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Author Topic:   Determine Proper Kicker Motor

home Aside posted 01-12-2011 01:39 PM ET (US)
Having never had a a kicker motor, how do you determine the proper size outboard to be used as a kicker motor? Is there a rhyme or reason to picking one? Is there a size threshold you should not go under or beyond?
In my case my Whaler is a 1985 Revenge 22 WT with 1985 Yamaha 225.
Pat
SJUAE posted 01-12-2011 02:49 PM ET (US)
HA
As were are talking displacement speeds generally you cannot exceed 1.34 to 1.51^−½ knot /·ft waterline length or 1.34 to 1.51 x SQR(waterline length) of the hull due to bow wave.
So for your 22ft hull if we said 18ft is the waterline length you would get 5.7 to 6.4 knts maximum
Theres not really a minimum, as just how slow do you want to go and the practcalities of this are not really worth considering.
Determing how much HP kicker to get to the hull maximum displacement speed is a bit harder :) as many factors have an influence.
Another factor of course is the prop fitted to the kicker, most standard props are best suited for small tender type hulls.
Fitting a large pitch or "high thrust" is generally considered better for larger boats.
If you search the forums for practical/real advice you will find most consider/find for a ~20ft hull a 8 or 9.9 will achieve ~6mph with a high thrust prop
Your less V'd Revenge will probably be ok with a 9.9HP where a newer more V'd hull may well be better suited to a 15HP.
Anything greater than this is a law of diminishing returns in speed although a 20/25hp ignoring it's weight impact would have more features, be running at half revs and likely to have a better altenator etc
Regards
Steve
JMARTIN posted 01-12-2011 02:53 PM ET (US)
Pat, most kickers are used for fishing or other go slow operation. In an emergency, they hopefully can get you home or keep you off the rocks until help arrives.
The "two hour out off shore guys" need twins where one will be able to put them on plane.
I have a 1989 15hp Evinrude on my Revenge 22. It is running off a separate premix tank. At full throttle, I do about 6 knots, at 2/3rds throttle, I do about 6 knots. A newer 9.9hp four stroke would be a good choice for you. You might be able to run it off your main tank.
If you want to go faster than 6 knots, you would need more that 15hp, I bet.
John
elaelap posted 01-12-2011 04:26 PM ET (US)
I don't think Pat's boat could do more than ~5-6 kts no matter what kicker he put on it, as long as it was in displacement mode. See Steve's right-on post above.
We run a 6 hp four stroke kicker on 21-ft 'Strike3', and it's plenty of power for our needs -- trolling slowly for salmon and halibut (2-3 kts), and keeping us off the rocks in an emergency. Getting home on the kicker from some of our 35-mile trips up our empty, harborless coast, especially if the wind and seas kicked up in the wrong direction? Hmmm...
I run a 6 hp Suzuki two cylinder four stroke kicker on my classic Montauk. Four horses would have been enough, but I wanted 2 cylinders for smoothness and they don't make one that small.
Eight hp or those nice 9.9s would be plenty for your boat IMO, Pat. You won't get any more speed out of a 15, but maybe more power would be of use pounding into gnarly seas if the kicker was being used as an emergency get-home motor.
Tony
Jeff posted 01-12-2011 04:42 PM ET (US)
Pat,
While I can not comment on kickers as I have never had a need for one, I do know of a local, very nice 9.9 Suzuki 4stroke (believe it is electric start as well) kicker with all controls that will soon be available.
Contact me if you want details.
martyn1075 posted 01-12-2011 05:05 PM ET (US)
We also used a 15 hp 2 stroke as well on our 22 Revenge WT. It was a Mariner and although it was very stinky little guy it was super light and offered more than enough power. I would like to say a tad over 7-8 knots. We currently use a Mercury 9.9 four stroke Big Foot model on the 25 walkaround and it is great engine clean and starts on every turn. Not a power machine like the 15 Mariner but it trolls really efficiently perfect for Chinooks.
Dela329 posted 01-12-2011 05:25 PM ET (US)
Pat
My last 21 Conquest came with a 9.9 Merc 4stk on it and I was really happy with it. I'm not sure how the dealer determined what size to install but it was a great match for that boat. They mounted it to a Panther lift with power tilt which was a real luxury. Only regret was the console control cables would kink causing the throttle to become touchy as the years went on.
On my latest whaler (205 Eastport) I'm planning to install a 15 Merc Prokicker that I'm pulling off my 24' Thompson hardtop. It has some really nice features like electric start, pwr tilt, and high thrust prop. Unfortunately it's a tiller and I'll probably miss the console controls (but I'm at the back tending rods and riggers most of the time anyway).
One thing I can tell you from experience about relying on a kicker to get you home - have patience. One evening I motored in from about 7 miles out(when it was attached to the 24' Thompson) and had an awful time because of the wind. All in all, it's better than a tow!
