Aluminum vs Plastic?

[Jrc1971]

Have ordered a new plastic prop for my '84 Yamaha 2HP, am waiting on it to arrive. In the meantime I found a guy on eBay selling the same prop, but aluminum. I would like to get it, and keep the plastic one as a "backup". The boat is a 13' Ark Trav Aluminum v-hull boat. Wondering if anyone else has a similar setup and could advise whether switching will have any effects, either good or bad. I figure the aluminum one will be heavier, and I don't want to overheat the motor, etc. Also wondering if it will improve performance. Prop size is 7 1/4 x 4, Yamaha series A.
PS: had to order a new one cuz I sheared a blade off of the original....plastic doesn't cut it in my local lake(rocks/stumps).

 

[gm280]

Re: Aluminum vs Plastic?

Have ordered a new plastic prop for my '84 Yamaha 2HP, am waiting on it to arrive. In the meantime I found a guy on eBay selling the same prop, but aluminum. I would like to get it, and keep the plastic one as a "backup". The boat is a 13' Ark Trav Aluminum v-hull boat. Wondering if anyone else has a similar setup and could advise whether switching will have any effects, either good or bad. I figure the aluminum one will be heavier, and I don't want to overheat the motor, etc. Also wondering if it will improve performance. Prop size is 7 1/4 x 4, Yamaha series A.
PS: had to order a new one cuz I sheared a blade off of the original....plastic doesn't cut it in my local lake(rocks/stumps).

I would think the aluminum prop would work better simply because the plastic prop will flex so much more then the aluminum prop. So I would run the aluminum prop as my main prop and keep the plastic one for an emergency for that once-in-a-life-time issue... But that is just my opinion...

 

[steelespike]

Re: Aluminum vs Plastic?

A 4"pitch should act like a 4" pitch.The aluminum should hold up better though it will bend pretty easily.
The weight of the prop is of no consequence. The aluminum will flex less and may produce a little more speed.
If you buy or make a tiller extension so you can sit in the middle seat it should run a little faster.
There is a little jon boat on You Tube with a 2 hp Evinrude it actually seems to plane with a light driver
in the middle seat.You might be able to raise the motor a couple of inches to avoid the rocks and still run ok.
You could even rig a homemade jackplate with a piece of plywood and a couple of bolts to avoid the rocks better.

 

[Jrc1971]

Re: Aluminum vs Plastic?

Appreciate the responses. I did fail to notice one thing when I originally posted this, don't know if it'll make any difference: the prop this guy is selling has 1" more "pitch"(I think that's the right term), original one is 7 1/4 x 4, the one for sale is 7 1/4 x 5. Will this make a difference? It looks like it will fit, judging from the photos, I just don't know if the extra inch will cause an issue. From what I've read, increased pitch seems to garner improved performance....with only 2 HP I can always use a little boost ;-)

 

[airshot]

Re: Aluminum vs Plastic?

The additional inch in pitch will lug the little engine down, as you are pushing a good size boat with a 2hp motor. Also remember the alum prop will not give like the plastic one does, so if you get a prop strike what else will get damaged besides the prop? I would stay with the plastic prop, more forgiving on impact and less drag on your little motor.

Airshot

 

[steelespike]

Re: Aluminum vs Plastic?

As far as I know aluminum props have safety hub that is supposed to slip on hard contact.
Agreed the 5" pitch will make it harder for the motor to get to the proper rpm,and the motor will lug causing premature repair problems.

 

[scott8058]

Re: Aluminum vs Plastic?

My dad used to run a plastic prop on his fishing boat and the main reason is bc we fished in a body of water w lots of stumps and hazards and it was nice with the removable blades when we hit stuff. May not apply here but just a thought, as for the flex there really wasn't my diff in performance from the plastic to aluminum, this was on a 16.5 ft deep V crestliner. good luck

 

[colbyt]

Re: Aluminum vs Plastic?

Surely the information for your Yamaha is online somewhere. Most motors can handle more than one size.

My 3.5 Tohatsu can do pitches from 4.3 - 7.00 with the 7.00 being the default.

Just my unexpert opinion, the small weight difference doesn't matter as long as it is balanced.