Need help with motor location.

[shelbert]

Hi, I recently put a long shaft 28 horse Evinrude on my 1968 13ft boston whaler. It is manual tilt on it and set up for cable steering. After reading alot of the post on the board I added a jackplate to raise the vent plate to about even with the bottom of the boat (The measurement on the boat is about 17.5 inches, the motor is actually 21 inches to vent plate). <br /><br />The Problem I have with the boat is it planes out pretty slow( i would say 8-10 sec) and throws dual rooster tails about 20 ft behind the boat after it planes. It also seems to drag a little. The boat also comes out of plain pretty fast if I get below 3/4 throttle.<br /><br />The boat weight was pretty heavy in the back and I am not the smallest man on the lake, so I tried relocating the weight up front to see if it helped, If it did it was not by much.<br /><br />My knowlege is pretty limited and all I have to refer to is the short shaft suzuki 30 hp that was on it before. It was a short shaft, and it too planed slow but did not drag or throw up the large tails. The short shaft vent plate sat about 2 inches above the boat bottom. <br /><br />I am thinking the motor is sitting to low in the water but wanted some opinions as to should Raise it more and to what good or bad effect this will have on the motor.

 

[sharkcat]

Re: Need help with motor location.

Hi Shelbert,It sounds like the motor is trimmed out too far.It will cause the boat to drag its rear & be very slow out of the hole.Move the pin into towards the boat but be cautious if you go too far it will cause the boat to nose dive at high speed.The best solution would be to fit power trim.Hope this helps

 

[shelbert]

Re: Need help with motor location.

I have tried moving the motor in both direction to the full levels ( and all between), the only way I will get the motor any lower is move it away from back of boat and even then I dont think I could get much due to pysical restriction on the mounting bracket. I would say in that position it is maybe a 5 degree angle under the rear bottom of the boat. The boston whaler back is already slanted inward so I have to be about middle setting to even get the motor strait up and down on the back of the boat.<br /><br />The boat will plane in any position, and once it plains it runs very well with the exception of a slight drag and the rooster tails. The front end does not even come close to nose diving at any point even in heavy waters.

 

[catfish1]

Re: Need help with motor location.

shelbert, read the post on "boat questions"(not engine) the "jon boat planeing" thread, i think it could help you.

 

[shelbert]

Re: Need help with motor location.

I read that post and it really does not match my situation very well. My boat takes a bit to get to plane, but once on plain it is smooth as silk, no steering problems or performance issues. The boat levels out nicely, the front is not staying high or anything. It moves very fast (dont have a speed guage but it is plenty fast enough to get me fishing). <br /><br />It just seemed to me that having two 5' x 15' rooster tails coming out the back was telling me I have something not right and may be causing strain on the engine. <br /><br />Oh and one more test I did this morning was fill the livewell all the way up (external 15 gallon tank) It sits all the way up front. This tank prob weights more than my motor and my batteries together. The boat still planed about same and the rooster tails about the same.

 

[Dhadley]

Re: Need help with motor location.

I believe you are on the right track thinking the motor is too low. since you have a jackplate, just raise it an inch or so and test. <br /><br />I love these excuses -- errrr, reasons to test!<br /><br />let us know! Good luck!

 

[shelbert]

Re: Need help with motor location.

I will raise it this afternoon and head out to fish/test this evening and let you know how it does. At what point is it too high other than the water intake being in the water to cool the engine?

 

[Dhadley]

Re: Need help with motor location.

Height largely depends on the technology built into your prop and, as you mentioned, the water pick ups (water pressure).<br /><br />Ah, the ol' fishing test. Cool.<br /><br />Good luck with both!

 

[lakensea]

Re: Need help with motor location.

Keep raising the engine untill the prop loses bite when you cut the helm hard over, then lower it one hole. Then hook a tachometer up to the engine and prop it to maximum rated RPM with a light load. This is the only way to get optimum performance. Everything else is just guesswork.

 

[shelbert]

Re: Need help with motor location.

Just a update on my planing problems. <br /><br />I raised the engine 2 inches. The vent plate now sits about 2 inches above the v bottom of the back of the boat. This moved my plane time to near instant and made the steering much easier ( I didnt even think it was hard before but it is much nicer now. I didnt notice any problems with the motor coming out of the water in tight turns and it was still cooling well. <br /><br />I dont have a speedometer but I seem to be going much faster as well, but this could be my mind playing tricks on me. <br /><br />This also lowered my rooster tails from 15' to about 4'.