boat skips on plain

bow bobs up and down when the boat first gets on plain, only way to stop it is to trim mtr. all the way down. boat is a 1994 four winns 160 with a johnson 140 ob. please help

Re: boat skips on plain

What you are experiencing is called Porpoising and it is very common. It has to do with weight balance, and you have a relatively large motor on a small boat. The solution is shifting weight forward, or adding trim tabs, or probably both. I will never recommend a hydrofoil although it might help.

You say it starts when you get on plane. What happens at full speed?

Welcome aboard iboats!! If there is anyplace that can help you get her fixed up it is here.

Re: boat skips on plain

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Agree...

I found that smart tabs took away all of the porpoising as well as the large bow rise when coming on plane. I also was not able to trim my motor out properly untill installing the tabs.

Re: boat skips on plain

yep!!!! you are tail heavy, move passenger and gear forward.

Re: boat skips on plain

Smart Tabs
Just over $100 on e-Bay and worth every penny

Re: boat skips on plain

My MFG did the same. I moved weight forward by removing the two 6 gallon portable tanks under the splashwell, and put in a 14 gallon permanent tank under the closed bow (thats only about 100lbs of hardware and gas on a full tank). That and adjusting the trim pin (no power tilt/trim) removed the problem without adding trim tabs and the boat really handles nice.

Before spending money on something you may not need, you should evaluate the weight distribution in the boat and your trim. Nothing wrong with having the trim all the way down, as long as the boat performs right. The boat most likely didn't porpoise when it was new, and it shouldn't now and it shouldn't need trim tabs unless there are some major changes to the boat like adding live bait wells, etc.

Re: boat skips on plain

vtfwfreedom said:

bow bobs up and down when the boat first gets on plain, only way to stop it is to trim mtr. all the way down. boat is a 1994 four winns 160 with a johnson 140 ob. please help

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There's nothing wrong here...If your saying you CAN stop it,by trimming down...then that's what you need to do.All boats will experience Porpoising unless the motor is trimmed correctly.If trimming gives you a smooth ride,don't waste money on smart tabs.

Re: boat skips on plain

I tend to agree with you ^^^^ . . . like sorta . . . Trim Tabs of almost any type are never a "waste" . . . And if you can trim further out at almost any speed you can get better efficiency and of course speed. Even with a small boat, the stability and control that trim tabs give you make me believe they should be standard on all v-hulls. I prefer helm adjustable tabs, but for a boat this size and considering cost, Smart Tabs are probably the right product.