|
|
Posts: 546
Location: MN |
I have been hunting around the internet for the prop specs for this engine. I found some info, but it seemed pretty generic. The site said the standard prop was 10-3/8 R 13, but I am not too sure about this. Any thoughts? I know my WOT range is 5000-6000 rpm, but really don't know much else.
The motor is on a 16.5' alumacraft john boat which is used for duck hunting and fishing while I am at college. I am looking for a lower cost prop to serve these purposes. Any ideas if the actual size and pitch are correct? |
|
| |
|
Posts: 532
| I have a mariner 25hp 1988, very close to the same motor. not exact but close this is some tests i posted a few years back on another site
http://forums.iboats.com/showthread.php?t=399148
To sum it up I like the solas amita 4 prop the best. I run a 13 pitch on my boat, I have thoughts to lowering that to an 11 just to see what it does, If i do i dont expect to much out of top speed (out of effeciency) but maybe better out of the hole preformance.
Make sure you get a tach so you know the numbers you are at. But I feel a 11 or 13 pitch in a solas amita 4 would do very well for your application.
|
|
| |
|
Posts: 546
Location: MN | Thanks for the info. I was wondering if you, or anyone else has any preference on brands of aluminum props for general purpose? |
|
| |
|
Posts: 532
| Solas, You will not find a better prop for the money. Go with the 4 blade, its call Amita 4 |
|
| |
|
Posts: 3504
Location: Elk River, Minnesota | Hiya!!
Most definitely solas!! The Amita is a great prop. The blade design has a full cup throughout the fin with a good cup at the tip and trailing edge. The blades are strong and a little thinner due to the squeeze cast design. Good price too.
Steve |
|
| |
|
Posts: 546
Location: MN | How would going from a 3 blade prop to a 4 blade design change my performance and engine stats (rpm, etc.) |
|
| |
|
Posts: 3504
Location: Elk River, Minnesota | Hiya,
If you are going from a 3 blade to a 4 blade in the same pitch, you would see a reduction in RPM's of some sort and a loss in top end speed. The reason for this is the extra blade. With one extra blade in the water, you are increasing the amount of surface area for your prop to grab water, thus it takes more for the motor to turn the prop.
On the other hand, going to a 4 blade will increase the handling characteristics of the boat. You could make harder turns in either direction, and the prop will continue to grab water well. It very well may increase your bow lift a touch too, so you might have to play with your trim rod settings. If you are lucky, you will get to move the trim rod away from the boat.
Steve |
|
| |
|
Posts: 532
| With all my tests of different props, i have done more since i wrote that review, I have a better top speed with a four blade compaired to an average 3 blade. This is because of the effeciency of the a four blade. I have also seen very little effect of rpm with the forth blade. I know with larger boat with bigger motors the extra blade should decrease rpm 200 (rule of thumb) but have not found that to be the case on smaller outboard motors.
Overall the handling is better, and better hole shot with my four blade.
Please note this is a 25hp motor going 21-24mph (depending if i am going with the wind) in a tin boat, it isnt a ranger 620 with a 250 hanging on the back that has power trim and a hydrolic jack plate. So 1mph is a fairly big change for just a prop change. |
|
| |
