I have a 320 voyager with 3 blade props. I rarely plane the boat but like to have the ability to run on plane some. I saw a mariner with 4 blades that were considerably larger than mine. Much more blade surface. What is the advantage/disadvantage in the 4 blade prop?
4 blade vs 3 blade prop comparison
- Thread starter Wintersux
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4 blades props give smoother ride than 3, give you better handling around the dock, better hole shot and most give better cruise speed.
On outboards/sterndrives, they can also lift the stern up higher out of the water.
On outboards/sterndrives, they can also lift the stern up higher out of the water.
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I changed to 4 blade last year and noticed a big difference in my hole shot. Most prop suppliers will suggest that you go down one size from the 3 blade if you move to a 4 blade. I love the 4 blade performance.
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4 blades due keep u on plane at lower speeds. I've kept my 3607 on plane rb2@gr5t 12 knots and yes one great hole shot
imspacemancraig
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From my experience playing with various size/configurations, the 4 blade gives you a faster hole shot (5 blades even faster) but lower top speed. You can compensate that with the different pitches though. The real key is to make sure you don't over/under prop your boat. You want to make sure the prop gets you to the perfect Wide Open Throttle (WOT). Then tweak accordingly. Probably harder to do with the bigger boats, but I had the opportunity to try different props on my run-about and I was amazed at the performance differences between the pitch and number of blades. There is a guy up in MN that was a wealth of information and also allows (at used to) to try out different props. His site: http://www.propmd.com/ has a lot of information on it too. He also does prop repair. Very reasonable but even more important to me, awesome customer service!
My 86-3297 mariner from the factory is supposed to be 18 x 19 - 4 blades which should run at 4100/4300 WOT / I found out I have 22 x 22 4 blade and although it will get on plane at mid/low RPMs (about 2400 rpm) she will not get above 3100/3300 RPMs - she also has a lot of side face for the wind to push around when docking but with these big buggers under her she swings that stern around like a CW dancer doing a spin - I read that for ever 1 inch down in prop size you should see a 300 RPM increase so if I go down to 18 x 19 I should see the optimal RPM - question is what mfg. of prop and is nibral really al that much better than brass - guess I'll post that question. Stay dry!
imspacemancraig
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ecmark,
I have the exact same boat. LOVE IT!! I have 18 x 18's, brass, 4 blades. I pushed her for the first time this year and had it up to 4200 RPM's. I changed out to the spare props I got with the boat and wanted to see what she would do with new props on it. I usually run her around 3400 while cruising mainly because I don't gain much by pushing harder. I think I gained a whopping extra 5-7 miles per hour but more importantly, she probably drank a lot more gas (had it up to 30 mph) just to get that little bit more. At 3400 rpm I run about 25 mph as per the GPS. This fluctuates obviously depending on number of people and stuff you have aboard. But a lot easier on the gas tank and the engines.
Everything considered, she runs great, gets out of the hole well (for a big boat), planes well, and really, the gas usage isn't that bad. The usual trip on the weekends is about a 4.5 hour total run time with a balanced mix of on plane and no wakes. I will burn around 50-55 gallons on that trip.
Here is a good link to more information on propping: http://www.lake-link.com/boating/props101.cfm
I have more, but not sure on what the rules are on posting links to other sites here. Google "boat propellers 101" and a load of good stuff comes up.
I have the exact same boat. LOVE IT!! I have 18 x 18's, brass, 4 blades. I pushed her for the first time this year and had it up to 4200 RPM's. I changed out to the spare props I got with the boat and wanted to see what she would do with new props on it. I usually run her around 3400 while cruising mainly because I don't gain much by pushing harder. I think I gained a whopping extra 5-7 miles per hour but more importantly, she probably drank a lot more gas (had it up to 30 mph) just to get that little bit more. At 3400 rpm I run about 25 mph as per the GPS. This fluctuates obviously depending on number of people and stuff you have aboard. But a lot easier on the gas tank and the engines.
Everything considered, she runs great, gets out of the hole well (for a big boat), planes well, and really, the gas usage isn't that bad. The usual trip on the weekends is about a 4.5 hour total run time with a balanced mix of on plane and no wakes. I will burn around 50-55 gallons on that trip.
Here is a good link to more information on propping: http://www.lake-link.com/boating/props101.cfm
I have more, but not sure on what the rules are on posting links to other sites here. Google "boat propellers 101" and a load of good stuff comes up.