SoCal Jet Boats
Tech Talk => I/O's => Topic started by: TRUCKIN_318 on May 19, 2014, 03:00:47 PM
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Hey there fellas, I have a 83, 21 ft open bow Carrera, with a 330 hp 350, and Volvo 290 outdrive. I was curious how to make my manual trim tabs work best for top speed. Does this boat even need the trim tabs? Right now, they are slighty down. What is the best position to have them in? What kind of top speed should this boat get?
Thanks
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You probably won't get much usable advise here because most of us don't have much experience with boats that use the little spinny thingy out back. ;)
As for the trim tabs, you're going to have to try them in several different positions with similar water conditions (and probably a GPS) to determine if you are making gains with the changes. Use a long straight edge along the bottom of the boat and out next to the trim tab (if down) and measure how much down it is (or get the hull leveled and use an angle finder on the trim tab) to get a base line. Then adjust it so it is level with the bottom, then up about 4 degrees. After each change go give it a good test day and compare your top speeds vs ride quality. You might find that you prefer the ride over the added mph.
Good luck.
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I use the tabs to keep the boat even (fat friends all seem to sit on the same side) and to control stability. This boat is supercharged and fuel injected and will run hard to about 100mph. I have played with the tabs in just about every location an all they do is keep the boat balanced. The drive trim on the other hand has a great effect on speed and/or ride (up=fast and loose! down=stable and smooth). Every boat is different, see where your boat likes to be set. Start down and go from there... Be careful on turns
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Hey there fellas, I have a 83, 21 ft open bow Carrera, with a 330 hp 350, and Volvo 290 outdrive. I was curious how to make my manual trim tabs work best for top speed. Does this boat even need the trim tabs? Right now, they are slighty down. What is the best position to have them in? What kind of top speed should this boat get?
Thanks
I assume you have what they call "manual tabs" sort of like a set it and forget it type deal?
3* up from square with the bottom... The 290 Volvo is somewhat of a pig for speed, see if you can find yourself a Duo Prop lower... I have the same boat I am building with a Mercruiser.
GT
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Thanks for the info guys
GT, how big a project is changing over to a mercruiser drive? How about cost?
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Thanks for the info guys
GT, how big a project is changing over to a mercruiser drive? How about cost?
trying not to be a killjoy but this is a gigantic job.
The largest problem that you have is the transom cutout is completely different and will need to be completely replaced including gel coat.
The best recommendation I can make for the best bang for the buck with me to find a duo prop lower.
I can expand more on this later.
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i took my boat out for a chance to really open her up last weekend. i found that my bow was riding a liiiiitttle too low and i didnt take it over 4k rpms. still had plenty left in it though. i hit the trim button a few times with little change... but i didnt adjust the trim gauge sender when i originally installed the drive so i dont really know how far up i was going. decided to call it a day. ill mess with it more next weekend.
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Not a killjoy at all. That's what I needed to hear. I ain't looking for a project of that size. Now, putting a duoprop lower, that may be doable. I'm gonna try my manual tabs in a 3* up position and try to trim the motor up as far as possible. I'll let you guys know how it goes.
Thanks
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BOOM! http://stockton.craigslist.org/boa/4444832802.html (http://stockton.craigslist.org/boa/4444832802.html)
GT
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Thanks! Might be a little hefty on the pocket book right now
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You probably won't get much usable advise here because most of us don't have much experience with boats that use the little spinny thingy out back. ;)
Hey... I have a little spinny thingy out back. ;D
Truckin_318
If it's not an ordeal try removing the tabs to see if you pickup a few mph, that way the tabs and drive are not fighting each other at top end. Just a quick experiment and reason to take the boat out. If you don't have a gps you can get a speedometer app for you phone.
Good luck