prop advice

Hi,
I need some advice on a prop. I just bought a 1994 Baja 180 islander and would like to change the prop. The one that came on the boat is a composite material info that is stamped on the prop is this 4x345x508 and 4x13.6x20 and m4550L. with this prop it runs about 42 to 43 mph but turns the engine around 5200 to 5300 rpm at wot. I think this rpm is to much, not sure.The boat weight is 2400 lbs it has a 4.3 mercuriser in it and I normaly have 2 adults and 3 to 4 teenagers in in. We mostly use it to ski so I would like a 4 bladed prop.Any help would be appreciated.

Re: prop advice

Max recommended RPM for your engine is 4400-4800. Do you have the LX-175HP or standard 155 HP motor? Is your current WOT with 2 adults and 3-4 teenagers? Your current prop is mfg by Comprop. A good SS 4 blade will
be much better for your load and skiing, but you will need you to be careful when lightly loaded as it will rev above your Max recommended RPM. Pitch and Dia will depend on your above answers.

Re: prop advice

I do not know which engine it is, do you know how I can find out? And yes my current wot is with 2 adults and 3 to 4 teenagers. I would like to use an alliminum because the area I boat in at low tide has alot of low spots so I would be worried about hitting ground and breaking something with a ss prop.

Re: prop advice

because the area I boat in at low tide has alot of low spots so I would be worried about hitting ground and breaking something with a ss prop.

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That is probably the reason reason it has a composite prop on it now. They will break a lot easier than an alum and do no or minimal damage to the drive. Also they are real easy to replace when floating in the water.

Re: prop advice

What is the engine serial #? (I'll bet you have the 175HP engine) Is your time to plane with a skier and full load acceptable right now? If it is, I would look at a Solas Amita 14x21

Re: prop advice

The engine serial number is F823639 and yes my plan is to get on plane with full load and a skier. I just remenbered one thing when I am just cruising along it seems to porpous if I stay at full trim and full throttle. Thank you for your help .

Re: prop advice

I do not know which engine it is, do you know how I can find out?

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Ayuh,... Is it a 2bbl. carb, or 4bbl. carb,..??

I just remenbered one thing when I am just cruising along it seems to porpous if I stay at full trim and full throttle.

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So, trim it In alittle...

Re: prop advice

it is a 2bbl carb

Re: prop advice

barons said:

Hi,
I need some advice on a prop. I just bought a 1994 Baja 180 islander and would like to change the prop. The one that came on the boat is a composite material info that is stamped on the prop is this 4x345x508 and 4x13.6x20 and m4550L. with this prop it runs about 42 to 43 mph but turns the engine around 5200 to 5300 rpm at wot. I think this rpm is to much, not sure.The boat weight is 2400 lbs it has a 4.3 mercuriser in it and I normaly have 2 adults and 3 to 4 teenagers in in. We mostly use it to ski so I would like a 4 bladed prop.Any help would be appreciated.

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Baja nice boat..Am i reading this right??? a 20p 3 blade prop turning a 2400lb boat with 2 adults and 3 teenagers to 5300..Could you post your gearing, it is stamped on your outdrive..

You might want to check your tach also..That boat.. motor.. and prop combo should not be able to push to 5300 with that load..Its worth checking before you leap

Re: prop advice

where on the outdrive would it be? the only number I found was on the bracket on the bcak of the boat that the outdrive bolts to it is a serial number which is 01194615.

Re: prop advice

I think you can take that to the I/O forums and someone may be able to decode that number....Ive refinshed my alpha and i cant remeber but i think it was stamped on the decals...aka someone punched 1.98

Re: prop advice

I found the stamp you were taking about it is 1.84 is this the right ratio?

Re: prop advice

barons said:

I found the stamp you were taking about it is 1.84 is this the right ratio?

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Ok 5250 @ 45mph With a 20p 3blade i assume..1.84 gearing nets 22% slip...Thad be a tad high That is pretty short gearing for a 4.3 your hole shot is going suffer somewhat to achieve top end speed...Or vice versa

ITs hard to really get close with such a high slip factor...From what i understand if that tach is correct and the speed is Gps measured...That would make it a 4 blade..22 on a 18' 4.3...With 5 people...

IF your tach is really correct and your speed is gps verified... Then As Uss says 21..safe bet...I show you could turn a 22 ..... Damm a 2bl 4.3... 5 people turning a 22p or 21p 4bl @ about 50 Hmmmm

But if your tach is correct and you have used gps those are the numbers...... trust me most are not accurate..tachs and speedos


Ok I used a similar boat....400lbs heavier....8" longer with 1.66...both hulls are 20 degrees....It took a 24 with 1.84 gearing....Thats ss to...

Not saying its not possible...But id check that tach and speed very carefully the tach from 800 all the way to 5000

Re: prop advice

I would say your tach is suspect my brothers 92 crownline 182br same engine 1.84 19 p SS turning 4600 running 42 with the same load as yours.