RPMs rise boat doesnt go newbie in need

[SteveM12065]

So just bought my first boat over the weekend. Took it out Sunday boat ran great. Came through a choppy section of water at a pretty slow speed when I seen a small log/ big stick I slowed down. We didnt here any loud hit to the boat but when I went to take off the boat raised up rpm went up but it stopped going. The rpms kept revving with throttle but the boat wouldnt go. Tried to go a couple times same thing. Sat there for a minute scratching my head then I looked back and seen the stick float out from underneath. So I try to go again and wow like nothing happened took off and planed out just fine so back to dock. Well I am talking to a guy today whos pretty familiar with boats he had me take the prop off. I then pushed the throttle all the way forward to engage it in gear and he could spin the shaft that the prop is on and we could hear it clicking. I drained a little bit of oil from the lower unit and there is like small metal flakes more like dust in the oil. Can you guys help out a newbie here.
The boat is a 2008 Tahoe q7i with mercury 4.3 220 hp motor with alpha one stern drive

 

[1980Coronado]

Re: RPMs rise boat doesnt go newbie in need

Sounds like the log got stuck in front of the outdrive and wouldn't let the boat plane and then floated free when you stopped. It's not likely that the small metal flakes are related to the log. Change the outdrive oil and keep an eye on it. When was the last time the gear oil was changed in the outdrive? Should be done annually.

 

[SteveM12065]

Re: RPMs rise boat doesnt go newbie in need

Thanks for the response. I just bought the boat saturday I am not sure about the maintenance. Do you think this would affect the way the rpms were rising? This was the first time Ive operated a boat in my life. So I am a complete newbie. If my info seems a little confusing I can try explaining as best as I can. The boat would start out fine rise up but at about 1/3 throttle the boat would stop accelerating but the rmps would still rise.

 

[1980Coronado]

Re: RPMs rise boat doesnt go newbie in need

But...when the log came out from under the boat it ran fine...correct? The log may have been causing cavitation (prop slipping) because it was disrupting the flow of water back there......I'm just speculating here based on the fact that it ran fine after you saw the log come out from underneath....and the prop wasn't damaged.

 

[81 Checkmate]

Re: RPMs rise boat doesnt go newbie in need

I would say the tree branch off the log got caught bettween your prop and drive fin housing and would not let the prop spin correctly, causing it to spin on inner plastic hub, then when you slowed down the log detached itself from your drive.

When the boat is not running put shifter in forward and check your prop, It should turn and click clockwise and stop turning counterclockwise lock in place, then do the same for reverse, just the oppisite should happen. And when in neutral it should spin free both ways.

Then i would change you drive oil. Please read up on how to do this!

Good luck

 

[1980Coronado]

Re: RPMs rise boat doesnt go newbie in need

I would say the tree branch off the log got caught bettween your prop and drive fin housing and would not let the prop spin correctly, causing it to spin on inner plastic hub, then when you slowed down the log detached itself from your drive.

When the boat is not running put shifter in forward and check your prop, It should turn and click clockwise and stop turning counterclockwise lock in place, then do the same for reverse, just the oppisite should happen. And when in neutral it should spin free both ways.

Then i would change you drive oil. Please read up on how to do this!

Good luck

If that happened I would expect to see damage to the prop from hitting the branch. I would think you'd be able to hear the prop hitting the branch when he tried to plane out. This is a weird one.

 

[SteveM12065]

Re: RPMs rise boat doesnt go newbie in need

Again thank you very much for the replies. I sure do hope you are right. Looking at the hub it is intact. Is there something I can look at to see if it is spun.

 

[81 Checkmate]

Re: RPMs rise boat doesnt go newbie in need

well it is weird one. it could have happend so fast that it just felt like the boat was going nowhere.

Take the prop off and have a look see. you should be able to tell by looking at the inner hub if its spun or bad. The flat spots on it are what holds it to the prop when you tighten it down, if they are all rounded off it will not grab the prop.

Maybe im wrong in my asumpsion.

