help? Campbell 20' bow lift

[thecampbellman]

I have a 77 Campbell 20 v-drive,13x13 (per campbell boats) full cav plates. BBC TH400 trans Casale 500. I have always had issues with this boat porpoiseing. I am told Campbell had lots of trouble keeping the 20' in the water. I have been in enough Schiada,Howard,Spectra of the same era to know I should be able to get this bow down. I have adjusted the action on the plates and it has helped a bit. I was told at one point that the prop my be to far toward the rear of the hull? I seem to remember a very old issue of ***boat talking about this very issue. If I can come up on the cav plates this thing will do much better than the 55mph I get now....any help or ideas?
thanks for reading, andrew

[CampbellCarl]

Send a PM to Danny Kahn (InKahntrol here on the boards). He's just finished a 20' Campbell and can share his knowledge of Campbell handling issues. He and his dad have many hours in the seats of Campbells.
CC

[InKahntrol]

Hi Carl! Good seeing you at Irvine. You can't believe how much mud I had to blast off the rockers of my truck.
Campbellman-
This is pretty standard stuff for the 20' Campbell. It takes a little work to get the porpoising under control. The first step is having full length plates without the 16" gap, but it sounds like you might have that already. Also, you'll need to relocate the strut and v-drive, as these boats are set up '50s style, even the ones built into the 1980s.
We changed from a 12-degree to a 9-degree strut, and moved both the strut as far forward as we could without putting the v-drive through the bulkhead or floor. It ended up moving about 14" forward. Finally, when I did the glass work to patch the hole left from the last strut and shaft locations, I also took most of the hook out of the bottom. The best way to do that is with a long air file and a straightedge. Basically I just worked on the last 4' of the boat, running the air file back and forth until the straightedge would lay flat running lengthwise.
With those mods made, the handling of the boat changed dramatically. It will still porpoise if I pull the plate all the way up, but in the neutral position it carries the bow and doesn't porpoise at all. Handling and top speed are also dramatically improved.
I can get you measurements and photos if you want next time I go up to LHC.
-Dan

[thecampbellman]

THANKS CARL... maybe because i am new to this forum, i dont have PM availible on my account?...i'll try the campbell owner web site

[thecampbellman]

Hi Dan,
Thanks... any info you could send would be greatly appriciated. I do have the gap between my plates. this boat is still the way it left the factory, short of a motor and guages. I am a bit scared to lengthen the plates due to the glass work. I guess i will have to bit the bullit since it seems to be a starting point.
I also wonder... the plates ride on the trailer bunks when loaded, i have thought over time the plates may have a bit of curve in them and will be shortening the bunks to end at the transom. Moving the v-drive and strut sound like alot of work. going to a 9 degree strut, will it work with the same c-500 unit. when you where finished it sounds like the prop was 14" further forward? sounds like I will have to get busy. I do love this old boat, and would love to solve this issue for good.
I remember talking to you at few Regatta's be for I moved to Texas
Thanks again