Active Active   Unanswered Unanswered

porpoising 1959 cc ski boat

Framing, planking and fairing. Repair, or reconstruction. If it's hull related, you'll find it here.

Moderators: Don Ayers, Al Benton, Don Vogt

vance
Posts: 5
Joined: Tue Nov 03, 2015 7:36 pm
Contact:

porpoising 1959 cc ski boat

Post by vance » Thu Nov 05, 2015 10:12 pm

My 1959 cc ski boat starts porpoising at 32 mph, has anyone else had this problem or have any ideas on how to fix it?

User avatar
mfine
Posts: 1405
Joined: Sun Jun 06, 2010 8:16 pm
Location: Pittsford and Penn Yan NY

Re: porpoising 1959 cc ski boat

Post by mfine » Fri Nov 06, 2015 7:11 am

Generally you would need to move the center of gravity or adjust the motor angle. Not really an option with an inboard. You can add trim wedges at the stern to push the nose down. It will cost you some speed but keep the ride flatter.

boat_art
Posts: 556
Joined: Sun Feb 12, 2012 6:09 pm
Location: United States
Contact:

Re: porpoising 1959 cc ski boat

Post by boat_art » Fri Nov 06, 2015 7:12 am

a. Drive it at 31.
b. Trim tabs may help.
Tom
http://www.boatartgallery.com
1956 CC Connie 47'
1959 Caulkins bartender
1965 Cheoy Lee Frisco Flyer
1953 Chris Craft Holiday
1941 Chris Craft Deluxe
Plus 8-12 customer boats at any time
God don't count the days spent messing around in wood boats.

boat_art
Posts: 556
Joined: Sun Feb 12, 2012 6:09 pm
Location: United States
Contact:

Re: porpoising 1959 cc ski boat

Post by boat_art » Fri Nov 06, 2015 7:15 am

I'm assuming you have tried shifting some weight forward right?
http://www.boatartgallery.com
1956 CC Connie 47'
1959 Caulkins bartender
1965 Cheoy Lee Frisco Flyer
1953 Chris Craft Holiday
1941 Chris Craft Deluxe
Plus 8-12 customer boats at any time
God don't count the days spent messing around in wood boats.

User avatar
tkhersom
Posts: 983
Joined: Wed Feb 27, 2013 6:56 pm
Location: Edgecomb, Maine
Contact:

Re: porpoising 1959 cc ski boat

Post by tkhersom » Fri Nov 06, 2015 7:16 am

Don't have much experience with the ski boats, but trim tabs are usually the best answer.

A quick try might be to put some weight in the bow to see it that will hold it down and steady, maybe Helen Michele could help you?
Troy in ANE - Former President CCABC

1957 CC 21' Continental "Yorktown" (Mom's boat)
https://www.chris-craft.org/boats/22625/
1985 Formula 242LS "Gottago"
1991 Formula 36PC "Band Aids"

Life Is Too Short To Own An Ugly Boat

jim g
Posts: 1003
Joined: Wed Dec 14, 2011 10:55 pm
Contact:

Re: porpoising 1959 cc ski boat

Post by jim g » Fri Nov 06, 2015 4:55 pm

vance wrote:My 1959 cc ski boat starts porpoising at 32 mph, has anyone else had this problem or have any ideas on how to fix it?
Are you still running the 283 or has it been changed to a 350?

Wedges on the bottom at the transom will cure the problem but it will knock off some speed.

Does it still have the original bottom on it?

The other thing to look at is what prop do you have on the boat?

martinfeletto
Posts: 32
Joined: Mon Jan 01, 2007 5:03 pm
Contact:

Re: porpoising 1959 cc ski boat

Post by martinfeletto » Sat Nov 07, 2015 12:06 pm

You likely have a hook in the bottom from the trailer or other storage.
Get 2 6 inch pieces of half round or fender rail. Screw and bed them into the bottom at the transom just on each side of the rudder going side to side not for and aft. This will solve some or all of your problem. Longer if you need more - this breaks the suction that is causing the porpoise.

vance
Posts: 5
Joined: Tue Nov 03, 2015 7:36 pm
Contact:

Re: porpoising 1959 cc ski boat

Post by vance » Sat Nov 07, 2015 3:22 pm

jim g wrote:
vance wrote:My 1959 cc ski boat starts porpoising at 32 mph, has anyone else had this problem or have any ideas on how to fix it?
Are you still running the 283 or has it been changed to a 350?

Wedges on the bottom at the transom will cure the problem but it will knock off some speed.

Does it still have the original bottom on it?

The other thing to look at is what prop do you have on the boat?
Thanks every one for their input. To answer a few questions I have tried moving weight forward which seemed to help very little. It is receipted back to 1974 and I can't find any record of new wood on the bottom just fiberglassed. It does still have the 283, what effect would the 350 have on this issue? I am running 12/15 prop on it.

Look forward to hearing more.
Thanks
Vance

jim g
Posts: 1003
Joined: Wed Dec 14, 2011 10:55 pm
Contact:

Re: porpoising 1959 cc ski boat

Post by jim g » Sat Nov 07, 2015 4:55 pm

The problem your having is caused by the bottom being out of shape. I have restored 3 of these and this style bottom due to its non trip chine design is the weakest Chris Craft built. Once the bottom is redone correctly with the 283 in it. It will run full speed without any porpoising.

A 350 will cause porpoising because its more horsepower and will run faster.

One thing that will help is going to a ACME brand prop. The blade design helps pull the bow down.

vance
Posts: 5
Joined: Tue Nov 03, 2015 7:36 pm
Contact:

Re: porpoising 1959 cc ski boat

Post by vance » Mon Nov 09, 2015 9:29 pm

Thanks everyone

Post Reply

Who is online

Users browsing this forum: No registered users and 11 guests