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| Looking for new prop https://www.smwebhead.com/phpBB3/viewtopic.php?f=3&t=13670 |
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| Author: | newbiechris [ Thu Dec 18, 2014 10:16 pm ] |
| Post subject: | Looking for new prop |
Looking for recommendations on a new prop. I do a lot of pulling looking into maybe 4 blade stainless. I'd like to have a bit more acceleration but keep top end similar, right now I have a 3 blade and I think pitch is 22 |
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| Author: | zims1993 [ Fri Dec 19, 2014 5:46 am ] |
| Post subject: | Re: Looking for new prop |
What's your boat specs? |
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| Author: | newbiechris [ Fri Dec 19, 2014 7:21 am ] |
| Post subject: | Re: Looking for new prop |
What specs? It's a 1998 horizon rs. 5.0gi sx drive |
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| Author: | Walt [ Fri Dec 19, 2014 12:22 pm ] |
| Post subject: | Re: Looking for new prop |
My rule of thumb is "add a blade, add an inch". If you are happy with your top end on the 22P (that's an unusual pitch for a 3 blade), then I would go to a 4Bl 22-23P, or a 5Bl 23P. For example, my FW came with a 3Bl 19P (SS of course). I tried a 4Bl 20P, and said nah, then went with a HiFive 21P. My top end dropped by 2-3MPH, but I can carry a FULL load, and still pull 2 boarders simultaneously without moving people around inside to "trim". |
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| Author: | Surface Interval [ Sun Dec 21, 2014 3:28 pm ] |
| Post subject: | Re: Looking for new prop |
According to the Four Winns "Fast Facts", your boat should have come new with a 14 1/4 diameter X 21" pitch prop. Some general guidelines for props are listed below 1. Reducing pitch 2 inches from 23" to 21" should increase top end by 300-400 rpm with the same make and model of prop. Less pitch means less load on the engine, which means higher rpm. This is similar to downshifting to a lower gear in your car. 2. Changing to a smaller diameter will increase max rpm slightly, but not as much as a change in pitch. Less blade area means less load on the engine and higher rpm. 3. Replacing an un-cupped prop with a cupped prop of the same size is like adding 1 to 2 inches of pitch. "Cup" is the curved lip on the back edge of each prop blade. 4. Different brands and models of props can vary significantly in performance for the same diameter and pitch. Or there may be no difference at all. I went from an aluminum Volvo 3 blade 14 1/4 X 21 to a Stiletto Stainless of the same size and there was no difference. 5. When going to a prop with more blades, the diameter is often reduced slightly. Adding the blade area of 1 or 2 more blades will make the prop slip less and hook up better, but this will increase the load on the engine causing lower top end rpm. That is why a reduction in diameter or pitch or the blade area of each blade (or a combination of these) is common when going to 4 or 5 blades. 6. Changes in blade "Rake" angle, cupping, size of blades, diameter, pitch, and other factors can affect how the boat performs and how it behaves when trimming the drive. Boats will tolerate more trim at higher speed than at slower speeds. This is due to several factors including the boat being higher in the water, and less forward hull area in the water at higher speeds. Less vertical distance from the prop to the surface of the water means less leverage to lift the bow. Less forward hull area in the water means more forward weight unsupported by the water. 7. An increased rake angle will generally produce more bow lift. This may be good on some boats but maybe not on others. Bow lift may affect how well you can trim your boat at different speeds. To a certain extent, changing props can be a lot of research leading to a scientific wild a$$ guess (with emphasis on the dollar signs), followed up by trial and error. Best of luck. |
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| Author: | GottWhat [ Mon Dec 22, 2014 2:50 pm ] |
| Post subject: | Re: Looking for new prop |
When I bought my boat this past summer, it had an older stainless steel 14 1/4 x 23p propeller installed. The problem was I would max out at about 4200 to 4400 rpm. According to FourWinns "fast facts", my boat (2000 Four Winns Horizon 180 LS w/5.0Gi Volvo Penta - 250 HP) originally came with an aluminum 14 1/4 x 21p prop with top speed revving at 4800 to 5000 rpm. This makes sense as this is the size AL prop I was given as a spare when I bought the boat. Looking around at new props, the SS Apollo appeared to be a good match for my performance needs and budget (total with hub kit and shipping was only $291.57). The only problem is they did not make a 21 pitch prop with a diameter of 14 1/4. They only had slightly smaller or slightly larger. After an email to Michigan Wheel describing my issue, I went with the 14 inch. With just my 6-year-old son, me, full tank of fuel and bimini top all the way down, we achieved a GPS indicated top speed of 53+ MPH at 4800 rpm. I think we still had room to go and believe 55+ mph is achievable on a completely flat lake. The best part isn't the top speed though. The hole shot is awesome and the boat plains even faster now which is amazing considering how fast it would do it before. Pulls tubes with no complaints. Great acceleration from 25 to 40 MPH as well. |
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