Motor size

secondcurve · 12-07-2005, 05:21 PM

I have a 12 foot John Boat that I use on a small pond (about 150 acres). I have used an electric trolling motor to power the boat, but I want to upgrade to a small 4-stroke motor next season. I'm thinking that a two horsepower motor is the way to go. My question is roughly what horse power is an electric motor? I bought the strongest electric motor I could at the time I purchased it a couple years back. I'd like to know if I would be going up in power or down in power with the two horse power motor. My sense is that two horse power would probably give me a little more oomph than the electric. The lady at Melvin Village was pleasant and helpful, but she didn't have a clue about the answer to my question.

Thanks

Resident 2B · 12-07-2005, 06:37 PM

Although you must also consider torque, the conversion factor from brake horse power to kilowatts is 1 bhp = .746 kW

Therefore, if you are looking to convert, a 2 bhp motor would equate to a 1,492 kW motor.

However, life is not that simple. You must look at the torque outputs available at the shaft to get a more accurate conversion in your application.

ITD · 12-07-2005, 09:12 PM

I have a 12 foot row boat that I used to use my 2hp four stroke Honda sailboat motor on. The motor pushed the boat pretty well, was (is) very reliable and economical to run. I bought an 8hp Yamaha this year to increase my range when I fish. This motor will plane the row boat and is light enough to carry easily. That being said on a small pond or lake the 2 hp motor would be more than enough and when you consider the chore of recharging batteries, much easier to use. I'd go for the 2 hp. Good luck.

fatlazyless · 12-07-2005, 09:21 PM

I used to have a Honda 2hp for use on a 14' sailboat, and it was very noisy because it is the only Honda outboard that is not water cooled. It is air cooled so it ran hot and loud even though it was a four-stoke. By the way,I have a 24 volt - 67 lb thrust, bow mount MotorGuide trolling motor for sale in new condition. New, it cost $575. and will sell for 275., firm.

Woodsy · 12-08-2005, 07:37 AM

Make sure you can use a gasoline powered motor on the pond. Alot of the smaller ponds don't allow them. other than that, a 2hp ought to do it.

Woodsy

Phantom · 12-08-2005, 08:01 AM

Well -- I fought the urge to post this -- but lost!!

Secondcurve, I also think a 2HP will be fine if all you want to do is "putt" around. I too live on a smaller pond- when not at Winni-- about the same size (160 acres) and we have some (relatively) reasonable sized boats that water ski/tube etc here. They range from 12ft- 20ft Malibu ski boats.

My thinking is that if you should desire to do anything other than "putt" consider something a little greater in HP. When my son was younger we had a 10ft skiff with an 8HP.

I'm not advocating an 8HP but perhaps you may want to "bump up" your 2 HP and consider something in between. The cost differences are relatively minor.

fatlazyless · 12-08-2005, 09:56 AM

Looks like my 24v troller has been sold to someone in Texas. Anyway, the Honda 2hp sounds like a lawn mower and gets very hot because it is a one cylinder, air cooled two-stroke, just like a 20" lawn mower. Every other Honda outboard is water cooled and runs much quieter and cooler. Suggestion: go with an electric troller and save your neighbors from one more noisey outboard on a small pond.

ITD · 12-08-2005, 11:18 AM

Come on Less, it's not that loud. Sure it's louder than an electric trolling motor and it is air cooled, but it does exhaust below the water. It's not much louder than my Yamaha 8hp and it uses much less gas. At a couple hundred feet you can barely hear it when at full throttle.

fatlazyless · 12-08-2005, 12:13 PM

Remember the Volkswagon 4 cyl-air cooled engines in the old beetles. The Honda 2hp runs hotter and sounds different & louder than other two-stroke or a four stroke small 2-4-6-8 hp outboards. I had one for about five years.

Here's a thought....how to turn a 12' jon boat or vee hull into a hybred dual propulsion system. Use a small 30lb thrust 12v stern mount trolling motor wired up to a battery located in the middle of the boat. The central location of the heavy 40 lb battery helps stabilize the boat. the trolling motor is almost toatally 100% quiet.....just a tiny whirring sound. By locking the troller into the staight-ahead postion wth its' locking know, one can very effectively use the oars and stern electric trolling motor at the same time. The motor provides propulsion and the oars provide either steering or forward motion. It's a dual hybred system that gives the user exercise, something that many of the lake's overweight boaters could sorely use. Plus, it is extremely quiet, no smelly gasoline fumes or odor from the gas tank, plus it makes for safer operation and is more challenging to use. Also, by sitting in the middle of the boat while rowing it gives the boat better stability as opposed to sitting in the stern while using a tiller controlled gas outboard.

