Hi guys, Is anyone in the Great Grady group running a 4 blade prop on their 208 or Seafarer? I am running a Reliance SDS 17p on my 208, getting 5600 WOT. Was thinking of trying a Rev 4 from Mercury or some other recomended 4 blade prop to see the difference. Difference as in better fuel economy, quicker on plane, and maybe a little stern lift. Would probably drop to a 15p to up the WOT. It is very difficult for me to source a prop just for a trial run so was hoping someone in the group may have tried or is running a 4 blade, and would be will to share their results. With thanks, trapper
4 blade props on 208
- Thread starter trapper
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In general, fuel economy will be worse if you drive at cruise speed often since the 4 blade will present more drag than then a 3 blade. Bottom end may be better with respect to torque and perhaps time to plane but that depends on a lot of factors, carried load being one of the more significant ones. If the usual load is light, time to plane will not change a lot. I am not sure what you mean by stern lift but if you are asking if the stern will ride higher in the water, the prop probably won't make a lot of difference or nearly as much as adjusting the motor trim will.If you want stern lift, trim tabs will make a bigger difference.trapper said:
Thanks seasick for your responce to my questions. The reason I have been considering the 4 blade is from info I have read on my research. Here are two opinions that I have found that may or may not be correct but certainly have made me give it some consideration. Yes I do have trim tabs which I use a lot depending on weather conditions. I will include these other thoughts on 4 blade props just so you know where I am coming from. Thank, trapper
Solas Props
In general, 3- blade props are the most common. They are available in wide size ranges and cost less than 4-blades. They typically yield a slightly higher top end speed than 4-blades. They are available in a wider variety of designs and offer more left hand rotation pitch options for twin counter-rotating engine applications.
Four-blades have some features of their own, though. They often provide more lift at the stern which will help accelerate the hull, especially if it is stern heavy. They come out of the hole strong and work well for pulling skiers and water toys. In fishing and offshore boats, they are oftentimes slightly faster than 3-blades at mid-range rpm’s, where coastal anglers most often run their engines. They also deliver slightly better fuel economy at mid-range rpm. Oftentimes, a poor-handling boat will improve by switching to a 4-blade propeller, and more often than not, a 4-blade will run smoother with better balance than the 3-blade equivalent.
Boat test .com
The increased blade area afforded by the addition of the fourth blade can provide increased water displacement capability, lift, and grip, as compared to the comparable 3-blade propeller. In terms of actual boat performance, these characteristics can combine to enhance handling, hole shot, low-speed planning ability, cruise efficiency, fuel efficiency, load-carrying performance, big seas performance, following seas/down current performance, ventilation/cavitation resistance, motor elevation capability, etc. In short, a 4-blade propeller can improve all those characteristics that make for practical, all-around boat performance.
Solas Props
In general, 3- blade props are the most common. They are available in wide size ranges and cost less than 4-blades. They typically yield a slightly higher top end speed than 4-blades. They are available in a wider variety of designs and offer more left hand rotation pitch options for twin counter-rotating engine applications.
Four-blades have some features of their own, though. They often provide more lift at the stern which will help accelerate the hull, especially if it is stern heavy. They come out of the hole strong and work well for pulling skiers and water toys. In fishing and offshore boats, they are oftentimes slightly faster than 3-blades at mid-range rpm’s, where coastal anglers most often run their engines. They also deliver slightly better fuel economy at mid-range rpm. Oftentimes, a poor-handling boat will improve by switching to a 4-blade propeller, and more often than not, a 4-blade will run smoother with better balance than the 3-blade equivalent.
Boat test .com
The increased blade area afforded by the addition of the fourth blade can provide increased water displacement capability, lift, and grip, as compared to the comparable 3-blade propeller. In terms of actual boat performance, these characteristics can combine to enhance handling, hole shot, low-speed planning ability, cruise efficiency, fuel efficiency, load-carrying performance, big seas performance, following seas/down current performance, ventilation/cavitation resistance, motor elevation capability, etc. In short, a 4-blade propeller can improve all those characteristics that make for practical, all-around boat performance.
Hi Trapper,
I have no insight on 4-blade props, so I'm interested to see what other feedback you get from the community here. On the other hand, I have been doing some reading on the advantages of stainless steel 3-blade props. Are you currently using an aluminum prop?
I have no insight on 4-blade props, so I'm interested to see what other feedback you get from the community here. On the other hand, I have been doing some reading on the advantages of stainless steel 3-blade props. Are you currently using an aluminum prop?
