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shawn.faherty1

Kicker motor size

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Hi everyone,

 

This fall i bought a 2002 Bayliner 2655 and am looking to rig it with a kicker motor and a tr1 gold autopilot. I have been trying to decide how much trolling motor i need to push the boat.

 

I had a 7.5 hp 2 stroke on my 21ft bayliner trophy and it did a decent job unless it started to get choppy, then i would have to start the main.

 

I am planning on getting a 4 stroke kicker but not sure if a 10hp will be enough. If anyone has advise wold appreciated

 

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I have a Mercury 9.9 25 inch shaft that does a great job on my 24.5 ft, 1986 Chaparral Sport Fisherman that weighs 3500 lbs dry. Tops out at about 6 knots, can get down to under 1 knot with ease. 

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I have 9.9 Yamaha high thrust on a 91 pennYan pro hunter 265 with tr1 gold it will push the boat in any thing u want to fish. I have fished into wind waves in 5 footers plus and kicker hold course and speed of 2.5 to 2.7.  

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If it were me I'd be going with a 15 HP 4 stroke. A 9.9 is going to working harder to push the boat and if you have to get off in a hurry the 15 will do a quicker job of it.

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I’m with Sk8man on the 15hp. If your on the finger-lakes I could see going with the 9.9 but up on the big pond I’d go bigger if you can afford it or have a line on a good deal.


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Thanks for the feedback so far. I had been leaning towards a 15hp, but budget wise i was looking for a early to mid 2000s used motor and there seems to be a lot more 9.9s out there. Does any one know if the high thrust 9.9s make a big difference? I will be doing most of my fishing in senica lake, but i don't want to be under powered on lake Ontario because i like to go out at least a couple of times a season on the big lake.
Thanks again for the advice.

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9.9 are the standard nowadays, its big enough to push 30+ feet, but you need to get the ones they purposely make for kickers. they have lower gear ratio and are propped different, the work great but don't go over 4 or 5 mph no matter what, but can all ways push trolling speeds. Yamaha is same as merc but the stickers on the merc are more. 

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Just make sure it is a 4 stroke regardless as they seem to have more torque than the 2 strokes (I have had both), use less gas, and you don't have to mix the oil and gas. I found that with my boat I could even get away from my steering connector because of the torque difference.

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Might not be a bad idea to look at the weight difference too, 9.9 vs. 15.  If the 15 is significantly heavier, it may cause a list to that side, if it is not mounted in the middle.  I am assuming your boat is an IO.  If so, pretty tough to mount a kicker in the middle of the transom.  Just a thought.

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i have a crestliner eagle 2450 that came with a 25hp merc 4 stroke kicker from the factory. supposedly it weighs about 3400 lbs dry. the 25 hp kicker pushes it around easily. i can troll down to 1-ish mph/sog on the gps and it will run about 6 mph wide open. truthfully, i've been entertaining the idea of downsizing it to a 9.9 efi suzuki, just for the efi. the merc performs great though.. has never given me a lick of trouble, starts good, runs good etc, but i'm drawn to efi... just because it's efi! i've been pricing it out recently.. ouch. i just can't justify spending that much to replace a perfectly good motor. but if i were in your shoes, i'd be ordering a 9.9 efi zuke and an itroll!

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10 hours ago, Knotlost Charters said:

9.9 are the standard nowadays, its big enough to push 30+ feet, but you need to get the ones they purposely make for kickers. they have lower gear ratio and are propped different, the work great but don't go over 4 or 5 mph no matter what, but can all ways push trolling speeds. Yamaha is same as merc but the stickers on the merc are more. 

I agree my 9.9 will get my 25' to 5.5 mph and my buddy has a 17' alum boat with the same motor and gets the same mph even though my boat weights 3x more.The extra weight of a 15 is not worth what you will gain the other factor is "hull speed" the faster you go the boat will try to get on plane (which will never happen) and will create more drag in effect negating any gains from the extra hp.

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The weight differential is not necessarily really a major issue for the 9.9 vs. 15 HP but it does depend on whether you select options on one and not the other. For example trim and tilt and things of that sort. On some of the older 2 stroke motors the difference was non-existent and in fact as it was only the carburator setup that was different and they were virtually the same motor (e.g. 9.9 vs. 15 HP Johnson). On these newer 4 strokes if it is just the basic motor comparison they are usually about 15 lbs or so and again it depends on manufacturer to a degree too. As long as you have an appropriate  substantial mounting bracket the weight differential shouldn't be much of a factor on that size boat.

