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i have a newyamaha 115 2 stroke but am confused with propella. Wot is 5500 and speed is only 33 knots. 13*17pitch propella. I've been reading the yamaha performance chards at the speed should be around 39 knots. So if i change to 19 pitch, will that make the difference????.
The boat is cavitating a little so i will lower the motor one hole. Cavitation when i did steep turn. Will this increase or decrease speed.
Tim looks like a fishing rig, base your cavitation on how well it holds in the lumpy stuff, a little cav on tight turns is OK unless you ski with it. Going down a hole will slow it down and use more fuel + extra wear n tear, no advantages unless it airates too much in the lumps.
Sounds close to OK that doesn't mean you couldn't find another couple of knots with a different prop but they are expensive.
You could consider getting the cup knocked out of that standard yam prop, would probably help you a little.
Are the ones you are comparing it to the same prop? is yours 13dia or 13 something diameter?
mate - not sure what my SS prop is on my 93 115 Yammy 2 stroke, but I get a comfortable top speed of 35-36knots at WOT (about 5700rpm) on my 21foot 70s Seafarer Vagabond.
what sort of weight is your boat? Is your speed measured by GPS?
Probably sounds like I'm doubting you as I have a 5 metre Cruisecraft with a 115 Merc and it pushes around 36knots at 5500revs. I just ask as I was thinking your hull must weigh significantly more than mine.
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