Hi Jonah, I am running a Reliance stainless SDS 17p. Just questioning if a 4 blade would show a better performance mainly for cruising, which we do a lot of. Maybe be able to raise the raise the trim a little more, as now I run one and a half bars from the top when cruising. Anyway just interested what others are doing to reach max performance and fuel efficiency. Sounds like you are enjoying getting your new to you Grady ready to spend time on the water. We boat year round up here on Vancouver Island, but do have to dress for the colder winter months. Great prawning and winter Chinook fishing. Cheers and have fun on your Grady!
trapper said:
As I have mentioned in past posts, it is not a simple thing to compare 3 and 4 blade props. There can be a world of difference between two different models of 3 blade props even with the same specs.
Likewise a decent 4 blade might give better economy than a cheap 3 blade but in general, the more the blades, the more the drag and more drag means lower economy.
The bars on the tild indicator are somewhat ambiguous and the actual value displayed depends on a lot of things most importantly the adjustment of the tilt sensor cam. So use the display as a reference only.
To find optimal trim angle at cruising speed and probably best efficiency, use GPS speed indication, pick a cruising rpm and note the vessel speed. Adjust the trim in very small increments; Don't look for the bars to change, just hit the up or down on the trim switch for a half second to a second. Watch the speed to see if it increases or decreases. Keep 'bumping' the trim and note any changes. When yo get to the point that there is no increase in speed from changing the trim, you are close to the optimal setting. While you are doing this, the motor revs should remain constant. If you were adding up trim, back down a tick and vice versa. The best setting will change depending on boat load, weather, seas, etc. In addition, you may find the the optimal angle for speed is not necessarily optimal for handling.
Sometimes you can tell optimal trim angle just by the sound of the motor, prop wash and hull sounds.
Don't be tempted to add too much up trim, you may cause excessive cavitation. When it is excessive, you will hear it
Thanks seasick for your valuble input. I agree that the trim bars are ambiguous, but I arrived at the bars I did, by doing exactly doing what you suggested as in gps, trimming in small increments etc. I adjusted my trim sensor to show 0 bars at no trim. Depending on conditions and seas I trim up to the second bar from the top and adjust from there. Anyway I am finding out as you have said, that every blade is different regardless of pitch with the same specs. I suppose that is where this all started, trying to find from others with the same boat what they are useing for the most efficient prop and or how to arrive there. Thanks again for sharing your knowledge and I believe you to be a bit of a guru in the enjoyment and understanding of boats and motors. Cheers trapper
I'm running a 17" Mercury Rev-4 on my '05 226 Seafarer/F-225...It Does create more stern lift,actually helps lift the whole Boat at faster speeds.I did remount the Engine to it's highest point as the Rev-4 Props like to run High up.Sometimes in rough Seas if I have it trimmed up alot ,it will cavitate...I just trim it down some..Cruise speeds....Stays on Plane at lower rpm.s and less rpm.s than the stock Yamaha 17" stainless prop. also a Mirage I tried..I have heard from several good sources that the 15" Rev-4 and the Power Tech's don't work so well for what ever reason...As for some people saying You will lose a little top end.....Well,I disagree....If You get the Prop AND Engine Height right I don't think You will see much difference..Each different Prop You try may have to be run in a slightly different manner,i.e./Trim, Tab, settings to really compare properly...As for my Boat with the Rev-4....I can do a fast cruise 200 rpm.s Less and obtain the same speed than with the 3-Blades I've had on it...,Top End WITH the Rev-4,Engine mounted all the way up...Full Enclosure,Hard-Top,80 gals. of Fuel....44.5 mph. on GPS is the best I've seen one time..On a daily basis I can get 42.5 mph.All depends on Weather and Sea state..Again,the Rev-4's like to be run close to the surface...alot of Trim.
