Sizing kicker motor

[bashr52]

I'm looking to add a second engine/kicker motor to my boat. It's a 17 ft tri-hull, used mainly for fishing and swimming, but sees an occasional tube/knee board. I've got a early 2000's 3.5 mercury outboard with about 5-10 hours on it, and a late 70's 6hp Johnson I'm trying to sell for a relative. The engine would mainly be used like a trolling motor for moving me short distances to change fishing spots on my lake. I'm getting tired of having to fire up my 85 horse just to move the boat 50-100 ft down the lake. I do take the boat once a year down to Virginia to do some bay fishing and it would be nice to have a second engine to use as a backup to limp it home in case I ran into a problem (not trying to set any speed records with it). I'm leaning toward the smaller of the two engine for a few reasons:
1) I already own it
2) Internal gas tank. I would have to either carry a second external tank for the 6 horse (in an already cramped boat full of gear), or plumb it into my current line for the main engine, which would still leave me stranded if I ever ran out of gas and needed to get back.
3) For my primary usage, the smaller engine should have more thrust than an electric engine.

Would a small 2 stroke be enough to move a boat that size around without having to rev it to death and overwork it?

 

[cr2k]

Re: Sizing kicker motor

They use electric trolling motors on 21 ft. bass boats.

 

[JoLin]

Re: Sizing kicker motor

I do take the boat once a year down to Virginia to do some bay fishing and it would be nice to have a second engine to use as a backup to limp it home in case I ran into a problem (not trying to set any speed records with it).

BTDT. 6 hp is marginal, but it should get you home when wind, waves and tide flow are working against you. The 3.5 won't cut it.

 

[MH Hawker]

Re: Sizing kicker motor

A 9.9 is the motor of choice for most.

 

[dingbat]

Re: Sizing kicker motor

A 9.9 is the motor of choice for most.

even a 9.9 is marginal for his Bay trips. Tide running, wind opposite direction (outgoing tide)= going nowhere in a hurry.

 

[blackhawk180]

Re: Sizing kicker motor

even a 9.9 is marginal for his Bay trips. Tide running, wind opposite direction (outgoing tide)= going nowhere in a hurry.

Agree. I have a 9.9 kicker but the prop has so little pitch (allows for super slow troll speeds) that I would hate to have a long run back in the event of any main motor problems. I can't even imagine trying to use a smaller motor though in a lake with no wind or current, you can get away with very little. I rarely find myself fishing in those conditions. Murphy's law must be considered when deciding.

 

[JoLin]

Re: Sizing kicker motor

even a 9.9 is marginal for his Bay trips. Tide running, wind opposite direction (outgoing tide)= going nowhere in a hurry.

I'll respectfully disagree. It's only a 17' boat. The 15 hp kicker on my 21' Pro-Line walkaround powered me through some really snotty conditions (couple feet of chop and 20+ mph headwind) at max hull speed (6 mph). IMO, 6 hp will move it in most conditions, though a 9.9 would be a better choice for a backup motor.

Blackhawk, it's gonna be a slow trip no matter what he mounts up. Unless there's enough power to get on plane, you're limited to hull speed. On a 17'er that's gonna be 5-6 mph max. All you need is enough power to reach and maintain hull speed in any conditions.

 

[Home Cookin']

Re: Sizing kicker motor

I don't think it's worth it to have a back-up motor for break downs on a 17' boat, unless you are way out in the wilderness. Certainly not worth buying one, but you already have a motor or two.

I also don't see the problem with "firing up the 85 to move." It's electric start, isn't it? easier than messing with the spare.

If you do a lot of trolling or can't make your present rig go slow enough, then maybe so. Use the smallest motor.

Practically speaking, you can't equip your 17' tri-hull with a back-up motor to get you home quickly against storm conditions in the Chesapeake Bay. Your boat, regardless of motor, has its limitations so plan your trips accordingly and don't build in a false sense of security.

Carrying a motor strong enough for storm conditions is as practical as carrying a life raft. Some risks you have to take, just be smart about it.

I'd go with the 3.5 just because you already have it. Carry a 1 gallon gas can, too.

Seperate tanks is a better back up since many mechanical failures are due to the fuel and fuel path.

I can't speak to lake boaters but I know the bay; you never ever see kickers on 17' boats anymore, and rarely back in the day.

 

[Frank Acampora]

Re: Sizing kicker motor

For the lake, the 3.5 hp should suit your purposes fine. It should give you around 2 MPH. Don't count on it as an emergency engine in the bay though.

I had a 6 hp kicker on my 18 footer. When I broke a prop shaft in the Chesapeake, the 6 got me home. At 3-4 MPH, it took 2 hours for what usually is a 15-20 minute trip, but it got me there. However, I was not battling tide and current. The calming effect on my wife, because at least we were moving, was priceless. It more than paid for that engine on that one trip.

 

[dan t.]

Re: Sizing kicker motor

I used a 4.5 on a 16 ft fiberglass I had, saved my bacon once when the CDI system quit on the 80 hp main. We putted in from about 6 miles out on salt water. It was a great trolling motor or could be used to hold you in one spot against a light current for jigging.

 

[Fleetwin]

Re: Sizing kicker motor

General rule is: 10% of your main engine HP.

A lot of variables there. If you just want to "putt" around a calm lake, you don't need much. Electric is OK.

If you go offshore, or Great Lakes, stick with the 10% rule.

 

[dan t.]

Re: Sizing kicker motor

General rule is: 10% of your main engine HP.

A lot of variables there. If you just want to "putt" around a calm lake, you don't need much. Electric is OK.

If you go offshore, or Great Lakes, stick with the 10% rule.

True up to a point,lots of 24 footers have 260-300 hp but you wont see much more than a 15 for a kicker.

 

[greenbush future]

Re: Sizing kicker motor

I'll respectfully disagree. It's only a 17' boat. The 15 hp kicker on my 21' Pro-Line walkaround powered me through some really snotty conditions (couple feet of chop and 20+ mph headwind) at max hull speed (6 mph). IMO, 6 hp will move it in most conditions, though a 9.9 would be a better choice for a backup motor.

Blackhawk, it's gonna be a slow trip no matter what he mounts up. Unless there's enough power to get on plane, you're limited to hull speed. On a 17'er that's gonna be 5-6 mph max. All you need is enough power to reach and maintain hull speed in any conditions.

I agree with you on this, 6 will do the job just fine, but if money was no object I'd go for a 9.9. I used a 6 hp 2 stroke on my 19 lund (alum boat) and it trolled and saved me many times, with no issues what so ever. The extra tank was a pain, but it really never needed more than a couple gallons to run almost all day trolling. The weight of a bigger kicker should be considered too, and if it wont bolt on, you will need a bracket to mount, raise and lower too. The best option I found personally was the bow electric trolling motor, but that's because I used it to fish primarily, limp home second. If all you want this for is to move from one spot to the other (short) I would not do this. It will become a target for thieves, and when trailering, it does tend to bounce and add weight. Then when boating it gets in the way in back, and bounces some more when not being used. Then you need to be able to reach the deployed motor, start it, stop it, and then steer it, all require bending over in back to operate, I found that to be a real pain in the butt based on how my stern was set up, yours may be different.

 

[dmscarp]

Re: Sizing kicker motor

I use a 15hp kicker on a 20'deep v hull. Works great for trolling or just cheap cruising around the bay when speed doesn't matter and beer does... Drinks way less fuel than the evinrude 2 stroke 150hp gas-a-holic on its side which is easy on the wallet...lol...