Related/ Unrelated Mercruiser Problem (Maybe)

Now, that's a definitive question!

Got a Chaparral 19 footer with an Alpha One drive (305 SBC). Previously (several years) I was able to noticeably raise the bow with the trim buttons, then drop it back a bit (as one is supposed to) for a porpoise free ride. But this year the boat porpoises with the drive trimmed all the way in. Far as I can tell, nothing has changed: same prop, same load, roughly the same fuel load and 'cargo'. I thought the hull might have a bunch of water stored below deck, so I drilled a few inspection holes and found it was all foamed down there, so...


Any idea why this is happening? The drive is swinging all the way in, and there's no visible damage to anything.

Thanks,

Jeff the Befuddled

Often the foam just under the floor is dry.-----Stuff a few inches down near the hull is water logged.

Have the trim rams been changed?

..."Have the trim rams been changed? "

No, and they allow the drive to come in all the way.

How could I dry out the foam?

Jeff

Ever have one of those days when nothing goes wrong? This was it! To wit:

I made a trim tab (see photo) that absolutely cured my porpoising problem; furthermore, in an astounding side benefit, it greatly reduced that irritating "Mercruiser Boogie" at no wake speed. Like I said, I had a good day! What's truly amazing is that I hit the exact size and down angle of the tab first off.

I know what some of you are thinking:

1: "Hydrofoils" can wreck a cavitation plate. Agreed, but this one is off the far more rigid back end of the LU, not bending the sides upward

2. The stock trim tab is gone! Agreed, but I don't really need it. Why? I don't keep the boat in the water (anode effect) and it has power steering that doesn't yank the steering wheel to one side.

No pattern applied for yet, but...

Jeff

Bet you could add a shoulder to center in the trim tab recess and, if it thickens it up enough, just use the trim tab bolt to retain the FastJeff De-porpoising Tab - aka the FDT, (copyright and TM applied for)…..

And them Patents aint cheap....or lawyer-free.....

..."And them Patents aint cheap....or lawyer-free..... "

I know. Ditto for copywriting a novel. (Don't ask!)

If I needed that Merc trim tab/ anode I sure could bolt it on. Neat idea!

Jeff