Will this change any minds.........maybe not.........got to run...later....

Orion · 12-08-2005, 03:15 PM

FLL, you forgot to add a small bow mounted cat-rig mast with a sail to make it a 4-mode hybrid!

secondcurve · 12-09-2005, 07:33 AM

I appreciate the responses. I definitely want to get away from the electric motors since I hate carrying the battery, having it die etc.

One final question. Can you buy a 2-horse power 4-stroke that is water cooled or are all motors in this size class air cooled? Maybe a Yamaha or some other brand?

Resident 2B · 12-09-2005, 09:43 AM

SC,

Yahama make a 2.5, 4 and 6 hp 4-stroke.

I am not real knowledgeable on these, but I think they use water for cooling.

Their web site is: http://www.yamaha-motor.com/outboard...me/5/home.aspx

Good luck!

KBoater · 12-09-2005, 11:34 AM

Both these sites will lead you to spec. and reviews of some engine.

http://www.boatingmag.com/article.as...&page_number=1

http://www.boatingworldonline.com/Engines.htm

John A. Birdsall · 12-16-2005, 01:58 PM

I would suggest to you to find a good 5 hp Johnson or Evinrude. If in the future things change, and as we get older things do change, you will be pushing more weight, and might just need a little more power. Once upon a time I used a 6 hp elgin for about 6 summers, then I used a 18 Hp Johnson for about 8 summers, Now I use a 115 Hp Evinrude. I have gotten bigger, the first boat was heavier, but the boat now is heavy fiberglass. I also picked up some lightweight passengers.

I think for a 12' boat a 5 HP is fine. I think a 2 is too small, and not long will cost again to upgrade. Besides with a 5 you can throttle down and it will be quieter than a 2 hp in my opinion. Best of luck

jrc · 12-16-2005, 10:47 PM

Getting back to your original question, according to the Minnkota website most of there electric trolling motors draw 30-50 amps. So assuming you have a 12v motor (only one battery), that's 600 watts. One horse power is about 750 watts and those motors don't convert all the electrical power into prop power. So it's well less than one horsepower. Now if you a 24v or 36v motor you may get near one horsepower at the prop. A two horsepower gas outboard is 2HP at the prop.

That said, unless weight or money is an issue, I would get a 5 HP. I think it's a better investment. If you move up to a slightly bigger boat you won't need to buy a bigger motor.

secondcurve · 12-17-2005, 12:11 PM

JRC:

I appreciate your response it confirmed my assumption that my electric motor is in the range of 1hp or less. I also appreciate your recoomendation on the 5hp, but I am probably going to stick with the 2hp since all I do is put around the pond and fish. I have a 22 foot boat that is powered by a 2005 225 4-stroke Yamaha for the big lake, so I get my speed fix there. Now I just need to see if I can find a 2hp motor that is water cooled.

Thanks!!!!!!!!!

12-07-2005, 05:21 PM	#1
secondcurve Senior Member Join Date: Jan 2005 Posts: 2,084 Thanks: 1,267 Thanked 557 Times in 286 Posts	Motor size I have a 12 foot John Boat that I use on a small pond (about 150 acres). I have used an electric trolling motor to power the boat, but I want to upgrade to a small 4-stroke motor next season. I'm thinking that a two horsepower motor is the way to go. My question is roughly what horse power is an electric motor? I bought the strongest electric motor I could at the time I purchased it a couple years back. I'd like to know if I would be going up in power or down in power with the two horse power motor. My sense is that two horse power would probably give me a little more oomph than the electric. The lady at Melvin Village was pleasant and helpful, but she didn't have a clue about the answer to my question. Thanks

12-07-2005, 06:37 PM	#2
Resident 2B Senior Member Join Date: Apr 2004 Location: North Shore, MA Posts: 1,352 Thanks: 987 Thanked 310 Times in 161 Posts	bhp to kW conversion Although you must also consider torque, the conversion factor from brake horse power to kilowatts is 1 bhp = .746 kW Therefore, if you are looking to convert, a 2 bhp motor would equate to a 1,492 kW motor. However, life is not that simple. You must look at the torque outputs available at the shaft to get a more accurate conversion in your application.

