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IMCO SCX Drive Height

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Old 12-27-2010, 08:14 PM
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Quent
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Default IMCO SCX Drive Height

I have a new Lavey 2750 with a SCX upper and 2" shortie SC lower. The engine is a 509 with a Whipple 4.0 (built by Dustin) and about 1000hp. The best I've seen is 101 with a BBlades Maximus 30 (cut hub, 15 1/4").

I've tried several props the best being the BBlades Maximus 30, 6200 rpm on a cool day and good conditions. The 32 BBlades B4 was very close. I have lots of positive trim (7 on the Bluewater) and and some tab, about 3 1/2 on the Bluewater. If I don't trim to this point I get a very significant hop. By the way this is a midcuddy. I still have a slight hop at these trim and tab settings but no big issue.

I understand that the SCX positions the drive 3/4" further back than the Bravo and pseudo Bravo drives. Do I need to try going up 1/2 to1 inch or perhaps take a little diameter off the Maximus or just go boating. Happy winter. Quent
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Old 12-27-2010, 08:25 PM
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there are a number of things that could be it from height to adding a box, to the bottom of the boat. spacers are easy, may want to put a straight edge to se if your bottom is flat and then check with lavey to see if any hook or rocker is designed and what they suggest. also don't look past the fact that you just may be overpowered. approach it logically though.
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Old 12-28-2010, 01:06 AM
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Also having a similarly sized and horse-powered boat...with a mid-cabin open bow... I have a couple of suggestions.

First off... running a bow cover nets me a consistant 2-3 mph.

Switching to 1.35 gears and running a smaller pitched prop... gained me another 2-3 mph. I think the gear change helped on a couple of fronts. The smaller pitched props have better efficiency (lower slip), and their blades are less parrallel to the water...thus causing less stern lift, and therefore less trim needed ie.. the stern was more settled.

Chris

P.S. Awsome looking boat!

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Old 12-30-2010, 09:32 PM
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I put the SCX on my 36 Spectre and had to raise the drive height to get it to run. 3.5" above bottom. Then use 5 or 6 blade props as you will be running at surfacing heights. Get them cast with extra thickness. Send me a PM if you want more.
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Old 12-30-2010, 11:23 PM
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Quote:
Originally Posted by Sonny Spectre 30 View Post
I put the SCX on my 36 Spectre and had to raise the drive height to get it to run. 3.5" above bottom. Then use 5 or 6 blade props as you will be running at surfacing heights. Get them cast with extra thickness. Send me a PM if you want more.
I heard that was a lot of work
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Old 12-31-2010, 06:43 PM
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Default Scx

Sonny, thanks for the info. My V bottom has the SCX upper and 2" shortie SC lower. I assume that you have the SCX lower. I could try a 3" shortie SC lower and probably get close. I just don't want to spend that kind of money. I wonder if taking the 15 1/4" BBlades maximus down slightly in diameter would help. Quent
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Old 01-01-2011, 07:41 PM
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Unfortunately changing the prop diameter won't substute for raising the drive height.
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