which pitch?

[Master-Baiter]

I just picked up a 1985 merc 9.9s/s for my 14ft Delta alum. boat.It has a 9 pitch prop on it but it doesn't seem to come up to full power with me (200lb) and my son(140lb).Is there a way to run a tach to see if I am geting to the proper rpms? The motor was on a 12ft alum.boat that weighs about half of what the Delta weighs(200lb)Could someone give me a rough prop size for my application? <br /><br />Thanks for your help. Rich

 

[Grant Ingle]

Re: which pitch?

The easiest way to accurately measure the RPMs on a portable outboard like you have is to use a fluke meter with an inductive pickup and clamp it onto a spark plug wire. However, not everyone has one of these and they are rather pricey. It would be cheaper to buy a different prop and try it. The 9" prop you have now is rated for up to 16' and up to 1200#. the 8" prop is rated 14-17' and 11-2100#. Perhaps one of those comp-props would better suit you (four bladed).

 

[norman158]

Re: which pitch?

get a tiny tach so you can tell how fast it is turning these are fairly cheap and work very well http://www.tinytach.com/tinytach.html