OPINION/ADVICE, WHY IS MY BOAT SO SLOW? 2001 Starcraft Stardeck Aurora 2009 O/B..

[Globug]

[FONT=&quot]I have a 2001 Starcraft Stardeck Aurora 2009 with a 2001 Mercury Optimax 150 and Quicksilver TS 1056 Stainless prop, which appears to be a 21 Pitch.

The boat is in great shape and the motor has approx. 300 hrs and has also been checked out with near perfect compression and operation..

I bought it last year from a 65 year old who kept it on a lift on Lake Whitney in Texas..

Maybe I'm expecting too much, but since I bought the boat I've had it out 4 times and it just seems slow..

My last and only other boat of any size was a 19' Cajun Fish and Ski with 150 HP Johnson and that thing seemed like a rocketship, especially in comparison to this one..

It literally leapt out of the water and would do 55 mph on the GPS like it was nothing..

This StarCraft although supposedly with a more modern efi engine, doesn't seem to accelerate very fast to plane..

I can't imagine this boat would be any fun at all pulling a kid on a tube or trying to get someone up on skis..

It just seems to take a long time to get on plane with 4-6 passengers..

On the top end, the best I've seen on perfectly flat water, trimmed/tweaked the best I could do was 37 mph on the GPS..

Usually, unless I play with the trim and tweak it, with a nice neutral trim position, throttle to the stops and "wound out" is 35 mph with a few adults onboard..

So I thought maybe it's my prop?

Which is a Quicksilver TS 1056 Stainless prop, which appears to be a 21 Pitch..

If remember correctly, the best rpm I saw would out was 5,200 rpm...(and I've been led to believe the engine can/should do more)..

But it's neither fast accelerating or fast on the top end, so I'm going to lose even more of one or the other if I switch to another prop....right?

So perplexed..

Don't know what to do..

35 MPH seems like pontoon boat speed!

I really expected mid 40's at least with this boat..

Suggestions, thoughts, advice?

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[Sea Rider]

Is the engine in accordance with that size/model boat ? If engine is in opt working state throughout all throttle range probably prop is light spun and in the process of getting worst. Try a new prop and check if any performance difference.

Happy Boating

 

[Frank Acampora]

Fishing boats--that is, bass boats-- are specifically designed to minimize wetted surface and engine drag, thus top speed is higher . Your deck boat is a different hull design and probably much heavier. You are comparing apples to oranges. Yes, by experimenting with props you may be able to get a little more performance but don't expect 50 MPH. Your Mercury is a strong engine, but it is not a magic one. For example, I have a 150 on a light 20 foot cuddy cabin and I get about 43 MPH with me alone. Add a couple of passengers and top speed is only about 40. With a 125 on a 19 foot Bayliner bass boat I got 47 MPH--not too shabby.

 

[Globug]

Thank you all for the reasoned and thoughtful responses.. I guess I just thought this boat should run closer to 50 mph.. I'm a little worried that if I had a crowd of 10 on it (rated capacity of 12) that I could even get up on plane. I guess I'll just have to try it one day..

 

[steelespike]

First thing I noticed was the Auroa weighs 3075 lbs and is a DeepV. All the Decks I found were 20-22 ft 2300-2715.lbs.
running Etec 150s (easiest to find a number of similar setups) Speeds average out to about 43 mph low:40.2,high 45 mph.
Hole shot 3 sec. to 4.55 I assume usually 2 people plus gear and fuel.
Your Cajun 19 ranges from 1300 to 1600 lbs.

 

[Globug]

First thing I noticed was the Auroa weighs 3075 lbs and is a DeepV. All the Decks I found were 20-22 ft 2300-2715.lbs.
running Etec 150s (easiest to find a number of similar setups) Speeds average out to about 43 mph low:40.2,high 45 mph.
Hole shot 3 sec. to 4.55 I assume usually 2 people plus gear and fuel.
Your Cajun 19 ranges from 1300 to 1600 lbs.