With all that said, I'd bet a 9.9 longshaft 4stk would do the trick.
jimp posted 01-12-2011 07:01 PM ET (US)
My decision was easy. My 1990 Revenge 22 W.T came with an electric start 1989 9.9 Yamaha 4-stroke, high thrust. When that died (major exhaust housing cancer two seasons ago) I replaced it with an electric start 1999 Mercury 9.9 Big Foot Sail (extra long shaft as that was what they had).
The 9.9s push the boat at about 5.6 knots. Some have had a lot of luck with the newer 8 HP Yamahas. I don't think it makes much difference. No need for a 15.
JimP
littleblue posted 01-12-2011 07:03 PM ET (US)
I'm using a Yamaha T8 on my 22' Outrage for my kicker duties. I saved a ton of fuel and wear on my main engine this summer by using the little t8, 170 hours from mid June - early September to be exact. Most of it was accumulated trolling for Salmon.
So far so good, I don't have any regrets on the power. It does get a bit tough going into the wind, and uphill in rough conditions but overall I'm very happy with it.
In calm water it will do about 6.5mph if memory serves correctly. There is also a write up in the reference section about a t8 install on a classic 22' Outrage.
jimh posted 01-12-2011 10:33 PM ET (US)
For details of a very nice installation of an auxiliary motor on a 22-foot Boston Whaler hull, see the REFERENCE article
http://continuouswave.com/whaler/reference/yamahaT8Kicker.html
Based on the results reported in this article, the 8-HP Yamaha engine is an excellent choice for an auxiliary motor. It has good size, weight, and performance.
jimh posted 01-12-2011 11:01 PM ET (US)
There is a great deal to consider when selecting an auxiliary motor. The horsepower of the motor is just one element. Other factors to consider:
--weight of motor
--size of motor
--shaft length
--battery charging capability
--compatibility with steering gear and linkage to main motor
--compatibility with remote control system in place on boat
--compatibility with fuel system and type of fuel needed, particularly if pre-mixed oil-fuel is used on main motor.
Tohsgib posted 01-13-2011 11:41 AM ET (US)
Read any outboard brochure, especially from the 80's/90's and you will see that they make 4-9.9hp kickers because that is all you need. A 15 is not gonna do anymore than a 9.9 in 98% of kicker cases and hence why they do not make them. If a 9.9 can move a 38' sailboat it can move your 22. There is a huge reason why Yamaha chose the 8hp as the kicker in their T8 and why Mercury followed.
Buckda posted 01-13-2011 12:58 PM ET (US)
Pat -
If you're considering the motor we discussed the other day, my concern is propeller design. I'd contact Tom W. Clark or Lockeman's to find out if a modern propeller could be fitted to the prop shaft on that motor.
If it's not that motor, then please disregard.
Best,
Dave

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Author	Topic: Determine Proper Kicker Motor
home Aside	posted 01-12-2011 01:39 PM ET (US) Having never had a a kicker motor, how do you determine the proper size outboard to be used as a kicker motor? Is there a rhyme or reason to picking one? Is there a size threshold you should not go under or beyond? In my case my Whaler is a 1985 Revenge 22 WT with 1985 Yamaha 225. Pat
SJUAE	posted 01-12-2011 02:49 PM ET (US) HA As were are talking displacement speeds generally you cannot exceed 1.34 to 1.51^−½ knot /·ft waterline length or 1.34 to 1.51 x SQR(waterline length) of the hull due to bow wave. So for your 22ft hull if we said 18ft is the waterline length you would get 5.7 to 6.4 knts maximum Theres not really a minimum, as just how slow do you want to go and the practcalities of this are not really worth considering. Determing how much HP kicker to get to the hull maximum displacement speed is a bit harder :) as many factors have an influence. Another factor of course is the prop fitted to the kicker, most standard props are best suited for small tender type hulls. Fitting a large pitch or "high thrust" is generally considered better for larger boats. If you search the forums for practical/real advice you will find most consider/find for a ~20ft hull a 8 or 9.9 will achieve ~6mph with a high thrust prop Your less V'd Revenge will probably be ok with a 9.9HP where a newer more V'd hull may well be better suited to a 15HP. Anything greater than this is a law of diminishing returns in speed although a 20/25hp ignoring it's weight impact would have more features, be running at half revs and likely to have a better altenator etc Regards Steve
JMARTIN	posted 01-12-2011 02:53 PM ET (US) Pat, most kickers are used for fishing or other go slow operation. In an emergency, they hopefully can get you home or keep you off the rocks until help arrives. The "two hour out off shore guys" need twins where one will be able to put them on plane. I have a 1989 15hp Evinrude on my Revenge 22. It is running off a separate premix tank. At full throttle, I do about 6 knots, at 2/3rds throttle, I do about 6 knots. A newer 9.9hp four stroke would be a good choice for you. You might be able to run it off your main tank. If you want to go faster than 6 knots, you would need more that 15hp, I bet. John
elaelap	posted 01-12-2011 04:26 PM ET (US) I don't think Pat's boat could do more than ~5-6 kts no matter what kicker he put on it, as long as it was in displacement mode. See Steve's right-on post above. We run a 6 hp four stroke kicker on 21-ft 'Strike3', and it's plenty of power for our needs -- trolling slowly for salmon and halibut (2-3 kts), and keeping us off the rocks in an emergency. Getting home on the kicker from some of our 35-mile trips up our empty, harborless coast, especially if the wind and seas kicked up in the wrong direction? Hmmm... I run a 6 hp Suzuki two cylinder four stroke kicker on my classic Montauk. Four horses would have been enough, but I wanted 2 cylinders for smoothness and they don't make one that small. Eight hp or those nice 9.9s would be plenty for your boat IMO, Pat. You won't get any more speed out of a 15, but maybe more power would be of use pounding into gnarly seas if the kicker was being used as an emergency get-home motor. Tony
Jeff	posted 01-12-2011 04:42 PM ET (US) Pat, While I can not comment on kickers as I have never had a need for one, I do know of a local, very nice 9.9 Suzuki 4stroke (believe it is electric start as well) kicker with all controls that will soon be available. Contact me if you want details.
