Mercruiser pitch help

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UTKU

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good day

My name is utku from turkiye

I have a 1998 model bayliner 2855 ciera, ı have a mercruiser 5.7L 250HP engine I HAVE ALPHA ONE
ı have 19 pitch 3blades prop.but over engine 4000 turnover does not exceed

can you pls help me?

best regards
UTKU
 
UTKU said:
good day

My name is utku from turkiye

I have a 1998 model bayliner 2855 ciera, ı have a mercruiser 5.7L 250HP engine I HAVE ALPHA ONE
ı have 19 pitch 3blades prop.but over engine 4000 turnover does not exceed

can you pls help me?

best regards
UTKU
Click to expand...

looks like nobody else is going to reply ....
I suppose your Alpha One drive gearratio is 1,5:1 and beleive you are well overpropped.
Guess a 15' standard alu prop would be right - maybe your dealer would let you test the prop before you buy
 
Thank you for your message

now ı have alpha one 5.7 engine prop is 19pitch but but the boat does not go so well

ı cant our tail Picture if you are using whatsup +905304250316

some master says 17pitch
 
Yep, your prop is definitely too long, considering the (rather low) power and the boat size.
You don't tell if your current prop is steel or aluminum.
Assuming it's aluminum, I'll second piratos suggestion: the 15" version of the same prop should give you the correct max rpm, probably with a small increase of max speed.
If the current 19" prop is steel, maybe also a 17" aluminum could be enough - but there are only three ways to know for sure: test, test, test.
I would stick to alu for the new prop, anyway. The boat ain't fast enough to enjoy the higher efficiency of steel props.

PS: Oh, and welcome to the asylum! Not many folks around here are from your lovely part of the Med.
 
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good day dear MAPISM

thank you for your message

my prop is alimunıum 19pitch alpha one tail

is it possible can ı use 17pitch prop to our boat

also which shop ı can get 17 prob.in your country?

best regards
utku
 
dear mapism

because our knot is not enough 20 somtimes 17knot

in turkiye spare parts are very enpensive,I need to buy new prop but which site are cheaper can you advise?

also 15pitch or 17 pitch ????your suggestion

ı can sent the my tail Picture to you by whatsup if it is possible

can you add me 00905304250316?
 
Hi Uktu
I've got a Regal 255 XL. It's slightly smaller than your 2855 but it has a deeper vee hull (so less lift).
With the same 5.7L, Alpha 1 and a 17" prop, it's a bit underpropped so I would guess that a 17" might work for your Bayliner.
However, don't forget that if you're underpropped with a clean hull, you might be pleased that you can still accelerate when the season's growth starts to increase drag.
I agree with Mapism to some extent about the Stainless vs Ali props, but sometimes (not always) a stainless prop with a bit of cupping will increase lift at the back end. FWIW, I use a Ballistic SS prop.

Andrew
 
thank you Andrew

my prop is alliminum 19pitch

can you advise which diameter I will buy diameter,gear ratio, etc...?

now it does not pass my engine speed of 4000rpm,can you sent your suggestion prop Picture to my email utku@simseklerltd.com.tr

my max knot is 17-20 knot it is very small for 250 mercruiser engine,what is your knot?

utku
 
UTKU said:
I can not get my speed necessary Motoryacht
by boat is running 20knot
normally 30-32 knot
Click to expand...
Wait a minute.
Do you mean that your boat, with the same prop, has been able to reach the rated max RPM of your 5.7 engine (4600/4800, as I recall), achieving 30/32 knots, and now for some reason she can only make 4000/20 knots?
Because if so, the prop has nothing to see with the performance loss.
The most usual reason is a fouled outdrive/prop/hull, but there are also other possibilities, like overload or engine not working as it should, for instance.

When I suggested to reduce the prop pitch, I was assuming/guessing that you are already sure that there isn't anything else wrong, and that the boat never reached more than 4000 rpm with the 19" prop.
If one or both these two assumptions are not correct, you should look elsewhere before changing the prop.
 
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Good day

Sorry for wrong information i belive my engines technician he says to me 19pitch

Today i remove to my bayliner my prop and i check my prop it is 16x13p mercruiser

What can i do?it is normal or?

What can i do our rpm is max 4000
 
UTKU said:
Good day

Sorry for wrong information i belive my engines technician he says to me 19pitch
Today i remove to my bayliner my prop and i check my prop it is 16x13p mercruiser
What can i do?it is normal or?
What can i do our rpm is max 4000
Click to expand...

Good Morninbg Utku,
Normally we do not share private phone numbers.
In the Forum people will share their experience, tell their opinions and give advice, if possible. But its not possible to give any DIY instructions to repair of engines, To give any advice, full basic informations are nescessary, and in your case Im afraid but there is a lot of informations missing.

I take it that you only recently bought this boat and you have no records of earlier performance ?