I suppose that makes sense...it is a pretty "deep" V and feels like a heavy boat in rough water..

 

[SkiDad]

I think your operating range is 5250-5750. I would prop her for the top of that. a hair over will not hurt it. So for sure 19p. Maybe 18p if your can find one.

 

[Teamster]

A High Five 19p might do the trick,.......

 

[roscoe]

have you checked for waterlogged flotation foam?

 

[Globug]

have you checked for waterlogged flotation foam?

No, but how would I do that?

 

[steelespike]

You might be a candidate for the Merc. Spitfire 4 blade prop.It is said to give 4 blade performance without the loss of top end.
By the way "hole shot seems slow"is difficult to use to pinpoint what is actual hole shot.
The hole shots I gave were classified "time to plane"
As far as hole shot goes the Deep V will slow that.I don't know about the TS 1056 prop but it may not be good for hole shot.
If we use 5200 rpm,1.87 ratio,21" pitch and 37 mph we get 33% slip.Normal slip is in the low double digits.
When I see high slip the tach is my first suspect.We know we are on a 21" prop and gps speed.
I assume 1.87 is the accurate gear ratio.Perhap[s you can borrow a shop tach to check your rpm.
By the way while the tests are with a Etec the gear ratio is very close at 1.85 yet they are running 16" and 17" props.with rpm from 5150 to 5925 rpm
It is possible that besides the tach being off you may be over propped.

 

[Globug]

Does anyone think a heavy deck boat might be too much for an aluminum spitfire prop? I am a cheap bastard and the price ($165) is appealing, especially considering how easy it is to hit a rock in my lake..

 

[Tail_Gunner]

You might be a candidate for the Merc. Spitfire 4 blade prop.It is said to give 4 blade performance without the loss of top end.
By the way "hole shot seems slow"is difficult to use to pinpoint what is actual hole shot.
The hole shots I gave were classified "time to plane"
As far as hole shot goes the Deep V will slow that.I don't know about the TS 1056 prop but it may not be good for hole shot.
If we use 5200 rpm,1.87 ratio,21" pitch and 37 mph we get 33% slip.Normal slip is in the low double digits.
When I see high slip the tach is my first suspect.We know we are on a 21" prop and gps speed.
I assume 1.87 is the accurate gear ratio.Perhap[s you can borrow a shop tach to check your rpm.
By the way while the tests are with a Etec the gear ratio is very close at 1.85 yet they are running 16" and 17" props.with rpm from 5150 to 5925 rpm
It is possible that besides the tach being off you may be over propped.

As Spike is pointing out what is the Optimum wot on that engine. Once that is determined it is possible to find a prop that will lower that slip a bit....33% is quite high..just a opinion.

https://www.google.com/search?q=200...=93&ie=UTF-8#q=2001+Mercury+Optimax+150+specs

There's a pdf file in that link, If this pdf file is correct then your over propped

Horsepower 150 175
Kilowatts 110 129
Full throttle RPM
speed 5250?5750 RPM 5500?6000 RPM..........................................................................
Idle speed in forward
gear 550 ? 25 RPM
Number of cylinders 6
Piston displacement 2508 cc (153 in?)
Cylinder bore 88.4 mm (3.500 in.)
Piston stroke 67.3 mm (2.650 in.)
Recommended spark
plugs NGK
IZFR6J‑11
IZFR6J
Spark plug gap 1.1 mm (0.042 in.)
Standard gearcase
gear ratio 1.87:1
HP
LB
23884
- - - . - - -
XXXXXXX
-
XXXXXX XLX
Me rc ury Marine
Serial Number
Brunswick Corp.
Made in Japan
XX
XXXX XXX
HP XXX
LB XXX KG XXX
KW XXX
Model Number b
c
a
d

 

[Tail_Gunner]

As Spike is pointing out what is the Optimum wot on that engine. Once that is determined it is possible to find a prop that will lower that slip a bit....33% is quite high..just a opinion.

