SS prop for 40 hp???

[Patfromny]

Hey guys, just purchased an 05, 40 hp etec and am trying to figure out what prop to use. I believe the engine was on a pontoon so the present one is of no help. I have a 16 ft bow rider deep v hull with a 76" beam. It is aluminium. I used the prop wizard program from turning point and it says to use a 13.25 17 for skiing and a 13.25 19 for top speed. Does this seem right to you guys? Also, I was wondering if my engine would benifit from a Stainless prop. I was told that performance gains on my old engine (35 HP) wouldn't Warrenton the cost. Was wondering if theither same holds true for the 40 hp. Thanks in advance guys. Oh, the rpm range for the etec is 5500 to 6000 I believe.

 

[eavega]

Well, first off determining what prop you need is really the sum of all the parts (your boat and how its rigged and balanced, the engine and whether it is a little tired or can in fact put out full power with a given pitch, etc). That having been said, a 17 or 19 seems to be a typical stock prop size for those mid-sized outboards (50-85 HP). I've never sized a 40 HP, but would assume that if its well matched with the boat in terms of weight, then you are good to try a 17 (better hole shot) or 19 (better top speed). Your best bet is to work with a prop shop that can let you try different props until you can get dialed in with regards to making max RPMS vs pitch.

With regards to SST, The main advantage I've found would be the lack of flex you get with SST vs aluminum, which can provide a slightly better hole shot. The downside is if you boat in an area that a prop strike is likely or probable (i.e. stumpy, rocky, etc) SST is harder so that your prop may not get dinged up, but you may tear your gearcase apart. Given the cost difference, I would suggest go with Aluminum and see if that provides adequate performance.

Rgds

-E

 

[Sea Rider]

Been reading that SS props are good for large motors. What pitch is current prop that came with OB ? What need to do is tach current prop and check max wot revs lightly loaded. Substract 6000 wot revs from achieved rpm with current prop. Will know how many lower pitch need to run at top wot revs. For that need to install an induction tach which assume don't count with.

Happy Boating

 

[Patfromny]

Thanks guys, there is a large dealer not too far away that offers free on water proping when you buy a new etec. I might have to pay a bit because mine isn't new or purchased through him but I bet that's a good place to start.

 

[Sea Rider]

Thanks guys, there is a large dealer not too far away that offers free on water proping when you buy a new etec. I might have to pay a bit because mine isn't new or purchased through him but I bet that's a good place to start.

Install a center console tach if haven't one or buy an induction tach, without it whichever prop you test will be a blindly rpm guess. Dial a prop that revs OB towards max wot rpm range for that Etec as usually loaded. Is it too much trouble testing current prop with tach and going afterwords for a prop maximization with mentioned dealer.

Happy Boating

 

[Patfromny]

Absolutely a good idea. Unfortunately, i am four hours away so it will have to be done by the marina but I would def. Try that prop first.

 

[82rude]

Your boat looks very close to my 76 starcraft ss160.My boat is rated for 85hp ,also aluminum .I have a 2011 60 hp etec on mine.A normal load for me is me(240) plus 2 twelve gallon tanks and any fishing and camping gear that may be required.I bounce between 2 props ,first is a solas amita 4 blade 17p which will hit 5800 rpm and give me mid 30,s.The other prop is a omc sst 15p which will jump me up to 6200rpm which is very close to the revlimiter of 6250rpm.I will get about 30 mph with that one.I prefer the sst only because I can troll slower with it I have to say that my normal crusing range is around 5000 down to 4300 rpm which gives me decent mph and fantastic fuel economy.Im past the age where I need to go fast all the time and like loafing along and checking out the sites.

 

[Patfromny]

Thanks for the info 82rude,

Isn't 6200 a tad bit high for an etec. I thought most were rated to 6000 with the optimum rpm being 5400-5600. I hoped to get mid thirties but if you are getting that with a 60 I guess all this will be for about 4 mph. Lol.

I would be past the age of need for speed but I have never had speed. This boat has always had a 77 35 on her and top speed with me alone was 26. Put one other adult in the mix and you are loafing along and checking out the sites but without the good Gass milage.

I don't know if I'm ready to do the two prop thing. I'm usually up for long weekends and I just want to be in the boat, not in the water next to it changing props. If I teach my daughter to ski I imagine that might be a reality though.

My boat does resemble an ss160. I was actually surprised at how much it looks like Jason's islander in his last posted pic of it in the water. Aside from the size dif. It looks real close to mine. Could be the colors are so close too.

 

[82rude]

For the 60 max hp is at 5750.6000 is suppose to be max range but I know for a fact that the rev limiter kicks in at 6250.I suppose they made a little wiggle room of 250 rpm just for people like me though ive never hit the rev limiter since I bought it and that was on a different hull than now.Iknow my tac is accurate and speed was gps but I will test again and if I'm wrong will post but I don't think so.My buddie had the same boat as me with a 70 evinrude 3 banger and he said he could only get mid 30,s and he owns a prop shop and is good.

