Four Winns Boat Porpoising

Woodsy · 04-23-2012, 02:27 PM

dippasan....

A boat porpoises due to overtrimming the drive relative to the speed the boat is traveling. Too slow + too much positive trim = porpoising.

Another cause for porpoising is a nasty hook in the hull. You can take a long straight edge to the bottom of the boat to see if this is the case. I doubt it though. If thats the case its not a cheap fix.

You didnt say who made the powertrain... I assume its OMC? In anycase I would follow the advice above and look at changing your prop. Not sure what the prop size was originally, (prob somewhere around a 14.25 x 21) but if you can find that out that would be a good place to start. Def go with a 3 blade stainless steel prop over the original aluminum. You can have some cup added to the prop to allow more bow lift.

Here is a link to Four Winns website... http://www.fourwinns.com/past_produc...20(p12-16).pdf

Woodsy

04-23-2012, 02:27 PM	#7
Woodsy Senior Member Join Date: May 2004 Location: Weirs Beach Posts: 1,974 Thanks: 80 Thanked 984 Times in 443 Posts	dippasan.... A boat porpoises due to overtrimming the drive relative to the speed the boat is traveling. Too slow + too much positive trim = porpoising. Another cause for porpoising is a nasty hook in the hull. You can take a long straight edge to the bottom of the boat to see if this is the case. I doubt it though. If thats the case its not a cheap fix. You didnt say who made the powertrain... I assume its OMC? In anycase I would follow the advice above and look at changing your prop. Not sure what the prop size was originally, (prob somewhere around a 14.25 x 21) but if you can find that out that would be a good place to start. Def go with a 3 blade stainless steel prop over the original aluminum. You can have some cup added to the prop to allow more bow lift. Here is a link to Four Winns website... http://www.fourwinns.com/past_produc...20(p12-16).pdf Woodsy __________________ The only way to eliminate ignorant behavior is through education. You can't fix stupid.

The Following User Says Thank You to Woodsy For This Useful Post:
dippasan (04-23-2012)