Prop or Motor?

[Captain milo]

Hello. First time on forum.
I have a question regarding my 2008 sea ray 195 sport
I have the 5.0 tks motor. And 1.62 alpa 1 gen 2 outdrive. It originally came with a 3 blade 21 pitch prop
That couldnt pull out of the hole if your life depended on it.it would not pull up to wot either. But would eventually get up to 52 mph at 3800 rpm ( spec wot 44-4800 rpm
I had to put a 4 blade solas 15 pitch prop on to get good hole shot and get spec wot
Is this normal? Motor is timed perfect as per manual I have also seen larger boats with the same motor with 2 prop system pulling out of the hole. Is it simply the leg gearing that gives other boats the better holeshot?
I've run on a bit here but I hope someone might have reasonable answer for this.

Capitan Milo

 

[GA_Boater]

Welcome aboard Captain milo

Moved this post out of 5 year old thread and into the Prop section, it seems to be a prop question. Please start a new thread when asking for help. Few of us look at the old tropics and you are better served by starting a fresh thread of your own.

 

[QBhoy]

Definitely not normal. I'd say your tach is off or your speedo is off, for a start.
52mph is about right for your boat and engine, but no way is it getting this with only 3800 rpm.
Something is definitely not right. With that engine, boat, gear ratio and prop, it should give a good hole shot and decent all round performance.
All the given info is confusing me, if it's getting 52mph, the engine must be healthy...top end at least. Don't get why it's lugging on hole shot with that set up.
is the speed gps and is the tacho verified as accurate ?
Like I say, no way in this world is it getting 52mph and only doing 3800rpm with that set up. I can believe it does 52 mph, just not at those rpms

 

[QBhoy]

Man, with a 15" prop, that motor will be way over revving. I would be be really worried running that flat out.
I have the 5.0 mpi with a 1.47 ratio. Came with a 17" pitch (set up for wakeboarding) and it hit the limiter very easily at >5100 rpm. Your 1.67 and a 15" pitch will be doing crazy rpm if all is running right. Get the tacho looked at. It will be screaming in true rpms. I'd be worried.

 

[Captain milo]

Thanks guys. I have only used the tach on the boat
But I will set up an external tack to confirm and I will use gps for speed. The motor seems very strong only 132 hours on it. Before I went to 15 pitch I tried a 19
And it had good speed as well 49 mph on boat speedo
But still seemed sluggish out of the hole or pulling me out on skies. I am big... but not that big.

 

[Scott Danforth]

welcome aboard.

my searay 190 (hull 1 generation earlier than yours) with the 220hp carbed 5.0 and alpha had a 19 pitch SOLAS stainless prop and the 1.62:1 ratio. the boat weighed in at 3000# empty, or about 4000# with people and gear. I could hit 4950 RPM at just shy of 50mph on the GPS (speedo said 55). holeshot was good, not spectacular, however was good. I am also boating at sea level. I did verify that my dash tach was accurate enough at the dock at 1500 RPM and 3000 RPM and 4500 RPM, so I am fairly confident that my WOT RPM was around 4900-5000. my prop slip was in the 10-11% range

your boat is slighly lighter than mine dry, not sure of your weight loaded. feel free to roughly compare performance

using mercury's prop slip calculator, your specs of 52mph, 3800 rpm and 21 pitch with 1.62 ratio put your prop at -11% (something is wrong with your RPM's or speed)

using 10% slip as a baseline:
the 52mph if accurate would put your RPM's closer to 4700 RPM than 3800 RPM indicating your tach is off however if your speedo is highly optimistic and your tach is accurate, your actual speed would be closer to 42mph indicating your speedometer is off

i could pull small skiers up on one ski, could pull tubes all day long, and could get adults up on two skiis however not one. would have needed to drop down to a 17P to get my butt up on one ski or do a slack rope start. since the only person I trusted pulling me on skiis lived 1522 miles away, I pretty much gave up skiing in florida

dont use the boat speedo for diagnosing prop problems - use a gps or a gps app on your phone. pitot tube speedos are only accurate at one speed - 0. some are calibrated to be accurate-ish at 25-30. at WOT they are optimistic and highly suspect

for water sports, you may want a 17 pitch. 15pitch will be too light, however with 4 blades, its more like a 16p

I would go to autozone, and borrow a diagnostic tachometer and check your RPM's. and download a GPS app and check your speeds.

you may want to verify your motor is running right. compression test in all cylinders and make sure that you didnt loose a flapper on one side which dropped down and is blocking exhaust.

 

[Captain milo]

Thank Scott I will be checking the tach next time out with a digital one and just downloaded the speed app.
I will keep you posted.

 

[Captain milo]

I forgot to mention that there seems to be a little harder getting going in a lake. The ocean is easier to get going on.
I think I'll do a compression test like you suggest. It has low hours but could have sticky rings