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Hi everyone!

I have 2003. Mercury 40hp, 2 stroke, model ELPTO. 2 cylinders, 644ccm

I'll put it to 1992. 15' super sport. What do u think, which performances can i except with that engine? Most of the people i know that own 15 sport or supersport have stronger engine on their boats, mostly Yamaha or Honda 50-60hp.
I hope that my mercury will be strong enough for the next year or two, because i'm planning to buy yamaha 60HP 4 stroke, 4 cylinders (996ccm) but i don't have enough money yet so i'll have to use mercury until i get the new engine!

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The top speed lightly loaded should be in the low 30's. It should be fine unless your going to load the boat up with 5 people regularly or use it for high load watersports.

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That's very nice to hear, hope it would be as u said. Mostly, there will be only 2 ppl on board, and i'll use it for diving and fishing, not for any watersport or something like that. I'll let u know how fast is it when i try it out :)

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Hi guys!

I finally finished working on my boat, and tested it, and i'm not happy with what i got!

The engine works great, it has a lot of power, the boat jumps out of the water easy, and accelerate fast, but the top speed is very low, only 23kt. There was 2 ppl on, two big guys, but i guess it should go at least 26-27kt, even with two of us on. I guess it's the wrong prop for that boat, i think i need bigger pitch, but since the existing prop is in very bad condition, damaged by saltwater, i cant find out which propeller is that, his size, pitch etc so i can only guess. What do you guys think, for the BW sport 15, custom made console and seat, weights around 280-300kg, which prop should i use on this mercury to get the best performance?

Ty in advance, best regards from Croatia!

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First, do you have a tachometer? What is maximum RPM?

It sounds like you could use more pitch if " the boat jumps out of the water easy, and accelerate fast". But if the prop is "in very bad condition, damaged by saltwater", what does the damage look like? Is this prop aluminum or stainless steel?

With gear ratio, RPM and prop model and pitch, then some good advice can be given. Have you looked for numbers on the hub of the prop when removed from motor? Can you post a picture of the prop?