martyn1075	posted 01-12-2011 05:05 PM ET (US) We also used a 15 hp 2 stroke as well on our 22 Revenge WT. It was a Mariner and although it was very stinky little guy it was super light and offered more than enough power. I would like to say a tad over 7-8 knots. We currently use a Mercury 9.9 four stroke Big Foot model on the 25 walkaround and it is great engine clean and starts on every turn. Not a power machine like the 15 Mariner but it trolls really efficiently perfect for Chinooks.
Dela329	posted 01-12-2011 05:25 PM ET (US) Pat My last 21 Conquest came with a 9.9 Merc 4stk on it and I was really happy with it. I'm not sure how the dealer determined what size to install but it was a great match for that boat. They mounted it to a Panther lift with power tilt which was a real luxury. Only regret was the console control cables would kink causing the throttle to become touchy as the years went on. On my latest whaler (205 Eastport) I'm planning to install a 15 Merc Prokicker that I'm pulling off my 24' Thompson hardtop. It has some really nice features like electric start, pwr tilt, and high thrust prop. Unfortunately it's a tiller and I'll probably miss the console controls (but I'm at the back tending rods and riggers most of the time anyway). One thing I can tell you from experience about relying on a kicker to get you home - have patience. One evening I motored in from about 7 miles out(when it was attached to the 24' Thompson) and had an awful time because of the wind. All in all, it's better than a tow! With all that said, I'd bet a 9.9 longshaft 4stk would do the trick.
jimp	posted 01-12-2011 07:01 PM ET (US) My decision was easy. My 1990 Revenge 22 W.T came with an electric start 1989 9.9 Yamaha 4-stroke, high thrust. When that died (major exhaust housing cancer two seasons ago) I replaced it with an electric start 1999 Mercury 9.9 Big Foot Sail (extra long shaft as that was what they had). The 9.9s push the boat at about 5.6 knots. Some have had a lot of luck with the newer 8 HP Yamahas. I don't think it makes much difference. No need for a 15. JimP
littleblue	posted 01-12-2011 07:03 PM ET (US) I'm using a Yamaha T8 on my 22' Outrage for my kicker duties. I saved a ton of fuel and wear on my main engine this summer by using the little t8, 170 hours from mid June - early September to be exact. Most of it was accumulated trolling for Salmon. So far so good, I don't have any regrets on the power. It does get a bit tough going into the wind, and uphill in rough conditions but overall I'm very happy with it. In calm water it will do about 6.5mph if memory serves correctly. There is also a write up in the reference section about a t8 install on a classic 22' Outrage.
jimh	posted 01-12-2011 10:33 PM ET (US) For details of a very nice installation of an auxiliary motor on a 22-foot Boston Whaler hull, see the REFERENCE article http://continuouswave.com/whaler/reference/yamahaT8Kicker.html Based on the results reported in this article, the 8-HP Yamaha engine is an excellent choice for an auxiliary motor. It has good size, weight, and performance.
jimh	posted 01-12-2011 11:01 PM ET (US) There is a great deal to consider when selecting an auxiliary motor. The horsepower of the motor is just one element. Other factors to consider: --weight of motor --size of motor --shaft length --battery charging capability --compatibility with steering gear and linkage to main motor --compatibility with remote control system in place on boat --compatibility with fuel system and type of fuel needed, particularly if pre-mixed oil-fuel is used on main motor.
Tohsgib	posted 01-13-2011 11:41 AM ET (US) Read any outboard brochure, especially from the 80's/90's and you will see that they make 4-9.9hp kickers because that is all you need. A 15 is not gonna do anymore than a 9.9 in 98% of kicker cases and hence why they do not make them. If a 9.9 can move a 38' sailboat it can move your 22. There is a huge reason why Yamaha chose the 8hp as the kicker in their T8 and why Mercury followed.
Buckda	posted 01-13-2011 12:58 PM ET (US) Pat - If you're considering the motor we discussed the other day, my concern is propeller design. I'd contact Tom W. Clark or Lockeman's to find out if a modern propeller could be fitted to the prop shaft on that motor. If it's not that motor, then please disregard. Best, Dave