Prop sizes
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Prop sizes
Bought a new boat/motor and recently had motor issues unrelated to the prop. The new tech looking at it happens to tell me my prop is too small at 13x19 and should be x21. Says I’ve been over 6100rpms for over 2 hours of run time. Manufacturer says motor shipped with x21.
I understand the short term performance issues the smaller prop can have but any long term issues from this as well?
Should the manufacturer send me the right prop or keep rolling with what the dealer put on?
I understand the short term performance issues the smaller prop can have but any long term issues from this as well?
Should the manufacturer send me the right prop or keep rolling with what the dealer put on?
Re: Prop sizes
How long is your boat and what engine horsepower? My 2000 Triton TR19 (18'11") with a 175 Evinrude came with a four blade 25 pitch. I had some issues with chine walking and I wanted a better holeshot and midrange, so I had it worked down to a 23 pitch. Best decision I ever made.
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Re: Prop sizes
19’ with a 115hp. Boat is aluminum.
Re: Prop sizes
19 or 21 sound reasonable to me, but I'm no expert. Check the operating range of your engine to determine if 6100 RMP's is considered high. I will defer to more knowledgeable folks on this board regarding the best prop for your setup.AnglersPursuit wrote:19’ with a 115hp. Boat is aluminum.
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Re: Prop sizes
Right on and thank you! Can’t imagine I’ll be running WOT too often these days so not sure if the change will make a difference. Maybe it lowers the RPM’s at the lower speeds too?
Thanks again!
Thanks again!
Re: Prop sizes
Depends on a lot of factors, altitude you operate your boat, load and weight distribution you normally run with like 2 anglers, livewell full of water (8 lbs per gallon) and gasoline weight (6.5 lbs per gallon, number and size of batteries etc, etc.
5,800 Rpm at WOT is average for today's 2 cycle OB's.
If you are happy with the hole shot or time to get up on plane and top end speed at 5,800 rpm's keep what you have. 6,100 rpm's is adding wear on your engine.
A 3 blade 20 pitch SST prop will give you better overall performance and drop the rpm's about 300, the 3 blade 21" pitch faster top end speed if the engine can rev to 5,800.
If the dealer changed the factory 21"P SST prop to a aluminum 19" pitch you were had and they owe you a prop.
Tom
5,800 Rpm at WOT is average for today's 2 cycle OB's.
If you are happy with the hole shot or time to get up on plane and top end speed at 5,800 rpm's keep what you have. 6,100 rpm's is adding wear on your engine.
A 3 blade 20 pitch SST prop will give you better overall performance and drop the rpm's about 300, the 3 blade 21" pitch faster top end speed if the engine can rev to 5,800.
If the dealer changed the factory 21"P SST prop to a aluminum 19" pitch you were had and they owe you a prop.
Tom
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Re: Prop sizes
My boat is the same, 115hp motor on a tracker 190. Mine came with a 23p. I switched to a 21p and like it a lot more. 19 is undersized for that motor. When I switched I got higher rpms. So you will get lower rpms moving from a 19 to a 21. I hope that helps.
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Re: Prop sizes
Definitely installed a 19" aluminum prop. Was told when I picked up boat motor was sent without prop so they put that one on. When you say "had", you think this was done intentionally?WRB wrote:Depends on a lot of factors, altitude you operate your boat, load and weight distribution you normally run with like 2 anglers, livewell full of water (8 lbs per gallon) and gasoline weight (6.5 lbs per gallon, number and size of batteries etc, etc.
5,800 Rpm at WOT is average for today's 2 cycle OB's.
If you are happy with the hole shot or time to get up on plane and top end speed at 5,800 rpm's keep what you have. 6,100 rpm's is adding wear on your engine.
A 3 blade 20 pitch SST prop will give you better overall performance and drop the rpm's about 300, the 3 blade 21" pitch faster top end speed if the engine can rev to 5,800.
If the dealer changed the factory 21"P SST prop to a aluminum 19" pitch you were had and they owe you a prop.
Tom
So the 19 is ok, just don't run it WOT?
