porpusing problem
 

Well I'm to my end with this boat.... I have a 1997 232 islander with the 454 carbed motor and a 23 pitch 3 blade bravo1 prop. I have to bury my trim tabs mid throttle and cant even think about opening her up or I'm out of control porpusing and all over the place. Does anyone have any suggestions or do I need my head examined? Thanks in advance. Curt

Re: porpusing problem
 

Try putting about 40-pounds of sand (in plastic bags) in the anchor locker at the bow of your boat.

I had a similar problem with my 232 Boss when I first ran it. This modified center-of-gravity approach worked perfectly. After my tabs were repaired, I was able to remove the sand and retain the stability by running a slightly negative tab setting.

Re: porpusing problem
 

Thankyou I will try anything at this point

Re: porpusing problem
 

take the hook out of the bottom. lookat where the transom meets the bottom.see how much is there. Bajas are known for it. about the last 10 inches of the bottom will drop down instead of going stright to the transom.

Re: porpusing problem
 

I'm not clear on the hook? I'm not real handy when it comes to basic mechanics

Re: porpusing problem
 

Put a straight edge on the bottom of your hull in the transom area. If you have a large gap between the straight edge and the hull or if you cannot hold it flat against the fiberglass this could be a problem.

There is a fix for this.

Buck

Re: porpusing problem
 

I'm sorry I should have explained it better. do what Buck said , use a yard stick put the edge long way from the transom forward see how much gap is between the edge and the bottom. you don't want any. I would be willing to bet you don't need the edge. :eek:

Re: porpusing problem
 

That hull may be different, but the hook is there for a reason and the 2-3 people I know that have taken the hook out, had it put back because of very bad porpusing. Every pleasure boat hull I've loked at has hook of some degree.

Is this one just too much, and if so, has it always porpused like that? If so, seems like an issue that Baja would have wanted to fix.

Re: porpusing problem
 

That is a trip!! I will look at this tonight, I've owned the boat a bout 6mos the previous owner did not disclose this issue "SUPRISE" But as long as I've owned its always done this. I have two friends that just bought 242 h2xs with 496ho's so i'm pushing my boat a little harder to keep up and thats why it's become more of a problem. Thank you, Curt

Re: porpusing problem
 

Try contacting one of the prop vendors here for advice, maybe a 4 blade b1 22 pitch would help carry the bow better.

Re: porpusing problem
 

What Wobble said. Try a couple props with more or less cup. Some dealerships will have "loaner props" for you to try before buying. Also try a 4 blade. Do the simple stuff first

Re: porpusing problem
 

Thankyou. I tried a 4 blade 22 pitch b1 and lost all my top end as a matter of fact I lost about 8mph, Man I was extremely bummed, the prop guy said he could cup it some more but really wasnt happy about that. With the 4 blade the boat did alot better it still hopped a little and came out of the like it was nobody business I called throttle up and they did not do the loaner program with 22 pitch props so again back to the old drawing board. thanks again guys

Re: porpusing problem
 

did you ck to see how much hook is there? I agree that most pleasuer boats have a little hook or rocker in the hull to make them user friendly.Having worked for a Baja dealer and driveing alot of them and seeing what they do to the bottoms it generaly inxs of what you want there for higher speed running. I have sean them be as much as over 2 inchs at the transom but only go forward 6 inchs :eek: . just my 2cts :cool:

Re: porpusing problem
 

When you lost your 8mph, did you lose rpm also? If your rpms were up near max, then you could try a 24p b1 to pick the speed back up.

Re: porpusing problem
 

swaaby, read this thread on the subject...good info in there.

Re: porpusing problem
 

HOOK And ROCKER
The bottom is referred to having a ”hook” if it is concave in the fore-and-aft direction. A hook causes more lift on the bottom near the transom and forces the bow to drop. This increases wetted surface and reduces boat speed. A hook, however, aids in planing and reduces any porpoising (rhythmical bouncing) tendency. A slight hook is often built in by the manufacturer. A hook also can be caused by incorrect trailering or storing the boat with support directly under the transom.

The opposite of a hook is a Rocker. The bottom is convex or bulged in a fore-and-aft direction. It can cause a boat to porpoise.

This from Mercury Racing Manual.

