251 Convincor Handling

[ajexpress]

I've had my 251 for a year now and I have attempted to learn to drive it on my own. I think I've gotten better but I want to pick the brains of others who have or have had the same hull. Here goes:

When I bought my boat it had a 23P Mirage on it. I've read a lot of guys only use the tabs to level the boat. that won't work with my boat. I have to keep the tabs pretty much level with the hull or it bounces like a basketball. I keep the drive fully tucked till 40mph, then I can trim out the drive. To get the last 3-5 mph I pull the tabs all the way up and away she goes. If I pull the tabs up before that I get the bounce. And these bounces start small and get worse. ive tried driving through them speeding up and it gets so bad the boat starts hopping out of the water.

Bought a bravo 24P after reading a lot of posts online hoping it would help. Nope it was way way worse. Anything over 50 mph and it started hopping. tried to drive through it and speed up and it started bouncing. bounced so bad I think we were airborne. The better half said it was the first time she was scared in the boat. I tried keeping the tabs all the way up the whole time and that wasn't better. Overall I hated the 24P bravo.

Outside of this the boat tends to list to one side or the other at any speed below 45ish. Maybe this is the nature of a 7' beam but its kind of annoying.

I need advice on a couple things here. First is this normal or should I be looking for something wrong with the boat? Second I'd love to hear detailed responses on how others 251's act and how you guys drive them. I have checked the skeg and it's straight, and the drive does not have any play in it. tabs are working as they should, checked before left yesterday.

Thanks in advance for your help.

 

[Wrenchmate]

aj, I had some of the same problems when I first got my 251 but yours
sound worse than mine were. I spent 2 weekends both sat and sun plus
3 or 4 tanks of fuel before I got it figured out. Also nothing says you have to trim at all, most times if Im only going to run at 45 or 50 Ill leave
the drive down and when I trim at all its in very small amounts, just little
bumps on the trim button is a lot on the 251, the drive probably only moves a inch or so each time and usually only when Im accelerating or plan on going really fast or WOT do I trim at all. As far as the list side to side mine usually only gos to the port or passenger side, so I tell the wife its because shes getting to fat and this will ruin the whole day so don't try it. I just run the tab lower on the port side like maybe on 2 or 3 and
my side on 0 or 1, plus I try to position things in the rear compartments
like anchors and any thing heavy to my benefit. And when slowing down
I trim down almost right away or shes going to bounce.

 

[keith4216]

Soon as you notice a bounce click the trim down. i mean just a click, it takes nothing to change these hulls ride. I just use the tabs to level. Mine always leans port also. Drop that tab a hair and your flat. Its a drivers hull. I'm changing trim and tab constantly. More when I have people that want to always be moving around and dancing. You'll get it one day but keeping the drive always down has to hurt your gpm.

 

[ajexpress]

Thanks for the replies. What props are you guys runnin? I'm gonna keep playing with the Trim and tabs but it sure does seem to porpoise a lot.

 

[ajexpress]

Keith how much do you trim up after 40mph?

 

[Wrenchmate]

Thanks for the replies. What props are you guys runnin? I'm gonna keep playing with the Trim and tabs but it sure does seem to porpoise a lot.

I have 2 props, 26 and 28p both Bravo1 4 blade labed. Don't know what
your hp is or what rpms your turning but the 24 should be close.

 

[keith4216]

Keith how much do you trim up after 40mph?

It all depends on conditions. Don't know if my gauge is right or not but I never trim past 1/4 from all the way down. I just ride by feel ,rpm and rooster tail.

Thats with a 23 mirage in not perfect shape. Id like to try a 25 mirage. Seems the 23 is hitting 5g with almost no trim to quick.

 

[ajexpress]

I have a stock 454 mag with roughly 365hp. With a 23P mirage it was running a little high on rpm (5400 I think). The bravo 24P was running significantly less rpm, but I had a hell of a time controlling it enough to look down to see what rpms were at WOT. Thought about getting the mirage it labbed to bring it down a tad.

My thoughts on my hull are if the boat is porpoising as easily as it does maybe I should steer away from a bow lifting prop like the bravo and go with something more neutral or stern lifting? Thoughts?

 

[502GTX]

I'm running a 502 with unknown (to me) HP. My boat has the same characteristics that you other guys mentioned, it lists to the port side and porpoises at around 35-40 MPH when kept at a steady speed. I have learned to tuck the trim in and out a bit when it starts and can keep it under control. I have never had porpoising under acceleration at any speed, only when cruising at a steady speed. Mine has tabs but I don't use them. I have a 24p Hydromotive four blade in horrible shape and I get 4900 RPM at 68 MPH. I also have a worked 26p Hydromotive 4 blade which is too much for the boat. It planes slower than the 24 and I can't get over 4700 RPM with it, never checked the top end. The boat cruises nice with it though, lower RPM at cruising speed and hardly any porpoising.

