20 hp Merc kicker motor

[Crazy]

Hi all I have a 1978 18 foot fiberglass boat with a 115hp merc 6cyl , I have a chance to pick up a 85 20hp merc with little use for $400 bucks . would this motor be to big for a kicker motor ? I run in the great lakes , the boat has a kicker motor mount rated for 20hp .

 

[biloxiriver]

Re: 20 hp Merc kicker motor

Personally I think it would be fine. Probably a little more power than you need on an 18 footer, but the price seems right. I have never used anything larger than a fifteen on my 21 footer and it pushes me about 6 mph.

 

[Boatist]

Re: 20 hp Merc kicker motor

I do not see a problem with the motor if you change to a high thrust low pitch prop. Maybe 10 DIA x 7 Pitch x 4 Blade<br /><br />The motor bracket on the other hand I think is a big problem. First of all they are all over rated in my opinion. On My 21 foot boat I have a 15 HP Johnson 2 stroke that weighs 74 pounds. I started with a single motor bracket that was rated for up to 20HP. My motor bracket slides into a bracket that allow you to remove the motor bracket very easy. No one in my family could reach down and lift the motor by themself, except me. It was very hard. When trailering the motor would jump around pretty bad. On the water the motor was stable. <br /><br />I bought a second identical bracket and mounted right next to the other in the same type slide in bracket. Then I made a new mounting board to connect the two brackets. Also made a handle to attach the two release levers and give you something to lift the motor with. This made the motor much eaiser to lift and lower. It will lower to about half way and stop then you have to push the rest of the way down. When raise again will come up to about half way and then you have to lift to the top but now anyone can raise and lower.<br /><br />On the trailer with the two brackets side by side it took all the side to side sway out. The motor still jumps around some so I strap it down to the towing eye and I also added another eye on the other side of motor.

 

[Crazy]

Re: 20 hp Merc kicker motor

Thanks guys , Well then I think I'll get it . biloxiriver if a 15hp pushes your 21 footer at 6mph , then this 20hp should push me at 10mph ... haha I wont even start the 115hp Merc '' that thing is HARD on gas'' , maybe 2mpg and that is maybe ! Boatist ... Do I need a high thrust prop ? will it work with out ? for now ... I'm working 70hrs per week right now so I might see 1 day per week use . and I never even thought about the motor bracket , I'll have to find a way to tie the motor down , although I do have another motor mount I was going to put on E-Bay ... HUMMMMM Thanks for the help guys .

 

[Boatist]

Re: 20 hp Merc kicker motor

Crazy<br />You can try it with out the high thrust prop but I think you will see two things. My boat is a 21 Foot Crestliner Aluminum closed bow but probably weight less than your boat. The two problems I saw with the standard prop.<br />1: When backing with thru hub exhaust boat would hardly back up. Increasing the throttle just put more exhaust behind the prop and since backing up the prop is running in air not water. My boat would hardly back up against a 10 mph wind or up a 2 mile per hour river. When I added the high thrust low pitch prop it lets the exhaust come out in front of the prop when backing so the prop is running in water not exhaust gas. It backs up 5 times better even at idle.<br /><br />2: Motor trolled fine but If I wanted to circle back at a higher speed as I opened up the throttle the motor would load up and die. The standard prop I had was really for a 14 foot aluminum car top boat that weighs 160 pounds plus gear. With the bigger 4 blade high thurst low pitch prop as I increase the throttle boat speeds up nice and does not load up and die.

 

[dajohnson53]

Re: 20 hp Merc kicker motor

The only *possible* downside is the weight. I could be wrong, but my guess would be that a 20 hp probably won't push it any faster than a 15 or even a 10 unless it would actually plane it.(wouldn't it be limited by "hull speed?" - experts please respond). A lot of motors have a weight change when you bump up from 15 to 20 hp. That to me would be the only consideration. At my age and size, I just don't like messing with anything heavier than a 10 or 15 hp by myself, and I rarely have competent help around. Just a thought. I'd say at that price, buy it and if it turns out to be what I said above (about the extra weight not giving you extra speed), you can always sell it for that same price if/when you find a lighter 10 or 15.