Looking for more bow lift.

pastormark · November 20, 2008, 08:34:52 AM

I have a 184 Champion with a 150 EFI on it. I don't seem to be getting enough bow lift. I was wondering if trim tabs would help. I have a six inch jack plate with a 23 pitch Yamaha pro prop. The boat comes out of the hole great but seems to still be dragging in the water when running top end. Any suggestions?

scooter520 · November 20, 2008, 07:46:16 PM

I had the same problem with my 19' Champ. Course I had 100lbs of jigs in the front compartment too! I found that with the jack down, I could lift the bow much better. Champions like a low jack height. Is yours Hydraulic? What are your RPM's? Trim tabs on a smaller hull like yours may not be the answer. I'd borrow a 24" small hub trophy to see if it will help.

pastormark · November 20, 2008, 09:28:18 PM

I tried a 23 Trophy and it set my rev limiter off. Right now I am running right at 5700. It just seems like it is dragging in the water. I tried raising the jack plate but then I loss water pressure. I am running fourteen - sixteen pounds of pressure right now so I hate to do very much with the jack plate.

I know my dad runs a 115 Yamaha on a 17" Cajun and he can trim his motor up until it cavates with just one person in the boat. Right now I can trim my motor all the way up even at three quarters throttle and it won't cavitate at all. Is that normal for a Champion?

I thought maybe a little more tilt might get my boat up out of the water further. Am I thinking wrong?

WRBass · December 01, 2008, 02:54:52 PM

Your problem is more than likely the height the prop shaft is set verses the planning surface, should be about 3 1/2". Weight distribution is always a critical issue; the heavy stuff needs to be behind the driver.
6" inch jack plate set back should give you enough lift to plane of the last 12" of hull surface.
You can plug the top 2 water intake holes without loosing water flow or pressure; 10 to 15 psi, is normal.
WRB

pastormark · December 02, 2008, 10:31:42 AM

I ran my motor down to 3 3/4 but, have not been able to get it out on the water. Last time I went out with it at 3 1/2 I still had a rooster tail above my cowl so I dropped it to see if I might get some more lift.

I will let you know what happens.

Thanks Mark

WRBass · December 02, 2008, 12:39:11 PM

Level your boat sitting on the trailer. Use a 36 inch level or longer, placed on the center planning pad and use you trailer front wheel jack to move the boat up and down. Note any daylight between the boat bottom surface and the flat level, there shouldn't be any gaps or humps (hooks and rockers). Now level you engine, use smaller level sitting on the bottom surface of the cavitation plate. Next draw a chalk line through the center of the prop shaft housing, using the smaller level. This will be your reference line to measure the distance your prop shaft is down from the planning surface. Note the position your trim gage is sitting when the engine is level, it should be near the middle.
When you start to run the boat up on plane, the engine should be trimmed all the way down and the boat will get on plane quickly. Then trim the engine to the middle position and the rpm's and speed should rise quickly. The final trimming is dependant on your hull and weight distribution; about 3/4 trim should be maximum, a small 3' to 5' rostertail is normal at full trim/speed.
I'm trying to be condensending, just don't have any knowledge of your boating skills, so these are some of the basics to start with.
WRB

bass1cpr · December 02, 2008, 02:21:25 PM

Has your prop had any work done to it? You can have cup put in the prop to help give you more bow lift. Since your in the St. Louis area you can try Mazco props in fenton. John knows what he's doing and does very good work.

pastormark · December 02, 2008, 08:00:39 PM

Ok, I got the measurement. It is 3 5/8 on the nose. I am still seeing a rooster tail about 2 foot over my motor. Do I need to drop it more? Also, I can trim my motor up all the way to the top and never get any cavatation at all.

WRBass · December 02, 2008, 08:26:41 PM

Your set up sounds good to me, if the water pressure is holding steady and not fluctuating alot. You are focused on cavitation and that should only happen if the motor is over trimmed when trying to plane the boat or turn the boat.
Proper running trim is when the boat gets up on the pad, the stirring is light and easy and you reached max speed and running rpm's. Continuing to trim up the motor only causes the prop to slip and you loose speed.
How fast to expect your boat to run?
WRB

pastormark · December 02, 2008, 10:01:36 PM

I think it is running 61-62 right now. I just want it to be right. Whatever that is! My water pressure is about fourteen. Should it be more than that?

WRBass · December 02, 2008, 10:27:08 PM

Quote from: pastormark on December 02, 2008, 10:01:36 PM
I think it is running 61-62 right now. I just want it to be right. Whatever that is! My water pressure is about fourteen. Should it be more than that?

14 psi water pressure is good. Maybe some that has your boat can answer that better, but a 150 on a 18' Champion should run about 65, so your are close. Try the prop shop referenced, they set up a lot boats and will have a better idea how specific rig should run. Prop cup and rake can be tunes to optimize performance. You maybe able to go up to a 24 pitch.
WRB