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Author Topic:   Re-powering a 15' with a 4-stroke
Highwater posted 07-12-2002 11:02 AM ET (US)   Profile for Highwater  
In my oinion, the 15' with a 70 hp 2-stroke seems perfect except that it is too loud. However, I do not believe that anyone makes a 70 hp 4-stroke. So the options are to get a 50 hp, weighing around 200 pounds (Honda) or a 60 hp, weighing around 245 pounds (Yamaha and Mercury) or a 75 or 80 hp, weighing 360-380 pounds (same as a 90 hp). And if you are going to use a jack plate when you re-power your stern will seem even heavier.

Some people have written that they are satisfied with 40 or 50 hp on a 15'. Has anyone been dissatisfied? I would hate to be underpowered. We like to ski and carry a heavy load.

george nagy posted 07-12-2002 11:06 AM ET (US)     Profile for george nagy  Send Email to george nagy     
Suzuki & it's clone johnson make a 70 4 stroke. Also yamaha makes a 60 4 stroke that weighs nearly the same as the 2 stroke. The 15' with more than 300 pounds on the stern is a bad idea I think.
Bigshot posted 07-12-2002 11:16 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I would do the Merc 60 EFI or wait until 03 and see if Yamaha goes EFI on their 60. It would be perfect. The 60 & 70 Zuki weigh 340lbs which is too much on a 15 unless mostly solo, etc.
Highwater posted 07-12-2002 11:17 AM ET (US)     Profile for Highwater    
So the options are:
50 hp Honda (205 lbs)
60 hp Yamaha & Mercury (245 lbs)
70 hp Suzuki & Johnson (335 lbs)
75 hp Honda (380 lbs)
80 hp Yamaha (360 lbs)
90 hp Honda (380 lbs)

Right? Seems like there is a need for a light-weight 70 hp 4-stroke engine.

Would I regret getting the 50 hp Honda? Would the 60 hp Yamaha and Mercury engines really provide c. 20% more power?

george nagy posted 07-12-2002 11:50 AM ET (US)     Profile for george nagy  Send Email to george nagy     
There may be one right around the corner for merc/yamaha.
The new 150 sport is rated for a max of 70 hp and we now know that BW only rates boats for what merc manufactures.
So the speculation remains that in 03 they maybe will have one. As for the weight who knows?
JBCornwell posted 07-12-2002 12:26 PM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
You overlooked the Johnson/Suzi EFI DF50, 245lb.

I do not believe that the Honda BF50 or Yamaha options you listed are EFI.

The Merc 60, I believe, is EFI.

If there is an EFI 4 stroke in the range I am looking for, I would not accept a carbed engine, even a Honda. EFI makes that much difference.

I agree that 300lb on a 15 is too much.

Red sky at night. . .
JB :)

Highwater posted 07-12-2002 05:34 PM ET (US)     Profile for Highwater    
Thanks, JB.

It sounds like from what you and Bigshot say, EFI is much preferable. I am fond of Honda because I have owned two Goldwings and they were wonderful machines. And the Honda 50 is only 205 pounds. But you are getting me thinking that maybe the Suzuki is the way to go. On the other hand, I may wait to see if someone will come out with a lightweight, 4-stroke 70 hp in 2003.


ShrimpBurrito posted 07-13-2002 12:49 AM ET (US)     Profile for ShrimpBurrito  Send Email to ShrimpBurrito     
Highwater -

I've got a 40hp Johnson on my 15' Super Sport. With a VRO, 12 gallons of fuel, and a 50 qt cooler full of water and crabs, I max out at ~44 MPH, by myself and in fairly calm waters. Have never tried pulling a skier, but 2 adults in the boat can easily give someone on a tube a good ride. Have also had 4 adults and 2 large dogs in the boat, and cruised at 20 MPH. Not sure what it would max out at with that load.

