Just bought new motor....

[pugstori]

I just bought a Yamaha 8hp for my 11 foot (145 lbs) fishing boat and I have two small problems. First, the transom is slanted inward from the top to the bottom so the engine sits at an angle. I can run it in the "shallow water" tilt position and it runs fine. I am wondering if this is o.k. or if I should try to build up the back of the boat to straighten out the angle and run it in the normal position?? <br /><br />Second, when I am alone in the boat it will plane out and runs great (the bow is pretty high though) but with a person in front the boat it will not plane out. It feels like it wants to plane at about 1/2 throttle but the power will not increase from there. It feels like the boat almost goes faster at 1/2 throttle than at full throttle. I have tried shifting weight toward the bow but I still can't get it to plane. Any ideas??? I would be grateful. Thanks.

 

[JB]

Re: Just bought new motor....

Howdy. Is it possible your boat isn't intended to plane? Tell me about the shape of the hull, the type bottom, etc. It is possible to plane a displacement hull, but it is a little like making a barn door fly.<br /><br />"Normal" position of the motor should be with the anti-ventilation plate (usually called the cavitation plate) level with, and parallel with the keel, or bottom, of the boat. Your description of the performance sounds as though it is still tilted "in".<br /><br />You should have several options in setting the engine angle and ideally use the middle one to get "normal" position. You might make up a couple of wedges for your transom to allow this. If she still balks at planing with two aboard, tilt it out one notch and try again.<br /><br />Eight HP isn't very much for planing even a very light boat only 11' long. For a given weight, the longer the boat the faster. . . that's why those hot rod bass boats have those huge engines set back as much as a foot behind the transom to go 80mph.<br /><br />Check out the above and let us know.<br /><br />Good luck.<br />JB

 

[pugstori]

Re: Just bought new motor....

Hi JB...the hull of the boat is concave in front and the bottom is smooth with 1" ridges about 12" apart. I need to check the cavitation plate. The top of the transom is 17 1/2" from the bottom of the boat. I thought about a 20" shaft for it but I called the manufacturer about it and they said that it was designed for a 15" shaft...so that's what I bought. <br /><br />The boat will plane with just me, when I have the motor tilted, but the bow is a bit high and it sounds like the prop may sometimes come out of the water (it actually moves pretty well). I will check the tilt settings when I go back to the mountains this week and let you know. I don't care too much about going fast but it sounds like the engine struggles after 1/2 throttle...almost likes it's pushing a "barge" and wants to go faster. The manufacturer has a website, www.klindustries.com. My boat is the Pro 110. You can see what I mean about the engine angle from the picture on the web. She ain't much, but she's comfortable and great for fishing the mountain lakes. Thanks for your input. I look forward to hearing from you.