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Old 04-21-2020, 04:56 AM   #1
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Post Performance/newb questions

96 1900SR 4.3LX

1st time boat owner. I just picked it up and itís super clean. The wife and I took it to a local lake today and runs great.

WOT was right at 4800, 43mph indicated. Played with trim a little but thatís it for top end, nothing more. Three bladed prop with a little bit of paint knocked off of one blade.

We plan to use the boat to tow inflatables, the occasional skinny skier, and family cruising. Not truly concerned with top end speed but I want to ensure the best performance.

How do I ID my drive ratio? The serial number and the top of the drive unit is hard to read. Iíve got no problem buying a new prop, just donít want to waste money.

What is the long storage area just above and aft of the engine?

In the center of the boat floor, between driver/passenger seats, is an oval hatch. Is this just storage? A small live well?

Thank you,
Jim in idaho.
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Old 04-21-2020, 11:23 AM   #2
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Jim typically the engine and outdrive serial numbers are on the engine cowl, this will allow you to look up on line or call Mercruiser help for all information you will need. The prop should be stamped with its part number either on the side of the hub or the rear of the hub but youíll need to remove it if the latter.

In floor storage is ski locker and the aft may to for storing the Bimini.
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Old 04-21-2020, 01:07 PM   #3
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Quote:
Originally Posted by Marbee40 View Post
Not truly concerned with top end speed but I want to ensure the best performance.
What do you consider "Best Performance"??

Speed? Fuel Economy? Torque for towing? Hole Shot (Time to plane)?

Your Wide Open Throttle (WOT) RPM is right where you want it to be. Once on plane at WOT, trim the drive out until it cavitates, then immediately trim in until it stops. That will be your sweet spot. At that point, the RPM should be between 4500-4800 (the closer to 4800 the better.

If you add a blade or increase pitch, you will decrease the max RPM at WOT. This will more than likely increase top speed for a given RPM, decrease hole shot and add some load.

If you decrease pitch, you'll increase your max RPM @ WOT, however you'll decrease top speed and increase hole shot.
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Old 04-21-2020, 02:18 PM   #4
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Quote:
Originally Posted by shrew View Post
What do you consider "Best Performance"??

Speed? Fuel Economy? Torque for towing? Hole Shot (Time to plane)?

Your Wide Open Throttle (WOT) RPM is right where you want it to be. Once on plane at WOT, trim the drive out until it cavitates, then immediately trim in until it stops. That will be your sweet spot. At that point, the RPM should be between 4500-4800 (the closer to 4800 the better.

If you add a blade or increase pitch, you will decrease the max RPM at WOT. This will more than likely increase top speed for a given RPM, decrease hole shot and add some load.

If you decrease pitch, you'll increase your max RPM @ WOT, however you'll decrease top speed and increase hole shot.

+1 On what shrew said.
That is the best advise.
Don
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Old 04-21-2020, 03:09 PM   #5
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Default Gracias

Gents, thanks for taking the time.
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Old 04-21-2020, 06:07 PM   #6
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+2. I think you've got another 5-7 mph of top end with your current setup.
Not that you're looking to go 50 in a boat, but you can make the boat ride smoother and be more efficient.
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