Highwater posted 07-13-2002 06:56 AM ET (US)     Profile for Highwater    
Did you get that speed from a GPS, ShrimpBurrito? According to , the 15' tops out at 28 mph with a 40 hp motor:

HORSEPOWER vs. SPEED (from 1977 Factory brochure)
20 HP = 20 MPH
35-40 HP = 28 MPH
50-55 HP = 34 MPH (exactly my observation--JWH)
65-70 HP = 42 MPH

jameso posted 07-13-2002 10:46 AM ET (US)     Profile for jameso  Send Email to jameso     
WOW! 44 with that engine, I have a 50 OMC on 15 sport with seat back, just me with no pacs and no cooler, 36/38. Recent tune up and new prop. This is better than the reference sections figures,,,Tell us your secret?
Jim Armstrong
ShrimpBurrito posted 07-13-2002 09:10 PM ET (US)     Profile for ShrimpBurrito  Send Email to ShrimpBurrito     
Hmmm......that measurement was with a Lowrance depthfinder with a speed/temp probe. I was in a bay, so I didn't bring the GPS. I was going in the same direction as the tide, but it was almost high tide, so the current shouldn't have been too strong. I'll take the GPS with me next time for a retest.
Highwater posted 07-14-2002 08:30 AM ET (US)     Profile for Highwater    
Thank you! I'm also interested to hear how the 40 and 50 hp motors perform when the 15' is carrying 1000 pounds. With the modified deep-V hull design, I would think that these engines would perform worse on a 15' than they would on a 13', and maybe even worse than they would on a Montauk.

I don't need to go 40 mph, but I do want to be able to go 25 mph at 80% throttle while carrying 1000 pounds of fuel, gear, and crew. Thanks!

skookum point posted 07-14-2002 03:21 PM ET (US)     Profile for skookum point  Send Email to skookum point     
My 15 with a 40hp Evinrude(1987) will go 31mph with a light load, 28mph with 3 people and gear(GPS). Cruising speed at 4200 rpm is 24 - 25 mph.
I think you'll need more hp for pulling waterskiers.
Highwater posted 07-14-2002 06:06 PM ET (US)     Profile for Highwater    
I'd hate to be underpowered. The 40 and 50 hp Honda 4-strokes weigh exactly the same (205 pounds) so I would definitely go with a 50 if I did buy a Honda. But Bigshot and JB have me thinking that the EFI engines are the way to go, so that makes the Mercury 60 the logical choice unless Yamaha or someone else comes out with a light-weight (under 250 lbs) EFI 4-stroke 60 or 70 hp engine in 2003.

Thanks for helping me think this through.


half shell posted 07-14-2002 07:21 PM ET (US)     Profile for half shell  Send Email to half shell     
Go with the Honda.I have a BF50 on my Montauk and it performs great.All day and have never used more than 10 gallons.Instant starts no smoke reliable and quiet.I have had it on this transom since 1996 and am more than satisfied.
However you will pay more for this than other 4 strokes .My thought is that its worth every penny.Good Luck in your search.
Highwater posted 07-14-2002 10:03 PM ET (US)     Profile for Highwater    
If the Honda outboard is anything like the engine in the Honda Goldwing motorcyle, I'm sold on it. I just wish it was EFI as I understand that carborators are yesterday's technology.

Do you have enough power with the 50 hp Honda to pull up a slalom skier?

Thanks! David.

Highwater posted 07-14-2002 10:06 PM ET (US)     Profile for Highwater    
I'm not sure that the Honda is the most expensive. I believe that the Mercury 4-stroke 60 hp EFI that Bigshot refers to is over $8000. I think that the Honda is closer to $6000.
jstachowiak posted 07-15-2002 09:16 AM ET (US)     Profile for jstachowiak  Send Email to jstachowiak     
Check out [Hyperlink]

Price for a Mercury 60 HP 4 Stroke Big Foot $5890.
Bass Pro Shops will beat that.
I priced out a 90 HP 4 stroke from Bass Pro and it is $5,500 plus install and controls.

Bigshot posted 07-15-2002 09:36 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Do NOT get a Big foot!

