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Sutitable prop for a 40HP Mariner

Sharkbait99

New member
Hi there, I'm a little stuck, I've got a 40 HP Mariner that pushes a 260pd alloy boat (14ft) - the motor weighs around 160pds and fully loaded the boat would weigh in at about 500pds. Currently the prop is a ten inch with 16 degree pitch.

Problem is its a between 3/4 WOT and WOT theres really no increase in speed. Theres no rev counter so I'm unsure of RPM but I suspect the prop might be a little small in Diameter. I guess I really want it to go faster!!

I've done a little research but there really is no clear answer - does anyone have any experience or advice - Much appreciated.
 
You aren't really pushing alot of weight for a 40 horse.

But without a tach to determine what she's cranking out it's very very difficult to make a recomendation.

In that horsepower class, unless you go into a custom prop, a 10x17 is about as "big" as you can go and that would have a minimal increase compared with your current 16 pitch.

You really need to determine your "wide open" rpms with your current set-up...
 
Thx for that - Is it a major getting a tacho added on - FYI current top speed with the 10X16 is pretty much smack on 30MPH


thx again - will look into the 17
 
Check out "Tiny Tach" (and a couple other clones), sell for about 35 bucks (Bass Pro Shops is one source)

You just wrap the lead around your number one sparkplug wire and the rpms read out on a little LCD screen.

Great tool for boats that do not have a conventional dash and harness to hook up a regular tach...
 
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