Boat to small Motor to BIG

[cordell]

Hello, I have a 15 foot Nylox boat. The boat is fiberglass and has a 24 inch transom that has had about 4 inches cut out for the motor making it 20 inches at the outboard. My best guess is the year my boat was made is 1960, I bought it with a 1960 Johnson 40 horse that I got to run. I also bought a Force 1987 85 horse that I put behind the boat. Well here is where it gets interesting. I took it out with the wife and hit WOT with the 85 and was flying!! Very happy I took it out again with kids and another adult on board, this time WOT was hard to control and water filled up in the motors leg and bubbled into the boat, also more water seemed to find its way into the back as well. I slowed down and my problem went away. The boat has NO splash guard that I plan to make but my biggest concern is the size of the motor for the boat. The hull seems in good shape out of the water I stand on the whale tail and bounce around causing the transom to flex a bit, though not much. No cracking sounds when I do this either. The bottom of my boat if flat then up around the steering it starts to V out towards the front so I guess it is called flat bottom? I did find an old add online that shows my boat with a Merc 1000, that is 100 horse, so my 85 should be OK, right? I hope someone here has owned a Nylox or has some insite on one, the last thing I want is a sinking boat!!

thanks,

cordell


I also want to add that at the widest point by the steering the boat is 6 foot across and the narrowest point by the transom it is only 55 inches! And I do have an aluminum plate for the motor at the transom...

 

[erikgreen]

Re: Boat to small Motor to BIG

I am not an outboard person and I don't know what the specs are for that boat, but gut feeling says that 85 horse engine's too big for that boat.


But the thing I'm really posting to say is to check your transom again. It should not flex AT ALL. No cracking is good, but that's a secondary symptom of problems. Really it does need to be stiff, and if it's not look for rot.

Erik

 

[JCF350]

Re: Boat to small Motor to BIG

Has that 85hp a long or a short shaft?

 

[BigB9000]

Re: Boat to small Motor to BIG

Sounds a lot like my boat,

a 1965 15' fiberglass with 24 inch transom then the 4 inches making it 20 inches, and The bottom its flat then it starts to V out at the front...

mine says 40hp max, with a compasity of 600lbs.

i have a 20hp on it and its fine

 

[tashasdaddy]

Re: Boat to small Motor to BIG

you will find the formula to the max rating for you boat here:

http://forums.iboats.com/showthread.php?t=191283

 

[cordell]

Re: Boat to small Motor to BIG

BigB9000 it looks atlot like your boat! The motor is long shaft, I have been looking around for another hull. I was worried yesterday about the motor ripping the boat apart. I did not try to WOT with 5 people in there though half WOT was fast enough! Thanks everyone for your input, keep it coming.

cordell

 

[wbeaton]

Re: Boat to small Motor to BIG

Here's my not-so-helpful opinion...if it came with a 40 hp then that's probably not too far off the mark for what that boat should run.

 

[JCF350]

Re: Boat to small Motor to BIG

BigB9000 it looks atlot like your boat! The motor is long shaft, I have been looking around for another hull. I was worried yesterday about the motor ripping the boat apart. I did not try to WOT with 5 people in there though half WOT was fast enough! Thanks everyone for your input, keep it coming.

cordell

2 choices, raise your transom back up or find a short shaft motor. The water is climbing up the front of the exhaust leg and pushing the water into the boat the faster you go the higher the water will climb. I've noticed this with the Force/Chrysler outboard exhaust legs in the past.

 

[cordell]

Re: Boat to small Motor to BIG

With the math I came up with 60 HP. This is 25 less than what I have. I have now decided to locate a bigger hull, I just redid the floor and put down carpet. Added 2 back to back seats, you get the picture. Countless hours and lots of money! The reason I will be looking for a new hull is I cant part with the motor. I got this 85 horse for a awesome deal and the 40 Johnson that came with the boat I had gotten running in idle but needed rebuild and carb adjustment for fast idle, motor just bogged out. I have the parts but ran into my 85 horse before tempting the rebuild. If you seen the ol sea horse you would understand why I wont go back and try to make it work. The motor is beaten over and over again. When I drained the LU the oil was like a tan milk. Who knows what is going on in that LU. Thanks for the help everyone!!! :]

 

[beerfilter]

Re: Boat to small Motor to BIG

Holy CRAP !
That Force is the proverbial tornado strapped to a wash tub .

IMO , fix that Johnny .
You can still get all the parts for it you need , unlike the Force , which was orphaned by Merc .