Roostertail

[rboren]

Sounds to me the prop is not getting a good bite and it may be buried too deep. Check to see exactly what the prop is and check prop depth from bottom of pad. The majority of boats do not need to be trimmed all the way up for best performance.If set up with the correct prop and prop depth it will do better. I never need all the trim I have. With the prop I am running now,I am at 3" under pad to center of prop shaft. Best depth does depend on the type of prop. got to be the wrong prop if the engine can not turn more than 5400 rpm. 5800 would be fine. My boat is not the same model as your but the same rules apply.

[MMosher]

The Champion hull was designed to run max speed and performance with full trim in mind. Other makers such as BCB or Allison don't required as much. If your rig is going faster with less trim then your set up is off.

Sounds to me the prop is not getting a good bite and it may be buried too deep. Check to see exactly what the prop is and check prop depth from bottom of pad. The majority of boats do not need to be trimmed all the way up for best performance.If set up with the correct prop and prop depth it will do better. I never need all the trim I have. With the prop I am running now,I am at 3" under pad to center of prop shaft. Best depth does depend on the type of prop. got to be the wrong prop if the engine can not turn more than 5400 rpm. 5800 would be fine. My boat is not the same model as your but the same rules apply.

[pmgoffjr]

Your boats telling you what it wants. It matters not one bit what someone else is doing, your boat is telling you the motor is too high.

[rboren]

The Champion hull was designed to run max speed and performance with full trim in mind. Other makers such as BCB or Allison don't required as much. If your rig is going faster with less trim then your set up is off.

I doubt it. 74 mph loaded without power poles. Lost about 2 mph with poles. About 4-5 mph faster now than it was due to a Stage 1 kit. 4-blade prop however,by Mark. That is with nearly 400 lbs. of humans. 4800 rpm@60.3 mph this Saturday. Just cruising. It depends on which prop you are running as to needing full trim or not. T-1 prop is slightly faster but not by much, approx.2 mph. With a 25m Yamaha prop you almost need full trim but not quite.72 with a full fishing load and just 200 lbs of me. Yamaha engine,not Merc. Have had a bunch of boats and none actually liked the same prop. Still slow after my last boat which was an Ally. Modified Merc on back. And you are correct you needed little trim. Not much need to put a prop lower that you can't turn to max rpm. Smaller pitch prop and then drop motor if the same kind of prop. Some props just don't work good unless you send them to be worked. And some never work on the wrong boat for it.

[Lineman74]

Something is defiantly wrong. That 175 should push that 19' boat to at least 60MPH and you should be spinning a 24p 3 blade or a 23 4 blade. Time to start getting things checked out. Motor for performance and hull for water logged.

Is there any stamped numbers or anything on the side of the prop?

noting on outside of prop

[Lineman74]

Your boats telling you what it wants. It matters not one bit what someone else is doing, your boat is telling you the motor is too high.

that's what I think! I have a roostertail way over the top of the motor I trimmed up got 49mph WOT trimmed all the way and then trimmed down a bit got 52mph and roostetail is still way high. I'll start adjusting when I get to the lake next weekend

[getfished]

I expect the motor needs to be deeper. It is possible your report of 5" is not accurate. Make sure what rpm is max for that motor and pick a prop to pad starting point . Keep water pressure at 15 minimum. A 23 or 24 pitch should be prop for that setup. I had an 04 187 with a Merc 150 XR6. It would turn 5700 with me and a full load at 60 gps. Prop was a 23 Tempest worked by Croxton and a 10" setback.

[rboren]

I expect the motor needs to be deeper. It is possible your report of 5" is not accurate. Make sure what rpm is max for that motor and pick a prop to pad starting point . Keep water pressure at 15 minimum. A 23 or 24 pitch should be prop for that setup. I had an 04 187 with a Merc 150 XR6. It would turn 5700 with me and a full load at 60 gps. Prop was a 23 Tempest worked by Croxton and a 10" setback.

5 inches deep is why I said it is too deep. If it won't lift any at 5" seems to me the prop is wrong for that boat. Don't see how you would need to go deeper with a good prop. If truly at 5" with speed and rpm stated,the prop needs to be looked at. I ran a Fury on my boat and 4" was about right for it. Fury likes to be deeper than a Tempest on my boat. Correct me if I am wrong but is not a 187 the same boat as mine but a tad shorter?

[tdt91]

noting on outside of prop

Ok, just checking to see if the prop has been repaired/worked. Make sure you are measuring from the bottom of the boat and not a step.

[Lineman74]

Ok, just checking to see if the prop has been repaired/worked. Make sure you are measuring from the bottom of the boat and not a step.

I leveled the pad very bottom then the cavitation plate placed a small lazer light and measured 43/4" below pad I forgot to minus the light 1/4" that's why I said 5". I have noticed that these champions compared to my 2005 triton the transoms are long then has a step

[pmgoffjr]

Guys please don't bog yourself down in details. It doesn't matter if he measured five inches or twenty. A big high tail is your clue that it's too high. A different prop might run there but what he's got won't.

His next move is to keep going down until he loses speed. Only then will he know the exact right height for him.

[MMosher]

I don't. It's fact. The Champ hull was designed to run max speed and performance with full trim.