03's are out or should be by August. A call to each manufacturer should get you some answers. Bombardier is continuing with Suzuki's 340lb 60 & 70hp EFI's so the only ones remaining are Merc, Yamaha and Honda. Tohatsu/Nissan I doubt.

half shell posted 07-15-2002 08:37 PM ET (US)     Profile for half shell  Send Email to half shell     
Highwater I do not pull skiers so I have no idea what it takes to do that.However since 1996 the old carbs start first turn of the key.All I have done is change oil lube filter and lower unit oil.The carbs are untouched!
Also buy Honda prop for it is less money than the aftermarket ones.
FYI the F60 yamaha is less $ at my local dealer and is a good engine.
Good Luck in your engine selection.
Highwater posted 07-15-2002 10:06 PM ET (US)     Profile for Highwater    
What would be a good price for a 4-stroke 60 hp Yamaha with controls and a stainless steel propeller? I assume that power trim and tilt are standard.

If Honda would just come out with a light-weight 60 or 70 hp 4-stroke, I think that they could significantly improve their market share. The carborated engine doesn't bother me as much as the possibility that I will feel underpowered with the 50 hp.

lhg posted 07-16-2002 05:44 PM ET (US)     Profile for lhg    
For a Classic 15, if you look at weight, HP, cost and EFI technology, as mentioned above the Merc 60 EFI has the market to itself until the other guys catch up. Considering the Yamaha/Merc cooperation these days, if the Yamaha 60 gets EFI next year, it will probably be Merc's system.
half shell posted 07-16-2002 06:39 PM ET (US)     Profile for half shell  Send Email to half shell     
Update.I heard from the guys at the marina that Honda was running a special on the BF 50 at 5500.00 plus installation etc.My last look at the Yamaha F60 was around 6100.00 plus plus etc.Check if the 15 can handle 212# on the transom .
JBCornwell posted 07-16-2002 08:05 PM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     

I don't agree that the Merc 60 "has the market to itself." Order one and watch the Merc sales people try to shove a Bigfoot down your throat. Does it have a midrange torque problem that only the bigfoot can tolerate? Why else push a 'toon engine for a lightweight, fast boat?

There is no question that the 15 can handle 250lb on the transom. It was designed to use the 250lb OMC triple 70.

What is the prejudice that makes you guys, including Bigshot (!!), continue to ignore the John/Suzi EFI 50?

Granted, I have an aversion to Merc marketing tactics, but my choice would still be the Johnson 4 stroke EFI 50.

Red sky at night. . .
JB :)

JBCornwell posted 07-16-2002 08:08 PM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
Oh, for an edit function.

Replace ". . . continue to ignore the John/Suzi DF50?"

With "continue to exclude the John/Suzi DF50?"

ShrimpBurrito posted 07-16-2002 08:08 PM ET (US)     Profile for ShrimpBurrito  Send Email to ShrimpBurrito     
Don't forget, outboards are alot cheaper in Canada than in the U.S. I called a Honda dealer in BC a few months ago, and a 50 HP engine was ~USD$4200-$4400. Installation was something like $150. For any Honda engine purchased anywhere in North America, Honda will do warranty work anywhere in North America. However, if you buy in Canada and request service in the U.S., you might get the "I'll get to it in a few weeks" response. Then again, the warranty is only 2 yrs, and I wouldn't expect any service on a Honda engine until way after that.
half shell posted 07-16-2002 08:32 PM ET (US)     Profile for half shell  Send Email to half shell     
JB I didnt even know that Johnson made a 4 stroke.Other than the carb or the fix I mean the Ficht I just wasnt aware of the Johnson 4 stroke option.When you find an engine like the Honda you just stick with it.However it could shed a few #.
Highwater posted 07-16-2002 10:06 PM ET (US)     Profile for Highwater    
There is no weight problem with anyone's 50 hp 4-stroke (including Honda's). At 205-212 lbs, their weight is ideal. The question is, if you are use to having a 70 hp 2-stroke, will you feel underpowered with a 50? My concern is that a 50 hp motor may not be appropriate for someone who wants to carry 1000 pounds or who wants a good hole shot for water skiing.

I'm hoping that someone with a 50 hp motor on a 15 sport will tell us that the boat has no problem pulling up a slalom skier with three adults and 12 gallons of fuel in the boat.

