13.0x19 prop/5000rpm/38mph

[TOFINO TOM]

Got the tach working on my new/old boat. heavy deep vee 17 foot DOUBLE EAGLE. 110 evinrude(1989 v4) with factory OMC aluminum prop 13.0X19.0, it runs a hair over 38 mph (verified on 2 gps units) comes right out of the hole an up on plane with 2 dogs/2 big adults and 2 6 gal fuel tanks. 5000rpm on the nose WOT. weight, MINUS engine about 2100lbs. seems good to me or should i expect more? naturally the brand new "SPARE" prop is also a 13x19. TT:redface:

 

[Fl_Richard]

Re: 13.0x19 prop/5000rpm/38mph

If the current prop and new prop are 100% identical than I would expect the new prop to drop rpms a fraction as its probably worn a little.

I think you should be higher at WOT; 13x17 might be too much RPM gain. A more modern prop might increase RPM at the same pitch through wizardry.

This is way better answered by the real experts in this forum but I think you'd benefit with few more turns at WOT. .

 

[jestor68]

Re: 13.0x19 prop/5000rpm/38mph

Since the WOT rpm range of your motor is 4500-5500, I'd say you are in good shape with the present load. A heavier load will bring it down some, but you should still be within the range.

A 17 would add 300-400 rpm(on average) and put you near the top of the rpm range, while maintaining the ability to carry more weight if need be. I suggest swapping the spare for a 17 to have on hand should you decide to play with it a bit.

 

[TOFINO TOM]

Re: 13.0x19 prop/5000rpm/38mph

Thanks to fl richard and jester 88 for the replies. If anything, i will lighten the weight by leaving the wife on the wharf!!!!!!will look for a 13x17 as a 2nd. spare. thanks again. Miss our place in PORT CHARLOTTE.Sold it when "ANDREW"almost got it.

 

[meatyb]

Re: 13.0x19 prop/5000rpm/38mph

Not sure what your boat actually looks like or style of it but I have a similar 17 ft bow rider 1830 lbs without motor 115 merc outboard and with a 19 pitch two adults 25 gals of fuel and a tail wind best I can get is 35mph. At 5200 wot. Same load with a 21 pitch I get @38 if I'm lucky. Maybe both our numbers are off?

 

[V153]

Re: 13.0x19 prop/5000rpm/38mph

I would try the 'spare' prop & see what kinda performance it delivers. Then take the worst performer of the 2 down to the local prop shop and ask em to knock an inch or two of pitch outa it. Balance, etc.

5000rpm is nothing for that motor. They don't even start breathing hard til 5900 or so. Though they are capable of ingesting copious amounts of fuel at that rpm ...

Ya. Pic of the boat'd be nice.

 

[jestor68]

Re: 13.0x19 prop/5000rpm/38mph

5000rpm is nothing for that motor. They don't even start breathing hard til 5900 or so.

That is one huge load of really, really bad advice! Run any motor past it's factory recommended max rpm at your peril !!

 

[V153]

Re: 13.0x19 prop/5000rpm/38mph

That is one huge load of really, really bad advice! Run any motor past it's factory recommended max rpm at your peril !!

OMC doesn't give you a max rpm or "redline" if you will. Nor do any other manufacturers anymore. For liability purposes of course. OMC recommends a wot operating range of 5500rpm for that motor. Speaking from experience you can do that all day long. Provided the cooling system is working properly and you have enough fuel ...

 

[jestor68]

Re: 13.0x19 prop/5000rpm/38mph

They don't even start breathing hard til 5900 or so.

I was referring to that remark. It seemed that you were inferring that it was OK to run it up to that speed.

I agree that you can run it all day long at 5500rpm. The higher number in the recommended rpm range(in this case 5500) is the maximum recommended sustained rpm to run the motor; what some folks call the "red line". So the manufacturers do in fact publish the numbers. They're right there in every owners manual.

 

[TOFINO TOM]

Re: 13.0x19 prop/5000rpm/38mph

update Tried my spare 13x19 omc prop. dropped to 37.3 mph and 4850rpm. put original omc prop back on, raised the motor as high as it will go on last bolt holes, trimmed out, it JUMPS ahead like a scalled cat and and a little more trimming, hits 40.1-40.3 mph on 2 different gps units at 5250_+ afew rpm. i think that works for me, especially when a fellow with brand new BAYLINER came dockside and asked how ''THAT OLD FISHING BOAT" could accelerate like that. Being a quiet conservitave senior citizen, i simply told him that it has a modified lower unit and 140 hp. hi comp heads and special chinese spark plugs. Igot a knowing O YA, i knew it was modified. i bet he is still looking for those chinese plugs!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[steelespike]

Re: 13.0x19 prop/5000rpm/38mph

That prop must be close to a perfect match for your setup.
It does calculate out to 15% slip a little high but hard to find fault.

 

[Frank Acampora]

Re: 13.0x19 prop/5000rpm/38mph



Well, I agree with V153 up to a point.

The operating range is where the engine 1. produces its rated horsepower and 2. will give the best fuel economy at WOT. These 2 cycle engines have no valve train and have the ability to rev way past the maufacturer specs. Practically speaking, you wouldn't want to run the engine at 10,000 rpm--that would be reserved for racing and yes the engine life would suffer. However, a couple of hundred rpm over the max quoted would never be noticed by the engine.

In fact, I have a Force 125 that is propped to run at 5900 and 60 MPH with a cleaver prop. I run it "all day" (in this case all day is two hours) at WOT with no ill effects--except that it uses 15 gallons of gas in 2 hours (then I go home). Hole shot is breathtaking: One bounce with an immediate plane at 45 MPH. Then as I feed in up trim, RPM and speed rise to 5900 and 60 MPH

 

[jestor68]

Re: 13.0x19 prop/5000rpm/38mph

Well, it's your money; do what you want. You're the one paying for the new power head, not me.

 

[TOFINO TOM]

Re: 13.0x19 prop/5000rpm/38mph

2 HOURS AT WOT. WOW, I could make it across the SALISH SEA(straight of georgia) to downtown Vancouver or down to Washington state. But being on a more or less fixed pension,i am on a self imposed limit of 15 gallons(18u.s.) a week. heck, in 2 hours ,i would probably forget where i was headed!!!!!!!!!!!!!!!!!!!!!!!!!! all kidding aside, ya got to know your boats limits and i think i am pretty much there( CLINT EASTWOOD said that or something close) great forum enjoy it. TT