Bow bounce? not rise.

[lonemust]

Re: Bow bounce? not rise.

The hull won't break in half. The tabs you have look like just L shaped plates which essentially just extend off the back parallel to the hull running surface.

Other recommendations to put weight forward will help to a certain extent.

I think Smart Tabs would be your best bet though, replacing the "tabs" you have now. The smart tabs will act almost like a shock absorber, which is pretty much what they are, a shock absorber attached to a trim tab. When the bow starts to rise, the tabs will bite the water more, helping to keep the front down. When you are on a good plane, the pressure from the water will help keep the tabs compressed so they won't affect top speed much.

Yes the ones I have on there now are an "L" shape. They were on the boat when I bought it. They do have an adjustable bolt in the middle. I just don't know how to set them.

 

[NSBCraig]

Re: Bow bounce? not rise.

I'd think about losing the fixed tabs and go with smarttabs.

Are there still $100 blems available from iboats?

 

[metriccrescentwrench]

Re: Bow bounce? not rise.

Wife is worried that the hull will break in half from slamming down like it does.

Ha.... your wife must be related to mine. Soon as we leave the no-wake zone she's on auto-nag - "why do you have to drive so fast...". Also, that hull can take way more pounding than the passengers can tolerate.

Your boat sounds like a good candidate for smart-tabs.

 

[JoLin]

Re: Bow bounce? not rise.

Yes the ones I have on there now are an "L" shape. They were on the boat when I bought it. They do have an adjustable bolt in the middle. I just don't know how to set them.

Try adjusting them a little at a time- evenly on both sides. As you begin to angle them 'down' at the rear, they'll lift the stern/lower the bow when underway.

If you research the Bennett Trim Tabs or Nauticus Smart Tabs web sites, you'll understand how tabs work to change the shape of the hull and either exert or relieve downward pressure on the bow.

 

[Tabman]

Re: Bow bounce? not rise.

Trim Tabs are a very effective way to control porpoising (bow bounce). Of course I am biased towards remotely adjustable Trim Tabs since I work for Bennett . With remotely adjustable Trim Tabs you can deflect them so that they just contact the water flow when the boat starts to bounce. The added running surface increases lift aft as the bow begins to rise and "short circuits" the porpoising cycle. When you use Trim Tabs to control porpoising, you can still use the motor trim to get the best thrust. This results in better control and often a better top end. Plus you don't have to move passengers around the boat.

On a boat your size remotely controlled Trim Tabs allow you to control the boat's attitude as people move around, and the ability to hold the bow down at lower speeds really makes the boat run smoother in a chop.

Ok, remotely controlled Trim Tabs do cost more than Smart Tabs and the type you already have, but the do allow corrections on the fly resulting in better attitude control over a broader range of conditions.

 

[QC]

Re: Bow bounce? not rise.

What he ^^^^ said

 

[bsktball55]

Re: Bow bounce? not rise.

Basktball55,
The usual problem in porpoising is that as you trim the motor out, less and less of the hull is in the water. Eventually you get to a state where the trim is so far out and the speed so fast, it pushes the hull up too far for the water to support, sorta runs too fast for itself. So the hull falls back down until the water supports it again. This "up too far-fall back down" cycle just keeps repeating itself until you slow down or trim back in. By putting weight forward, you're helping keep the bow down, preventing the cycle from getting going. Trimming tabs down has the same effect, helps keep the bow down.

Would this be different on a bass boat that is designed more to run on a small pad? The reason I ask this is because when I start porpoising I can either trim back down or give it more throttle and it stops. The op seems to have the exact opposite experience, he has to throttle down in order to get his to stop. If I throttled down, the porpoising would get worse. I have a 19ft javelin bassboat with a 175hp that is capable of 65-70mph gps depending on load.