My new prop is here?

[Jencourt]

So I just received my new prop. I ordered the same pitch as I had (Yes I could achieve full recommended rpm with the 17pitch prop I had-between 5500 and 6000rpm ) I have gone to a 4 blade as discussed on a previous thread. I ordered a prop for a 2005 150 4-stroke Yamaha as that is what I have. I received a 14 1/4 x17 stainless 4 blade. Wen I removed the old 17- 3 blade I noticed it was a 13 3/4 x 17.

I have looked on the net and found that 14 1/4 is listed as one of the prop sizes for my motor along with other choices. My question is this.

dose anyone know or can find info to confirm that I will be fine to run the 1/2 inch bigger prop than what was on it ?
Fits fine and lots oc clearance from the cav plate.
I guess I am just looking for some expertise on the matter as I do not want to over work the gear-case ect if I am wrong in what I have read so far.

Thanks in advance :
A slightly confused Jencourt

 

[wildwest]

You may find that your top-end rpm will drop 200rpm,if so no problem.Usually .....when you go to a 4 blade they recommend dropping 1 inch pitch.Just stick it on there and go for a ride.I'm very happy with my stainless 4 blade,went from a 3 blade stainless 19 pitch to a 4 blade 18 pitch and my W.O.T. is the same.Now no more cavitation under any water conditions...

 

[Jencourt]

Glad yours worked well for you. I will test mine this weekend.

Kinda though I would get more feedback on this from some of you?

cheers: ray

 

[scott craven]

According to Iboats, plus minus 1/2" diameter will have little or no effect on performance.
not sure how the 3 vs. 4 blade will affect that?

 

[Sharphooks]

What R.S.C said. That small a diameter change should have limited effect on a F150. The real issue will be your new prop's "P" as Wildwest mentioned. The rule of thumb is to drop 1" in "P" when you go from a three blade to a four blade ( if your goal is to maintain the same RPM's)

Now that you own the prop, slap it on and take it for a test spin. If you're still pushing mid 5's at WOT you should be fine. Manufacturers provide a range.

I just went through all kinds of propeller double-think with my Honda BF150. When I purchased the boat, the former owner had a 14.8 x 19 Aluminum prop on the BF150.

I had one Honda dealer tell me that was ridiculous-- I should be running 6K for WOT and I should dump the 19P prop for a 15P. Another dealer told me as long as I was between 5K and 6K I should be fine. I'm right in the middle of the range when everything is trimmed right. So.....

I'm sticking with the 19P-- it's a good ride and the engine seems to like it as is.

I will tell you at this point that I decided to steer clear of stainless. I hit a log off Malcom Island last July and the motor vibrated so bad from the bent flukes (aluminum) that I decided to do the last 10 miles to Echo Bay on my kicker. When I replaced the tweaked prop with my 19P Aluminum back-up,the BF150 was happy as a clam again---no bad vibes, like nothing happened

Moral of the story: if I had clanged that log with stainless, I truly think I would have had lower unit damage. It was pretty aggressive the way I hit it

My .02's worth, for what it's worth....

 

[Charlie]

Sure hope that "C" doesn't refer to Charlie? As Charlie will say, talk to someone who knows what they are talking about when it comes to props!

There is a reason when you go to buy an outboard you will find all those new outboards don't have props on them. You have to match the engine, boat, and prop!

There is differences in performance of 3 blade and 4 blade, and a difference in pitch and diameter of props. Normally, the smaller diameter prop can have a higher pitch. Now you are throwing in 3 blades versus 4 blades? Yes, there has to be a difference in performace. You might as well throw-in construction of prop, hull design, deadrise, and most importantly... weight! The only way you can really tell if a prop works, is install the prop and check it!

It all equates to and really is all about WOT, regardless of the constuction or actual size of prop. Simply put, you want the boat to run at the top end of the manufacturers RPM at WOT! If you install a new prop, check the prop, and it exceeds that manufacturers WOT specifications? I would have two suggestions the first is get another prop. The second, if you choose to run an engine above manufacturers WOT specifications - just plan on buying a new engine!

Oh BTW... when it comes to "outboards" don't really worry about a SS prop, unless you plan on hitting something backing up. Experience has proven, at least to me - outboards are designed to tilt up when something is struck. Secondly, the lower units are designed to allow and let the prop to slip! That actually used to be a concern to me; however, after a couple of very solid log hits (all I can say... is there are people who haven't yet hit a log, and then there are people who will hit a log), it has been proven to me (and very gladly) they both work as designed!

