1995 four winns 170 freedom porpise problem

[mnbigbass]

Hello, I have a 1995 four winns freedom 170 , with a 4.3 omc . Just bought the boat from the second owner . been well takin care of w/ about 200 hrs on it. But it starts porpising around 20 mph at 1/4 trimed . same thing with a 19 and 21 " prop. 200 pounds in the bow and still porpises. Im sure trim tabs will work , but I want to know the real problem? Hull is in great condition . could it be something mech. ? Motor height ? Thanks for any help !

 

[Texasmark]

Re: 1995 four winns 170 freedom porpise problem

Four Winns is a good brand. 4.3 I/O on a 17' boat sounds like a rocket. An I/O in a 17' boat is obviously stern heavy. If you have trim tabs already on the boat and the fact that a 16 year old boat is in it's 3rd owner may be telling you something.

There are two ways to stop porpoising....speed up or tuck it in....possibly a third, don't use a high rake prop that provides bow lift. Trim tabs modify both requirements.

Mark

 

[mnbigbass]

Re: 1995 four winns 170 freedom porpise problem

i am going to try some smart trim tabs. was hoping to find out if it is possible to adjust the motor or lower unit somehow?

 

[TomB985]

Re: 1995 four winns 170 freedom porpise problem

Hello, I have a 1995 four winns freedom 170 , with a 4.3 omc . Just bought the boat from the second owner . been well takin care of w/ about 200 hrs on it. But it starts porpising around 20 mph at 1/4 trimed

So why not trim it down some to bring the bow down?

 

[mnbigbass]

Re: 1995 four winns 170 freedom porpise problem

I would be plowing water. I need it trimed all the way down for a safe ride. top speed is 34 mph (gps) without fliping over

 

[Bob_VT]

Re: 1995 four winns 170 freedom porpise problem

Check the hull for water logged foam. Normally weight distribution is the cause.

 

[Texasmark]

Re: 1995 four winns 170 freedom porpise problem

Check the hull for water logged foam. Normally weight distribution is the cause.

I had a FG boat like that once but that was back when they only sealed off an air chamber below the deck. Really a weird experience as the boat was only 13' long, 22 hp Scott-Atwater and when you got guys and gear in it there was already a good load without the water.

Mark

 

[tschmidty]

Re: 1995 four winns 170 freedom porpise problem

Is it better to plow water or porpoise? Trim it in or put the tabs on, but the trim tabs do sort of the same thing in that it will keep the bow down and you will be plowing a little more water.

 

[mnbigbass]

Re: 1995 four winns 170 freedom porpise problem

how do you check for water in the foam?

 

[mnbigbass]

Re: 1995 four winns 170 freedom porpise problem

the porpoising freeks the wife'e out

 

[mnbigbass]

Re: 1995 four winns 170 freedom porpise problem

decided to try a stingray hydrofoil first. WOW ! Works great ! its like a whole new boat now. smart tabs would have been below the swim ladder.