Thanks L.R. That is exactly the info I was hoping for! I know that it does not apply to me directly as I am running a 208 with other differences. It does give me an idea of the changes you found between the the 3 and 4 blade prop as it applies to your Seafarer. I am very interested in running a 4 blade and as I mentioned before, just looking for some real hands on experience with the 4 blade. Yes I could use a little stern lift as I have a HT yam 8 hp kicker strapped to the transom. I know I can do this with my trim tabs, but always looking for small changes of improvement. Did you change pitch going from 3 to 4 blade and if you did what was the change? If not did your WOT stay the same? My WOT is 5600-5700 with the Reliance 17p so do not want to go any lower. There is no places locally I can try props so I have to do a lot of homework and hopefully arrive at the correct prop when purchased. Love the 208 and enjoy working on it. Always looking for excuses to improve and make changes. Since purchase I have added bow pulpit (easier anchoring) on board charger(genius) flush mounted Lawrence and furuno gps/ sounder on hinges so can use the space behind for storage of documents and owners manuals, water pressure gauge, Bennett trim tab gauge, blue sea add a battery, access to the bilge pumps etc by installing Armstrong hatches in the splash well. Installed return springs on the seats glides, Scotty high speed down riggers, remote switch for trim on the kicker (raise and lower it outside the boat), bow bunks on the trailer( keep pulpit from hitting the winch on steep ramps, hinges on the battery access stern hatch covers, changed the fresh water tank access to a storage for down rigger weights etc with a slam latch and hinges. OK OK I'll quit, I got carried away, maybe this should have been under another heading "Changes I have made to my Grady" and we could all share changes we have made. Would make great topic, anybody into it? Enjoy very much doing all I can myself on and about the 208, knowing then what I have is a job done to my specs and understandably fixable if things go should go a little sideways. Apologies for the long winded post. Cheers trapper
I am running a 4 blade prop on my seafarer. I noticed better fuel economy at cruise. Better time to plane, lower planning speeds and better turning control with less cavitation in tight turns when pulling water toys. I also notice better performance in following seas of 3 or 4 feet over the 3 blade prop. I bought a power tech. Not had any issues with it in 3 years of ownership. My boat is a bracket boat and I also like the slow performance around the dock especially reverse handling.
trapper said:
A VERY good person to run this by is Ken at PropGods.He is on The Hull Truth and His Business in FL. VERY,VERY knowledgble in ALOT of Boat,Motor and Prop. combo's.
Thanks Smoky and LR, the quest continues. I will contact the Prop Gods, although I cannot purchase from them directly they may have info that would help me with the 4 blade decision. Cheers, trapper :hmm
trapper said:
What motor are you running out of curiosity? On my 208, I can only get 5300 rpm WOT on my 3 blade SDS Yam 200 hp inline 4 stroke on a Yam 17p SDS prop. I just repropped to a 3 blade 15p to try an get a bit more rpm.
Hello Socal, As you saw from my posts I am running the same Yamaha 200.with also a high thrust 8 kicker (100 lbs.) Raised my outboard to the 2nd hole from the top and gained some rpm there. I would like to know what you are getting with a 15 p SDS. As mentioned I am getting 5600rpm at WOT, some believe that is not high enough, but until I find a better prop, for now I will stay with it.Let me know your WOT with a 15. Thanks trapper
trapper said:
Offhand I don't recall which hole I have my Yam mounted too. I will check when I head out this Friday and let you know how the new prop does as well. I had the same concern on rpm. I'm not planning on running at 6k for a long duration but I want to be sure I can hit the full operating range or as close as I can get to it.
trapper said:
Sorry for the delay trap, here is the info. My F200 inline 4 is mounted 3 holes down from the top. I gained 300 rpm on the switch from the Yamaha 17" SDS to the Yamaha 15" SDS. Conditions today: Light chop, full tank, 2 onboard.
Cruise which improved 4200 RPM @28 MPH, 3.4 MPG
WOT which went from 5300 RPM to 5600 RPM @40 MPH, 2.0 MPG
I am pleased with the 15" Yamaha prop, I'll save the 17" for a backup.
Thanks Socalinsd, Correction on my part, I have my f200 mounted in the 3rd hole from the top (one left to go). I am just building a lifting ring for the Yam and I am going to go for the last hole. They want over $200 CAD for the ring and I can come in at $30. Have the template finished and will put the pieces together tomorow. This way if it is no go I can return it to the third. The toughest part is removing the sealant from the bolt holes and the mounting bracket. If you don't mind me asking, what do you pay for a ss Reliance 15p in your part of the country? Thanks trapper
trapper said:
My prop is a stainless steel Yamaha SDS 14 1/2 x 15p 3 blade. It wasn't cheap, around $450 from Sim Yamaha and they usually have the best prices on Yam parts. Probably could have gotten a Reliance much cheaper but didn't price those.
Good luck with it..
Thanks for that Socal, If you did not get a Reliance, what was the name of the Prop you chose assuming it was a prop made by yamaha? One of the saltwater series? Thanks trapper
trapper said:
My bad, it is a Reliance SDS prop.
http://www.simyamaha.com/mobile/Product.aspx?ProductCode=68F-45970-10-00