prop for a 14.5' alum. side con.

[yellowbelly]

the boat wt. is 440 so with both trolling and main with me its around 800...its has a 78 55hp rude with a bs 4 blade propulse running at 14p... i have no tach i order a tiny tach today it just dont sound like its hitting 5600 which is the power band for the motor and tops out at 27.5 mph.... what kind of speed should i expect once i hit the rpm range

 

[steelespike]

Re: prop for a 14.5' alum. side con.

Is your speed by gps? I would think with that setup 35-40 mph should be possible.While some look down their nose at the composite props some have
shown to perform very well.You might try raising the motor to a point just before venting(cavitation)becomes a problem.The Turning Point props
give close to stainless performance at aluminum prices.

 

[hwsiii]

Re: prop for a 14.5' alum. side con.

I must have found the wrong specs for your motor, I found your motor a 1978 Evinrude 55 HP to weigh 180 pounds turning 5,000 to 6,000 RPM with a 2.42 gear ratio. If you can give me the correct information I will tell you what prop you need. But your boat should run right at 38 MPH no matter what the specs are.

H

 

[yellowbelly]

Re: prop for a 14.5' alum. side con.

these are from my shop manual 55hp at 5500rpm
full throttle range 5000-6000rpm
180lbs.
propeller gear ratio:12.29
here is a pic of th boat

 

[hwsiii]

Re: prop for a 14.5' alum. side con.

No the specs I showed for your motor are exactly right. You should be able to reach 36 MPH on that boat, if your evinrude has good compression and is running right. But I do notice a spare motor on the back of the boat in the picture, if that motor is staying there it certainly is a lottt of added extra weight on the boat as well as it is directly at the stern, the worst place you could put it almost. When you get your Tiny tach get back with me and give me the RPM and GPS speeds you are attaining at that time. We will see what can be done then, and that boat is pretty, is it a custom boat.

H

 

[yellowbelly]

Re: prop for a 14.5' alum. side con.

not custom its a 1984 sylvan 14' sportster i took all the seats out and the pass. side consile and flip windsheild to make more room in the boat bought off the original owner who used it on a private 1 acre lake i boaght the boat and tailor and cover for 500 it was in show room condition it had a 50hp merc that i didnt need but should have bought it he only wanted 900 for the whole package..came with all the ads from the dealer too.

 

[yellowbelly]

Re: prop for a 14.5' alum. side con.

got some time off work today and got the boat out....28mph @5000 rpm with a 3 blade 12 1/4 x15 alum prop

 

[hwsiii]

Re: prop for a 14.5' alum. side con.

In my opinion you still have a problem, but if you you will buy a 13" pitch prop in the same make and model you have right now your RPM should increase to about 5,700 RPM. I would also move the motor up one noth on the transom first just to be sure it is high enough.


H

 

[steelespike]

Re: prop for a 14.5' alum. side con.

hwsiii figures are probably right on.As long as you are changing props take a look at the Turning Point Hustler.With your info their charts agree with H. Generally the Hustler works well when going same pitch to same pitch.
So a 13 should work.Hustler gives close to ss performance at al prices.

 

[yellowbelly]

Re: prop for a 14.5' alum. side con.

In my opinion you still have a problem, but if you you will buy a 13" pitch prop in the same make and model you have right now your RPM should increase to about 5,700 RPM. I would also move the motor up one noth on the transom first just to be sure it is high enough.


H

if i go one more notch up the boat hops across the water and is unstable there is also a ton of weight in the back of the boat.. last night it was a full 6 gal. tank a full 3 gal.tank a bat. and my buddy...the motor is like new runs great idles down to 850rpms in gear compression is 151 and 150....getting on plan is a pain i took the stingray off to see how it would react so it going back on..the prop is the stock prop that came with the boat in 1978 its my spare..the pro pulse i was running fell apart

 

[steelespike]

Re: prop for a 14.5' alum. side con.

When we say go up a notch we're talking vertical height not trim.
Instread of putting the foil back on try moving some weight forward.
Or add tabs something like smart tabs are easy to install and are passive tabs.Carefully adjusted they will plane faster,stay on plane with less power And will reduce no wake speed wander. All without hurting top speed.