Hull problem???
 

Anyone having trouble with porposing on their 27' Baja's, or any other quirks? What was the cure if you happened to fix it?
My hull starts its porposing about 70 mph, with the tabs neutral it quits but I lose about 2 mph at top end, over 75 if you pick the tabs up it you pick up speed but the porposing is a lot worse! :( :(

Re: Hull problem???
 

Most Bajas have a pretty generous radius where the boats running surface and transom intersect. If that is squared off it will likely help the porpoising. It will also make the boat run flatter which can hurt your top end depending how fast you run. If you are getting into the 80's or 90's you are probably running on top of the water enough that a small loss of bow lift won't hurt your top end speed, and it may even improve. We have done this on smaller Bajas running 80+ and the overall performance was much better with no top end change.

Craig

Re: Hull problem???
 

-Craig
Thanks, I did sand that once before but maybe not enough, I'll try it again since I have the motor out and the drive off, will make it easier.
-Ken

Re: Hull problem???
 

On ours sanding wasn't enough. We actually had to use some filler and re-paint. I don't know if this will solve your problem, but take a look at other hulls and compare the Baja radius and you will see the differance. Baja is a good boat, but most of their hulls are not manufactured to run much faster than what they can do with stock power. Look at Eliminator, or Fountain and that trailing edge is pretty sharp. My 1990 Baja 210 ESS ran in the upper 90's, and needed some mods to do it. :cool:

Re: Hull problem???
 

I do remember seeing the edges on an Eliminator, I will take that into consideration, Thanks again

Re: Hull problem???
 

Was that Eliminator upside down when you saw it?

Re: Hull problem???
 

What prop are you running and what HP engine?????

Re: Hull problem???
 

Yep, I'd try diff style prop. If your running round ears like a mirage, try a hydromotive with semi cleaver design, and vice versa. Sounds llike more bow lift of the cleaver is what you need. It will either make it better, or worse, and you don't always know till you try it on your boat.

Re: Hull problem???
 

Isn't a clever prop for transom lift?or less bow lift.

Re: Hull problem???
 

Uhhhh..... yep, meant to say "transom lift" in #8 above.......sorry......gonna have to proof-read more often!!!!

Re: Hull problem???
 

as a matter of fact it was, hanging in someones garage I think! :D :D

Re: Hull problem???
 

27p four blade merc, 700 hp

Re: Hull problem???
 

What is the make and model of the propeller?

Julie

Re: Hull problem???
 

kenny,are you using a nose cone? On my 272 i'm turning a 30 pitch 4 blade labbed prop around 5400,this summer while i was waiting for parts for my outdrive i bought a spare drive w/out nose cone and the boat felt like the nose was digging in,boat was hard to get trimmed out enough to loosen hull up. My hulls a 2000,ive had more problems with chinewalking above 70 than anything,full hyd strng helped take most of that out. Do you have a pic of your boat at speed,it really needs to be on hull pad towards back to air out enough to get good speed. I'll try to post pic if i can find one,Smitty

Re: Hull problem???
 

That pic is at about 80mph without a nose cone,everyone i boat with says when i'm going mid 80's i only have about 2 feet of hull in water and that it almost looks like just the drives in the water. I haven't done anything to rear edge of hull yet,everyone says these bajas will go 2-3 mph faster without it BUT that it greatly increases porposing unless your dragging your trim tabs,Smitty

Re: Hull problem???
 

Yep, looks good, I'am running a nose cone, my hulls 24 deg deadrise, is yours 24 or 22 deg, I know they changed them but I don't know what year it was. I raced a 2003 with a 496 blower motor and passed him, I think it was a procharger m3 on it. No problems with chine walking at all, I'll look for a pic at speed, should have one somewhere!

-Ken

Re: Hull problem???
 

kenny, how fast is your baja running and whats your setup, my buddies got a 1999 with a 502, bone stock. hes been considering mods or blower. what speeds are you seeing with 700hp and how are you getting to 700?

artic, how bout you?

thanks
kevin

Re: Hull problem???
 

2000 baja 272,540 motor with m-3 procharger,30 pitch lab prop,85.1 mph gps best ever w/boat empty,83.5 mph any day of the week with 3/4 tk gas and 4 people,84.5 w/just me and the ol lady 1/2 tank gas and cooler full of BEER :D . Boat went 78 mph w/502 w/procharger & lightning headers turning 28 pitch 4 blade around 5200. Boat went 62 mph bone stock w/4 people,3/4 tk gas,23 pitch at 5050,Smitty

Re: Hull problem???
 

-Kevin
I started out at 63 mph was out of the box speed, I started with a prop change, made 65, Then the headers, cam change, ported the steel heads, prop change turned 70. Next I was looking for 75, I didn't want to put a blower on it, I wanted to see what I could get out of it naturaly asperated. I started modifying the intake manifold, ported the s___T out of it, hand made a plenum, bigger injectors, tossed the vst setup, put some big a-- throttle bodies on it, a nasty solid roller cam, stroker crank, bored it and turned 77. Now still not wanting the blower, I'm lookin for 80, I think the hull is in need of a little TLC, so thats next, we will see what happens after I take a belt sander to it! There is potential to make the 502 run and run better, but there is some attention needed to the stock intake, fuel system and heads. Not knocking the blower motors but you can get speed to a point without one! What the heck else is there to do in the winter anyhow?

Re: Hull problem???
 

Kenny,how loud is your boat? I imagine you must be running dry exhaust with that big ol cam. I have lightning headers on mine and the molded swim platform seems to muffle it alot,at least from the drivers seat!How tall of a prop have you tried,with the kind of torque your making i'm surprised your not spinning a 30 or 32 pitch,Smitty

Re: Hull problem???
 

Ya know, my standard response to porpoising questions is that boats don't porpoise, skippers do. I've always had luck finding the right combination of tab trim and drive trim for conditions. I can make a boat porpoise or stop porpoising.

But this thread makes me think that Kenny knows what the heck he is doing, and still has problems.

Huh. Guess I've been kinda lucky.

Re: Hull problem???
 

Anyone can stop porpoising - trim in the drives or lower the tabs, sure....but both actions add drag and kill speed. Porpoising is simply the hull/trim setup creating more lift on the hull than the power can hold up....so at that given hull/trim setting either more power or less bow lift is needed.............

Re: Hull problem???
 

Wellllllll.....It's noisy, have CMI headers, shotguns tamed it down at idle but its still noisy!
I used to yell at the ole lady runnin on plane until I put the shotguns on, now we can talk to each other. I kinda liked it before , could not hear any *****in! :D If your not familiar with CMI's they mix water right at the tails. I'm still messing with props, I'll find the right one one of these day's! I feel once I can get the hull straightened out, it will be easier to ook up the right prop!

Re: Hull problem???
 

Tried most everything, I can stop it from porposing with the tabs, but it kills my top end by 2 - 3 mph, if I pick up the tabs I pick up the speed, then the nose starts bouncing. I felt the trim tabs were put on there to plane the boat easier, or keep it planed at low speed, not to hide a hull problem, IMO.

Re: Hull problem???
 

Didn't I see that thing running 92?

Re: Hull problem???
 

That may have been the only time a cat was behind me! :eek: On the trailer!!! :D

Re: Hull problem???
 

In some states that counts!