Re: porpusing problem
 

Now, Hydrolift has gotten to the point! "Hook" makes your boat plow, not porpoise. "Rocker" causes porpoise. The Mirage and Mirage+ props (what you run) are terrific "bow lifters", and that is NOT what you need. Try a known "stern lifting" prop (such as a Hydromotive O-IV) in your pitch range before messing with the hull. The folks at Throttle-Up can point you in the right direction if you can give them all the proper info. --- Jer

Re: porpusing problem
 

ECeptor, If I remember right I think I was maxed on RPM's. :drool:

Re: porpusing problem
 

jpclear, Thanks alot I will call them today with my specs again, The only thing is they do not have the prop program for a 22 pitch, However they said if I bought one they would exchange it for what I need. To me that is the same thing except you pay for it ?

Re: porpusing problem
 

Then try the 24p.

Re: porpusing problem
 

SWA--- If you have already called, then you already know. But if not; Talk to Julie or Matt and they will steer you right. Hydromotive makes props in every inch increment and Throttle-Up will make just what you need in between. You just have to buy the one that they customize for you. --- Jer

Re: porpusing problem
 

jer, So I guess a bravo doesnt have to be put on this boat. I was told not to switch brands of props....

Re: porpusing problem
 

try a rev4 by merc a 23p they work well with stock bajas

Re: porpusing problem
 

If you were maxed out rpm, but losing top end, our slip is too high. Go up a pitch or 2, but stick with the 4 blade. Some slip is good. If its still too much, try a spacer or a slight cup, but if its running right witout the cup, dont put one in. I hade hydromotive p-5's (no cup) and my boat ran awesome but i lost about 10mph top end. I ten tried merc props uo one pitch and with a cup and my boat ran like crap in anything but calm water. to much bow lift for a chop. I thinking abut trying a set of 6 blades no cup to try and reduce the slip or add a small spacer with the hydromotives.

Re: porpusing problem
 

I have a 93 nova spyder when i bought the boat it had a 23 mirage on it the boat would lean over towards left and would porpuse had to constantly adjust trim tabs. It would run level and straight if i got above 3800 with no tabs. I switched to bravo 1 24 pitch that cured the leaning and porpusing. But now I have the bravo1 24 labbed by hydromotive and the leaning and porpusing is back

Re: porpusing problem
 

Ok, A friend and I took the boat out Sunday morning(finally) on glass we trimmed the lower unit down and leveled the trim tabs like always. we got on plane then climbed up to 45. We started to raise the lower unit then started porpusing.we dropped the trim tabs, then it stopped, so then we opened it up we got to 4700 rpm and the rev limitor started hitting we were not at full throttle. so we went back and loaded up. we looked at the prop and its a 21 pitch mirage plus 3 blade. so I'm totally confused :eek: we dropped the lower unit while it was on the trailer, he said that my cavatation plates should be even with the bottom of the boat. Well mine are about 2inches higher ( if that makes any sense) he said I needed more prop. :confused:

Re: porpusing problem
 

Your cavitaion plate should not be even with the bottom of your boat. That would put your prop shaft about 6" below the bottom. I would say that is to low. I agree you need more prop. Try a 23p Mirage+ or a 22P Bravo1. You can find them on Ebay, then sell what you don't want.
What speed did you max out at? That will tell everyone your slip numbers.

Re: porpusing problem
 

Thanks we put a 3 blade 25 pitch and it did really good. I felt like there was no boat in the water. We got up to 62 mph with 4 adults and 2 kids. the porpusing stopped when we leveled off the trim tabs rpms were at 4700ish and no rev limitor problems :evilb:

Re: porpusing problem
 

Thank you all for the great info even though My information wasn't all that accurate. I need to slow down and pay closer attention to the finer details of my boat. I did not realize all the intersting detail and craftsmanship that goes into a hull and everything else. You guys that gave your knowledge and experience thankyou again, I would love to be able to buy you all a cocktail :drink: Thanks again as I always say a true boater is a good person especially if you own a BAJA.... hahaha just kidding thanks again, Curt :D

Re: porpusing problem
 

Let the record show that Swaaby owes the tech section a round of cocktails. :drink:

A labbed prop would probably be cheaper :evilb:

Re: porpusing problem
 

I think I can pick up a keg of hams light for about a" buck o five" :drink: hahaha

Re: porpusing problem
 

I have a 22 Baja and had a porpusing problem. When I took the tabs off it went away. I think I had the tabs mounted to low which caused the problem. U might want to remove the tabs and see how it runs.