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'09 Stratos 385 xf prop questions - Walleye Message Central
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  #1  
Old 03-19-2017, 12:15 PM
usmarine1 usmarine1 is offline
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Thumbs up '09 Stratos 385 xf prop questions

I have this setup ​with a 200 optimax. I run top speed of around 48-49 but I've been reading guys with a 150 setup achieve the same speeds. Hole shot is pretty good. There is an aftermarket mercury guage that tells me I'm running around 4750-4800 RPMs which is about a 1000 low. The current prop is a SS tempest 21p 3 blade. I plan to head to my prop guy at some point but even with him there has been some trial and error in the past. I'm pretty sure a 20-19p would help but what about motor position? Is a jack plate really necessary manual or hydraulic? If I move to a different pitch would staying with the tempest be the best choice? I just find it hard to believe a 4s 150 is the equivalent of a 200 Opti on the same rig. I had read somewhere a guy had this same discussion but of course I can't find it now.
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  #2  
Old 03-21-2017, 04:42 PM
slim1755 slim1755 is offline
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Something is wrong with your motor or prop unless you are loaded rediculously heavy. I have the same motor, hull and prop. I see 57+ at 5600 rpm with 2 people.
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  #3  
Old Yesterday, 08:37 AM
usmarine1 usmarine1 is offline
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the motor isnt my concern yet, i don't think. What pitch prop do you run? Is it a similar boat? Right now between where the motor sits and the prop are my two main focuses for solving the problem. the boat has a full tank but thats it I don't even have gear in it yet.
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  #4  
Old Yesterday, 10:04 AM
REW REW is offline
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us,
The 250 Optimax is a really strong motor. It is normally a "LOT" more powerful than the 150 4 stroke.

What elevation are you running your rig?

High elevations really kill the power of a normally aspirated engine.

Before doing much prop work, take your rig to a shop that has a marine dynamometer to verify the shaft HP of your boat.

You want to verify that you are getting 250hp at the prop shaft.

Once you have verified the power at the prop shaft - mount your engine in a hole that is as high as you can possibly run the motor and not have excessive prop venting or cavitation.

Then, you can try some different props.
But, as you know the motor height for a given prop may be different with a different prop.

But, yes, certainly the prop you are running now, or possibly a 20 or 19 pitch should be optimum.

Certainly, a 50-60 over the water speed is not unexpected from your rig.

In general with a clean hull, it would not be unusual to have the motor height set at a distance where the prop cavitation plate, with the motor in a vertical position would be 3 inches HIGHER than the bottom of the boat's hull. But, the correct height is determined by the boat's hull, prop design and manufacture, as well as the loading of the boat and throttle setting of the motor.

i.e. the nicest way to go with any boat and motor - especially those with higher hp, as you have is to have an electro mechanical jack plate on the rig. that way, you can tuck in the motor, drop the motor in height with the use of the jackplate.
Get the boat on plane, and then go back and forth between motor height and motor trim, until you are running your fastest over the water speed, at a given throttle setting and with the best motor height.

So, the motor height, the throttle setting, engine rpm, engine trim setting all interact at every boat speed to provide the most efficient boat operation.

For example, the motor height at a wide open throttle setting may be different than for a throttle setting for cruising speed. The motor trim position may also be different for a wide open throttle setting compared to a cruising throttle setting.



Be safe

Last edited by REW; Yesterday at 10:10 AM.
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  #5  
Old Yesterday, 10:15 AM
REW REW is offline
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I have posted this before, but you might give it a try.

Take every item out of your boat that you currently carry but is not needed to float and run your boat.

Use a scale to weigh all of the total items.

Then - before putting the items back into the boat - take your boat for a comparative run - just to see the light load boat performance compared to a heavy load performance.

Then, depending on how you feel - put all of the items back into the boat, or just some of them, if their need for you in the boat is somewhat extra.

Every now and then, folks end up carrying an extra thousand lbs in the boat all of the time, without the owner of the boat - really realizing that they are carrying this extra baggage.

Certainly - if you need an item in the boat - carry it.
But, if you don't really need an item in the boat - leave it out of the boat.
Maybe you want to have some items available at a camp, but don't necessarily need them in the boat. If that is the case, use the boat to transport the items to camp - but then remove the items from the boat before using the boat.

Be safe
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  #6  
Old Yesterday, 01:05 PM
slim1755 slim1755 is offline
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Quote:
Originally Posted by usmarine1 View Post
the motor isnt my concern yet, i don't think. What pitch prop do you run? Is it a similar boat? Right now between where the motor sits and the prop are my two main focuses for solving the problem. the boat has a full tank but thats it I don't even have gear in it yet.
I also run a 21 pitch tempest. I have a 386xf. Identical hull. I can check where my motor is mounted when i get home. Grossly overweight with 5 fat guys and coolers, and gear, I still run over 50. Lightly loaded with that motor and prop, you should be seeing 8-9 mph more than what you are getting.
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  #7  
Old Yesterday, 01:08 PM
slim1755 slim1755 is offline
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Quote:
Originally Posted by REW View Post
I have posted this before, but you might give it a try.

Take every item out of your boat that you currently carry but is not needed to float and run your boat.

Use a scale to weigh all of the total items.

Then - before putting the items back into the boat - take your boat for a comparative run - just to see the light load boat performance compared to a heavy load performance.

Then, depending on how you feel - put all of the items back into the boat, or just some of them, if their need for you in the boat is somewhat extra.

Every now and then, folks end up carrying an extra thousand lbs in the boat all of the time, without the owner of the boat - really realizing that they are carrying this extra baggage.

Certainly - if you need an item in the boat - carry it.
But, if you don't really need an item in the boat - leave it out of the boat.
Maybe you want to have some items available at a camp, but don't necessarily need them in the boat. If that is the case, use the boat to transport the items to camp - but then remove the items from the boat before using the boat.

Be safe
He said he does not even have gear in it yet
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  #8  
Old Yesterday, 08:26 PM
slim1755 slim1755 is offline
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Quote:
Originally Posted by slim1755 View Post
I also run a 21 pitch tempest. I have a 386xf. Identical hull. I can check where my motor is mounted when i get home. Grossly overweight with 5 fat guys and coolers, and gear, I still run over 50. Lightly loaded with that motor and prop, you should be seeing 8-9 mph more than what you are getting.
FYI my motor is mounted in the middle hole.
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