bracketed outboard,popousing problem, Need help

[rbulman]

Hi Guys,

I realize that my boat is neither a screamer nor a flyer and not really the focus of this site. It seems however there are some knowledgable folks on this site who may be able to help me.

I have a 96 Mako 232 which is a 23' with a closed transom and an armstrong type bracket. The boat has a 225 mercury and I cannot get it to ride right. I estimate the whole package Boat / T-top / 150 gallons fuel / gear to be about 5000 lbs.

This boat gives me a bounce even in the flatest of seas. It seems to me like she isn't getting her nose down enough to fight into the water. It doesn't like any positive trim or the porpouse gets worse.

When I got it the motor was down as far as it would go and it had a Merc Laser II 19p prop. I have changed the prop a few times and had some success. The best performance was from a Merc Revolution 4 blade, but I couldn't get the RPM's I needed.

I have tried playing with engine height (moved it up 1 hole) but the water pressure dropped below 5 and that scared me.

Right now the motor is back at the lowest position and I am running a 15p Merc Mirage Plus. The RPM's are o.k. but I still have a little bounce.

Anybody have any advise on what I can look for to solve this problem ?? Would more horsepower help ? The boat is rated up to 250 hp and I may go to that if I need to.

Any suggestions would be much appreciated.

Thanks,
Rich:confused:

[rbulman]

Sorry to jump on with another post but I thought I would include a picture of the Boat and motor height and maybe this would help.

Thanks,
Rich

[vector mike]

I don't have much experience on this kind of boat but most of the boats that I see like that have trim tabs on them. Maybe that is all you need.

[AnthonySS]

RBULMAN,,

Looks Like a cool rig!!

What are the current WOT Rpms with this setup.

Hope we can help you out some.

HEY don't sell 'er just cause she has some bounce:D

[rbulman]

Hi Mike,

Yes I have trim tabs and I do use them, but even they cannot take the bounce all the way out. They do help some though.

It doesn't seem like I should need to always use the trim tabs on this boat as it supposed to be a pretty good performer. I usually reserve trim tabs for leveling out the load when too many of my fat fishing buddies sit on one side of the boat.

Would an engine to low cause a porpoise ? It seems like the key is engine height or prop, but I am out of Ideas.

Thanks for the post,

Rich

[rbulman]

Anthony,

As currently rigged with the motor all the way down (like in the picture) and a 15 pitch Mirage plus prop the WOT is about 5300.

It seems like the performance of the boat is a little better when it is open, but the midrange is terrible. It gets up a little more and drops the nose.

I am more concerned with mid-range performance as I have three little kids that I like to take on the boat. It breaks my heart to see the 2 year old going airborne on a flat day !!!

By the way the pics are from when I bought it, but I thought they might help.

Thanks,

Rich

[vector mike]

Motor height does have some effect on porpoising. Usually if the motor is too low it will cause it. You get too much gearcase drag. You said you lifted it up and lost water pressure, well there is a trick that might help you out a little bit. You can plug the top two holes on each side of the water pickups. Just tap and plug with set screws. Be sure to use locktite on them. This will help not to suck air with the motor up. Just another suggestion. :)

[gaineso]

What's your water pressure with the motor all the way down??

It looks like it should easily come up a couple inches on that bracket. Are you absolutely sure there is no flex in the hull/motor.bracket assembly???

[rbulman]

Gainso,

Thanks your reply. Sorry tor the late reply, I couldn't seem to get logged from my home computer.

Normally my water pressure gauge reads 2.5 at idle and goes up to about 7 when I am running. This is with the motor all the way down. Like I said, once I raised the engine the pressure would not go above 5 even full RPM.

As far as the flex you spoke of I don't know how to look for that. The Bracket seems to be well supported on the boat and doesn't move under my weight. I did notice while running this weekend that the engine seemed to be bouncing. It was a little choppy, but the motor seemed to want to pop up when the boat stayed steady.

Let me know how I can check for flex in bracket, I assume I would need to have someone run the boat and watch the action of the bracket.

Also, can you let me know about water pressure. This is the first time I have had a water pressure gauge on a boat and I don't even know what the acceptable range is for pressure. Right now this gauge just stresses me out and I don't know when it is OK.

Thanks for your help.

Rich

:confused:

[vector mike]

What i have heard about water pressure is that you want atleast 10lbs. at WOT. When was the last time you replaced your impeller?

[CDave]

Looks like alot of setback for that combo. I'm no expert though.

I've got some friends with Robolo's and Grady's and they don't have near that much setback.

My guess is with that much setback the engine is reaching a point where it can't "lift" the bow anymore and is falling back down. The small improvment with the 4bald prop kinda supports my theory. Anyway like I said I'm not an expert, JMO.

Like Vector Mike suggested look into a waterpump kit also.

[rbulman]

Mike / Cdave,

Thanks for your responses. The impeller hasn't been replaced since 10/00 on this motor.

I think it might be time to do that. Maybe once that is done I put the engine up and try it again.

In terms of setback it is 30" from the boat to the engine mount. I called Armstrong and said the rule of thumb is 1" above the line of the keel for each foot of setback. Right now I am right about there.

I have corresponded with other people who have this same boat and they have no performance issues with it. I also tried Mako who claims that this boat is one of their best designs.

I am leaning toward putting a 250hp motor on this and running a 4-blade prop. I hate to spend that kind of money without knowing it will work though.

I cannot understand what the issue could be though as others with this boat and 225 Merc have no problems.

I'll check to be sure that the bracket is tight when the boat comes out of the water in 2 weeks. Very sad day, season too short here in Boston.

Best Regards,
Rich

[gaineso]

Season's kind of short here too. We only get about 51 weeks of good boating and fishing every year.

[gaineso]

You might wqant to check the bottom of the boat for a hook or a rocker condition.

Might be a source of the problem, especially if there's some excess hook right at the stern.

[Pro-Comp 2.5 260]

4 Blades usually help this situation. A Rev 4 is a big wheel! You might want to try a different 4 Blade. Possibly a stern lifting Prop.
Putting weight in the front will definately help.

[rbulman]

Hi Guys,

Thanks for your replies.

Gainso, I have had the hull checked already for Hook / Rocker and all seams o.k. That was one of my first thoughts and I fully expected it to be the problem.

Pro-Comp, thanks for your idea on the prop. The four blade definately helped but I am currently only able to run 15p and I can't find a 15P 4-blade. This is why I am thinking on a bigger motor so I can get the performance of the 4-blade.

Unless you have any suggestions on where I could find a 4-blade prop in a 15 pitch ?

Let me know.

Thanks,
Rich