Power Question - Maxum Boat Owners Club

Giantsfan · 09-08-2007, 12:42 AM

I bought a new 1900 this summer. Love the boat but it seems a little heavy / slow getting out of the water. The dealer put a new propeller on after my orientation. Just wondering if there's a way I can tell whether the boat / motor is performing the way it should. Is there a certain amount of time it should take to get to a certain speed, etc ?

Thanks.

seapuppy · 09-08-2007, 01:20 AM

well...it depends on how you have it loaded, water conditions and winds etc...
so...here's what you do...with you and one passenger...half tank of gas...and smooth water......from a dead stop..hit the throttle all the way to the stops...have the passenger with a stop watch....measure time to plane...that's when the bow drops to level...then the last thing you want to measure is the WOT...wide open throttle....that's the max speed the boat is going to run and watch your rpm's...you should top out at between 4200-4800rpms....your max speed should be measured with a gps....that will tell you if your too low or hi in pitch on the prop.......

welcome to the zoo.....

Giantsfan · 09-08-2007, 01:41 AM

Thanks for the response. two questions...When I do the stop watch thing how long should it take to get on plane ? Also, checking the speed at WOT, you mention using "gps" instead of speedometer. can you explain ?

Thanks again for your help I'm anxious to try this out on sunday.

seapuppy · 09-08-2007, 05:36 AM

you stop the watch when the bow drops down and settles..shouldn't be more than 5-7 seconds...12 max.....
and the gps...you know what gps is??...global positioning satellites?....there is a function on there that can measure speed..since it's not like your speedo that relies on water pressure to register speed...gps will measure actual speed over ground...or SOG.....SOG via gps is more accurate and less subject to currents....if you have a friend that has a hand held unit.might wanna ask him to bring his along for a ride......it won't take more than maybe 20 min...from dock to dock....make a couple of runs..average out your results.....let us know how you fair...
one thing else...if your hitting the max or redline of the engine..your underpropped...if your lugging and taking forever to get on plane and not hitting the operating range...then you overpropped.....over propping will load an engine up and put alot of strain on the engine....engine manufacturers would rather you be underpropped than over.....
also remember if you change the prop..1" of pitch will equate to 200 rpms...so if your running a 21" pitch and you change to a 19" pitch..your going to raise your rpm by 400 rpm........good luck...and post your results here....

seapuppy · 09-10-2007, 11:42 PM

GF..what happened???...did it all work out ok??

Giantsfan · 09-11-2007, 11:21 PM

I took the boat out today, by myself and here's what I found: WOT is
4800 RPMs, my top speed on smooth water was 44 mph. Hole shot, the best I could tell was reached in 7 to 10 seconds. Also, at 3,000 rpms I was cruising at 28 miles per hour. Does that sound like the engine is
operating as it should ? I read a review recently that said top speed should be 51 miles per hour. Not a huge difference to me with two little kids, just want to make sure everything is working right...

Thanks,

Joe

seapuppy · 09-12-2007, 12:03 AM

sounds about right..with a prop change to a shallower prop pitch..your hole shot will increase but your top speed will decrease...for a better top end...a steaper prop pitch will cause the top end to increase ..hole shot to be a hair longer and your rpms to drop some....so...yeah..your right at the top end of the scale.....your getting the best hole shot without going to a stainless steel prop....so...enjoy!!....28 at 3k rpm....man...at 28mph for me I'm doing about 4200 rpm!!!...
sounds like your close to being dialed in right....just at the top end of the spec sheet......

thanks for posting your results...