4 Blade Vs 3 blade

Anyone else test their new props yet? I still have not been able to get numbers in MPG with full tank and refill. It has been to cool to go out. Look forward to hearing others results. Rob
 
wakeup 19 said:
Anyone else test their new props yet? I still have not been able to get numbers in MPG with full tank and refill. It has been to cool to go out. Look forward to hearing others results. Rob
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I should have props in shipment this afternoon or tomorrow from Hill... excited to see what comes out.
 
Forgot to post these. Here were my stats that I sent to Hill Marine. Will post a comparison update once I get the new props in and on.

James

Boat - 2005 Sea Ray 300 DA
Beam - 10'5

Current Props - 3 Blade Aluminum 17.75" x 21P
Twin Mercruiser 5.0L EFI - 260 HP each
Bravo II drives - 2.20:1 ratio verified

Medium load with flat seas:
Hull = 12500 dry per spec sheet
Nearly Full Fuel - ~170 gal
Nearly Full Water - ~40 Gal
2 people - 400lbs total


Minimum Plane RPMs w/no tabs - 3250
Minimum Plane Spd w/no tabs - 20.2 kts

RPMs @ Solid Plane & levels out - 3600-3650
Spd @ Solid Plane & levels out - 25kt

Max RPM - 4875
Max Spd - 36.5kt
 
I have a 3 blade prop on my omc sterndrive, would it hurt anything to move to a 4 blade?
 
Paulie Walnuts said:
I think I lost about 3 MPH off WOT by switching to a 4 blade prop. I switched because I have a 15 year old that likes to go tubing with his friends and I wanted something to get me up on plane faster. However my mpg seems to have increased at mid range and cruising speeds.
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Paulie that's exactly why I'm looking into a 4 blade prop, better mpg is a bonus.
 
So I now have a pair of Hill Marine 4 bladed props in the garage over in Annapolis. Wont be able to put them on to try out until next week due to a boating event this weekend. I would change them out before the weekend, but since I'll have guests aboard, I'm leery of making any changes that could foul anything up!

Anyway... In discussing this upgrade from 3-bladed aluminums to 4-bladed stainless steel props, someone pointed out that I should be concerned about having two big chunks of stainless (Bravo II stainless props are 35lbs each) on an aluminum cased Bravo II drive. The point being made was that BIIs typically have aluminum props and it's the double stainless props on the Bravo III drives that causes the galvonic crosion issues that are so rampant with the BIII drive casings. Good news is that my boat lives on a lift most of the time, so its exposure to galvonic corrosion is minimized to marina visits and weekends on the water.

Any thoughts?
 
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Plenty of people run stainless on their aluminum drives. I've personally never run an aluminum prop. Just watch your anodes.

I did get a chance to run my boat with my new props!

She idled from the hoist to my slip beautifully. Sorry, couldn't resist the teaser. I'll be out running her this weekend.
 
Still interested to hear the results of your boats...keep us updated!
 
I run stainless props with my Alpha drives. I've noticed that the anodes just above the props wear more than the others, but they last me through the season. I do keep an eye on them though.
 
I read quite a bit about the four blade piranha composite prop and it seems like a no brainer. I'm going to get one next month, everything I read was about getting on plane faster and staying on plane at lower rpms.
 
After reading this entire thread I am pumped about getting 4 blade props for my 290. I also need a better hole shot and lower rpm planning. not worried about top end speed. The hill's or the composite piranha's? Any advice?
 
BurleyCove said:
After reading this entire thread I am pumped about getting 4 blade props for my 290. I also need a better hole shot and lower rpm planning. not worried about top end speed. The hill's or the composite piranha's? Any advice?
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I was quite pleased with my Piranha. The hub and 8 blades and a wrench for less than the price of a standard prop with equal performance. As said......no brainer.
 
I don't have a lot of firm numbers but I'm happy with the 4 blade switch. My cruise has dropped about 400 rpm to 33-3400. My hole shot is much better. Maybe it's wishful thinking but it seems like I have a little more bite at the dock as well.

We were full full full this weekend. Full fuel, full water and we literally had enough gear and food on board for a picnic of 10 people and a weekend on the water for my wife, son and myself. Table, chairs and all. It was my wife's birthday and we took the boat to the park, met the family there and had a picnic.

She came right up on plane nicely. I didn't need to completely open the throttle. With the 3 blades I would have to open her up and wait to climb onto plane. It's not going to set any speed records, but I'm happy.

