what is the advantage of a Jack plate

[petersfield]

Don't mean to sound stupid. What is the advantage of a JP? on one of my other conserns Mark had told me that the setup will be good until I get a JP. now my boat! the motor is to high so why would I want to raise or lower the motor If you get it sep up proper? just wondering? Mark if you read this I love your advise so I am not saying anything negative Just wondering! thanks very much

 

[petersfield]

Don't mean to sound stupid. What is the advantage of a JP? on one of my other conserns Mark had told me that the setup will be good until I get a JP. now my boat! the motor is to high so why would I want to raise or lower the motor If you get it sep up proper? just wondering? Mark if you read this I love your advise so I am not saying anything negative Just wondering! thanks very much

 

[merc245]

Jack plates are there to have the best of both worlds.When you are taking off it should be lowered to allow the prop to get a full bite of water. At this point there is the most friction on the hull and u need all u can get.Plus with the engine tucked down and under it brings the bow down and gets u on plane quicker.Once your gaining speed and starting to airing out the hull u bring up the the plate raising the outdrive, 1st it creates less drag = more free h.p. you should be triming your motor out at this time also to start flying the hull.2nd with less drag on the hull.You can bring the prop up nearer the surface allowing it to spin at a faster rpm = more speed. With normal water pick ups the top holes might be out of the water allowing air to cavitate the impeller.This is a very simple example.

 

[illMATTic]

here is my take on it.

when installing a jackplate there are a couple advantages gained.

1) with the weight of the motor further back, you get more bow lift with less trim. the prop runs more horizontal in the water.(more efficiant)

2) with the prop running further back, it is running in "cleaner water" meaning the water has less air in it. the prop has less slip. (more efficiant)

3) now after you gain all of the above you can start to raise the motor. since you are running close to 0 trim the prop is running straight and true through the clean water and can be raised to your desired height.

can anyone else add to this? maybe somethin on why raising the motor is better.

 

[Mark]

I would agree with all of this. The only thing I would add is that ther are some disadvantages on shorter boats. On a 17' hull it will give you more bow rise during hole shot. I have a 5" plate on my 17' Diplomat and I love the way it carries the bow even when loaded with people. It also has made the boat better handling in turns and the prop never blows out anymore. The trade off is, it is our ski boat and I could do W/O the bow rise when pulling skiers. Overall though, it has been worth it. I would not go more than 5-6" on these smaller Mates.

 

[175checkmate]

With all of the above being very true, the last note.......THEY LOOK COOL.

 

[daren34]

i had to put one on my diplomat to cure chine walk

it was a 6" cmc electric

we could have put it higher but we never installed a water pressure guage

major differene in the way the boat handled
pulled turned skied drove all better
needed dual cable steering though
you had to lock one arm against your leg to hold it with the plate and the trim all the way up
it wanted to make a hard left turn

traded the boat on a new mate before fixing the problem


daren

 

[illMATTic]

IF YOU GET THE NO FEED BACK STEERING , YOU WONT HAVE THAT PULL.

 

[wickedrister]

I plan to install a 6' manual plate and Teleflex bay-star hydraullic steering this winter. I will then be ready for the modern 135 merc and retire the 90 inline. Any thing I need to know about this set up. How do you think this will work out on my 86 Enticer ??