2003 Trophy 2302 wrong propeller?

[tobqluu]

Hello, I just bought a 2003 Trophy 2302 200hp EFI Mercury outboard. My question is, I can't get the boat to goes pass 30mph. it have a Mercury mirage Plus 15 3/4 X 15 P Stainless steel running around 25-30mph @ 5000-5200 rpm WOT. I've been reading that some get it to go upto 40mph WOT . Is the prop. on my 2302 is the wrong size? Thanks!

 

[TunaFish389]

Your target max rpms is 5850. With that prop you should over rev that rpm easliy. I would do a compression check on engine then go from there.

 

[dingbat]

With that prop you should over rev that rpm easliy..

Wouldn't count on it.

I'm run a similar boat with the same HP. The 15 x 15 prop I'm running gives me 38-39 MPH @ 5600 rpm.

Agree he has something else going on.

 

[Scott Danforth]

it sounds like your down a cylinder

 

[tobqluu]

I checked all the cylinders when i bought the boat....
they're all 120-125 psi on all 6.

if i have one cylinder out, wouldnt it backfire or shakes at idles? my idles are smooth. Loaded with 3-4 persons onboard.


I did installed a outboard hydrofoils on the motor, don't know if that slow it down or not.

 

[dingbat]

I checked all the cylinders when i bought the boat....
they're all 120-125 psi on all 6.

if i have one cylinder out, wouldnt it backfire or shakes at idles? my idles are smooth. Loaded with 3-4 persons onboard.


I did installed a outboard hydrofoils on the motor, don't know if that slow it down or not.

Just because the compression is good doesn't mean it's not dropping a cylinder.

You would have know if your missing a cylinder on a 6 cylinder. Especially, if your dropping out at higher rpm the miss

Are you trimming out once on plane? A buried prop will slow you down big time

btw: A whale tail is a very poor substitute for ails your boat.

 

[tobqluu]

Yeah, i trim up and down, i can see my speed goes up or down. I leave it at the faster trim level. No, there's no shakes or backfire at WOT ... I had a boat before this one, and that thing backfire at WOT after 15mins , so i had two boats b4 this one.

How would i go about finding a bad cylinder? spark tests one by one cylinder for spark?

 

[QBhoy]

That’s a hell of a diameter on that prop. I wouldn’t imagine you need a big diameter like that. Not too familiar with props that low a pitch but is that a normal diameter for a 15” prop for the big gearcase ? That’s nearly 16” diameter. It’s never going to be a sped machine with that big a diameter.
Have you tried a conventional 17” ? The diameter will be much smaller

 

[dingbat]

I wouldn’t imagine you need a big diameter like that. Not too familiar with props that low a pitch but is that a normal diameter for a 15” prop for the big gearcase ? That’s nearly 16” diameter. It’s never going to be a sped machine with that big a diameter

I’m running a 15x15 on my boat as well. Same Hp....40 mph GPS....yes, you need it when pushing #5k in boat

Ran a 14x17, 4 blade for a number of years. The 15x15 out performs it in every aspect

 

[QBhoy]

I’m running a 15x15 on my boat as well. Same Hp....40 mph GPS....yes, you need it when pushing #5k in boat

Ran a 14x17, 4 blade for a number of years. The 15x15 out performs it in every aspect

Hi. His is a 15 and 3/4” diameter.

 

[QBhoy]

I’m running a 15x15 on my boat as well. Same Hp....40 mph GPS....yes, you need it when pushing #5k in boat

Ran a 14x17, 4 blade for a number of years. The 15x15 out performs it in every aspect

4 blade will always get outperformed by a 3 blade. I suggested trying a 17” standard 3 blade with much smaller diameter.

 

[Scott06]

4 blade will always get outperformed by a 3 blade.

Not in all cases I get best top speed on mine with a Revolution 4 , even bested a enertia, because I can trim out more vs other 3&4 blades I've run. Heavier boat I'm seeing less slip on top end with more blade area and cup

 

[QBhoy]

Not in all cases I get best top speed on mine with a Revolution 4 , even bested a enertia, because I can trim out more vs other 3&4 blades I've run. Heavier boat I'm seeing less slip on top end with more blade area.

Fair play. All have different reactions but is that Rev 4 of the same pitch as the enertia. If it is...that would be the first time I’ve known an enertia to be bettered. I suppose a bigger boat would change the game a little. You really need the power to turn an enertia to its full potential. Generally the enertia 3 blade would better a rev 4. Was it the performance enertia or the enertia eco ?

 

[dingbat]

Hi. His is a 15 and 3/4” diameter.

Didn’t realize until you said something.

I over rev a 14x17 3 blade with same Hp and similar boat, but it would be interesting to try

 

[tobqluu]

I'll take the whale tail off and see if i can get an extra 10mph . if it doesn't improve, should i try 14X17 or 15X15?

 

[Faztbullet]

loose the whale tail and retest

 

[QBhoy]

I'll take the whale tail off and see if i can get an extra 10mph . if it doesn't improve, should i try 14X17 or 15X15?

Hi
ive seen many guys with bigger 28-30ft cruisers with single 5.7 have great overall results with the 16x16 prop but never a speed machine. I’d imagine you’d get away with a good stainless 14 1/2 x 17 prop

 

[Scott06]

Fair play. All have different reactions but is that Rev 4 of the same pitch as the enertia. If it is...that would be the first time I’ve known an enertia to be bettered. I suppose a bigger boat would change the game a little. You really need the power to turn an enertia to its full potential. Generally the enertia 3 blade would better a rev 4. Was it the performance enertia or the enertia eco ?

The rev 4 is a 21, enertia a 22 as I needed to keep rpm down. The rev 4 also took in my experince more power to turn than the enertia. Seems that in my case the rev4 that plays well trimmed high in aerated water allows my set up to trim up more and get more of the hull out and get additional 300 rpm ( both enertia and rev4 wot are 4800-4900 rpm). Both are really, really good props, speed difference was 1-2 mph. Just unique as typically 4 blade gives up 3-4 mph.

 

[porscheguy]

Mirage props increase in diameter as the pitch goes down. I don’t think the diameter is your problem. Does the prop have vent plugs? Early mirage plus props didn’t have them. If it does have them, are they solid, or do they have holes in them? The vents can’t be wide open without some kind of plug in them or your performance will suffer.

Ditch the drive mounted hydrofoil. Unless the motor is trimmed perfectly flat and level it’s creating drag.

Is your motor mounted at the appropriate height? If the lower unit is buried, and you have a hydrofoil, and you’re carrying a heavy load, your performance is really going to suffer.

A 200 on a 23’ fishing rig is on the low side of the power range. So keeping weight down is critical. as well as rectifying other issues that can impede performance.

1. Ditch the hydrofoil.
2. Take note of the mounting position of the motor.
3. Get rid of the weight adding BS that tends to accumulate on boats.
4. Take it for a solo run and see what you get.

Currently you’ve got 25-30% prop slip. I would guess 10-15% is more appropriate.

 

[tobqluu]

I went out over the weekend, removed the hydrofoil. The waves were almost flat, got 32-33 @5300 WOT. i gained about
3-4 more mph, still not hitting 5800 rpm. saw some youtube videos about prop. in order to get my rpm up, don't i have to lower my pitch to 15X13 P ? I thought they says the higher the pitch the lower the rpm, as of today, 15 3/4 X 15 P 32-33 mph @ 5300 rpm WOT with 3 on board.