Looking for a used outboard wondering about "overpowering"

[rrkyle]

I have a 17 ft aluminum bass tracker that is rated for 70 hp.

I am looking at putting a new motor on and have come across some 85 and 90 hp motors.

Has anybody done this?
I am wondering if this would actually be dangerous?

The reason i have this question is i would like to also tube/kneeboard behind my boat.

And the other thing is i am an ex college football player as are most of the guys i still fish with and we are all at or above about 250, which is well over average size.

Im just wondering if it would be safe or not to put an 85 or 90 on the back because at minimum there will almost always be 500 lbs of passenger in the boat.

 

[CATransplant]

Re: Looking for a used outboard wondering about "overpowering"

Stick with the manufacturer's max hp rating. Seriously. It should perform just fine for you, and you won't risk overpowering.

 

[Home Cookin']

Re: Looking for a used outboard wondering about "overpowering"

agreed. don't use HP to compensate for weight; use hull size. IN other words, instead of adding 20 HP add 2 feet.
Freeboard is a big factor.
Consider this, also. you have a lightweight flat bottom boat. The load on the tube and even moreso, the kneeboard, will pull the boat around a lot. Getting up out of the hole will be a little bit of a problem--although I use a 17' fiberglass with a 70 for watersports and it does fine, although I don't have as much beef on board.

As many posts before have said, overpowering leads to many problems.

 

[kenmyfam]

Re: Looking for a used outboard wondering about "overpowering"

You are adding further weight by putting a bigger motor on it as well as the "bigger" passengers.
Stick with the manufacturers max rating.
My 2 cents.

 

[4JawChuck]

Re: Looking for a used outboard wondering about "overpowering"

I have a 90Hp on my 80Hp rated 16' boat now, its still not fast enough so I just bought a 200Hp motor but I need to reinforce the transom and tie the stringers in to make sure its strong enough.

All depends on if you can afford the insurance really, after the floor gets ripped out and the transom is done I will be registering the boat as a homebuilt. The US laws are completely different though, you can get a ticket for overpowering your boat down south...here in Canada we just pay higher insurance rates based on length of boat and HP.

Unless you know what your doing I wouldn't do it, my boat with the 90HP does 50 mph now which is plenty fast for the average person. This is a delicate subject on the board as the official line on I-Boats is don't do it, but lots or people do and the world doesn't end.

Its your life, act as if you are responsible for it.

 

[rrkyle]

Re: Looking for a used outboard wondering about "overpowering"

Thanks for all the input.

The boat is a semi v it doesnt have a flat bottom.

I think i am going to stick with the recommended 70 but i am in negotiations with a guy who has a Johnson 75 so i may go a little over.

Ive been reading alot of posts on the forum and i agree now that it would be safe not to put a 90 back there. Thanks for the input everybody

 

[rrkyle]

Re: Looking for a used outboard wondering about "overpowering"

Also just wanna add in that i post in a couple forums about my car and I wish that i got replies as quickly and informative as i do here.

Iboats is the best source of knowledge ive found about all water related activities.

 

[ezmobee]

Re: Looking for a used outboard wondering about "overpowering"

i think a 70/75 would be a great engine for your boat. They have some of the best HP/weight ratios of any motor you can get. You should be pleased.

 

[Reel Kahuna]

Re: Looking for a used outboard wondering about "overpowering"

I just bought a 150hp Yamaha yesterday for my 20' cuddy. The motor was on a 16' tri-hull (way over powered) that the seller and I took on a lake to test the motor. It was somewhat comical when he accelerated and the bow shot almost straight up that I had to move to the front of the boat so that it would get on plane . BTW I bought the motor.

 

[JimS123]

Re: Looking for a used outboard wondering about "overpowering"

I have a 90Hp on my 80Hp rated 16' boat now, its still not fast enough so I just bought a 200Hp motor but I need to reinforce the transom and tie the stringers in to make sure its strong enough.

All depends on if you can afford the insurance really, after the floor gets ripped out and the transom is done I will be registering the boat as a homebuilt. The US laws are completely different though, you can get a ticket for overpowering your boat down south...here in Canada we just pay higher insurance rates based on length of boat and HP.

Unless you know what your doing I wouldn't do it, my boat with the 90HP does 50 mph now which is plenty fast for the average person. This is a delicate subject on the board as the official line on I-Boats is don't do it, but lots or people do and the world doesn't end.

Its your life, act as if you are responsible for it.

EDIT
I realize your advice is only an opinion, but I hope nobody else heeds it!

Second Edit. I apologize if I was insensitive. It was not my opinion, it was sarcasm. It was also to point out that being irresposible can cause a never ending nightmare.

 

[diesel5599]

Re: Looking for a used outboard wondering about "overpowering"

You might want to read this thread before overpowering by even 1HP. And to 4JawChuck that's insane, I have a feeling we'll be seeing you on the news sometime soon and as the camera pans across the accident scene everyone will be wondering how a boat could have ended up in that position.

http://forums.iboats.com/showthread.php?t=204174

 

[4JawChuck]

Re: Looking for a used outboard wondering about "overpowering"

I think its kinda comical when a guy builds a 800hp BBC for his Vega with huge slicks and everyone thinks its cool but overpower a boat by 100HP and he is automatically crazy. BTW the weight difference between the 200HP Merc and the 90HP merc is only 113pds which is almost exactly the weight of my dual batts in the rear.

A wise police officer once said to me while writing me a ticket, "with great power comes great responsibility". Truer words could not have been said, never had a ticket since.

I don't recommend it for everyone, heck most people have trouble controlling their Honda Minivans without flipping them over or blaming their inability to handle or control a vehicle on sticking throttles or sliding floor mats.

You don't enter any re-engineering adventure without doing your research and knowing the limitations of your vehicle and your abilities. My intention is to be able to cruise at 65mph at partial throttle (where fuel economy is best) and will be limiting the top speed of the boat with prop pitch (25"). One of the things I found out with boats is running at part throttle is way more efficient than running WOT, if you do the math a larger engine running at a lower rpm can get higher fuel economy than a smaller motor running WOT where the mixtures are rich and loads are maxed.

Its not for the average person, just like owning an ultralight tunnel hull or pad equipped bass boat with a 300XS on the back. Are these people crazy? Are they less responsible than the guy who owns a 12ft duck boat with a 9.9 on the back who ventures out onto a big lake before a storm? What about the ultralight aircraft owner who builds it in his garage?

Its just a different level of dedication, danger is perceived and perception is often wrong...especially if it makes you feel safe.

http://www.youtube.com/watch?v=C-dlAZ9L4d0

http://www.youtube.com/watch?v=D0sqKIjoUcw&feature=fvw

Have fun out there!