14x17 or 13x19?

[1976CV16]

Hello everybody. I have a small 16 foot glastron, 1200lbs boat, motor, fuel and gear. Which prop would have the most torque for loading up the boat or tubing? My lack of math skills want me to say they are similar, but i dont know. Both aluminum 3 blade props. I have no gauges so the typical trial and error watching the tach isnt going to work. Its not a speed boat or anything fancy, just an old boat to play on. Thanks

 

[steelespike]

It is very important that the motor be able to operate within its rated rpm range at wot.Once established you can run at whatever speed you prefer.
Your motors health and performance depend on accurate propping.
We need a whole lot more info if we are going to help you.Get us as many answers from the sticky "read this first"at the top of the forum.
Boat dry weight,year, model hp of the motor.You need to get a tach.An induction tach will work on almost any motor. A gps for speed
may be available on your cell phone. I

 

[Maclin]

Just to answer your question about which one would pull better at launch and keep the boat on plane at lower speeds, of the two you are comparing.that would be the 17 pitch (14x17).

What motor do you have?

As to which is best for your boat, without a tach then trial and error like you mentioned. Just be sure when you try them out that you have similar loads and towing payload for same-same comparo.

That is a pretty cool boat to just be "an old boat to play on"...

Have you found the two sites shown below yet? There will be many members there that would probably beg to differ on your assessment of your CV16...

http://www.classicglastron.com/phpbb/

http://www.cgoamn.com/index.html (make sure to check out the CGOAMN Forum link)

 

[Maclin]

1976CV16, is this boat the one with the 150hp motor you are working on? If so, once the motor runs right then I would say the 19 pitch would be the lowest pitch prop to run. That is a lot of hp for that boat. My 16 footer with 90hp is a little underpropped at a 17p with just me in it but just right with 2 passengers and/or pulling something.

 

[steelespike]

If the 14" diameter is the right size I wonder if a 13" fits right.

 

[Bob_VT]

Simple solution - BUY A TACHOMETER!!! It has been commented on above and it really is critical to your motors health.

 

[Texasmark]

Basic design differences of the two props is the large diameter shallow pitch is for pushing heavy loads like you'd get with water toys. The other is for light fast operation. The 14 requires 7" plus at least 1/4" gap between the center of the prop shaft and the bottom of the AV plate where the prop mounts. On the 13, it's 6+ and the possible additional interference there would be hitting the trim tab located at the rear of the AV plate.

I agree with other's statements but I boated from the '50's to the late '70's, lots of boats, without a tach having few if any repairs and never lost an engine. FYI www.tinytach.com is the home site for an inexpensive tach that you can easily put on most any engine. If worried, get one.

Mark

 

[1976CV16]

Wow, great responses thank you! I bought an induction tach that wraps around a spark plug wire. Ill hook that up and seewhat rpms im looking at. I did post last week about a 150 i was working on but i gave up on that motor and went back to the old one. It is a 1979 evinrude v4. Its only an 85hp but still goes pretty good with 4 people onboard. For tubing its best with only one passanger though. I would like more power but cant justify spending money when this little 85 has been so reliable. I run the hell out of it during the week and weekends and has never let me down. With the exception of a broken choke solenoid this past weekend. I found the 2 glastron websites. They helped me through all the work i needed to get the boat sea worthy. Thanks again all. Ill experament and post some results.

 

[1976CV16]

I put a 14x21 aluminum prop on last summer and belive it or not that boat was up to 46mph on a gps app on my phone. I had a half of tank of gas, just me and trimmed as high as it let me. The app may be off and i probably had a little help from a windy day but still not too shabby for a 35 year old 85hp motor. With my wife and any of the kids that prop was pretty useless.

 

[jestor68]

The sizes offered by Evinrude, which might be considered "standard" sizes in aluminum and SSP are 13 X 19 and 13-1/4 X 17.

The 19 might be considered a good all around prop, while the 17 is for more serious water sports, like getting up a slalom skier.

Other odd ball sizes, like the 14 X 17 might be offered by other prop makers, but I would suggest sticking with the sizes offered by the motor manufacturer.

 

[Maclin]

I agree with Jestor on this for your boat...."The 19 might be considered a good all around prop, while the 17 is for more serious water sports, like getting up a slalom skier."

 

[dazk14]

At iboats a $105 Solas 12-3/4" x 17pitch will pull like a freight train and be darn close on the upper end of the RPM spectrum. $117 gets you their interchange-able hub if you prefer.

Wot rpm wise, a 17" 4 blade will be similar to an 18" 3 blade, but have much better hole shot and hold plane at a much lower speed, which is important for towing little kids, or cruising through rough water.

The 4 blade will scrub off 1-2 mph vs. a 3 blade, but raising the motor on the transom will often recover that and provide the extra benefit of less bow rise on take off.

If you're using good oil, revving to 5800 is fine (if needed). A decarb is always a good idea.

Order up!

 

[1976CV16]

You all rock! Ill give that 4 blade a try daz, hole shot and a slow plane is more important than top speed. I have the motor on a 6 inch manual jack plate so raising and lowering is a breeze. It is as high as i can go without blowing out while trimmed out or turning. I dont use high end synthetic oil, i use the penzoil gallon jug they sell at menards. Ill share some info when i make it to the harbor and find a prop.