Boston Marine posted 07-16-2002 11:33 PM ET (US)     Profile for Boston Marine    
Take a look at a 1978 Official spec sheet from BW.
Heres the link

Highwater posted 07-17-2002 12:28 AM ET (US)     Profile for Highwater    
Boston Marine,

Thanks for the link to your impressive website and Boston Whaler's 1978 estimate of the max speed of its boats with various engines installed. I believe that Jim uses the same figures in the continuouswave reference section (which I pasted into this thread, above). We have established that with 50-55 hp, the 15' sport will top out at 34 mph (unless Shrimpburrito gets new data with a GPS). What we don't know is how the boat will perform with this horsepower under a heavy load.

I believe that Clark Roberts mentioned a while back that his 15' with a 40 was a good boat for 2 or maybe 3 people, but with 4 or 5 people on board, he was underpowered. I believe that since then he has re-powered with more horsepower. Right?


Boston Marine posted 07-17-2002 12:30 AM ET (US)     Profile for Boston Marine    
The 15 on my site posted a 47.*** mph on gps trimmed very high,me only,full 6 gal tank.
JBCornwell posted 07-17-2002 01:02 AM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
For the Johnson/Suzuki EFI DF50 to shed a few pounds it would have to become carbureted, like the Honda.

I'm not knocking the Honda, mind you, it is a very good engine for obsolete technology.

If you never heard of the DF50, you obviously haven't read the thread and are not prepared to intelligenly discuss the options.

BTW, I have a 1996 Johnson 10hp 4 stroke engine as well as Suzi DF70.

Red sky at night. . .
JB :)

Clark Roberts posted 07-17-2002 07:49 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
HighWater is correct that my 15 with 40 (4 cyl) Merc was good for up to 3 people. I would guess that for skiing a 40/50, even if propped with a very low pitch, would not be very good... maybe for a couple of kids ok. but not for adults... Happy Whalin'... Clark... Spruce Creek Navy
jameso posted 07-17-2002 09:15 AM ET (US)     Profile for jameso  Send Email to jameso     
If you MUST have 1000# of people and gear on board and do a lot of skiing keep the HP above 50. While the 15 is a great hull it does need the power to get the hull lifted to it's best performance range. IMHO a 60-70 with correct prop weighing 200-25 lbs would be ideal.
My 02, Jim Armstrong
george nagy posted 07-17-2002 09:17 AM ET (US)     Profile for george nagy  Send Email to george nagy     

I grew out of my teens into my early twenties in a 15' sport with a 3 cyl 70 hp 2 stroke evinrude. I will admit that the engine was well abused over the years but I'm not sure I would go for anything less than at least 60 hp.
The performance would greatly decline when people were added. We did a fair amont of "hydrosliding" and "wakeboarding" behind that boat and as we got older (bigger) we really started to pull the stern when crossing the wake.
One thing I can tell you that now if I had the boat I would consider the yamaha/ merc 60 4 stroke, but I would research them further. I would probably even consider getting a great deal on 70 yamaha 2 stroke.

Be careful with the 50 hp I think it may be too little.

Bigshot posted 07-17-2002 10:00 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I had a 15 with a 48spl and it moved pretty good but nothing like my 60 2cyl or 70 3cyl Johnsons. I would do the 60 Merc. Although JB is trying his best to sell the 50 John/Zuki I would disagree. If hell bent on a 50 then yes it reigns supreme due to EFI Etc. But since you have a 70 the 50 will be lackluster. It should do more than 34 with a 50 being a Montauk will do 34-35. I say the 60 Merc would bring you into the low 40's and 4 strokes have more torque so loads and skiing will be fine. $ strokes feel slower out of the hole(they are) but what is amazing is that they will do the same holeshot with 5 people or 1.
Highwater posted 07-17-2002 10:12 AM ET (US)     Profile for Highwater    
I want to intelligently discuss the options, JB, so please don't give up on me. When you say, "if you have not read the thread...," are you referring to ?

I was just offered $1000 for my 1987 70 hp Nissan 2-stroke and I told the gentleman that I would get back to him today. From everyone's input, I think that I will keep it another year. I like to run it wide open and would be dissatisfied with less power. I have a 42 gallon Pate tank under the back row of seats, a family of four, and camping gear so I think I need to re-power with 70 hp. Please let me know if you hear of any light-weight 70-90 hp 4-stroke engines in the making. Thanks!

