First day out: Performance issue

[MAXXIE]

1st time boater, 1st time out. 16' 1985 Bayliner bowrider w/ 85HP Force O/B. WOT- 3600 RPM & 21MPH (GPS). That's the max RPM & speed it could muster. The only real issue I did notice, again 1st timer, is the vent on the fuel tank was never opened & it was all sucked in from the fuel pressure. It's a 6 gallon plastic tank. Could this have been the problem? I did not notice until it was back on the trailer & I was checking to make sure there was nothing in the boat that could blow out on the road, that's when I saw it, other wise I would have put back in & tried it again. The weather looks to be OK for today & I will be going back to the lake in a little while to give it another go. Any advice? I have a manual trim with 4 settings, prev. owner had it in highest hole & I moved it down to #3 hole before I put in. Would 1 hole, about 1/4" make that much of a difference or is it the fuel tank? Help! Thanks for comments.....

 

[RWilson2526]

Re: First day out: Performance issue

fuel tank would be my guess....give it another go with the vent open before looking elsewhere.

 

[95cajun]

Re: First day out: Performance issue

I've been having he'll with my "new" boat too. Does your jump up on plane? Or does it sit a little low in back and nose up? I can tell you that letting the motor trim all the way down. This is the position to take off in then trim it up untill your rpm's are right (5000 or so) and you have a reasonable ride. Your going to have to play with it until you get it the best you can. Raise it two notches and take it out. When you jump on the throttle you should get the bow up an motor down then as your speed picks up you will rise up out or the water and the bow should drop and your rpm's will climb. Then repeat one notch at a time till you notice the motor trying to overrev. Then drop back down one notch. Then try it in rough and in some tight turn making sure it doesn't cavitate (begin to overrev) you should notice that sweet spot between a good take off and good top end performance. You will find what you like. Btw this is assuning that your motor run good and the pitch on your prop is right! Does sound like you have problems with your fuel system!

 

[MAXXIE]

Re: First day out: Performance issue

I found the problem, spark plug boot was off on the top cylinder. The boot was bad & had electrical tape on it. I did not know this. When I first hammered the gas I could have sworn the RPM went higher for a few seconds & then never got them up again....the boot popped off & I didn't know it. Took it out yesterday & ran 5000 RPM @ 35 Mph (GPS), happy with that for now. I'm sure the "Fin" on the lower unit is slowing things down a bit, but it jumps right up on plane with no plow time. As soon as I hit the gas it go's right up on plane. I'll keep the fin until I get Smart Tabs.

 

[DuckHunterJon]

Re: First day out: Performance issue

Don't feel bad, I drove a snowmobile for an entire winter with a bad spark plug boot (looked fine, but broke internally). It was a tripple, and I thought it had plenty of power running on two cylinders (previous sled had about 1/4 the HP of this one). Doing some maintenance on it in the spring, I noticed a spark plug was in terrible shape, found the cracked boot, fixed it, and had a rocket ship the next winter.

Glad you got it fixed quick and cheap! Enjoy.

 

[180shabah]

Re: First day out: Performance issue

maxxie - don't ditch the "fin" yet. You have an OB, which means you can raise the engine so that the 'foil is OUT of the water while on plane.

If the fin is already out of the water while on plane, it is NOT slowing you down. If it is still in the water while on plane you need to raise the motor height, and will gain more speed.

 

[Utahboatnut]

Re: First day out: Performance issue

In addition trim tabs seem to be alot of expence and time to mount on a 16' boat. I would think a well tuned motor, correct motor height, and the right prop for YOUR needs, would be all thats needed for that small of a rig.

 

[Bayliner Customer Service]

Re: First day out: Performance issue

Based on the information you provided the vent screw on the top of the tank is closed and the tank cannot vent. This alone can stop the fuel from flowing to the engine.

Secondly, the standard tilt pin location should be the second hole out from the transom on the bracket. The first hole will work better for pulling skiers or with heavier passenger loads near the stern of the boat. The first pin location makes the boat plane out quicker and it forces the nose of the boat down.

Bayliner Customer Service

 

[95cajun]

Re: First day out: Performance issue

If she jumps up on plane that fast you might be able to add some pitch with another prop and gain speed! Do you have to back out of the throttle to keep it at 5000 or is this your max rpm all out?