12-08-2005, 03:15 PM	#10
Orion Senior Member Join Date: Feb 2003 Location: Cow Island Posts: 914 Thanks: 602 Thanked 193 Times in 91 Posts	Missing a big option FLL, you forgot to add a small bow mounted cat-rig mast with a sail to make it a 4-mode hybrid!

12-09-2005, 07:33 AM	#11
secondcurve Senior Member Join Date: Jan 2005 Posts: 2,084 Thanks: 1,267 Thanked 557 Times in 286 Posts	Thanks All I appreciate the responses. I definitely want to get away from the electric motors since I hate carrying the battery, having it die etc. One final question. Can you buy a 2-horse power 4-stroke that is water cooled or are all motors in this size class air cooled? Maybe a Yamaha or some other brand?

12-09-2005, 09:43 AM	#12
Resident 2B Senior Member Join Date: Apr 2004 Location: North Shore, MA Posts: 1,352 Thanks: 987 Thanked 310 Times in 161 Posts	Yahama Four Strokes - Portable SC, Yahama make a 2.5, 4 and 6 hp 4-stroke. I am not real knowledgeable on these, but I think they use water for cooling. Their web site is: http://www.yamaha-motor.com/outboard...me/5/home.aspx Good luck!

12-07-2005, 09:12 PM	#3
ITD Senior Member Join Date: Apr 2004 Location: Moultonboro, NH Posts: 2,860 Thanks: 461 Thanked 666 Times in 366 Posts	I have a 12 foot row boat that I used to use my 2hp four stroke Honda sailboat motor on. The motor pushed the boat pretty well, was (is) very reliable and economical to run. I bought an 8hp Yamaha this year to increase my range when I fish. This motor will plane the row boat and is light enough to carry easily. That being said on a small pond or lake the 2 hp motor would be more than enough and when you consider the chore of recharging batteries, much easier to use. I'd go for the 2 hp. Good luck.

12-07-2005, 09:21 PM	#4
fatlazyless Senior Member Join Date: Apr 2004 Posts: 8,525 Blog Entries: 1 Thanks: 295 Thanked 957 Times in 698 Posts	I used to have a Honda 2hp for use on a 14' sailboat, and it was very noisy because it is the only Honda outboard that is not water cooled. It is air cooled so it ran hot and loud even though it was a four-stoke. By the way,I have a 24 volt - 67 lb thrust, bow mount MotorGuide trolling motor for sale in new condition. New, it cost $575. and will sell for 275., firm.

12-08-2005, 07:37 AM	#5
Woodsy Senior Member Join Date: May 2004 Location: Weirs Beach Posts: 1,949 Thanks: 80 Thanked 969 Times in 432 Posts	Make sure you can use a gasoline powered motor on the pond. Alot of the smaller ponds don't allow them. other than that, a 2hp ought to do it. Woodsy

12-08-2005, 08:01 AM	#6
Phantom Senior Member Join Date: Jul 2005 Location: Berlin, Ma / Gilford Posts: 1,931 Thanks: 445 Thanked 604 Times in 340 Posts	Well -- I fought the urge to post this -- but lost!! Secondcurve, I also think a 2HP will be fine if all you want to do is "putt" around. I too live on a smaller pond- when not at Winni-- about the same size (160 acres) and we have some (relatively) reasonable sized boats that water ski/tube etc here. They range from 12ft- 20ft Malibu ski boats. My thinking is that if you should desire to do anything other than "putt" consider something a little greater in HP. When my son was younger we had a 10ft skiff with an 8HP. I'm not advocating an 8HP but perhaps you may want to "bump up" your 2 HP and consider something in between. The cost differences are relatively minor.

12-08-2005, 09:56 AM	#7
fatlazyless Senior Member Join Date: Apr 2004 Posts: 8,525 Blog Entries: 1 Thanks: 295 Thanked 957 Times in 698 Posts	Looks like my 24v troller has been sold to someone in Texas. Anyway, the Honda 2hp sounds like a lawn mower and gets very hot because it is a one cylinder, air cooled two-stroke, just like a 20" lawn mower. Every other Honda outboard is water cooled and runs much quieter and cooler. Suggestion: go with an electric troller and save your neighbors from one more noisey outboard on a small pond.

