Right prop to go to

[rudedogg]

Recently bought a 1994 Sea Ray 170BR. Took it out this past weekend for a ride and I'm not satisfied with speed, the boat has the 3.0l mercruiser with a 17p aluminum prop, it planed out real nice but would only hit 35mph with 2 adults and RPM's were around 4900 WOT. I'd like to pick up a little more speed and drop the RPM's some but keep the quick plane and be able to pull a tube well with say 4 adults in the boat. Suggestions would be much appreciated, thanks.

 

[steelespike]

Re: Right prop to go to

Welcome, Unfortunately I think you have other issues. That 17 or 18 footer would normally run about a 21" prop at about 4800 rpm and speed around 40. Normally a 17" prop would over rev.
A compression check is probably the best thing to start with. You can note the condition of the plugs at the same time.
Hopefully its something easy. Throttle may not be opening all the way. Be sure the timing is set right and advancing all the way.
I'll keep my fingers crossed.

 

[NWJeff]

Re: Right prop to go to

Congrats on the new boat! I recently became a new boat owner as well and love it! I have a 1994 Maxum 2000SR w/ the 3.0LX and I was super concerned with the prop that was on it when I got it, but it actually did crazy good and I was impressed. My little 3.0 really likes the 13.75" X 21 pitch 3 blade prop that is on there. Planes fast and cruises well on plane, top speed was 43 (handheld gps) @ 4700 RPMs. You didn't mention diameter of the prop, just pitch. Any chance it's under 14" and your just under propped? I'm not the wisest when it comes to boats, just thought I would share my experience and see if it works for ya! Good luck!

 

[rudedogg]

Re: Right prop to go to

Congrats on the new boat! I recently became a new boat owner as well and love it! I have a 1994 Maxum 2000SR w/ the 3.0LX and I was super concerned with the prop that was on it when I got it, but it actually did crazy good and I was impressed. My little 3.0 really likes the 13.75" X 21 pitch 3 blade prop that is on there. Planes fast and cruises well on plane, top speed was 43 (handheld gps) @ 4700 RPMs. You didn't mention diameter of the prop, just pitch. Any chance it's under 14" and your just under propped? I'm not the wisest when it comes to boats, just thought I would share my experience and see if it works for ya! Good luck!

Congrats on your new boat sounds like everything is going nice and smooth for ya. I am taking the boat in to be checked out based on what spike suggested, my hope is that the prop is the actual problem here and/or a tach that's not reading the correct rpm's. I'm not sure of the diameter though how do I determine that info. I'm sure the 17 pitch is definitely not right though, I've had a couple boats over the years about the same size and type motor and never ran a 17 pitch on them, I'm agree with spike that 21 is more the right pitch but before I throw money at a prop I want to make sure that something larger isn't the problem, you know?

 

[rudedogg]

Re: Right prop to go to

Engine checks out ok. I believe that the tach isn't reading right for one and the 17' prop is the wrong prop. Going to verify tach readings with a tiny tach on next outing, but I do want to try a different prop, I found a Solas 15.3 dia by 19 pitch for 50 dollars. I found the exact prop on iboats but right along with it is a 14.5 x 19'. My question is what to expect with the larger diameter compared to the smaller diameter?

The part number for the prop I found is 1511 153 11 I believe,

 

[NWJeff]

Re: Right prop to go to

Honestly I think that the 50 dollar prop you found is going to be too much for the 3.0? I'm sure someone else on here will know better than I... Just my opinion. Also going that big of diameter you'll probably run into fitting issues. On mine a 14.5" was pushing it and I would have had to trim the fin on the outdrive (anode I believe?). Your best option is to run the prop selector on this site and find out what is recommended and kinda start from there ya know.. Keep us posted how it all pans out for ya!

 

[rudedogg]

Re: Right prop to go to

Honestly I think that the 50 dollar prop you found is going to be too much for the 3.0? I'm sure someone else on here will know better than I... Just my opinion. Also going that big of diameter you'll probably run into fitting issues. On mine a 14.5" was pushing it and I would have had to trim the fin on the outdrive (anode I believe?). Your best option is to run the prop selector on this site and find out what is recommended and kinda start from there ya know.. Keep us posted how it all pans out for ya!

I agree NWjeff, all the research and questions asked are moving me in the direction of a smaller diameter higher pitch prop. I've decided to purchase a turning point hustler aluminum 14.25 x 19 and take a stab at that this coming weekend, going to use a tiny tach to verify rpm's and gps for speed. I know the prop(15 x 17 Michigan)on it is not right for this boat or for what I will use it for primarily, so we will see.

 

[rudedogg]

Re: Right prop to go to

Took the boat out yesterday with the hustler 14.25 x 19 prop, speed was still 35mph but the rpm's are down to 4800 at WOT verified with tiny tach and the boat tach also matched that. I'm surprised I didn't pick up a little speed but the hole shot is still good and planes nicely. The outdrive has a stingray fin on it, I wonder could it be scrubbing off a little speed. Any input would be appreciated.

 

[steelespike]

Re: Right prop to go to

No doubt the stingray could be stealing some speed.Right now the calculator says your slip is about 18% could be attributed to the stingray. I thinkl the slip is especially high considering the Hustler is
an agressive prop. If it is vented you may need to plug the holes.

 

[rudedogg]

Re: Right prop to go to

I'll take the stingray off run the boat and see what happens. Any concerns about the holes left behind by the stingray? I did notice yesterday when the outdrive was trimmed up at it's optimum spot I could see splash from what I think is the corners or ends of the stingray, so that's what made me wonder if maybe that thing is creating enough drag that it might be reducing the top end speed. We shall see.

 

[sweet addiction]

Re: Right prop to go to

I have a '94 Glastron 17'5" boat with the 3.0LX motor. I run a 14.25 X23p stainless on mine. Get 50 mph(gps). If I were you I would get a 14.25 X 21p stainless.

 

[jestor68]

Re: Right prop to go to

The Stingray hydrofoil causes lots of drag at speed.

I tried one on a boat some years ago, and it felt like I was dragging something. I put a Doel Fin on it and didn't experience any perceivable lose of top speed, but still enjoyed the faster planing.

With your 2.0 gear ratio, you should be able to run a decent size prop; if your motor is healthy.

 

[rudedogg]

Re: Right prop to go to

I've had the boat out a couple times since putting the new prop on it and here's what I'm getting. 37mph at 4500rpms wot, prop definitely likes to be trimmed up a lot, this is with three adults, full tank of fuel or nearly and normal gear.

 

[rudedogg]

Re: Right prop to go to

Forgot to mention I took the stingray off and boat still planes out just fine.

 

[Cortes100]

Re: Right prop to go to

You're not that far off......are you using GPS to verify speed? My manual for a 2008 says engine WOT 4400-4800rpm.
What is your elevation, cause that might effect performance. Only saying cause...I'm at 3000' for our local lakes. But I have traveled to a few lakes that are at 1000' above sea level, and the boat ran stronger at lower elevation.
For trivia, I have a '08 SR Sport175. Came stock with a Merc aluminum 14.5 x 19 prop. I have experimented with a few different setups, and the stock one out performs them all. Pulls good, jumps on plane, and WOT can squeek out 42mph @ 4800 rpm. But with a full load, 4-6 adults, there's no way I can hit 4800.