Crestliner 1850 Sportfish Top Speed Questions

[bkerschner]

So I just bought a used 2005 Crestliner 1850 Sportfish with a 150 Yamaha Four-Stroke. The boat came with a 23 pitch prop for some reason. Top speed was 37 mph at about 4200 RPM. I consulted several dealers, they all said the yamaha should be around 6000 RPM. I bought a 19 pitch yamaha aluminum prop, which was recommended by the dealer. That brought me up to 5300 RPM and a range of 42-45 mph. I had the injectors cleaned, replaced the fuel filter and new spark plugs. Is this a good range or is there something I'm missing? Any suggestions would be appreciated.

[Moose-Hunter]

So I just bought a used 2005 Crestliner 1850 Sportfish with a 150 Yamaha Four-Stroke. The boat came with a 23 pitch prop for some reason. Top speed was 37 mph at about 4200 RPM. I consulted several dealers, they all said the yamaha should be around 6000 RPM. I bought a 19 pitch yamaha aluminum prop, which was recommended by the dealer. That brought me up to 5300 RPM and a range of 42-45 mph. I had the injectors cleaned, replaced the fuel filter and new spark plugs. Is this a good range or is there something I'm missing? Any suggestions would be appreciated.

5300 is on the low end of the operating range for the F150. (5000 to 6000) I have the same engine and I'm trying to dial in 6000 +/- 100rpm with props as we speak. I'm running this on a Alumacraft 175 Trophy. Your speed is (IMHO) right about where it should be considering the power/weight. But your R's are a bit low. I'd suggest, if you can, borrow or demo a 18 pitch prop of about the same dia, or a bit smaller, than the one your running. You'll get a few more revs to bring you into the mid to upper 5K range. And "maybe" the added revs may get you a mph or two as well.

I'm no expert but I am learning...

[delcecchi]

One inch out of 20 is 5% or about 300 rpm. Going to a 17 would get you to about 6000. The advantage of a 17 is it seems like aluminum props come in odd number pitch only, near as I can tell.

How are you loaded when getting the 5300 with the 19? If it is just you, then the 17 would probably be better with a full combat load.

[311Hemi]

I would try a lower pitch prop to get the RPM's up, preferably a stainless steel if you can. If the prop you have right now in an aluminum 19, possibly try the same in a 17 if you are going to stay with aluminum.....that should get your RPMs up. I would personally try to get as close to 6000 rpm's, even if it means testing a few different props.

I am running an 02' Crestliner1850 Sportfish with a Yami F115 and I run 37mph consistently (38 on a good day) right at 6000 rpm's, loaded with fuel/gear trimmed out. After testing a certain model PowerTech stainless steel prop in both a 15 and 17 pitch, I determined I needed a 16 pitch which the prop shop needed to order as it was not one they stock. Much better performance than the 17p Aluminum Hustler that came on the boat and only ran around 5200 rpms...I could not trim out at all with that aluminum prop. Stainless made a big difference.

I would think you should be able to get that boat running 45-46+ mph consistently with the right prop.

[delcecchi]

If you get 38 mph with a 115, 45+ with a 150 is probably unrealistic.

A 150 is a 30% increase in HP which typically produces like a 15% increase in speed. Speed goes up as the square root of horsepower. Adding 15% to 38 gets you to like 43.

It will be interesting if anyone who has a 150 on that boat is able to confirm what actually happens.

[311Hemi]

45+ mph is definitely realistic. Yamaha performance bulletins for Alumacraft Trophy 185 (the heaviest tested 18' Alumacraft at just over 3000 lbs) put the boat at 46.8 mph at 5700 rpms with a Reliance Series 13 3/4x19 stainless prop. I have read a number of reports of 46-48 mph with various 150hp engines including the F150 (49.9hp with a 150hp Verado on boattest HSOforum) on the 1850 Sportfish.....so it is achievable.

My boat is loaded down with weight (full tank of gas, 3 size 27 batteries, 3 bank charger, gear, etc) so I may be able to get more speed if I removed some stuff and proped a little different. I am underpowered, but the boat handles just fine in almost all circumstances.

[hydro]

Taking 311Hemi's number of 46.8 MPH at 5700 RPM and a 19" prop, that boat had a slip factor of only 8.7%, or nearly race boat territory. Yamaha had the setup right on that one. Now in more real terms where 15% slip is a typical fishing boat number, spinning a 19" wheel at 6000 RPM through your 2:1 gears, you should see about 46 MPH. With those numbers on the table, you should be able to tune into the low 40's with a little setup work.

Same boat, motor, at 15% slip spinning a 17" wheel should net you about 42 MPH. These numbers are mathematical only and just a point of reference. Have fun testing props and tuning your setup!

[Sonicrunch]

I would try a lower pitch prop to get the RPM's up, preferably a stainless steel if you can. If the prop you have right now in an aluminum 19, possibly try the same in a 17 if you are going to stay with aluminum.....that should get your RPMs up. I would personally try to get as close to 6000 rpm's, even if it means testing a few different props.

Agreed. Although I think a stainless 17 with some nice cupping would be the ultimate.

[bkerschner]

Thanks for all the good information! It's hard when you talk to the dealer and all they want to do is sell you a $500 stainless prop. I don't want to get into bad mouthing dealers on here, for the most part they've been helpful. But when it comes to props they originally told me I should be around 5800 with the 19 aluminum, now they tell me the book says 18 stainless. I wish they would have said that from the start but I guess it doesn't matter, my wife was good enough to let me buy a boat and then still spend another $170 to get the right aluminum prop on there. I can't hardly ask to spend $500 more...

[delcecchi]

Thanks for all the good information! It's hard when you talk to the dealer and all they want to do is sell you a $500 stainless prop. I don't want to get into bad mouthing dealers on here, for the most part they've been helpful. But when it comes to props they originally told me I should be around 5800 with the 19 aluminum, now they tell me the book says 18 stainless. I wish they would have said that from the start but I guess it doesn't matter, my wife was good enough to let me buy a boat and then still spend another $170 to get the right aluminum prop on there. I can't hardly ask to spend $500 more...

To be fair to the dealer, often the more extreme cupping on a stainless prop will make it equivalent to a larger pitch. At least that is how I recall it. Perhaps that is why aluminum comes in odd number pitch and stainless in even?

[311Hemi]

If they have a book they are referencing they should be able to get you close to the RPM range, for either aluminum or stainless. But, that will be a general guideline and will be different depending on how much gear/fuel/passengers you have in your boat.....so I think testing to your setup may still be needed be beyond what they tell you.

Both stainless and aluminum mainly come odd numbers, but some do make even number as well but many places may not carry the even ( I had to special order). Not sure where your located, but Prop MD in Eden Praire or Soderblooms in northern MN (both prop shops)might be more helpful than the dealer and be able to get you better prices as well.

I know the PowerTech RAS series is around $300-$350, depending on what pitch you need. IMO stainless is worth the extra investment.