a big difference between performance with Aluminum and Stainless...

What are your thoughts?

[TomW1]

TomTom your Fitch has a top end rpm of 6000. So we will shoot for a prop that sets the rpms around 5800 at full throttle with a properly sized prop. This should get you down around 1500 at 7kts, maybe lower, there are so many things that come into play with this.

To do a really good job for you I need the weight of your C19 as you outfit her when you leave the pier. This means hull, passengers, gear, motor, fuel, beer, provisions, bait, etc. The more accurate the better but do your best. Then I will be able to calculate what size prop you need. I think the 13 pitch 4 blade will be good but want to be sure a 14 may be better.

Don't buy an aluminum its a waste of money at this point in time, there are so many differences between an aluminum and a SS.

Regards, Tom

[TomTom]

Tom - thanks for your reply - Powertech suggested the NRS4 in 15 pitch - I have placed the order as I have a friend coming out for Christmas and forgot about how little time I have to get it ordered.

I in the states in Jan and if it isn't right I can change the prop - so when I go down to the coast I will give you all the new numbers and we can go from there.

Really appreciate your help and advice. Fingers crossed I see a good improvement. Like I said my main concern is at trolling speed reducing the RPM.