jack plate QUESTION

[gl65stang]

Hey guys, so i have a quesiton about using a jack plate. I recently changed my 97 wellcraft eclipse from an I/O to an outboard setup. I plugged the hole where the outdrive was, and installed an armstrong bracket to clear the diving platform. Now that the bracket is installed I am concerned with clearance issues with the new 25" shaft motor installed, and I dont need any waves coming up over my new motor. I am not familiar with jack plates, so i dont know where to begin, they look like something you can make really, and I dont want to spend more that 300.00 for a jack plate. Any help?

 

[NYBo]

Re: jack plate QUESTION

Regarding waves, unless you plan to raise the motor each time one comes at you from the stern, a jackplate isn't going to help you. The motor needs to be at the proper depth. What clearance problems do you anticipate? That bracket seems to provide a lot of clearance.

 

[gl65stang]

Re: jack plate QUESTION

Im new to boats to be honest with you, I have been a car nut forever, and this seemed to be the next best thing for me, and I have always tried to plan, plan, and plan some more before making any big purchases. So im trying to pick yalls brains (experts) should I go with a 20" or 25" shaft? pros and cons to both?

 

[64osby]

Re: jack plate QUESTION

No a real expert here, but using your 3rd pic - find the horizontal line from the keel out past the bracket, measure from that to the top of your bracket. Needs to be a 90 degree angle. The height from the horizontal line to the top of the bracket will determine the shaft length.

You may need a jack plate to fine tune your motor setup even if you have the proper shaft length. As I recall from reading here the bracket will allow the motor adjustment to be higher than if is was attached to a normal outboard transom. Yours is obviously a different animal because of the transom modification. My .02.

 

[Chris1956]

Re: jack plate QUESTION

The setback of the bracket will allow you to raise the motor for better performance. First take the measurement as 64osby suggested. Choose the shaft length based upon that measurement. Install the motor in the lowest position and start to fine tune the performance by raising the motor in increments. Use a GPS and Tach to record top speed and RPM at each motor height setting. If it hits optimum before you get to the highest motor setting, you do not need a jackplate. If not, you may (may) benefit from a Jackplate.

 

[UncleWillie]

Re: jack plate QUESTION

Your shaft length is the measurement from the Top of the bracket to the bottom of the extended Keel line.
The Anti-Ventilation plate of the engine should run very near the water line while on plane.
Because the engine will be so far aft of the transom, The actual water line will need to be determined by trial and error.

Start an inch or two shorter than the nominal measurement and adjust from there.

 

[V153]

Re: jack plate QUESTION

I dunno. Considering the amount of backset ya might find a 25" gearcase a lil too tall. As has been mentioned hang a straight edge under the keel and align yer anti vent plate with it. Mebbe an inch above fer starters, and be prepared to go up.

Having said that, what kinda motor we talkin about?

 

[gl65stang]

Re: jack plate QUESTION

well im looking at a 2006 150hp yamaha

and thanks alot guys for the quick responses, this is amazing and very helpful!

 

[gl65stang]

Re: jack plate QUESTION

ok so I measured the distance from the bottom of my bracket where the motor mounts up to, to the boats keel line. It measures about 16'' on the dot. Im a little worried though that the extra weight from the motor that I want (2002 yamaha 150 HPDI 20") would cause the motor to sit too low in the water, would I be better off purchasing a 25" so that I can lift the motor higher and alleviate the problem of water entereing my cowl area?

 

[gl65stang]

Re: jack plate QUESTION

ok I measured from your lines and my distance was 23"