Prop question!

[craigman]

Fellas,
other than a prop getting nicks and dings, can a prop just generally wear out?
I buddy of mine was saying i should get a new prop cuz the edges of the prop were'nt all crisp and sharp.
Is this just b.s. or some truth to it?
Thanks!
Craig

 

[steelespike]

Re: Prop question!

It is possible for an aluminum prop to be worn enough that the diameter is undersize.
If it is dinged up the blades could be bent or out of balance.How is the performance?
Any odd vibrations?Venting(cavitation) issues? If you tell us about the booat and motor and your present hole shot and max rpm and speed we can tell you if your performance seems right.

 

[craigman]

Re: Prop question!

Thanks Steelespike!
My boat is a 1974 Reinell 15' tri hull with a 85hp Merc. I think the boat weighs around 1200-1400lbs. It's a pretty light boat.
If i remember, (haven't taken it out this year yet) it was taching out at 4800rpm's and around 30-32mph. (using a buddys GPS) And i can't remember off the top of my head what prop is on it right now.
Of course i'd like a little more speed out of it, but was wondering if the prop was "worn".
Any advise you could give me would be greatly appreciated!
Thanks again!
Craig

 

[steelespike]

Re: Prop question!

Dry weight of 1200-1400 would be heavy.
Couldn't find a 74 but a 77 15 ft was 850 dry weight.
Is the motor a 74? Your rpm is low and speed is low though at
the reduced rpm about right.
Until we get the prop numbers can't tell where the problem might be.
Prop numbers may be at the base of the blades or under the prop nut.

 

[craigman]

Re: Prop question!

Thanks again!
I'll try and get the prop numbers in a while. (hard to get around, just had knee surgury!)
That wieght i was assuming with 2 adults, and full tank of gas. Of course, i could be way off.
Yes, the Merc is a 1974 also that came with the boat.

 

[craigman]

Re: Prop question!

Went out and got some numbers of my prop.
They are: 48-65588a1 19p
Does this help?

 

[Bamaman1]

Re: Prop question!

If your prop is nicked up, you'll need to get it reconditioned. Prop shops are in most major cities, and can make your current prop look like new.

 

[craigman]

Re: Prop question!

Can someone tell me what prop i have?

 

[steelespike]

Re: Prop question!

Its a Merc. number the 19 makes it a 19" pitch prop.
Someone should be along with the details of the number.
I think you can assume boat alone is about 800lbs.
Add motor about 240lbs, gear, gas, people etc. for total.
Probably would be better to wait and do a light run for the max rpm and speed.
The 19" pitch may be a little too much but a light test run will tell more.
You could ask a prop shop what they think of the prop and cost for repair.
If needed you can likely get a new one for about $100 plus shipping.

 

[craigman]

Re: Prop question!

Yes, i was looking at the props thru iBoats. Can get a decent prop for around $100.

 

[craigman]

Re: Prop question!

I just don't know what size prop i should get.

 

[steelespike]

Re: Prop question!

We really need the info from a lightweight run to get more accurate wot max rpm and speed.
Also check the height of the motor.The antivent plate just above the prop should be about even with the bottom and up to about an inch higher. Measure with a straight along the keel.
Sometimes in the extreme you could lose a couple of hundred rpm and 1 or 2 mph.
Wouldn't hurt to check if the throttle opens all the way.
If all checks out with a light test run it appears a 15" prop would work.

 

[craigman]

Re: Prop question!

You know, you brought up a good point. I often wonder if i'm getting full throttle or not. I could only get about 4900 rpm's max. And it didn't sound like it was working hard.
I've read about the "link & sync" procedure. Sounds like it's pretty envolved, but i wonder if i would benifit from it. Hmmm...

 

[Robbabob]

Re: Prop question!

it's ALUM 13.00X19.00

 

[craigman]

Re: Prop question!

Thanks Robbabob!