40hp Mariner Magnum not plaining boat

[stevo67]

Hi guys,I have a 1994 mariner magnum 2 stroke 4 cyl that doesnt like plaining my boat off,i do have a very wimpy prop on it,i know there is alot of variables that could be affecting it,the motor runs good and top rpms are achieved!The boat i own is a 16ft sea nymph 161 fm. any information would be appreciated! Thank You!

 

[Texasmark]

Re: 40hp Mariner Magnum not plaining boat

Go to the Stickys at the top of the forums and read what we need from you to help you. We are talking to the world and it's occupants with their equipment that could be perfect or so worn out/abused a junk dealer wouldn't buy it.....you may be a seasoned seaman or a teen that is just getting started. The more revelant info, the better we can attempt to solve your problem.

Welcome aboard.

Mark

 

[Jake.]

Re: 40hp Mariner Magnum not plaining boat

If you're getting the rpms then the issue is not in the powerhead. I have a '92 mariner magnum on a 16 foot sea nymph and it planes the boat very easily. How much weight are you carrying in the boat? What is the pitch on the prop? Is the hull clean or coated with crud/critters? Is the motor mounted at the correct height?

 

[stevo67]

Re: 40hp Mariner Magnum not plaining boat

Hi guys,i bought this Mariner motor from a marina last yr,i had other issues with this motor that i had to deal with so i really never attacked the plaining issue,the motor issues are resolved,so now this!! I have a 3 blade prop,i looked on the prop and it had a bunch of serial numbers,at the end it had 15p stamped on there!must mean 15 pitch,there are 5 diff holes on each side of the motor bracket where it mounts to the transom,he has it in the top hole which brings the motor the deepest it can go into the water! there is also a bar that runs through the back of the motor to adjust the starting point of where the pitch of the shaft starts off,this is in the very bottom hole! my last motor was a 40hp and plained the boat very easily! Thank u for taking the time replying to my post,some smart guys out there! I usually only have 2 people on the boat including me,i keep my hull nice and clean

 

[stevo67]

Re: 40hp Mariner Magnum not plaining boat

Thanks Mark!! Not to sure what u meant about the stickys at the top of the foum,i did enter more profile info,maybe that is what u meant,Thank you!

 

[gjblanchard]

Re: 40hp Mariner Magnum not plaining boat

You will certainly have to get the trim on the motor to get max speed out of it, but the 15 pitch prop sounds way too high for a 40. I have a Merc 2 stroke 50 on a Lowe FM165 and found a 13 pitch prop (QA2076R) to be right. My brother in law has a Mariner mag 40 on a Smoker 160 pro tiller and he runs a 12 pitch prop (QA2074R) on it. These are the large blade versions of those props and getting the boats on plane is not an issue.

 

[40magnum]

Re: 40hp Mariner Magnum not plaining boat

I also have a 1994 Mariner Magnum 40 model ELHPTO on a 14' MonArk Jon boat running a 16p and turning 5500-5600 rpm. The motor is mounted in the middle hole and planes out just fine. Last week top speed was 43mph on gps. But now I have electrical problems.

 

[stevo67]

Re: 40hp Mariner Magnum not plaining boat

Thanks guys,i am really thinking that my engine is mounted in the wrong hole,its in the very top hole of the bracket that connects the motor to the transom!! Is there any way to check the height of the motor,there must be some set of guidelines they go by?