Ok,,,i posted in regards to the prop on my boat before, but now i'm confused more in general. I've got a 93 19' Baja boat with a 4.3 OMC I/O in it. Fresh rebuild on the motor. The boat doesn't seem to have any power though. Took it out for the first time today, it tops out at about 36mph at 3800rpms. Timings set at 9 degrees BTDC. Shouldn't this boat be doing more than that, i've got a buddy with a bayliner, similar setup that does cloeser to 50. Quite frankly...i was embarresed today.

 

So you're thinking you need to change the prop for speed rather than Torque/Pulling power for a skier, is this correct ?

 

well thats what i'm confused about...the boat doesn't seem to get up all that quick, doesn't seem to plane out, doesn't seem fast.....is it that its got a prop more geared toward towing than speed. I'm kinda new to the whole boat thing. I usually have wheels that i ride around on. LOL

 

Well there are different pitch & number of vanes for certain reasons.
Have to done any searching on Google for this topic?


http://homepages.apci.net/~michalak/...pellor%20Pitch

 

honestly i just got home from the lake about two hours ago...we ended up having a bonfire and such afterwards so this is the start of my research. I gotta figure something out...my friends are trying to name the boat "put put"

 

Read above link

 

Did you get y our prop fixed yet? 3800 rpm at WOT sounds low to me.
Try trimming your lower unit as your running. by this , i mean get up to speed then raise the lower unit. You actually get top speed with about half the prop above the surface of the water.
I have a fourwinns 170 with a 115 johnson that gains 1000 rpm and about 10 mph just by trimming it.
If this isnt your problem, you may need a lower pitch prop.

 

3800 rpms is to low,you are not propped right or the engine is not getting it done.If the engine is ok you have too much wheel,drop down in pitch.If the prop size ran well before then look elswhere for a problem.As far as trimming, trim out till the boat starts porposing, then trim in till it stops.

 

Your motor is not turning within the recommended WOT range. It's too slow. If you had the motor rebuilt, the shop may have put the wrong lower unit on yours and it has the wrong gear ratio for your motor/boat. If you did the work and know for sure that it has the right lower unit, I would suggest driving the boat at idle, put the timing light on it and increase rpms until it is WOT. The timing should advance. If it doesn't, the distributor isn't working correct. Does the motor seem to run hot? You can also have a restriction in the elbows. Also, check the fuel pressure and inspect the throttle plates to make sure that they are opening all the way.

 

I think the first thing to do is find out where your Baja's engine is missing some of it's "cojone's"...

Seems to me it must be running a little off.

Personally? I'd run a compression check and go from there.

 

The two happiest days in a boat owners life, the day he buys his boat and the day he sells it. Worked for me, I had similiar problems and having 6 land yachts that all needed attention left me with no time or patience for a sick boat. I paddled it back to the dock twice and that was it.

 

Figured it out finally.....rocker arm nuts worked there self off and were really really loose.....got them replaced with new locknuts and it revs great now.