 

[trendsetter]

what Charlie said...

And also, SS props will have a rubber hub that slips when you hit something preventing damage to your lower unit.

I`ve run both, SS and alum, 3 blad and 4 blade, and by far the best prop I have is a 4 blade SS Solas HR Titan. However it is only 15p and my new configuration on the boat needs a 17p so I run one of my aluminums most of the time. SS is stronger than alum so the blades can be cast thinner and allows for a better blade geometry and slightly better performance.

Also they look cool when the boats on a trailer

 

[Jencourt]

Thanks for the feed back folks. Thanks for the link Holmes.

Sounds like the options are endless for props,but one thing is the same if I am understanding things.

Wen I test run the boat I should be able to reach the recommended high RPM range at full throttle.In my case that is 5500 - 6000.

I will run it this weekend hopefully and see if I get the results I am looking for. (Better plane,less porpoise at lower speed ,mid range cruise)

Will report my findings :
Cheers ray

 

[Clipper]

Very interested in how it works out Jencourt. I've been pondering switching the 3 blade, 19p, painted stainless on my Yam 150 to a 4 blade but have gotten bogged down in all the details. I run 5500rpm at wot and want to bring it up to 6k with all the 4 blade benefits you mention. Will look for your report.

 

[Charlie]

On the "same" type of prop, with the "same" diameter, a lower pitch will increase your WOT RPM and get you out of the hole faster. (e.g. you have a heavier boat, want to get up on plane faster, and do something like pull water skiers). The higher the pitch, will decrease your hole shot, increase your top end cruise speed, and lower WOT RPM.

The biggest problem is manufactuers and users prop boats at WOT, when the boat is not rigged for normal use. IMHO, you are better off loading the boat with all gear and passengers (weight) as it will normally be used, and propping at the higher in of the WOT, even if you have to exchange a prop just purchased. They are used to that. When actually using the boat, you burn fuel (reducing weight), catch all those fish (adding weight), on all those special occasions you just want to make sure, which normally offset each other, you want to make sure the engine is not lugging down = longer engine life!

 

[wildwest]

Clipper, If you are close to your Wide open rpm I would only drop down to a 17 pitch 4 blade,and will probably give you 5700rpm,and a better hole-shot!.But if you want to go all for rpm a 16 4 blade will pop the skiers out nicely,but I doubt you want that...

 

[Sharphooks]

Aluminum vs. Stainless:

Hey Charlie, lots of good info in your prop talk but from what I've heard and come up with through research, I've decided to stick with aluminum on my Honda BF 150.

I've copied and pasted a few quotes taken from various websites, both quotes of which pretty much shake hands with what I've heard from several local Honda distributors and propeller guys:

QUOTE

The slip prop supposedly saves the gears from breaking and the prop from being severely damaged. However, when the prop is new, the ring is stiff, and too much stress is communicated to the gears. When the prop is old, the rubber slips too easily, even when the motor is accelerating. It would be nice to have a way to adjust the tension on the rubber ring to fit the boating conditions, but manufacturers haven’t gotten that far yet.

UNQUOTE


and another blurb from a propeller distributor:

QUOTE

The decision between purchasing an aluminum or stainless steel propeller can be difficult. However if you fully understand the differences between them, your decision can be much easier.

The most common understanding of the difference is that stainless steel propellers perform better than aluminum propellers. This is only half true. Material (Stainless vs Aluminum) only accounts for approximately 10% of the actual performance of the propeller. The other 90% of performance is in the blade design.

Well designed aluminum propellers will out perform an average stainless steel propeller. So it's important to research a propeller's performance before your purchase. It is also important to try different pitches and brands to get your boat dialed in to the best possible propeller.
The advantage of a stainless steel propeller over aluminum is durability. Stainless props can withstand more of the damage caused by small rocks, sand, or other loose objects in the water.

However, the disadvantage to a stainless propeller is that there is "minimal give" to the blades, so if you hit an object hard enough, the possibility of causing major damage to your lower unit is increased greatly. With aluminum props, the blades will most likely sacrifice themselves before any damage is caused to your lower unit.

