prop change cause and effect

1.72 rude model#50273c<br />2.13 1/4 x 17<br />3.unkown no tach<br />4.72 arrowglass tarpon 15' stick steering tri hull<br />5. no jack plate nor adjustable bracket<br />6. sterns hydro foil<br />7. prop has ding none availible localy for current set up but a 13 3/4 x 15 is.My question is poor old boat is hauling 2 old fat people,2 batteries and fuel tanks and fishing gear... 24mph on gps motor under no strain sounds like (no tach in boat) what would the prop change effect as far as top end?? I already understand there will be an rpm change.also there is no tilt or trim on the boat except for when I convince Maw to pick up the motor or move to the middle of the boat.Any opinions will be greatly appreciated

Re: prop change cause and effect

Not knowing what the maximum rpm is with the prop you have now we can't tell you what the results will be. If the engine is lugging now (less than rated maximum rpm) engine rpm with the 15 pitch prop will pick up about 400 RPM or so. Hole shot will likely be better and maybe -- just maybe -- speed might increase a little. However, if the engine is NOT lugging and is actually running at its maximum recommended RPM, the additional increase in 400 RPM will put it well over its maximum (over reving) with the potential for disaster. Without a tach, you are only guessing and so are we.

Re: prop change cause and effect

As upinsmoke said, you need a tach & good accurate rpm numbers for us to help.