Planing Problems

[DWNewt]

I have a 1977 Johnson on a 16" fiberglass deep v-hull boat. I have what is called a kickplate on the transom to raise and lower the engine. Problem is that when the engine is lowered in gear, I don't get planing power when I throttle the engine. When I put the engine in gear and increase the throttle, the engine slowly increases in power and the boat eventually planes out and runs. If I throttle and don't raise the engine, it sounds as if it is running very rough. I am not the original owner of the engine, purchased two years ago. When I purchased the motor, the aluminum prop blades looked a bit damaged. A mechanic grinded the blades smooth. I have cleaned the carbs and changed the plugs. Anybody have any idea what my problem could be?

 

[JB]

Re: Planing Problems

Read this, Tech Man: http://forums.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=28;t=036268 <br /><br />Then tell us what engine you have (model number).<br /><br />What is the max power rating of your boat?<br /><br />What rpm is the engine turning at top speed?<br /><br />What prop (pitch) is on it?<br /><br />You may be severely underpowered.<br /><br />You may have too much prop (pitch).<br /><br />You may have an engine with a dead cylinder.<br /><br />You may be using the engine lift and trim incorrectly.<br /><br />We need a lot more info to begin to eliminate some of those possibilities.<br /><br />Good luck.

 

[DWNewt]

Re: Planing Problems

Thanks, I'll do the best I can, Will pictures help? If so, I will attach with the post. You guys really help me a lot.

 

[DWNewt]

Re: Planing Problems

I did the compression check, cylinder #1 starting at the bottom was 105, #2 was 105, and #3 was 110. Serial #J0002197, Mod #75743S. I don't know anything about props except that a number stamped on it is 1123. At top speed I run about 30knts. Don't have a tach attached yet.

 

[JB]

Re: Planing Problems

Well, that's a start. We now know you have a 3 cylinder engine with good compression on all three. <br /><br />Model 75743S is a '77 Evinrude 75hp. Someone swapped a Johnny bonnet onto her?<br /><br />Without a tach reading or prop identification we can do nothing about possible over propping.<br /><br />Without knowledge of the boat's rating we don't know if you are underpowered or not, but it seems to me that 75hp should be enough for a 16 DV.<br /><br />If you are getting up on plane eventually I doubt that you have a dead cylinder, but it is the only thing left to explore.<br /><br />What happens if you pump the primer bulb while trying to get up on plane?<br /><br />What happens if you squirt a bit of fuel mix into each carb while running on plane?<br /><br />What happens if you disable each spark plug, one at a time, while idling on the muffs?

 

[Ron G]

Re: Planing Problems

Did you say and mean somebody took a grinder to your prop?that could have some effect also.