Seacraft 20 performance help
 

I have a new to me 1972 20SF with an armstrong bracket and a 2016 F150 hanging on the back. Now, I've been doing a lot of reading and realize these boats were meant for 300 lb motors hanging off the transom and they like perfect balance. But I need to work with what I have. I only have room to raise the motor one more hole. The cav plate is 4.5" above the keel. Speed wise, I am fine with what I'm getting, but ride is where I'm not satisfied. Current prop is a quicksilver thunderbolt 15.3x19P. WOT motor is turning 5400 RPM with a speed of 44 MPH.

Presently, I have a few issues:

1. Hole shot - Bow rise is substantial. Like I lose sight of whats in front of me. It stays that way until the boat finally jumps on plane which seems to me to take too long. I have not timed it.

2. Once on plane, any amount of trim makes the boat porpoise. If I keep the motor tucked, it rides great. Very little or no tab necessary.

Next time I'm able to get the boat out, I plan to check cav plate height while running and time how long it takes to jump up on plane.

I have spoken to Ken at Prop Gods and he has recommended a Powertech SFS4 in 17 pitch. When asked about the mercury rev4 he stated that it was a lot of prop for an F150 and doesn't have as much stern lift.

Any other thoughts or ideas? I was thinking about adding some lead ballast bags to the anchor locker to try and balance the boat further. Thoughts?

Thanks for your help.

PS - I know there is a performance forum but figured I would get more traffic in the general forum.

I forgot to add, the previous owner put a 30" setback bracket on it.

Do you have a Dolfin? Trim tabs? Motor height is very important.

Do your best not to add ballast. Shift weight (Batteries, coolers).

The Dude abides :cool:

Lloyd

https://www.hydro-shield.com/

This will be a great help.

Properly set up it provides stern-lift at all speeds without forcing your bow down. It's a hydrofoil that stays in the water. You can adjust trim without instantly looking like Flipper begging for a snack!

I ran one on my outboard 20' Seafari, both with the XR4 motor and later with the 90 Optimax. I just purchased one for my 18" Superfisherman with a 90 Etec.

The PT 4 blade should get you real close. Ken's suggestions for me (3 times) have been spot on!

Great screen name.

I'd love to see pics of the boat. I'm heavily considering enclosing my 20sf with an Armstrong but get nervous every time I hear stories like yours.

http://i.imgur.com/ur3eUHY.jpg
http://i.imgur.com/Eyy0U1g.jpg
http://i.imgur.com/phss3Wk.jpg

Beautiful boat! Registered in SC?

Vezo.

Yes, sir.