Kicker motor mount height

[huggyb1972]

Hi
I want to add a kicker to my 21' bayliner for trolling and as a backup and incase of main engine issues. My question involves mounting height of the motor below the water line. There won't be enough power planning so how low can the motor be or should it be in reference to the bottom of the hull. I would like to go 15hp remote control electric start. I have to build a mount that will push it out past the swim deck on the back. Does the prep need to be lower than the transom or can it be effective above it say like 6". I want to mount it on the port side or opposite of the swim ladder.

 

[airshot]

Gonna be an interesting mount your gonna have to make...Have you considered cutting the swim deck, either shorter or cut a notch to clear a kicker ?? Generally speaking the cav plate on the kicker needs to be even with the hull bottom when motor is operating. Not the very bottom of the hull but below the bottom point where the motor is mounted. Good luck !

 

[JimS123]

For a "normal" setup, the prop should be below the bottom of the boat, or "mostly" below the bottom. The position of the AV plate is less important because the boat won't plane. By normal I mean on a "std" type bracket positioned close to the transom.

If you are extending the mount past the swim platform, I would guess that the motor could be mounted a bit higher, just like when a bracket is used for the main.

The outboard length should be long enough to position the prop in the right place, while at the same time not be so short that power head is too close to the water.

I hope you plan to mount your new bracket to the transom, because i'm not sure that the platform is strong enough to handle that big a motor.

 

[huggyb1972]

For a "normal" setup, the prop should be below the bottom of the boat, or "mostly" below the bottom. The position of the AV plate is less important because the boat won't plane. By normal I mean on a "std" type bracket positioned close to the transom.

If you are extending the mount past the swim platform, I would guess that the motor could be mounted a bit higher, just like when a bracket is used for the main.

The outboard length should be long enough to position the prop in the right place, while at the same time not be so short that power head is too close to the water.

I hope you plan to mount your new bracket to the transom, because i'm not sure that the platform is strong enough to handle that big a motor.

View attachment 396340

Yeah I'll fab a bracket for the new motor that will register off the swim deck. I just wasn't sure if it mattered about the height to much.

 

[rxl650]

My only concern with mounting to high would be cavitation. I had a 9.9 mounted to high just for the ease of install and steering conections to the main. It was fine for trolling, but would cavitate when I tried to throttle up.
No big deal for me but if you need to rely on it to get you home, it should be installed correctly. Need that prop deep enough. Some wind and waves might have you going backwards if it cavitates too much. I see a boat around here that fabbed a bracket on the transom then added an auxiliary adjustable mount to clear his swim platform. I would think he added some reinforcement at the transom??

 

[JimS123]

I had a 9.9 mounted to high just for the ease of install and steering conections to the main. It was fine for trolling, but would cavitate when I tried to throttle up.
I would think he added some reinforcement at the transom??

I always tried to have a straight connection between motors. But I found out that it wasn't absolutely necessary.

If a bracket is cantilevered out far, there needs to be a heck of a big metal backup plate inside the transom.

 

[huggyb1972]

I always tried to have a straight connection between motors. But I found out that it wasn't absolutely necessary.

If a bracket is cantilevered out far, there needs to be a heck of a big metal backup plate inside the transom.

View attachment 396360

View attachment 396361

I'm probably going to have to do a seperate steering system to this little guy. I'm running a I/O so getting it to steer off the helm could be far more complicated than just a separate steering system. I had also though about autopilot for it should I get the urge.

What hp is to much for trolling. The boat is 20 ft and a cuddy. I'm just thinking 9.9 to 20hp is only about $1000 difference. More power is always gooder. Right?

 

[Scott Danforth]

I'm probably going to have to do a seperate steering system to this little guy. I'm running a I/O so getting it to steer off the helm could be far more complicated than just a separate steering system. I had also though about autopilot for it should I get the urge.

What hp is to much for trolling. The boat is 20 ft and a cuddy. I'm just thinking 9.9 to 20hp is only about $1000 difference. More power is always gooder. Right?

a simple metal link with two rod ends is easy to tie it to your outdrive. they do it all the time.

for a kicker, how far behind the transom will it be mounted. in many cases, the prop doesnt need to be below the running surface. there are even trim tabs with electric motors on them (google trolling tabs). the props on those are well above the running surface.

for your boat, a 6hp would be fine as a kicker. you can move a 37 foot sailboat with a 2 hp suzuki well above trolling speeds.

 

[JimS123]

I agree a 6 HP is adequate for "trolling", but it may not be big enough for use in an emergency. Based on my past boats, I believe a 9.9 will bring you up to hull speed, so a 20 would not provide any extra benefit and it would be more cumbersome to operate.

The picture in post 8 shows a store-bought steering bracket. I rigged my own setup on my last I/O. I made the rod using a SS threaded rod. QD ball joints were added to the ends. I made a SS bracket and bolted it to the OB's lower cowl. A second bracket was attached to the outdrive using one of the top 4 bolts. In this way the two ball sockets were quite a bit higher and easy to reach from inside the boat.

 

[airshot]

Yep, had a 9.9 on my 22' cuddy and it would push 12 mph at wot. Typically used much less than half throttle for trolling. I currently have a 16' SC with a 2.2 hp kicker, just over 5 mph at wot...

 

[huggyb1972]

Thanks for all the replies and suggestions. I'm thinking I want a remote setup for throttle and gear shift. Steering I'm still a bit not settled on. I considered using a remote tiller steering setup. We have one in our little fishing boat and it's far easier to operate than a wheel on tight spaces and saves space.

 

[JimS123]

Thanks for all the replies and suggestions. I'm thinking I want a remote setup for throttle and gear shift. Steering I'm still a bit not settled on. I considered using a remote tiller steering setup. We have one in our little fishing boat and it's far easier to operate than a wheel on tight spaces and saves space.

Some of the new fishing boats (Starcraft in particular) have factory setup kickers, with dual single lever throttle/shift. They are really cool. Most even have power trim on both engines, so you can be lazy and never even leave the driver's seat.

But, they also have full time dual steering. So, when the kicker is up it's still turning with the main.

Remember that when you run the kicker you will want to have the main down as well. It serves as a rudder and will help keep you in control. The kicker will be offset, so it will want to steer the boat in one direction only. If the main is up and you try to turn one way, it won't respond very fast, and if you try to turn the other way you'll lose it and make circles.

BTDT and only drove in a circle once.....LOL.