Propping my boat

[McShaft]

Hi there, does anyone have good knowledge/experience in propping? I have a 2012 Crestliner 1850 Sportfish with a Mec 150 4 Stroke. My pitch size is 19". Max RPM on this motor 5600RPM and I can only get about 5000 with the motor trimmed right up almost at blow-out. Max speed is about 44mph. It is a little bit sluggish getting out of the water when I have a boatload and seems to work hard while pulling a tube (With the ski bar accesory). Any suggestions on what size I should try next? And do you think it will make a big difference in performance?

[Shmag]

I would guess a 19 pitch is where you want to be. What king prop you running, 3, 4, 5 blade. Is the anti cavitation plate flush with the lake at WOT...(wide open throttle).

Tempest props like to run higher, enertia props like to run a bit deeper in the water.

[McShaft]

I just looked it up and my max RPM is actually 5800. I think I have the Enertia. Its a 3 Blade. Shouldnt I be able to reach max RPM? I get 5000 when Im like half blown out of the water. I would say about 4800 when im getting full traction.

[TROLLER]

Check with Stu at Propmaster they are in Airdrie but you can find their web page no problem

He will make sure you have the right prop for what you want to do and will not rip you off.

Great service and they will ship to you no problem.

[Team Beef]

http://www.mercurymarine.com/propellers/prop-selector/#

Should help you. Remember to allow for the weight of all your accessories, gear, batteries, people on board.

[walleye guy]

could be that your motor is mounted to high on the transom,your anti cavitation plate should be just below you kell with the motor down, have a look if there is room for adjustment.

[Andre1212]

My father in law has the creastliner 1850 sport fish we had the 19 we tryed the 21 and went with the 17 3 blade... He's got the 150 2 stroke on it though... The thing jumps out of the hole

[Bigdad013]

Sounds like you might be overpropped with the 19. You could try a 17, you'll get a better hole shot, more RPM's, but you will lose a little on the top end.
If you go to a 21, your hole shot will decrease but top end should increase with lower RPM.

[McShaft]

Thanks for the replies. I think I'm going to try the 17". Its good out of the hole when I have only my wife and I in there but as soon as I put 2 more people in or pull a tube its a dog. The whole reason I got a Sportfish and not a Raptor is because I wanted a dual purpose boat.

[Shmag]

Alot of boats are not set up properly from the dealer, motor height wise.

My guess is a 19 pitch would be what you want, but with the numbers you are providing it does look like you are over-propped. A 17 tempest is probably what you need.

But i would first determine if your height is correct before going through props, as they are not cheap. So if i understand this correctly if you trim to your max would you over-rev ?

A pro once told me to get the boat on a cement floor, take a level to the bottom of the hull and crank your jack either way til your perfectly level. Pull off the prop and same thing level the prop shaft. Then measure from the floor up to the bottom of the hull and then measure from the floor to the center of the prop shaft. You want to see 3 and a 1/2 inchs difference.

Unfortunately there is no prop demo's put on in alberta, that i know of. However merc does have a test props they will send to a dealer so you can try out. I beleive they call them "Blue props" ask them to recommend a few and bring them in for spring

[Shmag]

Your max rpm is 5800, but what is the normal op range for the motor, guessing 5400 to 5800. I think if you drop to a 17 you will only gain about 200 rpm so guessing you still might be too low, but better. I can give you a number to a guy in the states that runs prop gods, but before talking with these guys you have to know 100% certanty that your motor is set right.

Another thing for hole shot...on your prop will have little vent ports with plastic inserts in them. If you pull the inserts out your prop will loosen up and probably spin faster off the hole shot and give you more rpm on the hole shot. It shoots exhaust or air bubbles out those vent ports and once the prop blades hit that its not as tight and therefore spins faster or with less resistance. Unfortunately pulling these out will do nothing for your top end or rpm at WOT. But it should help the holeshot pulling tubes, less resistance, equals more rpm, equals prop spinning faster

[thorne]

And big thing guys miss when selecting a prop is optimal rpms. Meaning each outboard has an optimal operating range, and at WOT you should be hitting the rpms specified by the manufacturer. If at WOT you are not in the specified range you will be over working the motor and reducing engine life. Look up where you should be at WOT and go up or down accordingly. You may loose top end or reduce hole shot, but you will be where your motor should be for optimal efficiency and life expecentency. Over or under proping will have very negative effects on a motor over time.

[Tungsten]

I had similar issues on a 1650 sport angler w/ 115 merc 4 stroke. Came pitched with a 17" and I was several hundred RPM short of WOT spec. I brought up my concerns with my dealer (freespirit) and they offered to drop me to a 16" no charge. That one was closer but still not quite there, one more visit and I had a 15" that was perfect. Hole shot went from pathetic to decent. Top end dropped only a few mph. In the end wasn't too happy with corner bite and ended up with a Michigan wheel Apollo at same pitch. It's better but definately not a performance boat . Ok with me, I spend most of my time fishing anyways.

You have a local dealer you can try to prop down with? Good luck!

[topgun]

Goto a 17 4 or 5 blade. Adding a blade is like dropping half a pitch number. On my Larson 18ft it came with a 23 3 blade and showed 54 mph. I dropped to a 21 dropped to 52. Then I put a 19 5 blade and it does 48 but with 6 people in it. All while only gaining 350 rpm. My drive ratio is 1.81. Some I think we're 1.65 which would mean even a higher pitch number.

[topgun]

Recreational power sports is good to deal with in Edmonton.

[Shmag]

About 3 yrs ago, i posted a similar thread on another site. And had about 9 guys suggesting a different prop, and 1 guy insisted i check my motor height before doing anything. Sure enough with proper adjustments i gained close to 300 rpm, more boat lift at WOT as the boat is under-powered. Overall better boat performance. As mentioned in a previous post wanting 3 and a half inchs difference from the hull to prop shaft, i had almost 7 inchs difference. I went to my top setting and have 5 inchs now. I'm not quite where i want to be yet, but i am adding a 5 degree motor wedge to try and get more trim out of it...still running the same prop. A jack plate would be ideal but they arent cheap either. When people buy a new package they automatically think it should be rigged right as it should, but in alot of cases its not. So i have to be that guy, and stress to really check the motor height before spending money on props. A motor adjustment will make a huge difference in performance.

[Freedom55]

Supreme Sled and Marine in St Albert offer loaner props so you can try-before-you-buy. Maybe someone a little closer to you will do the same.

I got a better hole shot with a 4 blade prop, but mine is a smaller engine and Mercury marine advised it for my application.