Edited by Sk8man

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Other consideration is alternator output. When I rigged me new boat last year I went with then 15HP Merc Pro kicker vs the 9.9 as the output was double. Although this does depend on RPM.

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The 9.9 should be fine. Make sure you get the High Thrust. If you want to go bigger Yamaha also makes a 25 high thrust.

 

If you're looking for a price shoot me a PM.

Edited by Yankee Troller

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I've got a 9.9 Suzuki long shaft EFI with tilt and trim kicker with 60 hours on it for sale

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I agree my 9.9 will get my 25' to 5.5 mph and my buddy has a 17' alum boat with the same motor and gets the same mph even though my boat weights 3x more.The extra weight of a 15 is not worth what you will gain the other factor is "hull speed" the faster you go the boat will try to get on plane (which will never happen) and will create more drag in effect negating any gains from the extra hp.
Listen to this guy. The formula for hull speed is the limitation. If the motor won't get the boat on plane, you are limited by this formula. So the 9.9 will get you as much speed as a 15. Look up the formula and do the math.

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Listen to this guy. The formula for hull speed is the limitation. If the motor won't get the boat on plane, you are limited by this formula. So the 9.9 will get you as much speed as a 15. Look up the formula and do the math.

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Would that be the same for rough seas though? I could see that if the lake were flat but if it was rolling I wouldn’t think the two would compare for getting back in. Just me though. Having something is better than nothing.


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1 hour ago, Frogger said:


Would that be the same for rough seas though? I could see that if the lake were flat but if it was rolling I wouldn’t think the two would compare for getting back in. Just me though. Having something is better than nothing.


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I think this is exactly the issue  torque not speed. When it gets rough out and the main motor quits you'd appreciate the torque from the extra HP in pushing through the waves.

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I'm not sure. What I do know is that I had a 18 foot cimmaron, and a 22 foot Grady White. The 9.9 motor on both got about the same speed wide open. 5 to 6 mph as I recall. That's when I learned about hull speed. The Grady was quite a bit bigger and heavier. I think maybe a larger prop, versus horsepower, may give better control. I think Mercury sells a kicker motor with a bigger prop for that reason.

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I'm not sure. What I do know is that I had a 18 foot cimmaron, and a 22 foot Grady White. The 9.9 motor on both got about the same speed wide open. 5 to 6 mph as I recall. That's when I learned about hull speed. The Grady was quite a bit bigger and heavier. I think maybe a larger prop, versus horsepower, may give better control. I think Mercury sells a kicker motor with a bigger prop for that reason.

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Problem you’re not thinking about is the prop. You prop it for trolling so if you prop it for high seas an what you’re referring to you will be going to fast in normal water.


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More important than the HP on a trolling motor is the gear case gear ratio. The lower gears of a trolling motor allow them to turn props with larger surface areas. Large props spinning at slower speeds develop more thrust. Lower gears also allow the engine to turn faster and develop more usable hp. It’s a win win scenario.

 

If you think of this in extremes, consider a freighter going down the lake. The prop is gigantic but it rotates relatively slowly.

 

A 9.9 trolling motor with low gearing is completely adequate to push the boat. A 15 may produce more charging amperage at wide open throttle, but if it runs an even bigger prop than the 9.9 it will operate at lower rpm and may not actually generate any more real world charging at normal operating rpm trolling around the lake.

 

As to thrust at wot through big waves, if both engines have similar max rpm, gearing, and props, and both can wind up to full rpm then there’s no thrust advantage with the 15 over the 9.9. There would have to be a difference in gearing and/or prop.

 

Either way though, once you reach the hull displacement speed and the bow wave begins to pass behind the transom and the transom begins to squat no additional power is realistically useful unless it’s enough power to push the boat up the backside of the bow wave and begin to plane.

 

 

Sent from my iPhone using Lake Ontario United

 

 

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Just speaking from my own experience with my own boat but I switched from a 9.9 older two stroke to a new 9.8 four stroke and was able to get rid of the steering hook-up. The four stroke is either geared differently or there is some definite torque change that allows me to steer totally from my big motor without the steering hook-up now even in the wind which was not possible previously. The 2 stroke pushed the boat a mile or two faster top end but with less boat control than I  have now with the four stroke with the same 3 blade prop so it may be gearing but either way I'm happy:smile:

Edited by Sk8man

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