https://www.google.com/search?q=2001...imax+150+specs

There's a pdf file in that link, If this pdf file is correct then your over propped

Horsepower 150 175
Kilowatts 110 129
Full throttle RPM
speed 5250–5750 RPM 5500–6000 RPM............................................... ...........................
Idle speed in forward
gear 550 ? 25 RPM
Number of cylinders 6
Piston displacement 2508 cc (153 in?)
Cylinder bore 88.4 mm (3.500 in.)
Piston stroke 67.3 mm (2.650 in.)
Recommended spark
plugs NGK
IZFR6J‑11
IZFR6J
Spark plug gap 1.1 mm (0.042 in.)
Standard gearcase
gear ratio 1.87:1
HP
LB
23884
-
A guess would be the mid fourty's so using a prop calc a 17P at 12% slip would get you 42mph ...1.87 gearing 5600 rpm

21 get's 5200
20 gets 5400
19 gets 5600

Can you borrow a 17/19 pitch prop and give it a whirl...I am again quite sure your over propped...Ohh and then you can raise your motor height....Im just kidding...for now.. I just noticed you have a alum prop..part of the high slip.

 

[Globug]

Can you borrow a 17/19 pitch prop and give it a whirl...I am again quite sure your over propped...Ohh and then you can raise your motor height....Im just kidding...for now.. I just noticed you have a alum prop..part of the high slip.

All good points, but it is a stainless prop, just weathered and pitted..

 

[Tail_Gunner]

You want to prop you engine for 5750 rpm at WOT. It would benefit the boat in terms or launch..top speed and long term engine wear, a boat of that size and weight would again benefit from A ss prop good luck and have fun.

 

[roscoe]

No, but how would I do that?

You don't want to know.

Hire a pro to check it out and DON'T watch him do it, as it may involve using a power drill.

 

[Tail_Gunner]

Here let me make better sense of this....1.87 gearing 5750 recomended rpm 21p prop gets a 61 mph thero speed wtih 12% slip its 54mph....that's what hes trying to work make now it's no wonder its sluggish he's way over propped.

So one takes a 17 p prop and runs's 5750 gearing 12% slip and 46 mph....you will be pleased with your hole shot as well.By the way that's a pretty stout engine turning that 21 that high in the rpm band.

 

[Chris1956]

Glo, check out a Turning Point Hustler. They are a pretty high performance, vented aluminum prop, with a low price.

 

[Globug]

We'll I took it out on a "baseline" test yesterday..

It was myself, wife and daughter with a full tank of fuel..

Calm water and 38.3 mph on GPS at 4,950 rpm is the best I could do, trimmed as high as I could before the prop ventilated..

The prop is a Quicksilver 21 Pitch Stainless..

My local boat repair place and a Starcraft Dealer who said he emailed Starcraft directly, said they'd recommend a 17 Pitch..

My guy feeling is that is too radical of a pitch change, bit I really am just guessing..

I mentioned the "High Five" prop that Teamster wrote about and my boat dealer said "don't do it", that prop is not for a deck boat like mine and it would be a lot slower than it is now..

I was also told that the motor height can be checked with a straight edge and the lower fin on the motor should be 1" or so higher than the bottom of the boat..which It is..

I'm thinking a 19 Pitch stainless 3-blade would get me to 5,500 rpm, and/or 42 mph with less slip and give me better acceleration?

Your thoughts and advice on this train of thought?

EDIT: After reading some posts on various forums like "Optimax won't go over 5,000 RPM" I'm sweating and thinking. I may not have a cylinder firing...seems like a common thing on the Optimax's..

The engine is rather noisy between idle and 3,800 rpm where it feels quieter/smoother.. Even my wife said it's a noisy engine.. It almost sounds "rattly" from 3,000 - 3,800 rpm, but I've heard these are noisy engines, so I dismissed it..