smart tabs on a heavy boat

[numbskull]

Provided the engine is trimmed correctly, I would consider a different prop with less pitch and larger blades (or more blades).

[Van]

If a 20 footer needs trimtabs, there is something strange going on.
Gradys are a heavy boat but still should not need trim tabs.
Tabs can bring your bow up or down.

My hydfrofoil on my 21 proline with a 175 works great and can change the pitch while underway. But I'm pushing with an outboard.

You say your'e doing 40 mph but not at plane?
You may have a prop issue. Its a easy and cheaper fix.
Maybe look into that first.

[Mr. Sandman]

Originally Posted by numbskull

Provided the engine is trimmed correctly, I would consider a different prop with less pitch and larger blades (or more blades).

Bingo! we have a winner!

You have the wrong prop. Prop selection is a compromise that allows for decent low mid range performance with near peak at cruise. If you are far off it will not even plane. For example, many big boats with twin outboards (or inboards) can not plane on one engine because the props are selected assuming the other engine is operating, take it away and the single prop cant even push the boat on plane. (hence the "need" for trips and quads in those go fast tournamnt boats)