PT35= motor too high????

[parrotthead04]

I have a 2001 30 Yamaha on the back of a 14' alum fishing boat. It was a bear to tilt all the time so I put on a CMC PT35 power trim and tilt. I works great but it raised the motor 4" or so. The instructions said thats its ok because it sets the motor back from the transom. But since I intalled it, at full throttle the motor revs way up. Almost like going in to neutral. I installed everything as low as possible. I think its a ventilation problem. Has anybody else ran in to this prob? Any solutions? Will a smaller diameter prop help? or cupped? thanks

 

[roscoe]

Re: PT35= motor too high????

Hey Parrothead, Given the setback, it should be ok for the cavitation plate to be even with or up to 1.5 inches above the bottom of the hull. Any more than that and you will have the problem you are experiencing.<br /><br />Some how, you are going to have to find a way to mount it lower.<br /><br />I don't think changing props will make up for this.<br /><br />I am assuming you have the proper length motor for your boat?

 

[parrotthead04]

Re: PT35= motor too high????

Yes...proper motor. I mounted as low as it can go. I have already lowered it once a almost an inch and it helped a little. I can lower it more but things start hitting each other when tilted up...lol. thats the last resort....hopeing to find other solution..thanks!! I will go out tonight and measure the height of the cavitation plate from the hull

 

[parrotthead04]

Re: PT35= motor too high????

the cavitation plate is level with the bottom of the hull

 

[roscoe]

Re: PT35= motor too high????

Perhaps your prop hub has spun.<br /><br />Do you have a spare prop you could try?<br /><br />If not, take the prop and draw a line on it with a marker or nail polish. Line should start in the center hub area and go outward onto the housing. Test run the prop on the motor. If the line is still an unbroken line, it is good. But if the inner line and outer line are no longer connected, you have proof that the hub is spinning inside the housing.<br /><br />A prop repair shop can fix it for about $45.

 

[parrotthead04]

Re: PT35= motor too high????

tried a couple different props...I know they are not spun. Two were the same that were stock alum that came with the motor and the other is a ss prop. all did the exactly same thing.

 

[rickdb1boat]

Re: PT35= motor too high????

Might try a fin on it....

 

[cobra 3.0]

Re: PT35= motor too high????

Yup, a hydrofoil should solve it.

 

[OBJ]

Re: PT35= motor too high????

Just a question parrothead...ya' ain't got her trimmed to far out do ya'? With the cav plate even with the keel, ya' shouldn't have the vetilation problem unless ya' trim out to far.<br /><br />Anything in the water like a pitot tube or depth transducer that may make a wake to the prop?

 

[DS-3]

Re: PT35= motor too high????

PH, I feel your pain. I own a 2000 1756 Xpress with a 96 40hp Yamaha without T&T. It was a very nice running boat with a 14p mich big ear prop,but as you said, hard to tilt by hand. so I installed a CMC 130 T&T that adds 6" setback,I think yours is 5" or 5 1/2" setback. Now the boat freely spun the prop that before gripped like velcro. The T&T was installed per the CMC manual that said to raise the motor (somewhat). To make a long story short, I moved the motor a total of 5" up & down (even cut a inch off my 500 dollar T&T to lower the motor more). Installed Powertech 4 blade 14p prop semi chopper. Big difference, nose up (with Doelfin) on plane can you say PORPOISE? Final setup: My setup was, Prop shaft highth 2 1/4 below, Powertech 17p 3 blade Hi rake prop and homemade trim tabs. I can run in excess of 40 mph anytime I want to kick my buds out of the boat. My point is you may not need tabs,but you have to have a surfacing type propeller to run that CMC on that small a boat.See if you can find a prop shop as good as the one I had to deal with,I think you need a high rake 12p - 15p SS prop and to pick the motor up some. Don't surface an alum prop, It will flick the blades at you soon. Setback is bad for little boats like yours. Good Luck. I'll be gone for a week or so on (WORK) DS-3

 

[parrotthead04]

Re: PT35= motor too high????

thanks to everyone for the help and info. I know basically nothing about props. surfacing? What is considered a surfacing prop? Who makes such a prop?..Whats an examlpe of a high rake surfacing prop?

 

[parrotthead04]

Re: PT35= motor too high????

with the PT-35 on there i am able to adjust the trim while at full speed.I take it down til starting to get soaked, then slowly raise it til the rpms are correct and no more spray....thats when she starts slipping. I can keep it from slipping...but then getting soaked. I do have a fin on it also.

 

[walleyehed]

Re: PT35= motor too high????

You need to shim the mount back atleast 2", keeping the same cavplate/hull dimension. 2 pieces of 3/4" ply may work well.(2 layers)

 

[parrotthead04]

Re: PT35= motor too high????

I thought about that...but its a tiller..its already kind of a reach with the setback it has now. I figure I only have 2 options to make this work. 1. find a prop that will run that close to the surface (i think you are correct walleyhed...it's in the lowest part of the displacement. it would work better a little closer...or a little farther from the transom) 2. either get a longshaft motor or convert the one I have to longshaft. I really like the motor I have. I bought it new and have taken good care of it. Is it possible to convert it to longshaft without blowing lots of cash? I like the idea DS-3 had about raising the motor and putting a surfacing prop on. Right now its real low and far back. It would be nice to raise it up..even a little. I'm not familier with any good prop shops in the area. (Milwaukee, wi). Any recomendations on a prop? I dont even know where to look for a high rake surfacing prop

 

[walleyehed]

Re: PT35= motor too high????

Didn't think about the tiller situation there.....<br />As for a prop, that's a tough one, considering the "best" prop shops only work on OEM, unless you go with a Power Tech..they will keep tweaking until you get what you want, too.<br />Best prop-shop in the U.S. is: rich.boger@bogerprops.com