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porpising

You might try a prop change to get the bow up without so much trim. Do you have alot of extra weight in the bow? You might have to be sat. with the trim down or raise your speed with your current set up. If you stay on the trim button you should be able to find where you can settle the porposing withour raising your speed. My boat will pourpose between 35 and 45 depending on the trim setting, what is in the bow, if I'm into a head wind, turning, ect.
 
Hi thanks . I have nothing in the bow and with the trim all the way down it still porpeses unless I put the tabs way down under 40 45 mph. I have tried other props Iwill keep trying new ones .Iam only getting around 55 mph with a 454 efi
 
What does it do with the trim tabs up and just using the outdrive trim? You might have to much push from the tabs and the drive trying the lift the bow.
 
Force,

What prop are you running? What r.p.m. are you getting?? 55 m.p.h. out of a 454 magnum is very low. I have the same boat and motor. I get 68 g.p.s. abd about 73 speedo.
 
I have a 1990 Convincor and I have have been tring to cure this problem for years. Don't waste any more $$$ It's something you learn to work with.
 
Force,
I misread your previous post. I understood you to have a 454 Magnum, from re-reading the post it appears that you have a 454 MPI 310 h.p.
Which motor do you have??
 
force,
ive been plaqued with the same situation, imtrying a hydormotive prop this weekend, ill let you know how it goes.
ive got a 454 carb in my 242 convincor, ive run as fast as 59.8 gps on our river here, subtract current at 1.7 mph gps, im at 58.1, it runs best so far with a 23 mirage prop, the 23 mirage plus gave me more porpoise and 1mph less, which is different from what everyone else reports. I, too, get the porpoise pretty strong under 40mph and have to use alot of tabs, 40 and up it runs real clean w/o using the tabs.
i need more HP too!!
 
Force,

On our convincor, whats good is putting the trim-tabs about half way down then nailing the throttle. It gets you out of the water faster and doesn't porpous.

CB
 
I just bought a 1991 convincor 25', having porpoising problems also. Boat has a 502 with
some custom heat, has double ram steering and trim tabs. was also having problem with very sensative steering but I think I have solved the
steering problem with the trim tabs but the porpoising is a real problem. after I hit a wake
the boat will not stop porpoising.
 
I have a 98 253 convincor now I have alot of hp about 750 , I had twin wpm external steering tie in system my boat seering was bad at high speeds. The bennett sport tabs didn't work over 60 mph the peasure started bowing them up after a period of time they stayed bent. I went to Zieger hydralic helm got rid of the cable, Installed 24" billet K-planes with new pumps. It handles much better night & day differance I appreciate the chages more every time I take my boat out. It still will porpous at around the 40's but I can put the tabs in further and it stops. I spent alot of $$$ on it but it has been worth it.
 
Thanks, is porpoising a problem with this boat.
seems that a lot of people are having the same problem. I blew a hyd. hose today on the tabs.
really unhappy with the steering but love the boat otherwise.
 
I'm kinda new with trim tabs what is the effects when they are all the way down.'
will this help the porpoising.
 
Originally posted by mkhammer:
I have a 98 253 convincor now I have alot of hp about 750 , I had twin wpm external steering tie in system my boat seering was bad at high speeds. The bennett sport tabs didn't work over 60 mph the peasure started bowing them up after a period of time they stayed bent. I went to Zieger hydralic helm got rid of the cable, Installed 24" billet K-planes with new pumps. It handles much better night & day differance I appreciate the chages more every time I take my boat out. It still will porpous at around the 40's but I can put the tabs in further and it stops. I spent alot of $$$ on it but it has been worth it.
Click to expand...
 
mk hammer want to know more about that external steering. I have a 85 senator with 475 ponies it tends to get a little crazy. I have 2in of play in drive now. Any play with your EX steering . also price tag is it a fairly easy install thanks
 
Originally posted by johnboyz85:
mk hammer want to know more about that external steering. I have a 85 senator with 475 ponies it tends to get a little crazy. I have 2in of play in drive now. Any play with your EX steering . also price tag is it a fairly easy install thanks
Click to expand...
Sounds like the steering arm that runs to the gimbal ring is loose.It can be tightened up.Tell me more about what it's doing.
 
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