If you run in deep or familiar waters, or in salt/brackish water, a stainless steel propeller can be a good choice. But it is important to always carry a spare propeller on board, and a spare aluminum is an inexpensive choice.

UNQUOTE

Moral of the story: You pays your money and you takes your chances.....

 

[Charlie]

Personally? I would have no problem running SS, or aluminum, or even brass. I have ran all over the years. It is actually kind of nice to be able to take a hammer and straighten an aluminum (or brass) prop. Ever notice larger boats use brass? SS just might be the reason those Bravo III lower units have an electrolysis problem in salt water? It just depends on what an individual wants the prop to do.

I wouldn't recommend running out looking for logs to strike with any of them, as I know several running brass and aluminum both have had to replace running gears and lower units! I will go back to these two statements. "Sure hope that "C" doesn't refer to Charlie? As Charlie will say, talk to someone who knows what they are talking about when it comes to props!" "Oh BTW... when it comes to "outboards" don't really worry about a SS prop, unless you plan on hitting something backing up. Experience has proven, at least to me - outboards are designed to tilt up when something is struck. Secondly, the lower units are designed to allow and let the prop to slip! That actually used to be a concern to me; however, after a couple of very solid log hits (all I can say... is there are people who haven't yet hit a log, and then there are people who will hit a log), it has been proven to me (and very gladly) they both work as designed!

 

[Peahead]

(all I can say... is there are people who haven't yet hit a log, and then there are people who will hit a log), it has been proven to me (and very gladly) they both work as designed!

X2 on that one.... my log experience proves this statemetent to be very correct, thankfully !
When I turned to look back at my outboard after flying over a mostly submerged 10" dia. log ( probably only had time to slow from 25 knots to about 20 knots) I expected my outboard to be gone. Not only was it still intact but no damage at all to the leg, prop or hull. Continued on my way

 

[Clipper]

So Jencourt, how'd that new prop work out? I'm very interested in how it performed on your rig.

 

[Jencourt]

So I finally got a chance to get the boat wet last night and test the prop.

I had a 13 3/4x17 before and was testing a 14 1/4x17. 4 blade
Old prop made 5500-5700 at WOT
New prop only makes 4900-5000

My understanding now is that I am over pitched and should have got a 16 instead of 17?
wonder if I will need to go as far as a 15 to get the extra 500 rpm?
Not sure how many RPM 1 inch less of pitch will add. Any feedback on this would be helpful.
To note also is speed increased by about 2MPH

As far as hole shot with regular load and ability to plane at MUCH lower speeds the 4blade is doing very well and I will stick with the 4 blade.
It also did in fact reduce the proposing to virtually null. Only had a bit if I got trimmed wrong and hit some small rolls from a passing boat.

So now I need to decide on a 15 or a 16 ?? and make the switch. Hope we get it right the first time .

Cheers and thanks again for any feedback given or yet to come.

PS :we were out there anyway so we got the lines wet for a couple hours. Released a couple and boated a nice 12.5 LB spring.

 

[wildwest]

Always drop 1 inch of pitch when going to a 4 blade prop,because they bite better .In your case dropping to a 4 blade 15 would be perfect.I'm just saying this out of experience...........

 

[Charlie]

Now you know! As you already stated the new prop has a larger diameter - .5 inches! My GUESS, if you want closer to the 5900-6000 WOT the 15 pitch MIGHT get you there! Please note the two words guess and might! The only way to tell is to do what you just did - test it!

 

[wildwest]

When I look back I noticed your outboard MAY be underpowered...Most boats [outboard]should run nicely with a 18 to a 20pitch prop.Just maybe you may have to get down to a 15.

 

[trendsetter]

A 15" pitch prop of the exact same manufacturer, model, material and blades will bring you up around to 5500 - 5600 RPM at WOT.

It does sound as if your motor is a little underpowered for that boat but should be fine with the right prop. It's not as simple as saying you should be able to run an 18 to 20 pitch prop; different motors have different gear ratios for the same HP i.e. 2 stroke vs 4 stroke and the pitch required is a function of gear ratio, hp, hull design, weight, water conditions, propeller blade design, material.. and other factors.

I alternate between my 15p 4 blade SS and a 17p 3 blade alum depending upon weight and water conditions. My boat is also slightly underpowered like yours.