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Author Topic:   Prop question
DaveS posted 07-05-2003 12:24 AM ET (US)   Profile for DaveS   Send Email to DaveS  
I went out today on the delware river and had a great time. A friend and I decided to take our kids out and enjoy the sun and river. Now that I've installed my tach on my 1989 17' Newtauk, I was interested to find what my RPM's were and this was a great chance for me to open her up without any reservations. Well, I topped out at about 35mph (gps) and 4400rpms. Needless to say, I thought I'd do better. When I got back to the launch, I looked at the prop to see what size it was. The only thing that was stamped on it was the number 1666. What does this mean?

I then looked at the manual and the specs state the operating max range was 4500-5500rpms. My 1992 90hp evinrude ran like a champ and I was pleased at how smooth and fast the boat jumped on plan and just ran true.

I'm assuming changing the prop will be the answer but I'm curious what prop I currently have now. Any clue? It's an aluminum and there are no other markings I can see. I'd like to get a 13.5 x 17 aluminum or would something else be better?...how would that effect my top end RPM and speed?

Thanks for the help!

DaveS

tully_mars posted 07-05-2003 12:41 AM ET (US)     Profile for tully_mars  Send Email to tully_mars     
What size prop are you running now? If you are using a 19" pitch wheel the 17" will be much better, 200rpm per in.

My Montauk I run a 13.75x17" with the Evin 75 Ficht and can get 39mph.

Tully Mars

tully_mars posted 07-05-2003 12:43 AM ET (US)     Profile for tully_mars  Send Email to tully_mars     
Ooops, just re-read it and you are unsure of the size. If you can't find what the part number means, then take it to a prop shop. They can tell you what size it is, then I would go from there.

Tully Mars

Sal DiMercurio posted 07-05-2003 07:04 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
The prop is marked, just take it off & look on the inside.
All props are not marked on the outside.
We can't tell you a thing until you give us your prop size your now running.
Sal
grw66 posted 07-05-2003 07:38 PM ET (US)     Profile for grw66  Send Email to grw66     
Dave. If you find out the size of your prop and it's either a 13" or 15", I'd be happy to trade with you for a 17" prop that is pretty new and I realy doubt that I'll be using it real soon. I'd rather a smaller one to keep in case I'm in need of one. I'm running a 15" now but I was told I can go with either 13or 15 inch prop. Not a 17" and thats what I got an extra one of. Regards, Gary
Bigshot posted 07-06-2003 12:27 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
What was the load when you ran it? If just you, I would think you are running a 21", go to a 13.25 or 13 3/8x17" Stainless or aluminum, should get you at least 5300 and low 40's.
Sal DiMercurio posted 07-06-2003 01:36 AM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
4,400 maximum rpms on that engine is pure poison, your gonna kill that engine if you continue to run her like thatI think bigshot is correct on the present prop size your now running but I think you will be 300 rpms short of the maximum 5,500 needed with a 13 .25 x 17 .
If in fact the prop is a 21p i'd think about a Stiletto 13,25 x 15 with enough cup installed to equal 1 inch of pitch, that should put you right at 5,500 rpms or go with the 13.25 x 17 & raise the engine a hole or 2 to get those extra 300 rpms you need.
It depends on how high your engine is mounted.
Sal
DaveS posted 07-06-2003 10:12 PM ET (US)     Profile for DaveS  Send Email to DaveS     
Thanks for the responsed guys, I greatly appreciate them. I haven't had time to pull the prop yet but I should have a few minutes tomorrow to do the job. This is the same prop that the boat came with when I purchased it last year and this was the first time I could open it up. I'll post the prop size tomorrow when I get it off the prop.

Thanks again!

DaveS

DaveS posted 07-06-2003 10:18 PM ET (US)     Profile for DaveS  Send Email to DaveS     
Bigshot,

I was running with just myself and 14 year old son onboard with 20 gals of fuel. I guess a moderate load but nothing special. The engine is mounted all the way down. I guess I'll be looking for a new prop very soon.

I don't think grw66 would be interested in a 21" prop, would you? :)

Thanks again for the info, as always, it's greatly appreciated!

Sal DiMercurio posted 07-07-2003 01:12 AM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
You also need to raise that engine 2 holes or you wont get the rpms you need.
Before you buy any props, raise that engine, should really surprize you
Sal
Bigshot posted 07-07-2003 10:13 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Sal the 15" will be too small on a 17'. I had a 17 with the same power and the 17" alum and SS gave me about 5300 with 2 people aboard and pate 27 tank, engine on transom. If he raises the engine it will get closer to the 5500 as you suggested.
Sal DiMercurio posted 07-07-2003 11:00 AM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Big, I agree with you, just trying to give him a couple of options.
Personally, i'd opt for the 17p & raise the engine , should allow for more speed then the 15p.
Sal

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