New Boat with issues

[bbcman]

2007 Crestliner cx 17, Mecurcy 75 optimax same year. Bought this boat this week for a good price, but it has a few issues I hoping to resolve for not much $$$. So I came here.
First issue is I believe it is way under propped. I think it has a 17 pitch I believe. Running down the lake it was 5000 rpm but gps only said 30 mph. I hit 6000 rpm and pulled back because it didn't make much difference.
I will post only one at a time, to try and resolve these issues. I am mechanically inclined and able to do most work myself that does not require being hooked up to diagnostic equipment.

[Nobass01]

I have a 18ft lowes with 75 etec with 17 prop i get that same speed at 5000 rpm. With ss.prop

[bbcman]

I was reading an older review of the boat with a 50 hp and it was hitting 33 mph. This boat weighs in at 1040 lbs, boat was empty except me and half a tank of fuel and 3 batts and trolling motor.

• Top speed for the Crestliner CX 17 (2007-) is 33.7 mph (54.2 kph), burning 6.6 gallons per hour (gph) or 24.98 liters per hour (lph).
• Best cruise for the Crestliner CX 17 (2007-) is 18.9 mph (30.4 kph), and the boat gets 5.91 miles per gallon (mpg) or 2.51 kilometers per liter (kpl), giving the boat a cruising range of 101 miles (162.54 kilometers).
• Tested power is 1 x 50-hp Mercury 2-stroke.

[mrc.in.wi]

I was reading an older review of the boat with a 50 hp and it was hitting 33 mph. This boat weighs in at 1040 lbs, boat was empty except me and half a tank of fuel and 3 batts and trolling motor.

• Top speed for the Crestliner CX 17 (2007-) is 33.7 mph (54.2 kph), burning 6.6 gallons per hour (gph) or 24.98 liters per hour (lph).
• Best cruise for the Crestliner CX 17 (2007-) is 18.9 mph (30.4 kph), and the boat gets 5.91 miles per gallon (mpg) or 2.51 kilometers per liter (kpl), giving the boat a cruising range of 101 miles (162.54 kilometers).
• Tested power is 1 x 50-hp Mercury 2-stroke.

They forgot to mention "no tackle"

[Ranger 188]

I THINK YOUR PROP IS RIGHT , BECAUSE THOSE MERC ARE TO RUN 5800 TO 6000 RPM YOUR SPEED IS ABOUT RIGHT.

[MattVT18]

I had a CX17 with an older model Mariner 75 hp motor. I was running high 30s (usually 36-37 gps) at 5500 rpms with a 21p stainless prop.

[bbcman]

I had to pull back the throttle at that point because of porpoising. But the motor was still spooling up and I think I could have hit 7000 rpm.

[plki]

Try a 20 Laser II with 3 large plugs

[bbcman]

I was looking at props, what difference would a 13 1/4 vs a 14 make?

[Ship]

You need an 18'' Mercury Vengeance for a prop. Have a PT175 that had a standard 75 Opti and the Vengeance put the rpms right in the sweet spot. 20P Laser was to much, tried it. Maybe a 19'' Laser II if you don't want a Vengeance.

[bbcman]

Whats the difference between a Vengeance and a laser? And again will 13.25 vs 14 make much difference?

[gatorglenn]

The Laser has no cup. The Vengeance is a carbon copy of the Blackmax aluminum prop. It's SS with cup in the hard wall as well as the trailing edge. They have been around for along time. And for good reason, there great props. That will work on a wide range of different boats. Dang that sounded like a sales pitch.

And I always go for the larger diameter prop. It's just better for the bite in the turns and holeshot. The downside is it can rob some RPMs if it's a drastic change in size. 3/4s of an inch is big, but not drastic.

[bbcman]

you do mean 18 pitch?

[gatorglenn]

If your going to run the boat as your #3 post then yes, 18p Vengeance.

But if your going to fill the fuel tank, and livewell. With some what normal tackle load of 50-70 lbs. Then go with a 17p .

[bbcman]

Currently have a solas prop that is 17p not sure if 17p in a vengeance will make it any better.

[gatorglenn]

Currently have a solas prop that is 17p not sure if 17p in a vengeance will make it any better.

I've never ran a solas prop so couldn't say. If it's in good shape, I would have it worked ( with rake and cup) to match your setup. It's cheaper than throwing money at new props.

[bbcman]

Well I went by the local crestliner dealer yesterday and they recommended a solas 13 x21p. For the money he said they were good props. I thought a 21p would be way too much but he said the opti could handle it. I just spent a $1000 on a trolling motor so I will have to wait a few weeks before I drop mo money on the boat, but when I bought it I knew it need a new prop.

[gatorglenn]

Ask if they do a swap deal. In case the 21p i is to tall. Before you buy. 21 sounds a bit high. But 2007 opti with 2.33 gear at 5000-5750 max rpms. Well who knows just might work.

[bbcman]

I will check for the swap. The 17 is definitely to small. The rpm's for that motor are between 5000 & 5750. I think I hit 6000 and the rpm limiter cut in, and still had room to go before the stop.. I will check this week for the prop swap deal. Is there anyone on the innerweb who does it?

[gatorglenn]

Power tech is the easiest to work with on the mail order swapping I think. There are more but that can be expensive to. With shipping fees. If you can it's best to find a place near you to do walk in.