JBCornwell posted 07-17-2002 10:43 AM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
Hey, Highwater.

My remark about discussing the options was directed at the statement that Half Shell didn't even know that the DF50 existed.

I was referring to reading this thread, where the Johnson/Suzuki option had already been offered.

Except that I have an anti-Merc prejudice I have to agree with Bigshot on the EFI 60.

However, I caution you not to fall in love with HP. Torque is what makes the boat go, and other things being more or less equal, cubic inches are the dominant factor in making torque.

The Johnny is 49.7 cu. in. so it is not highly stressed making 50hp. The Honda is about the same and the Yamaha is 57 cu. in. I don't know what the displacement of the Merc is.

Red sky at night. . .
JB :)

Bigshot posted 07-17-2002 11:24 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
You have a 70 Nissan......different story. From what I have gathered here the 70 Nissan is kinda anemic in power. Some were saying with "new" they were only getting maybe 40mph. Being a $1000 offer.....not bad, but you will get a better deal in the fall on a leftover. Find a deal in FL and make a tri[p down in the winter when prices are good and weather is awesome & pick it up.
Highwater posted 07-17-2002 11:53 AM ET (US)     Profile for Highwater    
Sounds like a good plan, Nick. I will be installing a jackplate at the same time (as suggested by Clark Roberts et al).

I do not have confidence with any here in NC to do the installation. Can you refer me to someone in Florida? Or maybe I could pay you a couple of hundred dollars and you could help me do it one Saturday? :)

Bigshot posted 07-17-2002 12:11 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
You buy one near me and the dealer should at least hand it on the transom for free. So have the plate installed. Just as easy for them to lift it into a truck as it is to lift it onto a transom. The rigging on a 15' should take no time at all. The montauk is a bit worse with the tunnel and console, etc.
Highwater posted 07-17-2002 12:45 PM ET (US)     Profile for Highwater    
Bigshot, What is the name of that store in Florida that had the Suzuki DF 70s for sale? Maybe they have good prices on other engines, too. Didn't you say in another thread that you knew a place to get last year's DF 70 for $5500?
Bigshot posted 07-17-2002 01:15 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Was a 2000 for $4500. Some place near Miami but I have no clue anymore. Check E-Bay. dealers will sell new-old stock there frequently.
half shell posted 07-18-2002 07:58 PM ET (US)     Profile for half shell  Send Email to half shell     
JB you have to admit the last few years have not been kind to Evinrude or Johnson.I cannot find a reputable dealer in my area and availibility non existant.So forgive me for not knowing about a DF 70 or for caring to know.If the brand does not interest me I will not research it.Price availibility reliability whatever.

Besides I was not discussing engine brands or comparing just stating my preference.

If your happy with your brand great.I wish you the best of luck with your choice.

ShrimpBurrito posted 09-08-2002 10:57 PM ET (US)     Profile for ShrimpBurrito  Send Email to ShrimpBurrito     
Ok, I finally got all the wood in my 15' SS done and the boat is back in the water. I had an opportunity to go out today in some decent water to verify the speed on the Garmin GPS. With me (230 lbs), 10 gallons of fuel (60 lbs), anchor, VRO, battery, and ~30 lbs of other miscellanous stuff, with a 1986 40 HP Johnson, I maxed out at 36 MPH. The water was calm, but I might be able to get it to maybe 38 MPH if the water was like glass. I raised the seats and console during the wood refinish, so there is also some added weight from the additional wood (maybe 15 lbs).

These readings are considerably lower than my previous depthfinder readings (not surprisingly), but substantially higher than that posted in the ContinuousWave Reference section (also listed above).

David Jenkins posted 09-08-2002 11:14 PM ET (US)     Profile for David Jenkins  Send Email to David Jenkins     
That's an amazing motor, ShrimpBurrito. However, I imagine that performance will go down significantly as you add additional passengers and pull a skier. That's when more horsepower is essential.
ShrimpBurrito posted 09-09-2002 12:09 AM ET (US)     Profile for ShrimpBurrito  Send Email to ShrimpBurrito     
Yea, I doubt it would be adequate to pull a skier once you have 3 people and a cooler aboard. Not sure why it goes so much faster than what it's supposed to.....

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