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Re: Prop sizes
Definitely helps. Thank you!HappyDogBassFishing wrote:My boat is the same, 115hp motor on a tracker 190. Mine came with a 23p. I switched to a 21p and like it a lot more. 19 is undersized for that motor. When I switched I got higher rpms. So you will get lower rpms moving from a 19 to a 21. I hope that helps.
As a new boat owner I trusted the boat brand and dealer to help me understand my investment. Finding out it's been the opposite. No idea why a 19 was put on there.
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Re: Prop sizes
You can get a Black max 21p (for Merc outboards) on Amazon for $160. Keep the 19 on the boat as a back-up. Good luck.
Re: Prop sizes
Merc Optimax 115 hp is shipped with a aluminum prop as standard equipment. The Laser II 20 pitch SST prop is ideal for this engine if the aluminum 19 P is turning 6100 rpm's, the 20 P should drop down to 5800. Aluminum props flex SST props don't. As noted the aluminum makes a good back up prop. Someone changed the prop or the engine was shipped with a 19 P aluminum.AnglersPursuit wrote:Definitely installed a 19" aluminum prop. Was told when I picked up boat motor was sent without prop so they put that one on. When you say "had", you think this was done intentionally?WRB wrote:Depends on a lot of factors, altitude you operate your boat, load and weight distribution you normally run with like 2 anglers, livewell full of water (8 lbs per gallon) and gasoline weight (6.5 lbs per gallon, number and size of batteries etc, etc.
5,800 Rpm at WOT is average for today's 2 cycle OB's.
If you are happy with the hole shot or time to get up on plane and top end speed at 5,800 rpm's keep what you have. 6,100 rpm's is adding wear on your engine.
A 3 blade 20 pitch SST prop will give you better overall performance and drop the rpm's about 300, the 3 blade 21" pitch faster top end speed if the engine can rev to 5,800.
If the dealer changed the factory 21"P SST prop to a aluminum 19" pitch you were had and they owe you a prop.
Tom
So the 19 is ok, just don't run it WOT?
It's your boat, but I wouldn't run at 6100 rpm's and it's hard not to when under propped.
Tom
Re: Prop sizes
I have an old 18' champion with an '04 115 merc. Fish only at 5000'+ Came with a 19, sound right?
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Re: Prop sizes
Pretty much what I’m hearing from others is boat is under propped. Manufacturer of boat said motor was shipped with 21”. Wether it was or wasn’t, a 19” shouldn’t have been put on.WRB wrote:Merc Optimax 115 hp is shipped with a aluminum prop as standard equipment. The Laser II 20 pitch SST prop is ideal for this engine if the aluminum 19 P is turning 6100 rpm's, the 20 P should drop down to 5800. Aluminum props flex SST props don't. As noted the aluminum makes a good back up prop. Someone changed the prop or the engine was shipped with a 19 P aluminum.AnglersPursuit wrote:Definitely installed a 19" aluminum prop. Was told when I picked up boat motor was sent without prop so they put that one on. When you say "had", you think this was done intentionally?WRB wrote:Depends on a lot of factors, altitude you operate your boat, load and weight distribution you normally run with like 2 anglers, livewell full of water (8 lbs per gallon) and gasoline weight (6.5 lbs per gallon, number and size of batteries etc, etc.
5,800 Rpm at WOT is average for today's 2 cycle OB's.
If you are happy with the hole shot or time to get up on plane and top end speed at 5,800 rpm's keep what you have. 6,100 rpm's is adding wear on your engine.
A 3 blade 20 pitch SST prop will give you better overall performance and drop the rpm's about 300, the 3 blade 21" pitch faster top end speed if the engine can rev to 5,800.
If the dealer changed the factory 21"P SST prop to a aluminum 19" pitch you were had and they owe you a prop.
Tom
So the 19 is ok, just don't run it WOT?
It's your boat, but I wouldn't run at 6100 rpm's and it's hard not to when under propped.
Tom
Got a top notch mech working on it now. Good people will get me squared away. Thanks for the feedback!
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Re: Prop sizes
The Mercury Spitfire X7 is built for the 75-115 class motor . If changing props I would take a look at it.
The Spitfire is Aluminum, The SpitfireX7 is an Alloy
The Spitfire is Aluminum, The SpitfireX7 is an Alloy
TR177 Ranger/ Mercury/Lowrance/ Ghost TM
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