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Drive height questions with pictures

Old 11-18-2010, 12:28 PM
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Default Drive height questions with pictures

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Boat 1989 Cobalt Condurre 223
20* deadrise
7.4l 330hp 454 with bravo
top end is 4700 rpm at 59mph
Prop mirage plus 23p

This picture shows my drive at full trim out before it hits the limit switch, from there I have to press the trailer button.





While at full rpm and speed I can trim my drive to this position and still not break loose or ventilate the prop. If i start to turn I ventilate some but not severe. I can hit full rpm at any drive position. With the trim all the way down i can see speed fall off but rpm remains the same.

At this trim angle the bow of the boat is being carried fairly high.



Do you think I may benefit from a shorty drive, looking for more top end and perhaps a more level run angle. I would like to dial in the running gear before repower/rebuild for more power.

LC
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Old 11-20-2010, 01:46 AM
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What power are you pondering due to the fact that it will change your complete setup. If your going to pull the motor you might ponder putting on a extension box and depending on which box use a shorty, but ask yourself is the current boat you own worth sinking 5-6k into box and shorty? A shorty alone is going to cost you 2500-3500.
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Old 11-20-2010, 07:57 AM
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Believe it or not, everything looks about right for what's basically a family boat. True, performance boats are going to have the drive mounted somewhat higher in most cases - but they were designed for it. If you run with much more trim angle on a regular basis, your universal joints are going to be having a meanigful conversation with you shortly.

If you want my opinion, your engine HP is your big speed limiting factor right now. Want more speed cheap? Try some 4 blade props to lift the stern. Want more speed and have money? Motor mods. Start playing that game on that boat though and your resale value will drop faster than Obama's approval rating.
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Old 11-20-2010, 08:48 AM
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Originally Posted by looseconnection
Summary

Boat 1989 Cobalt Condurre 223
20* deadrise
7.4l 330hp 454 with bravo
top end is 4700 rpm at 59mph
Prop mirage plus 23p

This picture shows my drive at full trim out before it hits the limit switch, from there I have to press the trailer button.





While at full rpm and speed I can trim my drive to this position and still not break loose or ventilate the prop. If i start to turn I ventilate some but not severe. I can hit full rpm at any drive position. With the trim all the way down i can see speed fall off but rpm remains the same.

At this trim angle the bow of the boat is being carried fairly high.



Do you think I may benefit from a shorty drive, looking for more top end and perhaps a more level run angle. I would like to dial in the running gear before repower/rebuild for more power.

LC
on the side of your drive there a 2 sender it looks like a hocky puck. one is for trim guade the other is to set how high your drive goes up . loses the two serw then trun the sender were you want your drive to stop
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Old 11-20-2010, 09:48 AM
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Lower your drive down and get it level with the bottom. Then measure your propshaft centerline, if it is 7 or 8" a shortie would probably help.
Are you using the Dream O Meter or GPS for your speed, 59 sounds optomistic with a 330 and the size of your boat. Mine only ran 55 GPS with the 330.
Now I have mine up to 74, I gained about 3-4 MPH by raising mine up 3".
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Old 11-20-2010, 11:48 AM
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GPS not the dream o meter. Took it loose at the pick up on the transom. Gauge leaks and drips water on my feet; talk about the "what the hell" feeling the first time it happened.

Yea i am not too sure how much I would be willing to put in this boat money wise. When you start adding the cost of items, even used I get to the purchase prices real quick. was way south of 10k.

I could purchase an older take out 420 hp listed in the swap shop and see what that would get speed wise. We are looking at maybe 50 hours a year. Most of my weekend time is spent fishing the gulf, bought this toy during the oil spill to occupy my time in north alabama till the waters were opened back up to fishing. Kinda got the need for speed all you guys talk about.

Thanks for the info.

LC
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Old 11-20-2010, 03:16 PM
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don't take this personally, but you are pissing in the wind !! that transom design is terrible for performance and you continue to throw whatever you want at it...you want to go fast...buy a better hull...sorry Rob
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