12-08-2005, 11:18 AM	#8
ITD Senior Member Join Date: Apr 2004 Location: Moultonboro, NH Posts: 2,860 Thanks: 461 Thanked 666 Times in 366 Posts	Come on Less, it's not that loud. Sure it's louder than an electric trolling motor and it is air cooled, but it does exhaust below the water. It's not much louder than my Yamaha 8hp and it uses much less gas. At a couple hundred feet you can barely hear it when at full throttle.

12-08-2005, 12:13 PM	#9
fatlazyless Senior Member Join Date: Apr 2004 Posts: 8,525 Blog Entries: 1 Thanks: 295 Thanked 957 Times in 698 Posts	Remember the Volkswagon 4 cyl-air cooled engines in the old beetles. The Honda 2hp runs hotter and sounds different & louder than other two-stroke or a four stroke small 2-4-6-8 hp outboards. I had one for about five years. Here's a thought....how to turn a 12' jon boat or vee hull into a hybred dual propulsion system. Use a small 30lb thrust 12v stern mount trolling motor wired up to a battery located in the middle of the boat. The central location of the heavy 40 lb battery helps stabilize the boat. the trolling motor is almost toatally 100% quiet.....just a tiny whirring sound. By locking the troller into the staight-ahead postion wth its' locking know, one can very effectively use the oars and stern electric trolling motor at the same time. The motor provides propulsion and the oars provide either steering or forward motion. It's a dual hybred system that gives the user exercise, something that many of the lake's overweight boaters could sorely use. Plus, it is extremely quiet, no smelly gasoline fumes or odor from the gas tank, plus it makes for safer operation and is more challenging to use. Also, by sitting in the middle of the boat while rowing it gives the boat better stability as opposed to sitting in the stern while using a tiller controlled gas outboard. Will this change any minds.........maybe not.........got to run...later....

12-09-2005, 11:34 AM	#13
KBoater Senior Member Join Date: Apr 2004 Location: Wolfeboro Posts: 521 Thanks: 10 Thanked 29 Times in 15 Posts	Specs Both these sites will lead you to spec. and reviews of some engine. http://www.boatingmag.com/article.as...&page_number=1 http://www.boatingworldonline.com/Engines.htm __________________ Home Permanently in NH

12-16-2005, 01:58 PM	#14
John A. Birdsall Senior Member Join Date: Apr 2004 Location: Norwich, CT Posts: 599 Thanks: 27 Thanked 51 Times in 35 Posts	0utboards I would suggest to you to find a good 5 hp Johnson or Evinrude. If in the future things change, and as we get older things do change, you will be pushing more weight, and might just need a little more power. Once upon a time I used a 6 hp elgin for about 6 summers, then I used a 18 Hp Johnson for about 8 summers, Now I use a 115 Hp Evinrude. I have gotten bigger, the first boat was heavier, but the boat now is heavy fiberglass. I also picked up some lightweight passengers. I think for a 12' boat a 5 HP is fine. I think a 2 is too small, and not long will cost again to upgrade. Besides with a 5 you can throttle down and it will be quieter than a 2 hp in my opinion. Best of luck

12-16-2005, 10:47 PM	#15
jrc Senior Member Join Date: Apr 2004 Location: NH Posts: 2,689 Thanks: 33 Thanked 439 Times in 249 Posts	Getting back to your original question, according to the Minnkota website most of there electric trolling motors draw 30-50 amps. So assuming you have a 12v motor (only one battery), that's 600 watts. One horse power is about 750 watts and those motors don't convert all the electrical power into prop power. So it's well less than one horsepower. Now if you a 24v or 36v motor you may get near one horsepower at the prop. A two horsepower gas outboard is 2HP at the prop. That said, unless weight or money is an issue, I would get a 5 HP. I think it's a better investment. If you move up to a slightly bigger boat you won't need to buy a bigger motor.

12-17-2005, 12:11 PM	#16
secondcurve Senior Member Join Date: Jan 2005 Posts: 2,084 Thanks: 1,267 Thanked 557 Times in 286 Posts	Thanks JRC: I appreciate your response it confirmed my assumption that my electric motor is in the range of 1hp or less. I also appreciate your recoomendation on the 5hp, but I am probably going to stick with the 2hp since all I do is put around the pond and fish. I have a 22 foot boat that is powered by a 2005 225 4-stroke Yamaha for the big lake, so I get my speed fix there. Now I just need to see if I can find a 2hp motor that is water cooled. Thanks!!!!!!!!!