Cavitation plate...How high?? or how low??

[Heynow]

I just picked up a used Sylvan 16sea monster with a 70hp Force on the back. My question is, how do you know if the motor is mounted at the correct height?? What are the guidelines and pros and cons as to where it can be mounted. The previous owner told me the boat pulls to the right, I have not got the thing in the watter yet, but was trying to figure out what can cause it to pull to the right. I am a newbie, and any info will help me very much. Thanks in advance.

 

[Franki]

Re: Cavitation plate...How high?? or how low??

Hi, <br /><br />Start with your cav plate level with the bottom of the transom.. lower means slower more often then not.. you can also put it above the transom bottom as well, just be careful that you don't get cavitation and that your water pickup is still well and truely submerged.<br /><br />Its a matter of trail and error really, but if its close to level,, and it goes well, then its probably fine as is...<br /><br />regards<br /><br />Frank

 

[oldboat1]

Re: Cavitation plate...How high?? or how low??

I agree with Frank. Performance (unless you are really into racing, I guess) is related more to trim adjustment, propping, and weight distribution in the boat than motor height.

 

[Heynow]

Re: Cavitation plate...How high?? or how low??

I am not worried about speed....just want to be assured that it is mounted correctly, and that there is not something obvious that could be causing the pull to the right, the prev owner said he tried every single position for the trim tab and it still pulls, So i am just trying to come up with reasons why this could happen????

 

[oldboat1]

Re: Cavitation plate...How high?? or how low??

There is a 5/18 post called "Pulls To The Right" that discusses the problem. It appears the solution in that case was to change the trim angle, although I suppose the prior owner of your boat would have tried that (?). I guess I would check the weight distribution in the boat, and look for balance (guessing maybe the steering console is on the starboard side, so I would put the gas tank and battery on the port side) -- sounds to me like there might be too much weight on the starboard side. Then trim the motor up a notch and see if there is any improvement.<br /><br />just guessing about the cause ... but think you will want to rule out the simple stuff first.

 

[legend602]

Re: Cavitation plate...How high?? or how low??

I have an 18' Nitro NX882 bass boat with a Merc 150HP engine on it. When I bought the boat, it pulled really hard to the right, and when I would turn to the right more than just a slight curve, it felt like the engine wasn't getting any grip, and the boat would slip sideways really bad. Turning left didn't do this.<br /><br />First thing I did, was buy a trimtab for it. It still pulled to the right, untill I trimmed the engine way up (At which point the boat became QUITE unstable. I would hit a small wave, and the boat would start pourposing, and just keep going higher & higher & higher untill I trimmed down and pulled back on the throttle). It did help some, however.<br /><br />The next thing I did, is lower the engine 2 notches. Before I would hit 60mph at about 4700RPM, but now, I hit 60MPH at about 5200RPM and it just won't go any faster (I have a 23" prop. I've got a 21" in my garage I need to try out). Lowering the engine did give me MUCH more stabillity, however. Just at the cost of some speed (Which is fine, I normally cruise under 40mph). When the engine is trimmed all the way down, it still pulls to the right, but not nearly as bad as it used to...<br /><br />Hope this helps!<br />Mike Carlson

 

[DJ]

Re: Cavitation plate...How high?? or how low??

heynow,<br /><br />There is a trim tab under your cavitation plate. It looks like a fin. On a Force it may also be an exhaust outlet. Turn this in the direction of the pull. It may help some. Remember, you are fighting engine/prop torque which twists, with the prop shaft as a pivot point, to the right.<br /><br />The only way to eliminate it totally is to go with no feedback or hydraulic steering.