canadianfcat Posted January 16, 2014 Report Share Posted January 16, 2014 I need to get the rpm of my boat to figure out the right prop. Has anyone tried one of those digital ones off ebay that you just wrap a led around the plug wire and it gives you a reading? Link to comment Share on other sites More sharing options...
fishkid Posted January 16, 2014 Report Share Posted January 16, 2014 Haven't tried it on a boat but it would work just fine. It's the same principle as any other tach. Keep in mind if your boat is 2 stroke or 4 stroke it will make a difference. 2 stroke is spark every rev, 4 stroke is spark every other rev. Link to comment Share on other sites More sharing options...
Lundtastic Posted January 16, 2014 Report Share Posted January 16, 2014 Mercury has a good prop selection tool on their website. From what I can remember you might not need your rpm. Link to comment Share on other sites More sharing options...
canadianfcat Posted January 16, 2014 Author Report Share Posted January 16, 2014 I'll look there too Alex..Thanks On iboats they calculate using speed and weight and type of prop currently to see if you can prop up. I think my prop is leaving some speed and gas mileage on the table still. Especially gas consumption!! Link to comment Share on other sites More sharing options...
painter Posted January 16, 2014 Report Share Posted January 16, 2014 What make and hp and year Link to comment Share on other sites More sharing options...
Roe Bag Posted January 16, 2014 Report Share Posted January 16, 2014 I need to get the rpm of my boat to figure out the right prop. Has anyone tried one of those digital ones off ebay that you just wrap a led around the plug wire and it gives you a reading? Been using a Tiny Tach since 2001 on several different outboards. Built in battery life is supposed to be 5 years. Mine is still going after almost 13 years. Serves as a tachometer when the engine is running. Records and then displays engine hours when the engine is shut down. Perfect for prop selection as well as keeping track of oil changes on any four stroke. Ordered mine from Mississauga. Think it was about $60 shipped to my door back then. http://tinytach.com/foreign.php Link to comment Share on other sites More sharing options...
canadianfcat Posted January 17, 2014 Author Report Share Posted January 17, 2014 :thx:Ya Roe Bag..That Tach/hour meter is like $20 shipped on ebay.Thanks I'll order one. Hey painter my engine is a 1992 75 hp Mercury and a 1990 1606 Spectrum blue fin boat. It jump up on plain quick but tops out at 32 mph and not great fuel mileage. Hoping that propping up will give more top end and better mpg as I think there's lots of power to push more water. Link to comment Share on other sites More sharing options...
painter Posted January 18, 2014 Report Share Posted January 18, 2014 I would start with it Tackmeter first you need to get the boat on the water to determine what your RPM is at full throttle. If the manufacturer says 5500 RPMs that's where you need to stay at. The rule of thumb is if you change your pitch from let's say a prop pitch of 15 to a 17 your RPMs will increase by 300 to 400 rpm's I would start with it Tackmeter first you need to get the boat on the water to determine what your RPM is at full throttle. If the manufacturer says 5500 RPMs that's where you need to stay at. The rule of thumb is if you change your pitch from let's say a prop pitch of 15 to a 17 your RPMs will increase by 300 to 400 rpm's Link to comment Share on other sites More sharing options...
canadianfcat Posted January 18, 2014 Author Report Share Posted January 18, 2014 Ordered one of the digital Tachs like in Roe Bags picture this morning. From China direct. Shipped to the door under $14..Also 2 keyless remotes for the Expedition under $10 to my door.Man they work cheap over there. Link to comment Share on other sites More sharing options...
painter Posted January 19, 2014 Report Share Posted January 19, 2014 Child labor heck I can't get my kids to take out the garbage Link to comment Share on other sites More sharing options...
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