 

[Patfromny]

I believe your numbers are accurate. I had no data other than someone telling me it should go that fast. I guess I was just setting the bar too high. Oh well, 30 is nothing to sneeze at. Will still love the drivability and gas mileage. My 35 was tired and would stall most times when trying to dock. Could never get it right and I tried everything. It was also super loud compared to an etec and the two arm controls seemed to confuse everyone but me. Add to all that the trim and tilt I am gaining and its a win win anyway you look at it..

 

[Patfromny]

After talking to a few people, some of your suggestions here, and speaking to the mechanic installing the engine, I think I have decided to stick with an aluminium prop. There are several areas on the lake with some submerged rocks and stumps. This boat will soon be used by my nieces and nephew when they are old enough and take their boating course. I think the aluminium might just save the lower unit a few times in the next couple of years.Lol

Finding the right pitch is still a slight problem but it will be a learning experience like everything else has been on this boat. Amazing how much I have learned over the last few years.

 

[82rude]

If you want to get it up on plane and keep it there at a lower speed try a solas amita 4 blade .I HAVE A 17P solas and its a excellent prop.If my rig takes 17p for light and 15p for heavier maybe look at 15 or 13p 4 blade.Make sure you keep us updated please.

 

[Patfromny]

Will do. Thanks for helping out thus far guys.

 

[Patfromny]

Well, the motor is on the boat and it is just about ready for water testing. The prop on the motor now is a 13.75 13 which I think will be way to steep a pitch. I typed all my boats info into the TP prop finder and it said to use a 13.25 17 for speed and a 15 for ski. I do have a question about this. My brother has a pontoon boat with an etec 40 on it. For some reason he has a 13.5 15 prop laying around. Do you think I should ship that up to the marina and just heave him start there or is the .25 inch a big deal on the diameter?

 

[Sea Rider]

Ski and speed are very generic boating terms, whichever pitch 15-17 you choose, OB must wot rev at it's full rpm range with current load or boating application. If without a installed tach you'll be wild guessing when testing both prop pitches.

Happy Boating

 

[Patfromny]

The marina is going to find the right prop with there etec computer diagnostic tool which has a tach feature on it. They will hook it to the engine harness and test. Once the right prop is found I will have little need for a tach and still not enough room for one. I was wondering if the prop I have laying around is worth me shipping to them.

 

[Patfromny]

Ok, so I got a call from the marina. They put my supplied 13.5 x 15 pitch prop on the boat and it would only spin at 4900. They then put the prop that came with the engine on it and it was spinning at 5400 and 5600 once trimmed. The problem and question I have is...the prop is for a pontoon boat and is a 13 7/8 13 Hydrus prop by evinrude. I have read a little about them and it is for a pontoon or heavy loads. I don't consider my 16 ft. 800 pound bow rider heavy.
My question is. If I get a smaller diameter same pitch prop will the RPM'S stay the same?

 

[Patfromny]

So, my brother tested the boat today. The pontoon prop only pushed the boat at 23.6 which is 3 mph slower than the old 35 would go. He put his 13.75 x13 prop on and it went to 28.6 but at 5900 almost 6000. So, I have a 13.5x15 that I'm now sure the mechanic never installed that my brother is going to put on tomorrow. Any thoughts, suggestions?

 

[Patfromny]

My brother put the 13.5 15 prop on and it went 30.4 but at only 5100-5200 rpm. If using the 200 rpm per pitch formula it should have been in the 5600 range going up two inches in pitch? I looked up the part number 765182 and it says it is a cupped prop. Could the cupping be why the RPM's dropped so drastically? I'm kinda lost here as to where I should go from here. To further muddy the waters, I called a local marina who told me he had a 16 ft. Bass Tracker with an 11.75 x 17 prop on a non etec 40 hp and was in the 41 mph range. I would love to be that fast but I kinda want to just get this boat dialed in to the right rpm and I feel dropping that drastically will just be starting over again. Is there an estimated drop or increase in rpm when dropping down in diameter? Any ideas on what prop size I should try next to get me in the 5600 range? Thinking a 13.5 x 14 pitch cupped or a 13.75 x 15 non cupped? Any suggestions would be appreciated guys. I am leaning toward a smaller diameter prop thinking the smaller is better for top end but I'm not sure if that is even right. I would be open to a 13 x15 cupped if that would bring up the rpms but still be good out of the hole.

 

[Silvertip]

You either have a very dirty hull, the hull is water logged, or the engine is not making full power (throttle not opening fully) or some other set-up issue. The "go to" prop for boats in that range and engine almost always use a 15 or 17P. I've tested them all down to a 12P stainless on a 40 HP and always went back to the 15P cupped. 6000 RPM on the dot on a 16 foot side console walleye boat. Diameter and pitch go hand in hand. If you look at the range of props you will see that as the pitch increases or decreases so does the diameter by a small amount. It is a design factor. Props are designed for a certain engine HP range and gearcase size. Therefore you choose a prop "type" for your engine and then select the desired pitch. Diameter will be what it will be. Blade shape, rake, cupping and other factors determine how a given prop design performs. Some are biased toward hole shot, some biased toward top speed and some are a compromise of both. Even though Manufacturer A and Manufacturer B say their prop is a 15P they may and likely will perform differently. Choosing a prop is a pain in the behind especially if you are trying to squeeze the very last 1/2 MPH out of your rig. At some point you should just say "good enough".