I didn't test the top end because I don't care. My goal was better hole shot and lower cruise rpm. Mission accomplished.
 
jobofly said:
I read quite a bit about the four blade piranha composite prop and it seems like a no brainer. I'm going to get one next month, everything I read was about getting on plane faster and staying on plane at lower rpms.
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I was curious about the piranahs but they have a horsepower limit and I didnt find one on their site that would work for my setup. I'll go back and verify, but that's my recollection.

Update - Out of curiosity... I emailed them to see what they recommend since my engine/drive package (although standard) isnt listed on their page.
 
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JimFromMD said:
I was curious about the piranahs but they have a horsepower limit and I didnt find one on their site that would work for my setup. I'll go back and verify, but that's my recollection.

Update - Out of curiosity... I emailed them to see what they recommend since my engine/drive package (although standard) isnt listed on their page.
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I didn't seem to find a left hand rotation for my pitch prop either...but I needed to go out and verify my diameter.
 
CliffA said:
i just ordered and received a 14.25" x 17P four blade aluminum Solas prop to try on my boat this year....roughly $110 delivered to my door....i currently have the stock 14" x 19P three blade stainless prop that does OK with just a couple people on board and full fuel tank, but i am starting to do more water sports with my kids and grandkids....the stock prop will allow the boat to plane reasonably well and allow the engine to rev up to the lower limit of my WOT range at around 4400 rpm....maybe the new lesser pitch prop will allow me to gain a couple hundred rpm's at WOT even though it is a slightly larger diameter than the stainless prop...i am hoping the lesser pitch four blade prop will give the boat a little more 'grunt' and allow it to plane easier when carrying 4 - 5 adults while at the same time pulling someone on a ski or kneeboard....i am not concerned if i loose a couple mph off top end speed.....if the new aluminum Solas four blade prop works well i may opt to buy a stainless prop with the same specs, however i have stripped the gears in the upper section of an Alpha drive before when i hit some rocks with a stainless steel blade....the strength of a stainless blade is both an asset and a problem......i may just decide to keep running aluminum props and replace them as needed instead of having them repaired since they are more forgiving on the gears and shafts of the outdrive if the blade hits a rock, log etc.......it cost me $70 each time i have the stainless steel prop repaired so adding an extra $30 and i can buy a new aluminum prop....sure beats the cost of a new stainless four blade prop at around $500-600 each......although the stainless prop is more shiney and looks better while the boat is on the trailer....:grin:

cliff
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i thought i would post a follow-up to my post in this thread about my experience with switching to a 4 blade prop....we finally got our boat out the first time after changing out the stock 14" x 19P SS 3 blade prop with a 14.25" x 17P AL 4 blade prop on my 215EC with a 5.7L Mercruiser engine....it was just my wife and i but the boat was fully loaded with fuel, fresh water, coolers, water toys, grill, etc.....the water had a little chop due to the wind but not bad.....all i can say is the boat now handles, performs and rides completely different and in a good way.....from a dead stop i can quickly accelerate on plane with almost no bow rise....it is almost as if the boat just lunges forward and almost instantly on plane.....once on plane and cruising and after i get the trim tabs set and the sterndrive trim set i do not have to touch them again the rest of the day....when coming off plane and down to an idle or stop the engine i leave all of the settings on the tabs and the sterndrive alone....when we were ready to go i simply applied the throttle and again the boat just lunged forward and onto plane.....the 4 balde prop made a significant difference in the attitude of the boat while cruising by raising the stern and moving the bow down into the water....this made a significant improvement in the ride of the boat since the deep V of the bow now just cuts through the water chop and waves.....i can now cruise on plane at around 2,800 rpm's at around 25 mph and have much improved visibility over the bow while seated....i did not try to see what the rpm's were at WOT as i really do not care about top speed....the boat handles much better in fairly tight turns and does not loose any speed in the turn....the only slightly negative thing i 'think' i noticed was a slight increase in fuel consumption possibly due to the fact that more hull of the boat is in the water now while cruising with the stern higher and the bow lower which creates more drag....i can likely compensate for this with trimming the sterndrive up some more once i get used to the new prop....overall a very pleasant experience with the new prop.....

cliff
 
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thanks for the update cliff, this is good to hear as i am going to order my four blade prop soon.....right now i can stay on plane at 3200 rpms at 25 mph im hoping to under 3 to cruise on plane.
 
Just a follow up on my new 4 blade SS props. I have consistently been getting 1.1-1.2 mpg. with better handling and quicker planing. That is an increase on 10-15% . Very glad I made the switch. Burning on avg 14 GPH as well total. I do have a half hour of no-wake zone each way in Boston Harbor that may skew the numbers a bit. Last weekend did 90 miles and burned 76 gals. I'll take that for a 30 ft cruiser. Any other results out there?
thx Rob
 
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