I doubt it. 74 mph loaded without power poles. Lost about 2 mph with poles. About 4-5 mph faster now than it was due to a Stage 1 kit. 4-blade prop however,by Mark. That is with nearly 400 lbs. of humans. 4800 rpm@60.3 mph this Saturday. Just cruising. It depends on which prop you are running as to needing full trim or not. T-1 prop is slightly faster but not by much, approx.2 mph. With a 25m Yamaha prop you almost need full trim but not quite.72 with a full fishing load and just 200 lbs of me. Yamaha engine,not Merc. Have had a bunch of boats and none actually liked the same prop. Still slow after my last boat which was an Ally. Modified Merc on back. And you are correct you needed little trim. Not much need to put a prop lower that you can't turn to max rpm. Smaller pitch prop and then drop motor if the same kind of prop. Some props just don't work good unless you send them to be worked. And some never work on the wrong boat for it.

[rboren]

I don't. It's fact. The Champ hull was designed to run max speed and performance with full trim.

You are probably correct as to the design,but if so my boat would scream if I set it up to need full trim. Just don't believe mine would run any faster than what it does now. I am off the turning chines and on the pad alone at 74 mph. I like to experiment with it and it is fastest like it is. Maybe there is something wrong with my boat.Not saying they were not designed that way. All the talk about raising to find top speed and now we need to lower them. I still say he has a bad prop. He hasn't been able to find out what it is. Now he is saying 4.5 inches which is still deep enough for it to run good if the prop was working right for the boat. My experience is with my boat and one other Champ. Pat certainly has way more experience. But as for experience I have set up many boats to get the best top speed. Something could be off on his hull also. But if he cant trim up and gain speed with a tall rooster tail,like he reported then he must be at 3" or above if the prop has any cup and is a good prop for a Champ.

[getfished]

You are probably correct as to the design,but if so my boat would scream if I set it up to need full trim. Just don't believe mine would run any faster than what it does now. I am off the turning chines and on the pad alone at 74 mph. I like to experiment with it and it is fastest like it is. Maybe there is something wrong with my boat.Not saying they were not designed that way. All the talk about raising to find top speed and now we need to lower them. I still say he has a bad prop. He hasn't been able to find out what it is. Now he is saying 4.5 inches which is still deep enough for it to run good if the prop was working right for the boat. My experience is with my boat and one other Champ. Pat certainly has way more experience. But as for experience I have set up many boats to get the best top speed. Something could be off on his hull also. But if he cant trim up and gain speed with a tall rooster tail,like he reported then he must be at 3" or above if the prop has any cup and is a good prop for a Champ.

This is why I think something is possibly misunderstood in the prop to pad measurement. I agree with Pat when the roostertail is high, the motor goes down. May be the wrong prop or hull may have issues. Something is not right. Could the motor be a long shaft ? I've never heard of a champ setup at 4 & 3/4" throwing a high roostertail. Something's funky monkey.

[TL16]

Not mentioned, but weight distribution is key, too much in front, to much in back can be problematic....

[OldTimer57]

I keep hearing this max trim stuff, but that is really _wrong_. Optimal performance is produced when the prop shaft is parallel to the direction of travel, which would be parallel to the surface of the water. A simple bit of math:

thrust = cosine (trim angle) where parallel to the water is zero degrees. For every degree you trim up beyond level, you lose a bit of forward thrust.

That being said, if going beyond that point trim-wise improves speed, you definitely have a setup problem. Namely, the boat is too nose heavy. Most straightforward way to fix that is to increase engine set-back, moving that heavy motor rearward which will help lift the bow with less trim angle and lost thrust. Or, if you have a hundred pounds of heavy stuff in the front, move it back. These tall rooster tails simply show that power is being wasted.

[MMosher]

All your math was factored into the hull design in 1976 when the first 16'8 rolled off the line and was specifically built for the maximum trim angle of a Mercury engine. It provided maximum lift with a quick hole shot.

[QUOTE=OldTimer57;8701220]I keep hearing this max trim stuff, but that is really _wrong_. QUOTE]

[rboren]

[/B]
This is why I think something is possibly misunderstood in the prop to pad measurement. I agree with Pat when the roostertail is high, the motor goes down. May be the wrong prop or hull may have issues. Something is not right. Could the motor be a long shaft ? I've never heard of a champ setup at 4 & 3/4" throwing a high roostertail. Something's funky monkey.

Yeah, Pat may be correct after all! If he is not measuring correctly! I just know if it is 4.5-5" below pad the prop is not good or something is wrong with the hull. If the prop is junk,it won't matter how deep you put it. It will never run as good as designed. It might pick up some speed but will still be below par. Could go either way. Got to give accurate info to get somewhat accurate answers. RPM's sound too low for me. Wrong pitch prop or too deep could cause problem. Or it is really set at 2 inches deep and is coming out of water before lifting bow. Older model Mercury trim will trim all the way up and into the tow position. No bodies boat was designed to run with the engine in the tow position. Using max trim depends on how much an engine will trim and what angle the jack plate is made at.
'

[MMosher]

You're right, go plow water. Enjoy.

[Bruce2]

I don't know how everyone comes up with 3 1/2 3 3/4 and so forth my prop to pad always comes out 3 7/8 or 3 3/8 or 4 1/8... i guess i just have a weird boat..