Merc 2.5. Why are they better?
#22
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I was talking to a guy today that said depending on the prop, it is better to take off with the drives out (+ trim) as opposed to in (- trim). He said this is good to throw the boat up on plane and to get the stern out of the water.
Any opinions on that?
Any opinions on that?
#23
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In well over 40 years of boating, I have never found a boat that popped up on plane better with positive trim. If you want to get a boat up on plane, you need to get the bow back down as soon as possible. Whomever you talked to was wrong.
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It was a drag boat racer. I saw several others taking off this way with 2.5s, that is why I asked him about it. I thought it was odd as well.
#25
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I do that on my outboard boat actually, after lots of playing with it, we found that 0 works the best, not in, and not out, but the prop shafts straight in line with the bottom. It jumps way faster then when its trimmed in. 2 foot set back, engines mounted all the way up.
#26
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That being said I use 1/16 inch spacers to limit my trim in so that when I test I can figure out exactly every time where to start my trim out. I also use a delay computer activated by my foot throttle, then a duration programed so that my trim system runs the exact same time to set the boat. After that I fine tune the rest of the pass. I am also using a custom trim pump with a horizontal trim ram, and 24v on that trim pump to make all this happen FAST.
I can only see using positive trim if you need to aerate your prop(s), as a boat floping back into the water after it launches in all cases slows you down. could be that there trim isn't fast enough..... hard to say.
#27
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I am a Drag boat racer, I have a 530lb boat with 410hp and I trim it IN to launch, consider I am going 101-103 mph in 500 feet. If the boat leaves bow high and comes backdown again and kissis the water it kills your ET.
That being said I use 1/16 inch spacers to limit my trim in so that when I test I can figure out exactly every time where to start my trim out. I also use a delay computer activated by my foot throttle, then a duration programed so that my trim system runs the exact same time to set the boat. After that I fine tune the rest of the pass. I am also using a custom trim pump with a horizontal trim ram, and 24v on that trim pump to make all this happen FAST.
I can only see using positive trim if you need to aerate your prop(s), as a boat floping back into the water after it launches in all cases slows you down. could be that there trim isn't fast enough..... hard to say.
That being said I use 1/16 inch spacers to limit my trim in so that when I test I can figure out exactly every time where to start my trim out. I also use a delay computer activated by my foot throttle, then a duration programed so that my trim system runs the exact same time to set the boat. After that I fine tune the rest of the pass. I am also using a custom trim pump with a horizontal trim ram, and 24v on that trim pump to make all this happen FAST.
I can only see using positive trim if you need to aerate your prop(s), as a boat floping back into the water after it launches in all cases slows you down. could be that there trim isn't fast enough..... hard to say.
I might also add that drag boats are quite a bit different than offshore boats.
#28
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Now that explanation I can absolutely agree with. You want the bow down soon, but not slammed down. Too much negative trim could do that. Too much positive trim and all you get is a moon shot with the bow.
I might also add that drag boats are quite a bit different than offshore boats.
I might also add that drag boats are quite a bit different than offshore boats.
Forgot to mention that, there is a sensation that the boat is coming on plane faster when it lurches up (in drags) as apposed to sliding out.
With all that said, I spend a lot of time in larger boats and I still can't think of one that gets on plane better with positive trim, unless the tabs are down and the props need to break free and trim is used as a patch.
Anyhow back to 2.5's..... still the coolest motor ever made.
CLAMP-ONS RULE, Car motors belong in CARS.