New to boats, motor question.

[cj_hackett]

Hi everybody, I just bought my first boat this spring. It's a '75 starcraft v hull in great shape. Was kept in storage for 20 years of it's life. We've had it out about 5 times now and this last time was the first close to the load limit. We had about 800 lbs. of people in the boat (limit 900). Had an adult (230 lbs.) sitting in the back of the boat and the boat wouldn't plane out. After trying for about 5-10 seconds, there was a loud whirring sound from the motor and it lost power. Almost like a vehicle would sound if it was suddenly put into neutral. I immediately pulled back power and had the guy move up front. No problems after that. Just curious why it did that, what caused it, and if it possibly wrecked anything in the motor. Thanks for the help.

I have been lurking for the past three days and have learned a lot already!

Motor is a 79 Johnson 85hp.

 

[Aquaman-PSD]

Re: New to boats, motor question.

I may be wrong because I'm not a genius but this is the same thing that happens if you try to turn to sharply at high speeds. It may also mean that your prop is too small. Mine does this everynow and then if i hammer on the gas too hard. What is happening is the prop is trying to grab water but if you put too much motor to too small of a prop it can start to slip. What you are hearing is that slip. When the motor looses all drag it revs up real fast. Maybe try a bigger prop or applying pressure to the throttle a little slower. Again take my advice for what it's worth as I am not an expert I have just experienced the same thing and conjured up a reason for it

 

[cj_hackett]

Re: New to boats, motor question.

Thanks for the reply. After reading some of the other threads I thought that might be what was happening. The prop is a little bent up so it's probably not as efficient as it could be. I need to get a new one put on sometime, but it hasn't been a priority because it runs fine for pulling the kids on the tube.

 

[schematic]

Re: New to boats, motor question.

although unrelated, did you replace the water pump after its long storage?

 

[cj_hackett]

Re: New to boats, motor question.

There was a previous owner (for two years) before the storage and myself buying it. I'm not sure if they replaced water pump, but it spits water out the back and has run great so far. I'm going to do some maintenance on it this winter to keep it running good and to learn more about the motor.

 

[Aquaman-PSD]

Re: New to boats, motor question.

yes I have a Turbo prop on my jhonny 200 that has lost its cup on the ends. I am going to replace it with a raker two that came on the motor.

Also unrelated do you ever porpoise when on a plane and trimmin the motor out? I am having a problem with this and I think the problem is the Turbo prop is built for holeshot (tubing, Skiing) and the cup on the ends of the flanges had flattened out. This is also likely the root of my slippage when I pound the throttle. Let me know how you end up solving this one! sorry if I hijacked, I'm just curious to see if I am right on the cause of my slippage. I am changing props out this weekend when i do an impeller swap so I will let you know what i find

Does this sound like the blind leading the blind to anyone else???