Change Motor, Prop or what??? Please Read

[Floater49]

Hello all, I am relatively new to boating (3 summers) and I am struggling with an issue with my boat. I have a 17' Spectrum open bow console control etc, with a 1974 Merc 1150. The engine is very healthy with only about 6 trips on a complete overhaul. It is turning a 24x19"P 3 blade aluminum prop. I just replaced the entire floor (was 2 layers of 5/8" ply) and flotation media due to water logging. I added a bow mount minnkota. Here is the problem. I thought I would gain MPH after the floor thing but I didn't. It tops out at 32 MPH on the speedo and on GPS. The only improvement is in the acceleration. It jumps out of the hole like a rocket.
Would I gain more speed by switching to a lighter motor with less HP as this motor is 365#, or by adding another 1 or 2 inches of pitch?
I should mention that at full speed The water seems to hit the front of the leg and "roll" up and into the well, filling it to the top. There is also a lot of water splashing up behind the motor. It is about 2 feet high, 2 feet wide and 10 feet long. Like the motor is not cutting through the water.
Does anyone have any thoughts?
Thanks,
Floater

 

[rrhodes]

Re: Change Motor, Prop or what??? Please Read

Pictures would help but it sounds like your motor is mounted to low.

 

[mmccoy555]

Re: Change Motor, Prop or what??? Please Read

Does it have power trim?

 

[metriccrescentwrench]

Re: Change Motor, Prop or what??? Please Read

To make an informed decision on changing the prop you'll also need a tachometer to see if you're getting proper RPM at wide-open-throttle.

 

[Floater49]

Re: Change Motor, Prop or what??? Please Read

Pictures would help but it sounds like your motor is mounted to low.

The next time I go out, I will get pictures. But in the mean time, I will get pics in the trimmed down position to show the height. I can say that I have looked at the motor height thing, and the cavitation plate seems dead even with the bottom of the boat. I am using The Hydroplane fins too. I have tried with and without them and it is the same result.

 

[Floater49]

Re: Change Motor, Prop or what??? Please Read

Does it have power trim?

Yes it does have power trim.
I always cruise at the point just short of porposing. It is also planing on the back 4 feet of the hull. I don't know if that helps.

 

[mmccoy555]

Re: Change Motor, Prop or what??? Please Read

Just a thought. I've seen some motors that when trimmed all the way down create drag. If this is the case you can just trim up a touch.

 

[Floater49]

Re: Change Motor, Prop or what??? Please Read

To make an informed decision on changing the prop you'll also need a tachometer to see if you're getting proper RPM at wide-open-throttle.

Yes, I agree. I do not have a tach. I wish I did, but... Maybe I should leave the prop change until I have the water splashing sorted out. I was actually thinking about those planer boards that attach to the bottom of the hull on the chine.???

 

[Floater49]

Re: Change Motor, Prop or what??? Please Read

I think I stumbled onto something. I took a straight edge and checked the hull at the transom. It seems that this boat was designed with a "hull pad". I am no boat designer, so I needed to research it online. The bottom of the hull is canted up about 5/8 inch in the middle from about a foot forward of the stern and gradually reduces to the strakes, kind of creating a triangle shaped flat spot. I think this allows the pressure from the water to pop up in the middle and hit the leg at a posotive angle and splash into the well. Now I need to figure out how to stop it from filling the well. I wonder if I can add smart tabs to fix this?

 

[crb478]

Re: Change Motor, Prop or what??? Please Read

I would try to maximize the set up before buying anything else. If your AV plate is even with the bottom of the boat try raising it one or two holes. You really should invest in a tach to know if you need another prop or not. Smart tabs will help with your hole shot and planning speed, but you may not need them. Try the free stuff first.

 

[MikDee]

Re: Change Motor, Prop or what??? Please Read

Pictures would help but it sounds like your motor is mounted to low.

I agree