As to Propeller : 19' is too big and 13' to small.
With the 13' she will be "slow" but should have too much RPM - IF she makes only 4000 RPM with a 13' prop only there is something else wrong.
The boat may be heavily fouled, or too heavy (take it the doble bottom is not full of water :confused:)

My advise is that you skip your technician, and call an experienced mercruiser technician.

Good Luch
 
good mornınd dear piratos

this is my first boat in my life,I take a lot of enthusiasm

in turkiye the technician very expensive to check the boat because they say ''we are working only summer time'' it is not good

for that reason they need alots of Money for check the boat and repair

yesterday ı remove my prop I saw J 16X13 code, (the center of the propeller) my engine is 250hp gas engine 5.7 v8

now I suspect maybe my tachometer is wrong working, ı can chance it today

but normally mercruiser gas engine,250hp,v8,alpha one tail (bayliner 2855) which pitch it is good I need performance and economy TOGETHER 15 or 17 pitch

For that reason can you pls help me?

utku
 
Utku, it's difficult to give you any meaningful help, because the details you gave us are not consistent.

To summarize what I understood so far:
- 5.7 engine with Alpha outdrive
- aluminum 3 blades propeller, 16" diameter, 13" pitch
- max 4000rpm/20 knots
- no details about normal/previous boat performance

If the above is correct, the only thing we can tell for sure (well, almost) is that you can forget the propeller, because there must be some other problem.
Actually, the 16" diameter is unusually large for an Alpha outdrive - typical diameter is between 14" and 15".
But I don't think the large diameter alone is the reason for not reaching the rated rpm.
And if the boat doesn't reach it with a 13" pitch prop, you can only make things worse with a 15" or 17" prop.
 
GOOD DAY DEAR MAPI

**MY BOAT IS BAYLINER 2855 CIERA INBOARD ENGINE ALPHA ONE TAIL
**5,7 ENGINE 250 HP V8
**ALUMINUM J 16X13PITCH PROP.

today I will measure my engines rpm for electronic device(when she is idling)and then ı will let u know what is the rpm,because I suspect my tachometer maybe it is damaged

mr mapism thank you for your help,As ı understood I must buy 14-15diameter,17pitch prop.

it is correct????

we will measure and ı will let you know

best regards
 
UTKU said:
it is correct????
Click to expand...
Sorry., but no, it isn't.
At the moment it's impossible to tell what is wrong with your boat, but if after your checks you will confirm that you can only achieve 20 knots at 4000rpm, for sure a longer prop will not be a solution, I'm afraid.
 
UTKU, I'd like to point you to a few basics of planing boat speed.

First of all the deciding factor is WEIGHT, next the amount of HP available and the hull design type (flat, V or modified V).

A certain amount of HP and weight will enable a given speed. These are published figures for your boat

Length: 28′ 1″
Beam: 9′ 6″
Draft: 3′ 3″
Weight: 6510 lbs, 2952 kg
Fuel tank size: 102 gallons
Water tank size: 35 gals
Hull type: Deep V
Deadrise: 18 degs

2952 kg + 250 kg petrol + 30 kg Water + 250 kg persons + gear and equipment totals to approximately 3582 kg
Your 5.7 liter V8 presumably was rated at 260 hp when new. If in good order and no defects it still may deliver that much. Is is a prerequisite that your hull is clean from any growth or dirt and that your propeller is undamaged.

So:
260 hp is capable of pushing 3582 kg to 31 knots.
Your engine rpm range at Wide Open Throttle (WOT) or simply full gas, is 4400-4800 rpm. and you should aim for the upper limit.

4800 engine rpm transferred to the prop shaft at an 1,47 reduction returns 3265 propeller rpm. For that rpm to produce 31 knots you need an efficient prop pitch of 12" but as a prop in water is not as a screw in wood, there will be some slip - say 10-12% - hence making a 13" sound right.

Be aware, however, that if my weight assumptions are incorrect, the results will also be incorrect.

It is normal service for authorized propeller dealers to let you swap a purchased prop until you get the best fit, provided that it is in as new condition. Price may be higher than discount, on the other hand you have to pay for only one. Would Turkish dealers offer the same level of service? Alternatively, could you borrow a prop for testing - other boaters with Alpha drive (or large gearhouse outboards) might be able to help?

Points to consider:
Is the weight right?
Is the propeller undamaged? Is the propeller hub intact (if the propeller shaft does not bring the prop along you will get high rpm and low speed, if you have a Flo-Torq hub the Delrin bush is DIY replaceable)
Does the engine perform 100% = 260 hp?
Is your speed correct (GPS is a safe means of measure, pressure logs not so)?
Is your tachometer reliable?
How does your sterndive trim affect the performance?
 
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thank you dear spi for your interest

Today we measure the engine's idle speed from the thrust load with electronical device.

how many rpm it gives we will know,and ı will let you know ı think my tachometer is not good working

testing some of my friends I would suggest putting the burden on the boat but I could not do it because it is now on my boat propeller
 
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