Motor height help

[Jim Tongay]

I've got a 95 170TF with a 115 on it. I've been tweeking it since I bought it in feb.

It still does not seem to be where it should.I did the prop thing,went up and down

and settled in with a SS 21 pitch(cupped and ported).

The hole shot is horrible,(min 6 sec,10+ with a full tank and heavy passenger).

Tops out 42-43(gps).Motor seems too deep??

I've have no jack plate.The motor was mounted in the lowest(top)hole.you could tell

it was bolted one hole up at one time.Me and my son raised the motor up one hole and

seemed to help at first,now I'm not sure.

My question is,does anyone have simular setup, how high can I go and when do know I've

went too high? It's not a lot of fun lifting this with a 14 yearold,or I would just do

at a lake untill???? Any suggestions????

Nofishcatchin,Jim

 

[Michael Meier]

Jack plate issue. As a Mechanical Engineer I always like these!



Jim,

You need a jack plate.



How can you tell if your boat would benefit from a jack plate? What are some of the symptoms?

1. Poor/slow hole shot. Hull hanging for more than 2 seconds before coming down.

2. Your outboard is not perpendicular (straight up & down) in relation to the water at top speed. (Most normal reason for a JP)

3. You can trim the engine all the way up without the prop letting go or with no appreciable loss of water pressure at full throttle. (If you

 

[Jimmy Easterling]

Mike, I just installed a 5.5 inch manual on my Z6 w/115 and am waiting on a new prop to try. With the 20p, top end is the same and hole shot got a little worse and since I am usually a catch and release person I almost never have water in the live well. This past week I filled the live well and the boat didn't want to get on plane at all. From what I just read I think I am too low, correct? Another thing I noticed is that I am having to steer more to the left than before, is this due to the jp?

 

[Jim Tongay]

WOW...Capt.Mike,sounds like you know your s**t!

If I understand you correctly it is just as important to

get the motor out from the transom as it is to raise or

lower it.

ie.jackplate good...

I only have one small problem,been unimployed for almost a year.

Unless they're giving them away I'll have to pass for now.

I've went as far as to offer to sell my boat to help out,but

my wife won't let me,(as long as we still have money in savings).

I sold my old boat to buy this one,then spent too much upgrading

trolling motor,prop,depth finders,on-board charger,ect.

She knows that if I didn't have a boat and couldn't fish,

bury me now...

ie.Nitro good...

Mike,thanks for the info,maybe I'll put it on my Christmas wish list

for next season,I'll have to get by for now.I do have freinds in a

lot worst shape (12ft Jon w/9.9)or no boat at all.

Count your blessings and catch some fish,God Bless.

Nofishcatchin,Jim

 

[Michael Meier]

JimmyE,

It appears that you are to low. How did you deterime that the plate you have is the right distance back? Important!



Now that the plate is on, what is your optimum RPM range for your engine? What is your water pressure reading? What type/blade#/pitch prop are you running? GPS speed at WOT?

What were all of these readings prior to the JP install?



You must have a base line reading before you can improve anything.



Jim T,

You are correct. Distance back is the most important part. If you are not running the lower unit and the prop in the center of the swell then you have defeated the whole purpose of the plate.

 

[Jimmy Easterling]

Right distance back-17'9" boat and I bought it a year ago when I got the boat and just put it on a week ago, when I got it I thought it was height, not distance back now I just have to live with it.

rpm should be 5850 but with jp I have to back off because it goes well above that. Currently Lazer II 20P but have a Power Tech 22P on the way to try. Water pressure is in the same range as before jp, 16. Gps speed 47mph before and after, only after I have to throttle back because of rpm.

Here is another issue: Before and after jp, my boat falls off plane below 32 mph, hull design?

 

[Michael Meier]

Have you had anyone look at the lower unit while your running? If you are not seeing a little loss in WP then it may not be high enough or it may not be back far enough.

Falling off plane can be weight in the boat, trim, hull design, etc....



The increase in pitch on the prop will bring your RPMs back down and should increase your speed. Maybe? If you want me to help I will need some before/after data and pictures.

Mike