1989 15HP Mariner 2 stroke trouble getting on plane and slow top speed

I have the above on a 14" Fisher aluminum V hull, total weight with boat, motor, fuel, passengers is around 700lbs. Had it out today on the river for the first time since I bought it and it would not get on plane unless I had my 7 year old son stand in the front and run it wide open - dont have a tach so I dont know exactly what the RPM is. Motor runs well but the existing prop does have some dings/dents from the previous owner hitting obstacles. Seems to me this motor should move the boat faster than it does. Any suggestions on replacements props, would they increase the speed and allow boat to get on plane? Unless my son was up front, the boat was wallowing and best guess was top speed of 7-8 mph. Thanks.

Re: 1989 15HP Mariner 2 stroke trouble getting on plane and slow top speed

How bad is the prop??? The dings and dents definitely are going to affect performance. Get the prop either repaired and replaced, also, do a full tuneup on the motor including a compression check to make sure it's running the way it should.

Re: 1989 15HP Mariner 2 stroke trouble getting on plane and slow top speed

Is this a good full sized 14 overall length 14'+ nice broad beam.
Some 14s are a little small measuring under 14 and somewhat narrow.
Usually capacity under 700#.Regardless you are near the max. This makes it really hard to get on plane.A 15 or 16ft bare bones boat would most likely get up easier.
In the mean time be sure the throttle opens all the way.Trim down(prop closer to the boat).
Try to balance the weight moving some forwared may help just don't over do.
If your 7 year old helped you may not need much. Might be as simple as moving some weight from behind the middle seat to the front of it.You will most surely need to run at wot
And you may need to change to a lower pitch prop.
You really need a tach and gps.We need your prop size usually near the base of the blades or under the prop nut.An induction tach like a Tinytach will work on allmost any motor.
Also an optical tach would work.
If you get us the prop size and the wot rpm and speed lightly loaded it will help tell if your setup is working.

Re: 1989 15HP Mariner 2 stroke trouble getting on plane and slow top speed

Yeah I would have the prop reworked. I had the same thing with a '96 Force 15 hp I got. The previous owner (my uncle), hit some rocks and tour it up pretty bad. I put on my 14' jon boat and was maybe getting 18 mph. I recently had it reworked and now get 27 mph with it. I think the guy charged me 55$ to fix it. (The last pic is after i have used it for about 3 months on the boat so it has normal wear)

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