 

[SteveM12065]

Re: RPMs rise boat doesnt go newbie in need

The notches are still square. I definitely did not hear anything. I was going slow when i seen the branch and was able to slow up even more to just coasting over it. I tried 3 times to go all three times it ran normal up to about 1/3 throttle.

 

[Bondo]

Re: RPMs rise boat doesnt go newbie in need

The notches are still square. I definitely did not hear anything. I was going slow when i seen the branch and was able to slow up even more to just coasting over it. I tried 3 times to go all three times it ran normal up to about 1/3 throttle.

Ayuh,... Were there any Weeds involved,..??
Just the tree, sideways is enough to cause this issue,...

I kinda doubt there's anything to be done, other than staying away from trees, 'n other debris...

 

[SteveM12065]

Re: RPMs rise boat doesnt go newbie in need

No weeds just a floating stick. Thanks again for replies.

 

[SteveM12065]

Re: RPMs rise boat doesnt go newbie in need

Any other thoughts? Thanks folks greatly appreciated

 

[Fed]

Re: RPMs rise boat doesnt go newbie in need

It doesn't take much to disrupt the clean water flow to your prop, a stick will do it easily.

 

[joncrisler]

Re: RPMs rise boat doesnt go newbie in need

Most likely it was the drag of the stick / log that caused your problem. This has happened a few times on my Velocity (454). Inspect the prop to make sure its in good condition- if in doubt have an experience boater or marine mechanic look at it. Make sure you refill the oil with the proper type, replace the prop if its in good shape, and you should be fine. The clicking can be normal depending on what gear its in and which way the prop is spun.

 

[1980Coronado]

Re: RPMs rise boat doesnt go newbie in need

The boat is running fine now.....correct?

I have a couple suggestions.

1.) Since you've indicated that you see some metal dust in the outdrive gear oil, I would recommend that you have that drained and refilled by someone who knows how to do it properly. If done incorrectly (ie: filling from the top vent hole instead of the bottom fill hole) you will damage the gears in the outdrive the next time you run it due to lack of lubrication. It's not hard to do once you know the procedure. Find someone who will show you how to do it properly, or take it to a trusted service shop and have them do it. Since you just purchased the boat and don't know the history, this is cheep routine maintenance.

2.) Find out what prop you have and buy a second as a spare. It's just a good practice to have a spare prop in case something happens.

 

[SteveM12065]

Re: RPMs rise boat doesnt go newbie in need

Yeah the boat ran just fine for the 20 minutes or so it took to get back to dock. Being the first boat anything out of the ordinary I want to get some answers about. You guys have been great help. I need to get a service manual for the boat. I will do most of the maintenance on boat myself.

 

[1980Coronado]

Re: RPMs rise boat doesnt go newbie in need

Someone will be able to get you a link for that

 

[ingalp01]

Re: RPMs rise boat doesnt go newbie in need

I would change the lower unit oil, adressing the metal flakes... Then I would look into a new prop hub, or at least throw one in the boat along with a good sized cresent wrench, needle nose pliers, and a flathead screwdriver. You can change a prop hub standing in shallow water if need be. Ask me how I know... :facepalm:

 

[SteveM12065]

Re: RPMs rise boat doesnt go newbie in need

Thanks guys I will get a new propeller for spare and change out the oil. Is there a stamp on the prop somewhere to tell me the size? Also if anyone has a link to the manuals that would be great. The stealership want over $100 for motor and outdrive manuals. We are going out fo the 4th so Ill let u know how it goes.

 

[1980Coronado]

Re: RPMs rise boat doesnt go newbie in need

Thanks guys I will get a new propeller for spare and change out the oil. Is there a stamp on the prop somewhere to tell me the size? Also if anyone has a link to the manuals that would be great. The stealership want over $100 for motor and outdrive manuals. We are going out fo the 4th so Ill let u know how it goes.

See if this is the right one:

http://www.4shared.com/document/6Tj8rrms/Mercruiser_Service_Manual_32_A.htm