Porposing
 

I am the original owner of a 1996 Mariah 202 Shabah. The boat has a 350 mag engine with a bravo 1 outdrive. The prop is a high 5 stainless.

My problem is that when I trim out drive to raise the boat out of the water to go cruise, at about 40 mph the boat starts to porpoise and I have to trim it down. So I have a great hole shot, but since I can’t trim the boat for optimum cruising my top speed is very limited.

I have moved what weight I can to the bow, and I have considered smart tabs, but before making that investment I was wondering if any other Mariah owners have experienced this proposing problem, and what approach them have used to hopefully solve it.

Thank you for your help
Rob G.
Las Vegas, NV

Re: Porposing
 

Usually a slight bit of trim gets rid of it for me, but I never have to trim out of the optimal range, I still top out at 53 mph. I have no problems cruising at 30mph either. I carry a 15lb anchor and some chain up front, + whatever passengers and gear.

I have read on other forums where boaters have stated that Smart tabs helped to reduce porposing.

Re: Porposing
 

So what is "optimal range?" TBH: I'm new to this power-boat and outdrive thing, and I kinda figured the only time you'd trim the drive up was in shallow water or when you're getting ready to put the boat on the trailer.

Jim

Re: Porposing
 

^ When you start out, the drive should be trimmed all the way down. As the boat comes up onto plane, the bow will tend to "dig" into the water, because the drive is pushing the stern up. You then trim the drive out, to lift the bow until you are planing without the bow plowing down into the water. You will feel this as you drive. There is usually a few degress of trim (the optimal range) where the boat's forward resistance is minimized (neither the bow nor the stern are "buried") and your rpm's maximized. If you trim up too far the prop will ventilate, and you will quickly drop off plane.

Re: Porposing
 

Since you have a 202 as well, are you able to exceed 35mph when you are trimmed , or do you experience the porpoising I wrote about in this thread?

Thanks

Rob

Re: Porposing
 

He answered that in his first follow-up to you, Rob. The second post in the thread:
Jim

Re: Porposing
 

I missed that response; thank you for pointing that out. That leads me to my next question of Z202:

Since you are not experiencing porposing, what type of propeller are you using, and what engine and outdrive to you have?

My thinking is that if our engines and outdrives are similar, than my problem must be due to the prop .

Thanks again all who responded.

Re: Porposing
 

Rob, we have a '94 182 Barchetta with a 4.3L Mercruiser V6 and Alpha One, Gen. 2 outdrive and High-5 prop. Experimenting today, I found that our boat started porpoising if I raised the drive much more than about 25% by the trim gauge.

Crusing at about 3000 RPM (can't go much beyond that, right now, as we're breaking-in a new engine), I gained 3-4 MPH, maybe 5 MPH, by raising the drive to about the 25% mark.

Jim

Re: Porposing
 

Proper trim will always net you more rpm and a few more mph. As to porposing, a slight throttle adjustment, or a little bump to the trim switch usually makes it go away for me.