Formula boat porpoising

[XCR-700]

Originally Posted by LIforrelaxin

Go out on a calm day, start with the tabs all the way up, to take them out of the equation..... The get up on plane and go to about 3500 rpm... that is where most people tend to cruise... then slowly trim the boat up, see how it re-acts, the the tabs up and out of play, you should find the balance point, where the bow will bounce with the least little ripple.... Once you find that point, trim back down a little, and that is likely where you want the drive when you out and about...

Then put the trim tabs back into play, and use them as your supposed to, to control the attitude of the boat for the given conditions....

Tabs and trim on the drives are for different things, most people don't know how to use them in conjunction with each other... so the best thing is to find where you want the drive, and leave it there, and use the tabs to adjust the boat from then on out.....

This is exactly what I did.

What surprises me is how how little trim up this boat will tolerate.

Most boats I have driven never porpoise, you will simply just over trim an lose performance.

Clearly the combination of hull design, length, power and the ability to transmit that power into thrust have created the ability in this boat to porpoise.

Also it appears that Formula has picked an engine/outdrive angle that is very neutral. It neither allows you trim down to an angle that lets you plant the nose in really rough water, nor does it appear to need much trim up to reach the designed planing attitude.

No complaints, just not what I have experienced in the past and seems interesting/unusual to me, as most boat I have driven usually have a pretty wide range of trim they operate/tolerate. I honestly have no reasonable basis to say if this is common or uncommon, I only know what I have see personally and for my this is a different experience. And the experience that MeredithMan describes is pretty much how our boat performed, so it would seem to me there is nothing wrong with my boat per se, nor my surprise by the way it performed compared to my personal past experience.

Thanks!

[LIforrelaxin]

Originally Posted by XCR-700

This is exactly what I did.

What surprises me is how how little trim up this boat will tolerate.

Most boats I have driven never porpoise, you will simply just over trim an lose performance.

Clearly the combination of hull design, length, power and the ability to transmit that power into thrust have created the ability in this boat to porpoise.

Also it appears that Formula has picked an engine/outdrive angle that is very neutral. It neither allows you trim down to an angle that lets you plant the nose in really rough water, nor does it appear to need much trim up to reach the designed planing attitude.

No complaints, just not what I have experienced in the past and seems interesting/unusual to me, as most boat I have driven usually have a pretty wide range of trim they operate/tolerate. I honestly have no reasonable basis to say if this is common or uncommon, I only know what I have see personally and for my this is a different experience. And the experience that MeredithMan describes is pretty much how our boat performed, so it would seem to me there is nothing wrong with my boat per se, nor my surprise by the way it performed compared to my personal past experience.

Thanks!

Sounds to me that Formula has taken the stance that most people buying their boats, don't have a clue as to how to trim and adjust the handling of their boats. Thus, they have made things harder on those that understand how to make a boat perform they way we want.....

What this means, is that to really be able to trim and control the handling of your boat, you need to make more drastic adjustments, so that you get proper trim response... the problem is that would start to void a new boat warranty....

I would talk to a dealership or two, and see what can be done... The wrong answer from a dealership would be, "it is what it is"..........

Sounds to me, the the drive isn't really properly placed, thus you are porposing, because, you boat is riding on the hull further up, and the cavitation plate of the drive, instead of the rear pads of the hull, like it should....