I'm about to over power my boat with a Johnson.

[Home Cookin']

Re: I'm about to over power my boat with a Johnson.

You asked for it: consider this just one more negative comment.

Don't.

 

[kenmyfam]

Re: I'm about to over power my boat with a Johnson.

50hp to 115hp is a big jump i recently brought a boat 17 foot runabout it had a 135hp evinrude on it yikes!!!!!!! i have down graded to a 70hp as i personally think the engine was way over the boats limit i never took the boat out while it had the 135hp on it i thought that was the most sensable thing to do nothing worse than hearing a loud crack at WOT to see your motor going faster than your boat
good luck

My 17ft Doral is rated at 140HP max and that is what we have on it. It is 24 years old now and the transom is as solid as the day it was made.
Would I put a bigger motor on it ?? No Way. Do I use that motor to it's full capability all the time.....No....Is it reassuring to know you can use it if you need to ??? Absolutely.
If a transom is on it's way out then it is just a question of time no matter what is hanging on the back. But back to the theme of the original poster I still stand by never exceeding the boats rated capacity with either motor or loading.
But that is just my 2 cents.

 

[bob johnson]

Re: I'm about to over power my boat with a Johnson.

COMMERCIAL BOATS HAVE NO RATINGS.... and they drive past all you guys time and again, but you dont seem worried.

Id be more worried about an 18 foot bass boat with a 600lb-800lb!!!! 300 hp outboard hanging off the back of a 12" setback jackplate.

the top of the transoms of many of those boats are even with the water when at rest!!!!!

I have no idea if this 16 foot boat can really handle a 115 hp , either the force or the weight...

but I think many of the numbers are arbitrary....

I bought a tiller model 20.5 foot boat that was rated for 60 hp only. the same boat( same transom) but with a rear deck..( but no more bracing!! just rivets and small screws holding the decking to the transom) in a center console version, is rated for 115 hp!!!

I added a center console myself!!! added bracing for the floor to the sides and to the transom.... and hung a 115 hp on it....

I can get a four stroke 60 that weighs as much as a 2 stroke 115....

so we have to figure the weight isnt the issue....

same goes for the 80 hp in four stroke vs the OPs 2 stroke 115 hp.

I am not saying lets forget hp limit tags......but lets understand how and why the makers come up with these numbers!!

bob

 

[Lion hunter]

Re: I'm about to over power my boat with a Johnson.

Tiller models are always rated less that console. They have to figure 1 person in the boat and where they will be. So you may have been correct how you did it. But he is talking about taking a console boat and increasing it by 50%.

Commercial boats may not be rated but I'd bet most carry at least a million or more in liabilty. Haven't seen to many 16' commerial boats.

As said earlier it's not all about the weight. It's the torque on the transom as well.

I agree there is a safety and liabilty factor built into hull ratings. But what are they? No one knows and unless you get a maker to tell you you don't know if a 5hp will be it or a 50 hp increase. I guess you find out when an out board is dragging by the cables trying to jump back in the boat.

Like I said earlier when someone ventures into this they are kinda on their own. Not very prudent to offer advice on something like this.

 

[bob johnson]

Re: I'm about to over power my boat with a Johnson.

I found on a tidal mussle bed a huge stainless steel propeller. it was still on the spline and had a lot of lower unit gearing and parts still on the spline as well behind the prop.

it was laying in front of this 5 foot shear almost square rock on the mussle bed. there were about four other large boulders in a foot ball sized area...

but other wise nice and flat on the depth finder!!!


a boat with the max rated outboard on the back that hit this rock with enough force to rip the prop and guts out of the lower unit....has to be more force than "extra" hp on the back!!

just putting things in perspective.... and yes maybe playing the devils advocate...

of course who knows what happend to the boat...

at the least the driver lost a few teeth huh??

bob

 

[ilovefroggin]

Re: I'm about to over power my boat with a Johnson.

I found on a tidal mussle bed a huge stainless steel propeller. it was still on the spline and had a lot of lower unit gearing and parts still on the spline as well behind the prop.

it was laying in front of this 5 foot shear almost square rock on the mussle bed. there were about four other large boulders in a foot ball sized area...

but other wise nice and flat on the depth finder!!!


a boat with the max rated outboard on the back that hit this rock with enough force to rip the prop and guts out of the lower unit....has to be more force than "extra" hp on the back!!

just putting things in perspective.... and yes maybe playing the devils advocate...

of course who knows what happend to the boat...

at the least the driver lost a few teeth huh??

bob

What does driving where you should not drive have to do with over powering your boat?

 

[bob johnson]

Re: I'm about to over power my boat with a Johnson.

What does driving where you should not drive have to do with over powering your boat?

you cant figure it out?

safety margins...

people worry about things that have a 2% chance of causing them trouble and ignore things that have a 25% chance of happening..

dont ask me to explain that one please

buenos noche!

bob

 

[rspar]

Re: I'm about to over power my boat with a Johnson.

I dunno a big block in a chevette sounds good to me.

 

[Lion hunter]

Re: I'm about to over power my boat with a Johnson.

people worry about things that have a 2% chance of causing them trouble and ignore things that have a 25% chance of happening..

Yes we do, it's probably human nature. You've just got to weigh the consequences of what might happen against the action and decide for yourself if it's worth it. I done a lot of stupid stuff and didn't need any help from any one to do it. I managed to screw it up all on my own. But, when it went bad it was my fault.

My dad told me not to put the 350 in the Courier. I didn't listen. After the 1st test drive I figured there might be a little to much twist so I chained the block to the frame on the drivers side. 1st time I raced it the top of the motor came through the hood. Should have used better chain .

 

[tal]

Re: I'm about to over power my boat with a Johnson.

I thought I'd post a follow up on what I did. I ended up scoring an 85 120hp for cheap. I went through the carbs, new fuel line, sealed the lower case and installed it in place of the little 50hp yamaha. Recent posts I've made have usually been about working on this engine. Since the transom of the boat is still in good condition the extra weight/twist from the bigger motor doesn't appear to be causing any harm.

Test ran with 2 6 gallon plastic fuel tanks. Never used up the first 6 gallons I was hooked to and ran a 30 mile round trip. I'm averaging at least 5 mpg with this old looper on my 16ft boat. This is equally as good, if not better than what I was getting with the little yamaha. Mainly because it took everything the little 50 had to get up and going and cruise, usually running about 3/4 throttle. I did do a few WOT runs with the Johnson, turning a little over 6000rpms with a 21 pitch prop hitting a peak of 64mph on 1 of the full throttle runs I did. I could use a higher pitch but don't really need anymore speed.

The boat does sit a little lower in the back and will take a little splash over if I come off the throttle hard. Coming off normal doesn't seem to take any splash. Testing was done with 2 passengers(160lbs,180lbs), 12 gallons of gas, 140 piece tool set, 1 tackle box, 1 small ice chest, front live well full of water. Speed/mileage were not GPS certified. I have an older Raytheon fish finder with the paddle wheel that does speed and logs miles driven on trip. Always been pretty accurate in the past though. No fishing poles on this trip, but those don't weigh much.

 

[BWR1953]

Re: I'm about to over power my boat with a Johnson.

Now we need pix and videos!

 

[Ironsides]

gone...