 

[linn]

How similar is the 251 and the 253 hull?

I know my boat likes to porpoise in smooth water when I'm cruising around 35-40 but, on my boat (253) it's easily controllable. I just tuck the drive in and give it just a bit of tab and she rides smooth.

AJ, does your boat have a stock lower?

 

[ajexpress]

I don't know exactly how similar the 251 and 253 are, outside of the obvious beam difference. I can do the same as you linn, it's why I run the tabs level with the hull. If she starts to bounce I tick down the drive and it's fine (this with a 23P mirage). I guess I just wondered why I have to use the tabs at all, when most seem to just use them for leveling. If my tabs are all the way up she'll bouncy bouncy, unless I'm WOT.

My lower is all stock.

Everyone says these hulls like bow lift, but I just have a hard time believing I should be using a bow lift prop when there is obvious porpoise. Making an initial assumption that all is ok with the hull, etc., and assuming I correct via prop, that would make me think the hull, already designed for hull lift, doesn't need as much prop help to do so. This is why I'm thinking about looking at a more neutral prop to see how it responds. Anyone have suggestions?

 

[ezstriper]

I had a 251 for years..now have a 253..lots of difference...but in your case something is strange...they all lay over coming on plane, trip up that goes away...I used the tabs to level boat out side to side as withe 7' beam very sensitive to load/water/wind...but I found a 24 bravo 1 the best all around prop hands down..but could run almost 2 mph faster with a 23 mirage +....do you have a bunch of weight along sides the engine ? also maybe your floor and foam under soaked with water(mine was) causing a weight issue ??

 

[ajexpress]

In the back I have dual batteries on the drivers side, and my anchor with 6 foot chain on the other side. Other than that its a couple life jackets and bouys. Not much else in the boat besides people and coolers.

My floor is rock solid, but not sure about the foam under. How did you find out yours was water logged, and how'd you take care of it?

Also, how do I check to make sure all the drainage is working correctly from bow to stern?

I'm kinda at a crossroads and I'm trying to determine what to do. When I start thinking of the money I'll spend upgrading this boat & motor, the cost starts getting to what a newer boat would run.

 

[502GTX]

I think the listing is mainly due to the narrow beam and how the boat is loaded. Mine will level out with just a light twitch of the steering wheel, and will list with just one passenger in the back seat if they sit off to one side. I can tell where my anchors and cooler are located in the boat by which way she leans at low speeds. Over 35 MPH and she runs nice and straight.

 

[ezstriper]

I would put batteries each side of the engine, better balance, keep them as far forward back there as possible, I had a very small soft spot in the floor, took the floor out and found the foam soaked..bet it weighed 100lbs or more, took it all out and did not replace it...also do you have a stock length drive ?

 

[ph1ngering]

Been here myself, just takes some seat time i think.. Gotta find the right combo for the water conditions, how many people on and knowing your boat.

I run my trim almost 1/2 way up once on plane with just a little tab to keep her level, but once she starts bouncing i gotta hammer through it or drop some trim to get her to clam down again. Some days i can't run more than a click or two above all the way down, just depends on the load and water.

I thought people saying it was a drivers boat were just talkers, but after three season of running my 279 its 100% true, always adjusting something on that thing. I love it.. Keeps me busy while everyone else is drinking and getting wild..

 

[ajexpress]

After thinking about it more I've realized a few things. One is that in the slop & chop the boat handles like a dream. It seems most of my issues are when the boat is in calm water....but really that issue is my persistant attempts to not run the tabs level with the hull. If I don't run them level it will porpoise unless over 50mph.

You are right, it's a drivers boat....and moreso than most. I guess my learning curve has been steep since this is my first performance boat. Normally it was just trim and go on any boat I ever ran. And maybe a tad bit of stubbornness in that I didn't feel I should need to run the tabs level under 50. Still going to play with the prop and see if I can resolve that issue....or at least reduce it. Oddly I heard many say the 24P bravo was good for this boat, but I found the exact opposite. My mirage 23+P is much better.

 

[bigsbetter]

I hated the way the 251 drove when I first got it too. At wide open throttle they are perfect, anything around cruising speed they porpoise and lean. You guys can laugh at me, but I put on a Stingray Hydrofoil and it really helps. I've since taken it off during all my expierementing, but put it right back on after a week or 2 because I like the way it handles much better with it on.

 

[2tonchevy]

there are at least two ways to get porpoise (hop) that i have found

too much bow lift...

too little bow lift...

this can be brought on by at least a few variable: x too low or x too high combined with the wrong prop.

i had the same problem when i got my 2800. its good to go now after some playin around.

on my hull the 4 blade hydromotive (cleaver style) props are a waaaaay better rough water prop but are a couple mph slower.